The World Bank (WB) is also a key partner in climate adaptation in the tea sector. It announced during the March 2019 Nairobi Summit that an Emission Reduction Purchase Agreement (ERPA) would be signed between the Carbon Initiative for Development (Ci-Dev) trust fund, with WB acting as trustee, and KTDA Power Company Ltd. (KTDA Power). The contract aims to purchase carbon credits from small hydropower plants that provide power to 350,000 smallholder tea farmers and 39 of their regional tea factories in Kenya (Africa Times 2019). ETP, an alliance of tea packers working toward the sustainability of the tea sector, is another key partner. They started work in Kenya in 2010 and implemented a Climate Change Adaptation Program with GIZ, a German development agency. ETP utilized technology developed by its partners, such as Cafedirect Producers' Foundation, which developed a tool called WeFarm, an SMS platform for farmers (Budsock 2015). ETP also created a partnership with ITC and other nongovernmental organizations and founded a project to help farmers in climate change adaptation and mitigation. The program trains farmers and tea factory managers in carbon standards compliance, conservation and management of water, soil conservation, and use of biogas instead of wood. A partner factory, Makomboki Tea Factory that was using 2,000 cubic meters of wood per month as fuel for drying tea, changed to alternative energy sources. This included sawdust, rice husks, biomass, macadamia, and cashew nut shells and briquettes made from sawdust and rice husk. The new initiative saved more than 30,000 trees while lowering operational costs of that factory by 20% (Omondi 2015).

Multilateral partnerships are particularly effective in adaptation strategies. An example is the "Upscaling and Embedding Sustainability for Smallholder Tea Farmers," which is a collaborative initiative by KTDA Management Services (KTDA-MS), Unilever, and IDH – the Sustainable Trade Initiative. More than 85,000 (about 15% of 560,000 farmers) small-scale farmers had been trained by 2015 on Sustainable Agricultural Practices under a farmer field School (FFS) program (Cameron 2017). Another multilateral collaboration is between Germany, China, and the Food and Agriculture Organization (FAO), which was formed with the aim of promoting sustainable agricultural development and combating climate change in Kenya. This is through a project on carbon-neutral tea value chains. Germany through GIZ has been working with the KTDA, the Ethical Tea Partnership (ETP) among others in an integrated development partnership with the private sector to increase energy efficiency in all the factories to save GHG emissions and increase income of the farmers (Sino-German Center for Sustainable Development 2019). KTDA in 2015 signed a loan for Ksh.5.5 billion for the construction of seven small hydropower projects. The loan agreement was with the International Financial Corporation (IFC) which is a member of the World Bank, in partnership with other organizations including the Global Agriculture and Food Security Program (GAFSP) the French Development Institution (Proparco, the Netherlands Development Finance Company (FMO)). The expected reduction of reduce Kenya's carbon footprint from using hydropower is approximately 63,000 tons of carbon dioxide equivalent per year. On average, tea factories spend approximately Ksh. 30 million to Ksh. 65 million each per year on electricity (KTDA 2015). The hydropower plants have a total installed capacity of 16 megawatts and will provide captive power generation with the excess energy being sold to the state-owned power company. The farmers provided 35% equity on the loan via green leaf delivery, making it perhaps the first initiative in the world in which a farmer-owned institution is undertaking a renewable energy project of such a scale (IFC 2016).

KTDA Foundation, a nonprofit charity, also engages in environmental sustainability and climate change. Programs under climate change focus on promoting climate change mitigation, adaptation, and resilience building among smallholder tea farmers. In partnership with factories it has established over 31 indigenous, exotic, and fruit tree nurseries. Over 2.4 million trees have been planted in farms, major water catchment areas, and public forests. It is also undertaking an environmental conservation campaign for schools. Farmers are encouraged to adopt clean, renewable energy through promotion of and access to clean and renewable energy such as energy saving stoves, solar lighting products, and biomass. Adaptation measures include planting tea bushes along hill contours to reduce soil erosion. Seedlings from KTDA nurseries (commonly native species) are distributed throughout the local community for planting along farm boundaries, as buffers for waterways and forests, and to create small forest patches on farms. These native trees store carbon, stabilize the tea microclimate, and increase soil fertility. Planting native trees on steep slopes or degraded lands can also reduce vulnerability to heavy rains or prolonged droughts which creates resiliency to extreme weather. The KTDA is working to secure its own sources of sustainable fuel by acquiring land and encouraging its farmers to grow woodlots. Eucalyptus is commonly planted for fuelwood in the region. However, eucalyptus takes up large amounts of water, and KTDA and Rainforest Alliance are supporting farmers' efforts to replace eucalyptus in buffer zones with indigenous trees.

Although tea is on the "receiving end" of climate change, it also exacerbates it through deforestation. The common processing method of tea used in Kenya is the Cut Tear and Curl method, known as CTC. This involves the tea leaves going through a process of cutting, tearing, and curling, followed by oxidation and drying. The drying is often carried out using wood fuel due to the high price of electricity. Tea manufacturers are, however, gradually utilizing renewable energy alternatives such as electricity generation through micro-hydro plants to reduce energy costs and potentially generate further revenues by selling surplus electricity back to the national grid. Other mitigation measures include the use of biomass waste to power the water boiler systems. Gravity-powered ropeways are used by Finlay's, a multinational company, in some of its tea plantations. The KTDA also requires factories to acquire open land in order to plant seedlings and grow trees as a sustainable source of firewood. This saves money on the purchase of firewood or alternative fuels and could potentially generate revenues from carbon trading if the planted forests are managed sustainably. Varieties of tea other than Black CTC tea undergo a less emission-intensive process, as the wilting and CTC process are not required. Black CTC tea is manufactured by all 69 factories while only ten process black orthodox tea and four process other specialty tea.

#### Coffee Sector in Kenya

Kenyan coffee is grown on an estimated total area of 115,570 ha in 32 of 47 counties in the country. The sole type of coffee produced in the country is Arabica, which is planted during the rainy season from April to October with two harvest periods, April to June and October to December. Production is enabled by a combination of deep red volcanic soils, high altitude, rainfall, and moderate temperatures. The sole type of coffee grown in Kenya is Arabica. Coffee is grown in the high potential areas between 1,400 and 2,200 m above sea level, with temperature ranging from 15 C to 24 C, in red volcanic soils that are deep and well drained. Over 99% of Kenyan coffee is Arabica, whose main varieties are SL 28, SL 34, K7, Ruiru 11, Batian, and Blue Mountain (ICO 2019a). Coffee is an evergreen shrub and is therefore an important contributor to carbon sequestration, effective in stabilizing soils and permits the preservation of much of the original biodiversity in planted areas (ICO 2019b). The coffee sector contributes annually an average of US\$230 million in foreign exchange earnings and is ranked as Kenya's fourth most important export, after horticulture, tourism, and tea. In 2018 coffee earnings amounted to Ksh. 14.8 billion. The value of coffee as a percentage of all export goods represented 5.5% in 2017, while its share of GDP was 0.22%. The coffee industry contributes an average of Ksh. 23 billion per year in foreign exchange earnings, ranking fourth after tourism, tea, and horticulture (ICO 2019a). Coffee is grown on 115,600 ha, 90,000 ha by smallholders and 25,000 ha by estates. Production was 41,400MT with 30,000MT from cooperatives and 11,000MT from estates (KNBS 2019). In 2017/18, the major importing countries of Kenyan coffee were Germany, the USA, Belgium, and the Republic of Korea, who imported about 58% of Kenya's coffee. Thirty-two of the 47 counties in Kenya are coffee producers (ICO 2019a).

Kenya has about 700,000 coffee farmers and about 99.63% have less than five acres. All coffee farmers with less than five acres are mandated to cooperative membership. There are between 500 coffee cooperatives (ICO 2019a) and 651 coffee cooperatives (KNBS 2019). Each coffee cooperative has factories where farmers deliver coffee berries for processing. At the factory, the coffee berries undergo pulping, which is a process of washing and drying, which results in "parchment." Parchment is then delivered to a coffee miller who further processes and grades the coffee, resulting in the "green" or "clean" coffee which is then sold by marketers at the Coffee Exchange through auctioning. Cooperatives also have the option of selling coffee directly to buyers without going through the auction. The Coffee Directorate is mandated to develop, promote, and regulate the coffee industry in Kenya. The Coffee Research Institute (CRI) conducts research in all areas of production, processing, and marketing of coffee. The global organization for coffee is the International Coffee Organization (ICO). It is comprised of member governments who represent 98% of world coffee production and 67% of world consumption. One of its objectives is to encourage members to develop a sustainable coffee sector in economic, social, and environmental terms (ICO 2019b).

#### Climate Change Challenges in the Coffee Sector

It is estimated that half the world's coffee-producing land will be unsuitable for coffee production by 2050 (Bunn et al. 2015; CIAT 2011). Other estimates indicate that the area unsuitable for production could be as high as 88% in Latin America (Worland 2018). Climate change caused by changing rainfall patterns and rising temperatures is affecting coffee production in several ways: directly through negative effects on the coffee plant and indirectly by altering the population dynamics and incidence of coffee pests and diseases (Jaramillo 2013). Rising temperatures will especially damage the Arabica bean, which accounts for about two-thirds of global coffee production, but whose production is limited to subtropical highlands in Brazil, Central America, and East Africa (Cameron 2017). This narrow region of the tropics is known as the coffee belt, and stretches from Central America to Sub-Saharan Africa to Asia (Worland, 2018). Rising temperatures will bring drought, increase the range of diseases, and kill large swaths of the insects that pollinate coffee plants (Worland 2018). Recent trends indicate that coffee growing is shifting from traditional optimal growing zones to higher altitudes. In traditional growing zones random flowering patterns and differences in berry growth stages has resulted in difficulties in disease and pest management, harvesting, and processing (Daily Nation 2012).

The effects of climate change in Kenya include unreliable and erratic rains with shorter seasons (ICO 2019b). Changing rainfall patterns affect the flowering of the coffee plants which impacts the whole production cycle. The altered flowering pattern with coffee berries at different stages of maturity poses a challenge in disease management, insect management, and harvesting (Ethical Tea Partnership 2011; Mugo 2016; Mwaura 2010). Extremely heavy rains lead to higher erosion levels, resulting in loss of soils, leaching of nutrients, and consequent soil infertility. On the other hand, the dynamics of incidence of coffee pests and their management are evolving rapidly due to changing climatic conditions. The changing environment is also posing challenges to patterns of cherry ripening and drying of parchment because of unpredictable rainfall patterns (ICO 2019b). Changing rainfall patterns cause uncertainty regarding the timing of fertilizer application and the drying of parchment. Most coffee growing zones in central Kenya, particularly Kiambu and Murang'a, are no longer suitable for the crop due to rising temperatures (Kamau 2017). Intermittent rainfall in the 2007/08 crop year caused a severe episode of Coffee Berry Disease that cut Kenyan output by 23% to 42,000 MT. This happened because farmers were not able to spray the crop on time (Mwaura 2010). Climate variability and its effects is however not a "new" problem, as evidenced by research shortly after Kenya's independence. This is illustrated by a 1969 journal article by Nutman and Roberts, titled "Climatic conditions in relation to the spread of coffee berry disease since 1962 in the in the East Rift Districts of Kenya." (F.J. Nutman & F.M. Roberts 1969)

#### Adaptation and Mitigation Measures by Small-Scale Farmers in the Coffee Sector

The Coffee Directorate in collaboration with stakeholders provides capacity building to the counties' agricultural staff and other value chain players. The collaborating private agencies include Technoserve, Solidaridad, certification bodies such as UTZ, 4C, and Fairtrade, and management services providers. CRI develops technologies, releases new coffee varieties, and carries out research on disease and pest management, while the Ministry of Agriculture sets policy guidelines (ICO 2019b). The Coffee Research Foundation (currently CRI) started a program in 2012 to help farmers reverse the effects of global warming and boost coffee production. Farmer sensitization clinics were held and farmers were encouraged to plant indigenous trees to provide shade and to practice water harvesting (Daily Nation 2012). The CRI has made various recommendations on approaches toward environmentally sustainable coffee production systems. One approach is integrated farming, in which mulching, conservation agriculture, organic fertilizers, and use of bio-stimulants are recommended. Other measures include the use of suitable shade trees and the adjustment of spraying programs to cope with changing trends in the manifestation of coffee pests and diseases (ICO 2019a). Most Kenyan coffee is grown without shade, but shaded coffee is becoming increasingly popular in order to mitigate the effects of climate change, although quantifying the area under shade has not been done. Research is ongoing to determine the appropriate shade trees (ICO 2019a). Research shows that biodiverse shaded coffee is far more resilient and productive than coffee grown in monoculture. Shading coffee therefore improves the resilience of agro-ecosystems. Shade trees protect plants from microclimate variability, the effects of lower precipitation and reduced soil water availability, and reduce high solar radiation. It also improves soil fertility, protects coffee from insect pests, and provides economic benefits for farmers (Jaramillo 2013).

The need to develop disease-resistant coffee varieties was felt in early 1971 and breeding programs were initiated whose optimal outcome was the cultivar Ruiru 11 (Njoroge 1991). The CRI currently has developed two improved varieties of coffee – Ruiru11 and Batian. The improved varieties are resistant to Coffee Berry Disease and Leaf Rust Disease, thus lowering the use of agrochemicals and reducing production costs. The CRI estimated that the production cost of the traditional variety is four to five times more than Ruiru 11 and Batian. Over 300,000 farmers are estimated to have planted the new varieties (ICO 2019a). The traditional variety of coffee grown is SL-28. Other Arabica varieties include SL-34, K7, and Blue Mountain. A study of the coffee sector in Nyeri County showed that 50% of farmers in certified coffee cooperatives and 57% in the noncertified cooperatives had only the traditional SL variety of coffee on their farm. An additional 45% in the certified and 39 per in the noncertified had other varieties in addition to the SL (Okech 2019). It therefore means that less than 5% had the disease and drought resistant varieties exclusively on their farms. Incentives therefore need to be provided to encourage planting of new varieties, beyond the step of providing free seedlings.

The International Coffee Organization (ICO) has pilot projects in Africa and Latin America to address climate change by assisting coffee farmers use environmentally friendly technologies. These include building the capacity of institutions, improving access to credit and risk management mechanisms, reducing vulnerability to income volatility, and promoting gender equality. It also engages in long- and short-term adaptation strategies as well as mitigation strategies (ICO 2019b). Several organizations including private companies involved in coffee production and marketing have taken the lead in climate change adaptation and mitigation in the coffee sector. The World Coffee Research (WCR), a consortium supported by major coffee retailers, distributors, and exporters, has an \$18 million coffee-monitoring program that covers 1,100 farms in 20 countries including Kenya. It conducts farmer training, provides technical assistance, and is testing coffee varieties and adaptive farming methods (Worland 2018). Since 2013 Starbucks has support centers in nine countries and a 10-year, \$500 million investment fund that supports sustainability programs, including adaptation training for farmers and the testing of new coffee varieties (Worland 2018). Sangana Commodities Ltd and GIZ implemented a three-year project creating a link between coffee smallholders and carbon markets, and developing a verifiable and voluntary climate change module, which can be integrated into the existing 4C's standard (ETP 2011).

Sustainability standards in the coffee sector are geared toward sustainable agricultural practices, which include adaptation and mitigation measures. Certification in the coffee sector is, however, not as extensive as in the tea sector. In Nyeri County, which is a leading coffee producer, Fairtrade was the most common certification with at least 12 of the 23 cooperatives having received this certification. The earliest reported Fairtrade certification in the cooperatives was from 2006. At least seven cooperatives had obtained Rainforest Alliance certification and four had acquired 4C certification. Benefits of certification included payment of premiums and improved quality and quantity of coffee. Challenges included difficulty of maintaining certification as it was involving and expensive. This is illustrated by the example of an estimated Ksh. 400,000 for certification and renewal, with additional costs of up to Ksh. 1,000,000. Enforcing requirements as well as nonconformity to requirements was also costly. Certification organizations also did not source for markets and the cooperatives therefore used the conventional marketing channels, which were viewed as opaque (Okech 2019).

#### Recommendations and Conclusion

Tea and coffee are essential to farmers and other Kenyans as a source of livelihood, to the government as a contributor to GDP and foreign exchange and to the commodity chain players such as marketers and retailers. Tea and coffee also contribute significantly to climate change mitigation. Climate change, however, threatens to disrupt the production of these crops and by extension the economy of Kenya and the livelihoods of those who depend on it. Continued and increased uptake of climate adaptation and mitigation measures is critical for the sustainable farming of tea and coffee. Climate change can worsen the socioeconomic condition of farmers and conversely fragile socioeconomic conditions can exacerbate climate change. Various measures can be taken to increase the adaptive capacity of smallscale tea and coffee farmers.

#### Farmer Empowerment

Farmers are rational economic actors and farming has to be profitable for adaptation and mitigation measures to be implemented. Climate adaptation and mitigation activities such as uptake of improved crop varieties are carried out in view of perceived economic benefits and particularly for the most vulnerable, in view of immediate economic benefits. Activities such as the adaptation of improved crop varieties can be neglected due to small land size and the resultant "lost" while the new variety matures to the point of harvest. Other measures such as water harvesting may require capital expenditures whereby the capital is either unavailable or the returns to investment are deemed uneconomical. Interventions that deal with commodity chain weaknesses that reduce profitability are critical. Profitability of farming is the largest incentive to adopting sustainable agricultural practices. Increasing the adaptive capacity of tea farmers therefore requires farmers' economic empowerment. It is essential that stakeholders provide incentives for the implementation of measures whose returns are long-term or not tangible. This could include measures such as insurance for climate-related crop losses and a minimum guaranteed price per kilogram. Farmers also need to be politically empowered as decisions in farmer organizations are often made by elected representatives. Civic awareness is therefore an integral component of farmer empowerment. Social empowerment majorly revolves around gender. Men predominantly own land but women provide 60% of the labor on the farms and in the wet mills (ICO 2019b). Women therefore need to be major actors in activities involving climate change adaptation and mitigation. When they are not empowered, especially in terms of access to resources, various adaption and mitigation activities may not be implemented.

#### Strengthening of Institutions

The common features of the tea and coffee sector in Kenya is that both are cash crops, grown majorly for export and production is predominantly by small-scale farmers. Profitable production therefore requires that farmers organize so as to share costs. In the tea sector, the KTDA is the primary agency through which farmers produce process and market their tea. In the coffee sector, coffee cooperatives are the primary and mandated vehicle for production, marketing, and processing. However, there are coffee farmers with more than five acres who choose to remain in cooperatives due to economies of scale. Institutional capacity therefore has a large influence on farmers' activities, including those related to climate change adaption and mitigation. Lack of institutional capacity in farmer-owned organizations or institutions that support farmers can reduce productivity and profits and therefore constrain farmers' adaptive capacity. The average age of tea and coffee farmers is over 50 years and this further constrains the availability of alternative livelihoods. Unlike the tea sector where almost all small-scale tea farmers operate within the institutional structure of KTDA, coffee cooperatives are not homogeneous. For example, coffee payments for the 2017/18 year varied from Ksh. 9 to Ksh. 105/kg of coffee cherry (exchange rate in this period was approximately one USD to Ksh. 100–103). While there are climatic and soil-type differences, the differing payments were also within the same region. In Nyeri County, which is a leading coffee producer, the payment range was between Ksh. 12.75 and Ksh. 105. This points to institutional constraints at the cooperative level, although constraints occur across the coffee commodity chain. The challenges facing the coffee sector are well documented. Toward this end, a Coffee Taskforce was created to investigate the challenges and make recommendations for sectoral improvement. The tea sector has also encountered various institutional challenges. In January 2020, the president directed that the KTDA be restructured for the benefit of tea farmers (Cheruiyot 2020). The organizations that farmers engage in and the institutions within which they operate can either facilitate or constrain the activities of farmers, including those pertaining to climate change adaptation and mitigation.

#### Collaborations and Partnerships

Climate change adaptation and mitigation requires the long-term involvement of all actors in the commodity chain including the consumers. Stakeholder mapping is necessary, whereby a list of relevant groups, organizations, and people who can collaborate in climate change adaptation and mitigation can be invited to collaborate towards these measures. These stakeholders include the International Coffee Organization, the Tea and Coffee directorates, agricultural institutions and departments, producer organizations, certification organizations, technical support providers, financial institutions, and supply chain actors including processors, marketers, and retailers. Research, information, and best practices on sustainable agricultural practices and on measures to streamline the commodity chain can be enhanced and widely adopted through collaboration.

#### Certification

The 2017 SAN Standard aims to support farmers in advancing sustainable livelihoods, improving farm productivity, and becoming more resilient to climate change. Changes of note include climate-smart agricultural practices. These are built into the standard to help farmers address climate change risks. The effect of irregular rainfall, changing temperatures, and related increased pest and disease attacks can be reduced through soil conservation, water-use efficiency, and the conservation and restoration of natural ecosystems. The Standard is built on principles of sustainable farming including biodiversity conservation, improved livelihoods and human well-being, natural resource conservation, effective planning, and farm management systems (Rainforest Alliance 2019). The SAN Climate Module is an add-on for voluntary verification within the existing Sustainable Agriculture Network certification system. Farmers who achieve compliance with the module will be able to assess the risks posed by climate change to their farms and communities, analyze their practices to quantify and reduce GHG emissions, and increase the carbon levels stored on their farms through the restoration of degraded lands, reforestation, and improved soil conservation while also being able to better adapt to altered growing seasons and other conditions (Sustainable Agriculture Network 2011).

Fairtrade aims to help farmers become more resilient to climate change while giving consumers, retailers, and traders the opportunity to reduce their carbon footprint. Farmers can spend the Fairtrade Premium on climate change adaptation projects such as tree planting, irrigation, crop diversification, and clean energy. Farming communities can also benefit from access to carbon finance, which can be used in mitigation or adaptation activities (Fairtrade International 2015). While certification has numerous benefits, acquiring and maintaining of certification by coffee cooperatives and estates requires the collaboration and financial support of stakeholders.

Rainforest Alliance and Fairtrade are the major certification bodies in the coffee and tea sector in Kenya. Majority of the small-scale tea farmers in Kenya comply with the SAN Standard and have received Rainforest Alliance. This extensive certification can be largely attributed to the institutional arrangement of the tea sector. KTDA acts as the management agent for 69 factories, which comprise the vast majority of small-scale tea farmers in Kenya. In the coffee sector, however, more than 700,000 farmers are members of an estimated 500–650 coffee cooperatives. Certification depends on various factors including membership numbers, productivity levels, number of factories, cooperative leadership, and relationships with a multiplicity of commodity chain actors. While some cooperatives are certified by multiple certification bodies, others do not comply with any sustainability standard. Certification ensures the implementation of climate change adaptation and mitigation measures. Acquiring and complying with sustainability standards is therefore key for small-scale farmers.

#### References

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3

# Adaptive Capacity to Mitigate Climate Variability and Food Insecurity of Rural Communities Along River Tana Basin, Kenya

## David Karienye and Joseph Macharia

## Contents

#### Abstract

Climate variability is one of the leading natural threats and a root cause of food insecurity in the developing world, more so in Africa. It is a major impediment to the accomplishment of the global Sustainable Development Goals (SDGs), Vision 2030 and Big Four agenda in the Kenyan context. The rise in occurrence and brutality of extreme events resulting from variability of climate including prolonged flooding and drought has become more pronounced in the relatively

D. Karienye (\*)

This chapter was previously published non-open access with exclusive rights reserved by the Publisher. It has been changed retrospectively to open access under a CC BY 4.0 license and the copyright holder is "The Author(s)". For further details, please see the license information at the end of the chapter.

Department of Geography, Garissa University, Garissa, Kenya

J. Macharia Department of Geography, Kenyatta University, Nairobi, Kenya

drier areas. This chapter presents a synthesis about rural communities in Garissa and Tana River Counties, Kenya. The key environmental conditions that face the rural communities in the two counties are prolonged drought and recurrent flooding events. The two conditions have resulted in various challenges facing the communities in these regions through low agricultural production (food and pastures), poor infrastructure, human displacement, and the resultant extreme poverty, overall food insecurity, and tough livelihoods. The problems have been exacerbated by lack of capacity by most of the community members to cushion themselves against these impacts. However, as the conditions continue to manifest themselves, the community members have also identified adaptive mechanisms that are best suited in the region including planting drought-resistant crop varieties, diversifying their livelihoods, embrace sustainable land use, and made efforts to plant trees. We, therefore, conclude that integrated information sharing including early warning alongside affordable and appropriate technologies and crop insurance could be an entry point in cushioning the local communities in the arid and semiarid lands (ASALs) against the extreme weather conditions experienced in the region.

#### Keywords

Adaptive capacity · Africa · Climate variability · Food insecurity · Mitigation · Rural livelihoods

#### Introduction

Climate variability has been on the rise due to increased global atmospheric greenhouse gas emissions (GHG) comprising mainly of nitrous oxide, carbon dioxide, and methane (IPCC 2014). Carbon dioxide is the key GHG, while as much as methane and nitrous oxide are emitted in trivial quantities in reference to carbon dioxide, they play a significant role in global warming and their associated global effects. For example, N2O, a potent gas with a high potential to deplete ozone layer, is over 265 more powerful while CH4 is 28 more powerful in their global warming potential relative to carbon dioxide, over 100 years' time limit (IPCC 2014). These three main GHGs accounts more than 80% to the present global radiative imposing to enhanced global warming and consequently climate variability and its negative resultant effects (Myhre et al. 2013).

Climate variability characterizes one of the extreme economic, environmental, and social intimidations facing the earth presently (Nnadi et al. 2019). In emerging countries, climate variability has a substantial influence on the livelihoods and living situations of the rural communities. Sub-Saharan Africa (SSA) is a "vulnerability hot spot" of climate variability influences (Asfaw et al. 2018). SSA challenges on adaptation will raise considerably, even if the global emission gap is maintained lower than 2 °C due to limited adaptive capacity. The IPCC's Fourth Assessment (AR4) demonstrated that Africa's vulnerability to the effects of climate variability is relatively high due to low adaptive capacity and over-reliance on natural systems for their livelihoods (Mpandeli et al. 2019). Extreme occurrence of droughts is likely to become more rampant and severe in Africa (Schellnhuber et al. 2012). Consequently, climate variability is negatively affecting agricultural production, particularly in SSA where most countries rely heavily on rainfed agriculture as the mainstay of their economies (Abdul-Razak and Kruse 2017). Climate variability related to biophysical stressors is expected to worsen the existing vulnerabilities by dipping the crop yields (González-Orozco et al. 2020).

It is postulated that warming more than 3 °C worldwide will see almost all of the current crops such as maize, sorghum, and millet-cultivated regions in Africa becoming unfeasible for present cultivars. Water unavailability, lower feed quality which is inaccessible, and effects of disease and heat stress will negatively affect production in the livestock sector (Schaeffer et al. 2013). According to Huq et al. (2004), climate variability has a direct impact on how humans manage natural resources and which results in food insecurity. The risks associated with climate variability threaten the capacity of livelihoods to meet basic needs, such as food and water. These effects will be more intense in the arid and semiarid lands (ASALs) where the resources are already limited, vulnerable, and could, therefore, suffer the most.

To mitigate climate variability, community adaptive capacity must be pursued. According to Levina and Tirpak (2006), the term adaptive capacity has been defined differently by different authors. Different authors have explained the concept of adaptive capacity to simply mean the capacity of a natural system to positively respond to the impacts of climate variability. Policymaker also use the term adaptive capacity to refer to the ability of individual communities to respond and adjust their way of life based on the effects of climate variability and lead to adaptation. Therefore, whenever we use adaptive capacity, society and communities must come up with coping strategies especially when dealing with impacts of climate variability in order to minimize its adverse effects.

Communities living in SSA are facing climate variability in a very tough way due to their lack of capacity to respond. The influences include increasing temperatures, more inconsistent rainfall, and increasing incidence of floods and droughts (CARE and ALP 2013). These impacts have severe consequences especially among the rural poor whose livelihoods are directly pegged on the very vulnerable environment. These communities heavily depend on land resources for agricultural production and therefore the impacts of climate variability have a direct impact on their livelihoods. Crop yields will decline transversely in the landmass as ideal growing temperatures are surpassed and growing periods reduced. The areas and timing of cropping activities that were previously suitable for certain crop are anticipated to shift as home-grown climates varies.

In Kenya, the adverse effects of climate variability have also been witnessed particularly in the ASALs which forms ~80% of Kenyan land mass (582,646 km2 ) (Macharia et al. 2020). The main effects of climate variability in Kenya have been demonstrated by prolonged and frequent droughts, floods, resurgence of diseases, pests, and environmental disasters. As a result, agricultural productivity is significantly reduced, resulting to increased food insecurity and threatened livelihoods which in most instances leads to human conflicts over scarce land and water resources (Enya et al. 2013). For instance, the La Nina occurring between 1999 and 2001 in SSA was the most prolonged and most severe ever, causing devastating effects especially on human livelihoods. The drought affected over four million people due to crop failure and the resultant reduced yields. Droughts have caused starvation, loss of life, and degradation of the environment as a result of deforestation.

Variability in climate poses major threats to environmental sustenance, commercial, and sustainable development in rural areas of the arid regions of Kenya. In particular, the ASAL region of Garissa and Tana River County has been experiencing severe prolonged drought and flooding despite having River Tana traversing the region. This has led to loss of vegetation cover, drying of water catchment areas, rivers, and seasonal streams. This is then followed by heavy lack of pastures and shortage of drinking water resulting to livestock deaths. Recently, in short rains of 2018/2019, Garissa and Tana River counties experienced floods which caused severe havoc resulting to over 50 fatalities, over 15,000 people displaced, and thousands of livestock killed as a result of bursting of River Tana's banks. In addition, extreme weather events such as flooding has spoiled or destroyed transport and communication networks and affected other nonagricultural portions of the food system badly. This has led the communities to seek alternative ways of meeting their livelihoods such as charcoal burning hence environmental degradation resulting to double tragedy from the loss of their only source of livelihood and land degradation. Against this backdrop, this study aimed to close the gap by identifying possible adaptive capacity of the vulnerable communities in the region for the purpose of coping mechanism. This study was conceived to explore the existing adaptive capacity which is sustainable and viable and which the communities would easily embrace to act as adoptive buffer towards the impacts of climate variability in Garissa and Tana River Counties.

#### Impacts of Climate Variability

Key among the impacts of climate variability includes the following.

#### (a) Drought

Drought is a major threat globally and more so in Africa due to low adaptation capacity resulting from limited resources. Drought results in decreased moisture emanating from inadequate and erratic rainfall and high extreme temperatures. As observed by Keya (1997), moisture storage is largely dependent on rainfall received prior to the onset of drought conditions and the permeability of the soil (micro edaphic conditions). Drought has led to loss of pasture for the livestock as well as wildlife, vegetation loss, and food insecurity. This threatens the source of livelihoods of local communities in the arid lands.

#### (b) Loss of biodiversity

Ecosystem varieties will hypothetically change rapidly as heating increases with reduced precipitation, and will result to biodiversity loss. Some species may be impotent to adapt to the varying climatic conditions (Schaeffer et al. 2013). High temperatures and lack of precipitation affects distribution and abundance of fauna and flora species. Substantial shifts in climatic situations could result to loss of some standing biomes and the general aesthetic appeal of our environment (Williams et al. 2007). In some instances, the changes in climate may favor the growth of invasive plant species hindering the alien species such as Prosopis Juliflora "Mathenge" a common plant in the northern Kenya.

#### (c) Food insecurity

Extreme temperatures above the ideal may have harmful consequences on crop productivity (Wheeler et al. 2000). These changes have a significant effect on the facets of food security since they negatively affect food availability, access, and utilization resulting to unstable and unreliable food systems. Kenya may experience reduced yields with the changing climate (Herrero et al. 2010). Crop yields are drastically reducing in SSA as the optimal temperature increases altering cropping and seasonal calendars (Schaeffer et al. 2013). In Africa and to a large extent, the ASALs region of East African such as Sudan, Ethiopia, and Kenya have in the past experienced hostile climate change. This has hampered crop production leading to acute shortage of food, pastures, and fibers, hence food insecurity. According to Lobell et al. (2011), yields are likely to diminish by ~1% daily for maize crops if such high-temperature regimes are consistent similar with other crops such as cotton and soybeans (Schlenker and Roberts 2009). Similarly, livestock production will be severely affected through quality feed and water availability (Schaeffer et al. 2013).

#### (d) Human health and diseases outbreak

Water availability and increased rates of disease outbreak are transformed by climate change (Schaeffer et al. 2013). The impacts of climate variability will be felt through increased infectious diseases which are relatively high in SSA. Extreme weather events may lead to illness and mortality. The level of malfunction may also be on the rise up to between 35% and 80% due to a rise of between 1.2 °C and 1.9 °C (Lloyd et al. 2011). As reported by Patz et al. (2008), flooding results to disease outbreaks including diarrhea, cholera, trachoma, and conjunctivitis. Other diseases like malaria may shift and be felt to areas where they were not felt before due to changes in temperature suitability responsible for pathogen growth.

#### (e) Water resources

Change in the hydrological sequence due to climate variability has a direct impact on water timing and circulation (Goulden et al. 2009). With most of the countries in SSA facing challenges with provision and supply of clean usable water, climate change will exacerbate this and lead to more water shortages in the coming years (Schellnhuber et al. 2012). The resultant effect will be increased disease outbreaks due to poor sanitation, low agricultural production, food insecurity, and general influence on livelihoods. Rise in temperature due to global warming would lead to a complex rate of evapotranspiration leading to increased loss from water bodies (Ogolla et al. 1997).

#### (f) Land degradation

Population increase combined climate variability impedes good resource management leading to environmental degradation (UNEP 2002b). Climate variability is slowly encroaching and engulfing countries thus rendering their land unproductive due to variations in weather patterns and global warming. As human population grows further, the natural distribution of vegetation on earth will be altered. This leads to opening new land for agriculture and cultivation of marginal areas (UNEP 2002a). This has led to loss of natural habitats, reducing vegetation cover and exposing soils to wind and water erosion in many parts of Africa. Soil erosion has increased the rate of siltation in dams and rivers and at the same time reducing the productivity of the land.

#### Adaptive Capacity to Mitigate Climate Variability Impacts

Adaptive capacity calls for strategies to help the communities to adapt to these extreme events such as drought and flooding. Adaptation simply means adjustments made in the existing systems as a response mechanism toward countering the effects of climate variability by the communities and individuals involved. These adjustments are mainly meant to act as a buffer and to assure proper exploitation of the new opportunities that minimize harm and as they present themselves. Therefore understanding the adaptive capacity by farmers is crucial to effective adaptation planning since it assures continuous production crucial to effective planning and guarantees human survival (Chepkoech et al. 2020). With the projected increase in global temperature, likely to result to increase in global warming, it's thus inevitable for individuals and communities to find adaptive ways which guarantees their survival. Adaptive measures toward climate change are no longer regarded as second measured but should be taken as primary consideration especially by farmers. However, the adaptation capacity in most African countries is low mainly due to lack of capacity to invest in the recent technologies which have been studied and found to promote better survival and livelihoods. Majority of agriculture in SSA is rainfed with only a very small percentage of farmers with a capacity to carry out irrigation which makes it difficult to predict due to climate variability. Further, the challenges are associated with lack of reliable weather data to inform on policy, and therefore most of the countries lack early warning systems that can be used early enough to caution the governments of possible climate-related calamities.

#### Impacts and Adaptation Strategies to Climate Variability in Arid and Semiarid Lands: A Case of Garissa and Tana River Counties in Kenya

#### Rainfall and Temperature Impacts on Food Security

From a data synthesis on annual rainfall and temperature over a period of 20 years for Garissa and Tana River counties indicate that rainfall was characterized with extended dry season occurring between January and February. The long rainy season occurs between March and May (MAM) while prolonged dry season occurs from

Fig. 1 Reduced River Tana flow during the month of October. (Courtesy of D. Karienye)

mid-May to mid-October, while short rainy season begins in mid-October to end of December of each year. There are fewer days of more intense rainfall with the rains often starting late but intense which are described as "very unreliable" (that is seasonal failures are common).

Similarly, for temperatures, the highest temperature amounts were observed between February and March, which coincides with the same time when rainfall is lowest in the study area. Around September–October, the temperatures are also at highest. Temperature increase has an important impact on water availability, thus aggravating drought conditions. Decreases in rainfall have profound repercussions on river flows leading to declining river discharge (Fig. 1). The months that saw an increased rise in temperature also experienced drought. This can be explained by the high evapotranspiration making the vegetation deficient of moisture leading to crop and pasture failure.

However, in trying to escape the droughts, the few well-endowed farmers practiced drip irrigation and greenhouse farming as indicated in Fig. 2. This ensured a reduction in the impact of droughts. This low number of farmers adopting new farming mechanisms, and which is a shift from rainfed agricultural production can be explained by the high cost of the greenhouses' infrastructures. This represents an innovative technology in response to the changing weather patterns though the adoption rates remain relatively low due to high cost.

#### Community Perception on Climate Variability and Its Impacts

From the interaction with the community, majority of the households were extremely worried about climate variability and identified rainfall to be very unpredictable

Fig. 2 Farmers practicing greenhouses and drip irrigation. (Courtesy of D. Karienye)

Fig. 3 Land degradation through charcoal burning. (Courtesy of D. Karienye)

stating that there exists a consistently prolonged dry period every now and then. Nevertheless, farmers believe that temperatures have already increased and precipitation has declined or is unpredictable (Karienye et al. 2019).

The impact of climate variability has been felt mainly by reduced crop production, extreme cases of flooding, and land degradation as evident by charcoal burning (Fig. 3) and reduced biodiversity. The reduced precipitation coupled with flooding leads to crop failure which destroys the crops that are grown along River Tana. Floods have in the past been responsible for causing disruption in transport systems and displaced residents living in the low-land areas which are prone to flooding (CARE and ALP 2013).

Fig. 4 Community-based agro forestry programs. (Courtesy of J. Macharia)

#### Adaptations Strategies to Climate Variability in Arid and Semiarid Land

Based on their own experiences and from sharing information among themselves, most of the households in these ASALS of Kenya have identified several adaptive strategies to cushion them against the extreme conditions. The communities preferred livelihood diversification (business, cropping, and livestock) as an alternative livelihood option, sustainable use of the land including conservation agriculture, mulching, building trenches and ditches around the homesteads and watering crops using cans during dry spell. They have also adopted drought-tolerant and early maturing crop species, changing eating behaviors and afforestation (Fig. 4).

#### Conclusions

From our synthesis, the rainy seasons are no longer predictable thereby prohibiting any farming activities. The impacts of climate variability in the ASALs are mainly through extreme conditions of drought and flooding. The two conditions have resulted to various challenges facing the communities in these regions through low agricultural production (food and pastures), poor infrastructure, population displacement resulting to extreme poverty, overall food insecurity, and tough livelihoods. These challenges are exacerbated further by the inability of the majority of the communities to cushion themselves against the impacts of climate variability and this becomes a cyclic problem year in year out. The better-endowed community members have invested in greenhouses and drip irrigations to ensure continuous supply of food particularly for their domestic consumptions. However, efforts by the local communities have been identified where they have, through experience over time, resulted to planting drought-resistant crop varieties, diversified their livelihoods, embraced sustainable land use, and made efforts to plant trees. It's imperative to note that well-informed, adaptive, and forward-looking decision making is central to adaptive capacity of the host communities. In order for community to respond to expected changes and to participate in adaptive decision-making, they require precise information, knowledge and skills that enable them to actively address climate risks to their livelihoods. Therefore, adaptation energies must aim to ease access to information and the development of the skills and knowledge needed for accurate adaptation targeting. Institutions and agencies responsible for policy formulation should ensure an enabling atmosphere for local adaptation efforts.

#### Recommendations

In order to embrace the adaptive capacity as long-term practical solutions, the following are recommended:

#### References

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# 4

# Agricultural Interventions to Enhance Climate Change Adaptation of Underutilized Root and Tuber Crops

## Joseph P. Gweyi-Onyango, Michael Ajanja Sakha, and Joyce Jefwa

## Contents

J. P. Gweyi-Onyango

Department of Agricultural Science and Technology, Kenyatta University, Nairobi, Kenya

M. A. Sakha (\*) · J. Jefwa Botany Department, National Museums of Kenya, Nairobi, Kenya

This chapter was previously published non-open access with exclusive rights reserved by the Publisher. It has been changed retrospectively to open access under a CC BY 4.0 license and the copyright holder is "The Author(s)". For further details, please see the license information at the end of the chapter.

#### Abstract

Agricultural intensification worldwide is increasingly relying on a narrow range of crops such as rice, wheat, and maize. The reliability on this relatively small numbers of food diversities raises a very serious concern about the sustainability managing our nutrition today and in the future. We conducted a scoping review using online databases to identify various agricultural interventions that can be utilized for enhancement of underutilized root and tuber crops adaptability under the current observable effects of climate change. This is because reports of underutilized crops' adaptability to climate change continues to remain anecdotal with limited research capacity to support them. The results mooted a wide range of crop production techniques that can be utilized in production of root and tuber crops. They includes biofertilizers, tied ridging method, improved seed varieties, management of community seed banks, cropping systems, irrigation methods, exploiting abandoned lands, agroforestry practice, clean seed production technologies, and nutrient use efficiency. Based on the findings, each of these interventions plays different roles in management of the negative impacts brought up by climate change and thus they would be useful when adopted in combination since package adoption would enable farmers to benefit from the positive synergy of the selected interventions. The interventions are therefore recommended not only for sustainability but also for profitable production to meet feed, food, energy, and fiber needs and foster economic growth in the ever changing world. Therefore this chapter contributes immensely towards the development of innovative mechanisms for strengthening the resilience of root and tuber crop.

#### Keywords

Agricultural intensification · Sustainability · Adaptability

#### Introduction

The root and tuber crops are group of plants which yields tubers, starchy roots, corms, stems, and rhizomes. Okigbo (1989) defined while tuber crops as crops with edible carbohydrate-rich storage organs developing wholly or partly from underground stems while root crops as edible crops with energy-rich underground plant structures developing from modified roots. Major tropical root and tuber crops are: cassava (Manihot esculenta); potato (Solanum spp.); sweet potato (Ipomea batata); yam (Dioscorea spp.); aroids like elephant foot yam [Amorphophallus paeoniifolius (Dennst.) Nicolson]; taro [Colocasia esculenta (L.) Schott.], and tannia [Xanthosoma sagittifolium (L.) Schott.]. Additionally, there are minor tubers such as Chinese potato [Plectranthus rotundifolius (Poir.) J.K. Morton.]; yam bean [(Pachyrhizus erosus (L.) Urban], and arrowroot [Maranta arundinacea (L.)]. These crops are vegetatively propagated and plays major roles in food sector especially by managing the well-being of people in developing countries. According to FAO (2009), these crops are produced in approximately 53.93 million hectares globally and this produce about 736.747million tonnes annually.

In Sub-Saharan Africa (SSA), many people highly depend on root and tuber crops but not all as a contributory if not the primary source of their food and nutrition. This is also because of the role they play in food security, their ability to resist drought, as well as their capacity for commercial processing in Kenya. Actually they were ranked as the second most important food crop in 2019 by the ministry of agriculture after cereals (MoALF 2019). At the moment, the Kenya is producing 3.68 M MT of Irish potatoes, cassava, sweet potatoes, yam, and cocoyams. However, their yield is below average which is much way below country's potential. For instance Irish potatoes stands at 7MT per ha compared to the potential of 25 MT achieved under optimal husbandry practices (MoALF 2019).

Root and tuber crops are considered to be resilient because they are more adaptable to marginal areas. This areas are characterized by edaphic and climatic conditions that may not be favorable to the non-native materials. These crops are tolerant to poor soils and drought stress. They also grow very well on welldrained soils, with good organic matter, and especially those with loose and friable fertile clay loam or loam. Moreover, the optimal conditions for their growth are: annual rainfall ranging between 1000 and 2000 mm, temperature of 18–35 °C, and a soil pH ranging between 5 and 7.5. Nevertheless their planting differs from another case in point Coleus potato, tuberous rhizomes, or seed tubers are normally planted about 5 cm in depth on raised beds and are spaced at 15–20 cm while in Amora; they are planted at about 15 cm deep and a distance of 30–40 cm (Codd 1985).

These crops are also well known to serve as important components of subsistence farming system in their native areas and have played crucial, if not weighty roles income generation and in household food security of the rural areas. As food crops these crops are very rich in carbohydrates and on that account they play a paramount role as part of our daily diet, accounting for over 50% of the total staple food. In terms of energy requirements for global population, they contribute 3.9% energy that is sweet potato 1.5%, cassava 1.9%, yams and other root and tuber crops 0.3%. Along with this potatoes produce additional protein and dry matter per hectare than key cereals (Birch et al. 2012). Monneveux et al. (2013) also reported that potatoes have higher water generative capacity than cereals and are considered among the most energy productive crops, producing 5,600 kcal/m<sup>3</sup> of water, compared to 3860 in maize, 2300 in wheat, and 2000 in rice. Other root and tuber crops such as taro, yautia, and yam, also have notable energy values and inconsistent nutritional properties, including vitamin C, dietary fiber, and carotenoids (Asiedu and Sartie 2010). At the same time these crop plays a meaningful role as cash crops. They literally hold strong economic potential and can be financially rewarding to the agricultural economies. Finally these crops are progressively being used as a source of raw material for industrial use and for feeding the livestock. In comparison to other staple food crops, they provide comparatively huge amounts of nutrition and energy per unit area and time, they require lessintensive management systems even under risky environmental conditions. Consequently, these crops are very important in fighting famine caused by floods, droughts, civil strife, and other climatic catastrophe such as pests and diseases which seems to be unending in some countries.

Climate change is a menace posing extreme stress to the environment and also to the humans. Deschenes and Greenstone (2006) reported that it has an adverse effect on humans and their income-generating activities especially agriculture owing to its dependence on nature, largely temperature and precipitation. In addition climate change influences soil functions both directly and indirectly. The direct influence include soil process, namely, changes in organic matter and nutrient cycling and this is through adjusting temperature and moisture regimes or through increased soil erosion rates caused by increased frequency of intense rainfall occurrence. This causes severely effects on agriculture especially on the crops being grown. As a matter of fact, Africa is one of the riskiest continents to the ongoing climate variability causing robust negative economic impacts. This vulnerability is accentuated by development challenges specifically ecosystem degradation and endemic poverty which are supported by limited access to capital, infrastructure, markets, and technology (IPCC 2007).

Small-scale farmers in sub-Saharan Africa, who are the majority, have historically been confronted with high climate variability. Some of its negative effects on farm include decreased soil fertility and limited plant growth (Dhankher and Foyer 2018). Despite smallholder farming systems having proven to be resilient and being viable in risk-prone environments, climate change is likely to outpace their current coping capabilities (Morton 2007), if effective measures are not implemented. Specifically, low levels of income and technology, coupled with isolation from markets and lack of institutional support, are common characteristics of smallholder farming systems that make them particularly vulnerable to changes in external conditions (Morton 2007). This is worsened by the fact that food security and livelihood programs mostly stress on grain crops such as maize, rice, and wheat. In support of this, Atakos (2018) reported that only one or two studies have looked into the future potential of root tuber crops and their possible importance even with climate change. Our dependence on this relatively small number of food species therefore elevates serious concerns of feeding the whole world sustainably. In such context, investment in sustainable agricultural technologies and practices becomes crucial for adaption to sustain crop productivity to be able to feed the growing populations. In particular to able to reduce the negative effects of climate change on the agri-food system, Sombroek and Gommes (1997) proposed that populations and economic systems must be able adapt to future climatic conditions.

Since root and tuber crops play a great role as source of nutrition, and on the other hand, researchers are advocating for mitigation and adaptation as possible options to combat the adverse effects of climate change on agriculture, this chapter therefore focus on agricultural interventions that can enhance climate change adaptation of underutilized root and tuber crops.

#### Major Roots and Tuber Crops

#### Cassava

Cassava (Manihot esculenta) is a perennial woody shrub which grows as an annual crop. It is also referred as manioc, mandioca, or yuca, which is in the spurge family (Euphorbiaceae) (Hillocks et al. 2002). This crop is also known as the "king of tropical tuber crops" and has a significant position in the global agricultural economies. According Bennett (2015), the crop is ranked as the second most important food source in Africa with regard to calories consumed per capita. Cassava is native to South America (Allem 2002) but it is grown all over tropics and subtropics. It is largely produced in Brazil followed by Thailand, Nigeria, DR Congo, and Indonesia, even though about half of the global production is in Africa. The crop is grown in about forty African countries where it is recognized as an important food crop particularly in Nigeria, DR Congo, Ghana, Mozambique, Uganda, Cameroon, Madagascar, Angola, Côte d'Ivoire, Tanzania, Benin, and Kenya. FAO 2000 revealed that about 70% of Africa's cassava production is obtained in Nigeria, Tanzania, and DR. Congo.

It has been proposed that cassava could potentially be hardy to climate change than other staple crops (Jarvis et al. 2012). Likewise Nweke et al. (2002) revealed that cassava can grow well in marginal lands, and that it requires low farm inputs. The average cassava root yield is about 11.6 t/h worldwide (FAO 2018) which is exceedingly lower than its potential yield of 60 t/ha under better farming practices which was reported in some parts of Africa (Kintché et al. 2017). Even though FAOSTAT (2014) reported that world production of cassava storage roots improved tremendously from 176 to 277 million Mg between 2000 and 2013. Major limiting factors for cassava production are low soil fertility and pests and diseases.

#### Sweet Potatoes

Sweet potato (Ipomoea batatas (L.) Lam) is a herbaceous dicotyledonous plant belonging to Convolvulaceae family (Purseglove 1972). The plant has creeping, perennial vines and adventitious roots (Purseglove 1972). It is grown for its green leaves and storage roots which are very useful for human consumption, feeding animal, and to a certain extent, for industrial purpose (Woolfe 1992). For that reasons, according to Motsa et al. (2015), the crop plays a critical role for food security and income generation for many households. Consequently, the crop is extensively cultivated in tropical, subtropical, and frost-free temperate climatic areas of the world (Onwueme and Sinha 1991).

Sweet potato is ranked as the seventh most important food crop globally because it contributes majorly in terms of energy and nutrition (Marques 2015). The crop also matures at a very short time on marginal lands and play an important role in the economy of poor households (Nath et al. 2007). As stated by Ukom et al. (2009), the crop is important for its storage roots which can either be baked, cooked, fried, or roasted for human consumption. Its storage roots can also be processed into flour for baking bread, making noodles, as well as for alcohol production. In addition, the storage roots are very good source of vitamin A, vitamin C, vitamin B6, dietary fiber, manganese, copper, potassium, and iron (Baybutt et al. 2000). Even though the crop has a high storage root yield potential ranging between 20 and 50 t/ha (Kivuva et al. 2014), in Sub-Saharan Africa, this is yet to be realized since its production is still less than 10 t/ha (FAOSTAT 2017).

#### Yam

Yams (Dioscorea spp.) are tropical plants with large food reserve in their underground tubers and comprise of various species that originated from Southeast Asia, West Africa, East Africa, Brazil, and Guyana. The main species are Dioscorea alata (greater or water yam), Dioscorea cayenensis (yellow guinea yam), Dioscorea esculenta (lesser yam), and Dioscorea rotundata (white guinea yam) (Arnau et al. 2010), and this comprises both annual and perennial species. They cultivated all over the tropics and in some parts of subtropics and temperate areas. FAO (2000) reported that up to 95% of the world's production is realized in West Africa.

The tubers are very important and constitute stored wealth since they can be sold all-year-round by farmers because they can be stored for relatively longer period of time in comparison with other tropical fresh produce (Aidoo 2009). The tubers also provide a substantial amount of vitamins (vitamin B1 and C), potassium, and iron (Rudrappa 2013). Most essentially many of the yam species have high content of steroidal saponins which make them suitable for industrial use as corticosteroids precursors and anti-cancer bioactive compounds. Besides being staple food that is consumed by about 155 million people in the world, yams are grown as cash crop, as medicinal plant, and have high cultural value for the groups cultivating it (Coursey 1981).

Major hindrance for intensifying yam productivity is low soil fertility (both in terms of macro- and micronutrient deficiency) (O'Sullivan and Ernest 2007). This is because Dioscorea spp. are high-nutrient-demanding crops (Carsky et al. 2010). Therefore, yams still remains being categorized as orphan crop (Naylor et al. 2004).

#### Irish Potato

Irish potato (Solanum tuberesum L.) is indigenous to South America near the present border of Peru and Bolivia but not Ireland (Spooner et al. 2005). According to Robert and Cartwhight (2006), it belongs to the family solanaceae, and is named after Ireland country because it is associated with the Irish potato famine, also known as the Great Hunger. This was a historic famine caused by Phytophthora infestans which infected Irish potato crop. This crop plays a crucial role in the economy and is ranked number one non-grain food commodity (Rykaczewska 2013). Globally it is ranked third most important food crop in consumption after rice and wheat (Birch et al. 2012). It has a worldwide cultivation exceeding 19.34 million hectare in more than 158 countries, with an approximate yearly production of 364 million tons (FAOSTAT 2014). According to Tshisola (2014) in Africa, it is regarded as one of the most important food crops.

Practically the crop contains all the requisite dietary components such as protein, vitamins, carbohydrates, essential nutrients, and minerals (Sriom et al. 2017). Additionally it is a source income and employment opportunity in developing countries. Unfortunately, limiting factors to its production include short day lengths, low light intensities, high temperatures, and most importantly low soil fertility (Jones and Wendt 1994).

#### Cocoyams (Arrow Roots)

Cocoyam (Colocasia esculenta (L.) Schott.) is a member of Araceae family (Purseglove 1975) and is a subsistence and emergency food source globally (IFA 1992). It is an important starchy tuberous herbaceous perennial plant (Purseglove 1975). The crop has different varieties and commonly produced varieties are Colocasia esculenta (Taro) and Xanthosoma sagittifolium (Tannia). They also occur in all tropics and have been domesticated in most communities in Oceania, Africa, and Asia (Ramanatha et al. 2010).

The crop is cultivated for its edible cormels, corms, and leaves as well as other traditional uses (Pinto and Onwueme 2000). As food for consumption, it is essentially a source of calories obtained from underground corm and cormel (Davies et al. 2008). Their leaves which resemble spinach are nutritious and are source mineral and vitamin (Sefa-Dedeh and Kofi-Agyir 2002). Primarily, fresh cocoyam hold about 70–80% water, 20–75% carbohydrate, and 1.5–3.0% protein (Udo et al. 2005). It actually contains over 80% and 240% higher digestible crude protein than yam and cassava, respectively. Therefore this crop is high-ranking nutritionally than cassava and yam in terms of protein and other elements such as vitamin and mineral content. However, the crop still remains to be underexploited food resource (Onyeka 2014).

#### Root and Tuber Crop Production in Kenya

Ministry of agriculture, livestock, and fisheries of Kenya report indicate that roots and tuber crops production stagnated for a period of 3 years (2012 to 2015) with an average cultivated zone of about 240,000 ha, which gave a total production level of 3.3 million MT although these reduced to 2.4 MT in 2016 (MoALF 2019). This elicited the national government to draft a strategy (the national root and tuber crops development strategy 2019–2022) to help in upscaling their production. This was an initiative of the national government of Kenya, but it was being supported by other key stakeholders such as the European Union, and by organizations like Self Help Africa (Table 1).

Source: MoALF 2019

In sub-Saharan African counties, there are noticeable cultural preferences for root and tuber crops, and using the Impact General Equilibrium Model, a 2015 analysis the International Food Policy Research Institute revealed that per capita consumption of these crops continues to rise (Fig. 1). Therefore, because of its low productivity brought by the effects of climate change and which cannot meet their demand, there is need to enhance their resilience to climate change using innovative ways.

#### Agricultural Interventions for Adaptation to Climate Change

Farmers, especially small-scale farmers, still use indigenous farming practices which lead up to ultimately low yields. This is coupled to farmer's nonadoption of better crop production strategies and lack of improved and high-yielding varieties. Moreover, these farmers on their own do have other alternatives that can help them bear and share loses or modifies threats. On the other hand, climate change adaptation should be built on sound and a working ecosystems, as it provides a variety of benefits and services on which agricultural production systems and rural livelihoods depend. Therefore, this calls for adoption of new technologies while producing these crop to help us throughout this challenging times. To this end, this chapter provide the suitable technologies available that can be exploited to increase root tuber crops adaptability to climate change. The technologies include:

#### Bio Fertilizers

By definition, bio fertilizers are products containing natural occurring microorganisms that are artificially multiplied for ameliorating soil fertility. Each and every type of crops grown in different agro-ecological zones can benefit from their use, since they are valuable to the environment. This is because they are enabling farmers to minimize the use of modern chemical fertilizers in crop production. In particular, they are designed to improve nutrient availability or reduce pest pressure. According to Malik et al. (2011), constant use of microbial-based bio-fertilizers enables microbial population to persist in the soil which helps in soil fertility conservation (Table 2).

Phosphate-Solubilizing Microorganisms (PSM): They are a group of beneficial microorganisms that capable of hydrolyzing inorganic and organic insoluble phosphorus compounds to soluble phosphorus form that can easily be absorbed by plants. They include various soil fungi and bacteria, and important species are Pseudomonas, Bacillus, Penicillium, and Aspergillus. Hikmatullah and K. Nugroho (1994) reported that their abilities of phosphate solubilization from organic materials differs due to their differences in their capacity to produce organic acids that play a key role in releasing phosphorus bound by aluminum, iron, and calcium ions. Specifically, this is because organic acids released by microorganisms are different in quantity and quality (Jha et al. 2013). Some of the organic acids released that are capable of freeing AI-P bond include Malic acid, malonic, tartaric, oxalic, and citric (Marbun et al. 2015). These organic acids decrease the soil pH in their locality to cause the dissolution of bound phosphates in soil. Khan et al. (2009) reported that 1 g of fertile soil can hold 10<sup>1</sup> to 10<sup>10</sup> bacteria, and their live weight may exceed 2,000 kg ha-1 . Similarly Chen et al. (2006) outlined that among the whole microbial community in soil, phosphate solubilizing bacteria comprise 1–50% while phosphate solubilizing fungi comprise 0.1–0.5% of the total respective community. Therefore, microbial-based biofertilizers can be utilized to boost soil microbial population whenever they are low and when cultivating root and tuber crops. With high density of PSMs, it is expected that microbial phosphate solubilization can compete effectively with other microorganisms in the soil.

Phosphorus Mobilizing Fungi: This group comprise of the arbuscular mycorrhiza fungi (AM fungi) that belongs to the phylum Glomeromycota (Schüßler et al. 2001). The fungi form a mutualistic relationship with most terrestrial plants. In the association, the plants benefit through various ways such as water and essential

Table 2 Types of biofertilizers for root and tuber crops

Source: (Kumar et al. 2017)

nutrients uptake, and also by enhancing plant tolerance to biotic and abiotic stresses (Augé et al. 2015). This multifunctional ability and diversity of AM fungi has led to the development of mycorrhizal inoculants for use as biofertilizers in agriculture. Actually, most land plants are facultative symbionts such that they gain from AM fungi, yet they can also live without them, although at reasonable fitness cost. However, some plant species are obligate parasites on the fungus such that they are fully dependent on fungal nutrition (mycoheterotrophs) and have lost photosynthetic capacity (Graham et al. 2017).

Since mycorrhizal inoculations has been used for decades to stimulate plant growth for several crop, root and tuber crops which are highly mycorrhizal could also profit from the numerous services offered by this fungi not only in increasing their resilience to climate change but also their productivity. For instance, according to a report by Sieverding (1991) AM fungi inoculation of cassava increased its fresh roots weight by up to 5 t/ha.

Micronutrients Solubilizers: Such as Silicate solubilizing bacteria (SSB) are microorganisms that are able to degrade silicates and aluminum silicates in soil. These microorganisms such as Collimonas, Janthinobacterium, Proteobacteria, Aminobacter, Burkholderia, Dyella, and Frateuria are reported to solubilize the biotite which hold substantial amounts of silicate minerals (Uroz et al. 2009). During their metabolism, various organic acids are released which plays double roles in silicate weathering. These species supply hydrogen ions to the media which encourages hydrolysis. As well the organic acids let out such as oxalic acid, Keto acids, citric and hydroxyl carbolic acids form complexes with cations, which foster their removal and retention in the media in a dissolved state.

Since phosphorus and potassium are crucial macro elements for plant growth and development, P and K chemical fertilizers are regularly applied to replace the removed minerals in soil for yield optimization; SSB also plays an efficient role not only in solubilizing insoluble forms of silicates but also potassium and phosphates, hence this microorganisms when applied would increase the soil fertility, thereby enhancing root and tuber crops productivity.

Plant Growth Promoting Rhizobacteria (PGPR): Also referred as yield improving bacteria (YIB) are a group of bacteria that are known to increases plant growth and yield by-way-of several plant growth promoting substances as well as bio fertilizers. They are distinguished as free-living soil microorganisms colonizing plant roots and brings into play a beneficial effect on plant development and/or subdue plant pathogens. The microorganisms include; Alcaligenes, Agrobacterium, Bacillus, Bradyrhizobium, Burkholderia, Enterobacter, Frankia, Klebsiella, Pseudomonas, Arthrobacter, Azospirillum, Azotobacter, Rhizobium, and Serratia. The genera enclose most PGPR with well-known benefits on different crop species (Tailor and Joshi 2014).

There are numerous mechanisms through which the bacteria helps the plants including: inducement of increased nutrient uptake (termed Bio fertilizers), provision of nutrients by way of nitrogen fixation and phosphate solubilization, better plant growth promotion through the production of phytohormones (termed Bio stimulants), and the suppression of plant pathogens or the induction of systemic resistance to diseases (termed Bio protectants) (Vessey 2003). Also species of Pseudomonas and Bacillus produce plant growth regulators that stimulate crops to produce many fine roots which increases the surface area over which plant roots absorb water and nutrients.

Due to their multiple roles, research on these growth regulators has been rising and a number of experiments (both in vivo and in vitro) have been tested on different crops including root and tuber crops. For example, Bacillus and Pseudomonas sp. have been tried on potatoes and they have helped in improving phosphorus uptake, promoting indole acetic acid (IAA) production, and for biocontrol (Hunziker et al. 2015). Therefore, these microorganism can be very useful in fostering the growth and yield of root and tuber crops, with minor inputs of agrochemicals.

#### Organic Agriculture

Organic agriculture can be defined as a production system that sustains the health of soils, ecosystems, and people. This management system helps in mitigating climate change by diminishing the emissions of greenhouse gases and by sequestering carbon dioxide from the atmosphere. Organic agriculture is reported to be the most sustainable approach in food production. This is because it highly emphasizes on recycling practices and use of low external input for realization of high output. In addition, its principles dwell on increasing soil fertility, its diversity at all levels, and mitigating soil erosion.

Some management options of organic agriculture are generally considered to have both mitigation and adaptation benefits since they increase soil carbon. Ciais et al. (2013) stated that soil carbon provides a mitigation benefit by storing carbon taken out of the atmosphere by plants during photosynthesis. Soils with higher amounts of carbon are associated with greater water holding capacity, increased nutrient availability, and higher yield potentials, which could prove adaptive in a future climate (Stokes and Howden 2010). Organic agriculture practices are innovative way that can be used to increase these crops adaptability to climate change.

#### Soil Organic Matter Management

Soil organic matter (SOM) is a major measure of agricultural productivity and general soil health. Mean annual temperature and precipitation are major climatic drivers of SOM levels and dynamics. Long-term field trials and farm comparison show that organically managed soils have notably higher organic matter content. According to Foereid and Høgh-Jensen (2004), it was evaluated that under Northern European conditions, changing from conventional to organic agriculture resulted in enhanced SOM ranging from 100 to 400 kgha-<sup>1</sup> yearly during the first 50 years. Therefore, after a hundred years of organic agriculture, it is estimated that a steady state of stable level of SOM would be realized.

Environmental Protection Agency estimated that composting 1 ton of organic matter gave a net storage of about 600 pounds of carbon dioxide (EPA 2006). Even though all kinds of agriculture poses the capability of sequestering carbon, essentially organic agriculture can sequestrate remarkably more carbon than conventional systems (Don 2007). This is because organic agriculture restrains the use of chemical fertilizer and pesticide and integrates use of cover crops especially from leguminous plants, and place in order increasing soil organic matter as the first step. Therefore, to sequester more carbon as possibly brought up by climate change, it is necessary to incorporate SOM management practices when producing root and tuber crops.

#### Mulching

Mulching is a traditional practice which involves the covering of soil surface with organic material which plays a vital role in soil and plant protection. Mulches are capable of changing the environment around the plants and control weed sand annual grasses, soil erosion and runoff, and soil-borne diseases. Besides, they decrease moisture evaporation, increase water absorption and retention, and boost root growth. Organic or natural mulches such as compost provide many favorable and fertilizer-like effects for root and tuber crops production by supplying abundant plant nutrients, during their decaying process.

Owing to climate change that has resulted in land slide, high temperature and flashfloods, mulching is necessary since several types of mulching practices have exhibited reduction in soil erosion by more than 90% compared to bare soil (Mostaghimi et al. 1994). Unger (1994) argued that mulches with low carbon to nitrogen ratio decompose rapidly providing nutrients for crop growth at a faster rate. Furthermore, studies in Latin America and Papua New Guinea revealed the benefits of mulching cassava and sweet potato plants for yield stabilization (Ossom et al. 2001). To support this, Coling (1997) reported that mulches of plastic film enhanced dry matter accumulation, plant height, leaf area index, and tuber yield of potatoes. Similarly Sarma et al. (1999) after planting potato cv. Kufrimegha on ridges and flat seedbeds in combination with mulches and earthing up, he confirmed that mulching with black plastic film resulted in enhanced tuber yield which was greater than the normal cultivating method. This is because plastic mulch literally conserved the soil moisture which helped in better crop growth and tuber yield. Similarly, mulching the soil has been positively correlated with plant species richness.

As a normal practice, root and tuber crops are usually cultivated on ridges where soil erosion and weeds can be a menace. Therefore, for their effective production mulching is important since it is a valuable practice that can be used to control weeds. This is because mulching prevents weed growth and development by blocking light from reaching the soil surface where their seeds lie. In root and tuber crops, mulching could assume an important function of lowering soil temperatures in addition to soil moisture conservation (Sangakkara et al. 2004).

#### Zero Tillage

Zero tillage which is also referred as direct drill or no till is an agricultural practice of cultivating crops or pasture without disturbing the soil surface through tillage. Its aim is to conserve soil and moisture through nondisturbance of the soil surface and also by ensuring that 30% or more of crop residues are conserved on the surface (Erenstein and Laxmi 2008). According to Fernández et al. (2010), the practice has been documented widely for its benefits including protecting the soil against erosion

Table 3 Area under zero tillage by continent

Source: Derpsch et al. (2010)

and managing soil structure. Also, this practice increases carbon sequestration and activities of the microorganisms (Helgason et al. 2010) (Table 3).

Studies show that practices that reduce soil disturbance and intensify cropping have the potential of increasing soil organic matter (SOM) and improving soil health. For instance, soil disturbance with tillage generally promotes loss of SOM by facilitating microbial degradation of SOM, promoting crop-residue-soil contact, and placing residues into more favorable subsurface moisture regimes as compared to surface placement under no-tillage (Halvorson et al. 2002). By adopting no till practices in root and tuber crops production, soil conservation would be improved greatly, water and wind erosion would be considerably reduced, while the crops would yield more since they would protect from pests and external environment.

#### Tie-Ridging

Tie-ridges are soil and moisture conservation structures that involves the construction of small basins that are rectangular shaped. This basins are formed within the furrow of cultivated fields mainly to enhance the storage of rain water and for allowing more time for water to percolate in the soil (Wiyo et al. 1999). Belachew and Abera (2010) reported that the stored water can accessed by plants for a longer period of time better than it can be used when there is run off. Ridging across slope is highly recommended in dry areas for soil and water conservation in crop production (Kumwenda 1999).

Mechanized ridging is achieved either by animal-drawn ridgers, as it is commonly practiced in African for cassava and other food crops production, or by tractor-mounted ridgers which is a major practice for cassava production in Asian countries (Suyamto and Howeler 2001). The purpose of mechanization is to reduce hard work and in the process increase the scale of production crops. Although when using tie-ridging the optimum height of the ridge depends on the soil type and the cultivar being grown.

Benefits of tie-riding reported include: increased number of roots per plant which is identified as a major contributory factor to the higher yields on ridges (Suyamto and Howeler 2001). In particular, ridging has been shown to increase sweet potato yields by 38% (Ennin et al. 2003) over mounding, mainly as a result of increased plant population density and better weed suppression on ridges. Shetto (1999) reported that many farmers find weeding of cassava to be easier on ridges than on mounds; it is also effective in soil erosion management and results in high yields. Ennin et al. (2009) recommended the cultivation of cassava, yams, and other tuber crops on tie-ridges for realization of economizing the available planting space and thus increase on the planting density. Ridging is also responsive to improved farming practices such as herbicide application, fertilization, and yam staking, and this is due to the regular spacing of crops obtained under the systems.

The concept behind creation of tie-ridges is to optimize water infiltration, improvement of soil-water management, enhancement of root growth and nutrient uptake, and enhancement of rooting depth which is also supported by FAO (2000). Therefore, tie-ridge would play a significant role in production of root and tuber crops.

#### Improved Seed Varieties

Unlike the other true seed crops, root and tuber crops are propagated vegetatively. The benefits of improved seed varieties for root and tuber crops can only be realized through breeding and addressing the challenges in their seed value chain. This can be achieved through having a functioning seed systems and directly linking of the systems as a key tool of addressing the issue of improved seeds. This can further be linked in addressing the issues of climate change.

To this effect, the International potato center (CIP) has fostered and expedited their breeding schemes that shortens the time it takes in developing and releasing new varieties of root and tuber crops actually from 8 to 4 years. To this effect, their breeders have released potato varieties that are tolerant to heat, salinity, and drought. Some of the varieties are Tacna and Unica which were developed and tested in Peru; Raniag variety in Philippines; and Kinga, Kiningi, and Meva developed in Africa (Atakos et al. 2018). Further variety Tacna was released in the Republic of China under the name Jizhangshu 8, and had covered 20,000 ha by 2008. Recently work has been going on to develop climate change resilient potatoes that have the characteristics of drought and salinity tolerance, and according to Atakos et al. (2018), variety Sarnav has been released in Central Asia (Uzbekistan and Tajikistan), while heat and salinity tolerant BARI Alu-72 has been released in Bangladesh. With minimal precipitation being realized ranging between 15% and 20% and new experiences in temperature increase of 2–3 °C due to the effects of climate change, these clones have shown a high degree of tolerance to these effects (CIP 2017). On that account, such efficient breeding practices that delivers improved seed varieties of root and tuber crops should be supported especially in the area of improving their resilient to climate change.

#### Management of Community Seed Banks

Community seed banks are entities that are governed locally and they are managed in an informal manner by institutions whose core function is to maintain seeds for local use (Development Fund 2011). Vernooy et al. (2014) reported that the community seed banks were founded by Rural Advancement Foundation International (RAFI) now known as ETC Group or Action Group on Erosion, Technology, and Concentration. The three key functions of the community seed banks are: (i) to conserve the plant genetic resources; (ii) to make the availability and accessibility of diverse seeds and planting materials according to farmers' needs and interests easier; and (iii) facilitating seed and food sovereignty (Vernooy et al. 2014). Community seed banks are globally located in Guatemala, India, Malaysia, Mexico, Nicaragua, Sri Lanka, USA, Honduras, Bhutan, Bolivia, Brazil, Canada, Bangladesh, China, Costa Rica, Nepal, Trinidad and Tobago, Rwanda, Uganda, Mali, Burundi, Norway, Zimbabwe, and South Africa. Recently it was launched in Kenya in Nyando in smallholder farmer areas by the Consortium of International Agricultural Research Centers (CGIAR) research program on climate change agriculture and food security (CCAFS) in sub-Saharan Africa which works in partnership with Bioversity International to establish community seed banks in Kenya, Tanzania, and Uganda. The idea behind is that when you take one seed you return two, if you take five, you return ten. This protocol aids in their sustainability. The idea of community is excellent; however, the existing community seed banks are focused on cereal crops neglecting the root tuber crops. Although the International Potato Center (CIP) researchers are promoting innovative ways that allows storage of seeds of root and tuber crops.

Specifically sweet potatoes farmers are encouraged to mass-produce their own vines during planting time. The system is known as Triple S (for storing vines in sand to make them sprout). It involves storing the vines in dry sand following harvest, and thereafter planting them in seedbeds 6–8 weeks before the rainy season, and watering them to produce enough vines to plant when the rains begin. The practice results in increased vines, earlier harvests, which provides food and income at a time. In addition in order to maintain disease free planting materials, the farmers in high virus pressure zones are advised to use net tunnels systems to protect against insects such as whiteflies and aphids which are known in spreading viruses. This practice is effective in suppressing the infection rate by sweet potato virus disease thus supporting the availability of clean planting materials. According to Atakos et al. (2018), such tunnels also have contributed in moisture retention by reducing the amount of water required for irrigation. The major benefits derived from community seed banks that can be exploited for production of root and tuber crop seeds are pest and disease reduction, increased production of seeds, and climate stress buffering.

#### Cropping Systems

Cropping systems plays important roles in crops adaptability to climate change since the practice encompasses on farm adaptation of improved farming technologies and in this case planting more than two crops with different maturity periods. This system has various advantages including: better utilization of the environment, greater food yield, increased return per unit area, and insurance against crop failure. Therefore, root and tuber crops which have great flexibility can be part of such a system. This is because they can be intercropped with plantation crop such as areca nut, coconuts, coffee, rubber, and fruit crops like mangos, bananas, and litchi as these crops are adapted to the same ecological conditions (Nayar and Suja 2004). In this system, the principal crop provides cash while root intercrops provide as highenergy secondary staple to the farm family and feeds for farm animals, behave as insurance crop against risk and natural calamities, ensure food security, enhance resource use efficiency, augment net income, and increase employment opportunities.

To support this, cultivation of root and tuber such as yam, cassava, sweet potatoes, and edible aroids in the interspaces of perennial plantations such as rubber, coffee, coconut, and banana is common in tropical countries. Crops such as elephant foot yam and yam grow as intercrops horticultural and planation crops. Also intercropping maize and yam is believed to be productive and compatible mainly because maize is a short season crop (3–4 months), while yams are long are long duration (7–12 months) crops. Sagoe (2006) also revealed that yams and cocoyams are usually cultivated in association with cocoa and furthermore new innovations propose use of cassava trees in cocoa production. Davis et al. (1986) reported that sweet potato are grown as intercrop and in rotation systems with crops like soybean, bean, sorghum, maize, and cassava. In India, cassava, yams, and edible aroids are intercropped with rubber plantations during their immature phase whereas in Malaysia cassava is grown as intercrop in Rubber estates (Leihner 1983). The cropping system also includes practices such as adjusting the planting dates, irrigation applications, and fertilizer application (Sagoe 2006). This examples suggests that when managed appropriately, cropping systems can enhance the adaptability of these crops to climate change especially when the right crops are chosen for the system.

#### Irrigation Method

Climate change causes in drought which is a major abiotic factor that limit crop production. On the other hand, global warming causes rainfall fluctuations increasing the risk of plant exposure to repeated drought (Miyashita et al. 2005). Other factors ever berating the drought situation include limited fresh water bodies which cause serious issues globally, particularly in arid and semiarid regions. These fresh water bodies are also decreasing due to population pressure, comping demands from the industries, low rainfall, agricultural and urban development. Furthermore drought is considered one of the major constraints for root and tuber crop production.

Root and tuber crops have much capacity in terms of their water use efficiency and nutrient use just like other food crops. Additionally, these crops have a unique growth characteristics and functionality. Therefore a suitable irrigation method must be selected while cultivating these crops such as: an irrigation method that releases the exact amount of water required, and time and method of water application. To this end, sprinkle and trickle irrigation methods therefore becomes the best option for these crops. This is because they save irrigation water by up 30% and 50%, respectively, as compared with surface irrigation (Al-Jamal et al. 2001). Amer (2011) revealed that in small-scale farming using gated pipes and double planting row beds, with partially wetted furrow irrigation, water saving is achieved just as in trickle irrigation. Even though partially wetted irrigation can be very useful especially because it decreases installation cost compared to trickle and sprinkle systems, in this case it is important to consider the right method for climate change adaptation. Considering this, trickle irrigation becomes the best method for theses crops under the prevailing climatic conditions since it conserves water, prevents nitrogen leaching, allows deep water percolation, and reduces soil erosion. Also it gives famers an opportunity to apply water at the right time.

#### Exploiting Abandoned Lands

In this chapter, land abandonment concept is used on a land where traditional or recently agricultural activities have stopped due to their marginal characteristics. Lands are classified as abandoned when their productivity level is situated close to the margin beyond which management expenses are not compensated by the profits obtained after harvesting. To this effect, cropland abandonment has become a common occurrence globally due to the improper agricultural practices being used.

To reclaim this types of lands and to increase the arable lands, alternative crop productions (in intensive form) should be used. This is because the remaining arable land is being lost to urban and industrial uses, deforestation, rural development, such as afforestation, and land fragmentation into smaller units. According to FAO (2011), many efforts to revamp land productivity have continued over the years since the abandoned lands represents a valuable resource for crop production. Such efforts are supported by the farmers desire to pass productive farmlands onto the future generation in just a good condition as when they inherited them (Greenland et al. 1998).

Root and tuber crops can therefore be very useful for use in reclaiming these abandoned lands. This is because of their agronomic advantage such that these crops are adapted to diverse soil, environmental conditions, and a variety of farming methods with minimum agricultural input. Also, variations in the growth pattern and adopting cultural practices make them specific in production systems. In addition, these crops are relatively easy to grow since they are highly adaptable in growing at a wide range of altitudes, on both flat and sloping lands, and on both sandy and clay soils where other crops are not well adapted. Finally, the variety to choose from for these crops is very high.

All these characteristics indicates that root and tuber crops have a comparative advantage for cultivation in marginal lands than other crops since they can be selected to resist stress conditions and in contributing to sustainable crop production with low input cost. Similarly, IPGRI (2000) reported that these crops contributes to the food crops diversity and hence exploits fully the abilities of agro-ecosystems. Under this scenario of large abandoned land, root and tuber crop can be produced effectively on these lands, and after years of their production, the lands can be returned for production of other agricultural crops production. In return this would lead to reduced clearing of additional forests and grassland for farming purposes.

#### Agroforestry Practice

Agroforestry is an interaction of agriculture and trees, including the agricultural use of trees. This encompass trees on farms and in agricultural landscapes; farming in forests and along forest margins and tree-crop production including coffee and cocoa. It ranges from traditional swidden agriculture to elaborate systems of fruits trees and vines in spatial complementarity. Examples of useful agroforestry trees include; Acacia albida, Leucaena leucocephala, Prosopis juliflora, Acacia scorpioides, and Euphorbia spp. Others include green manure crops such as Tephrosia spp, Desmodium spp, Dolichos spp, and Indogofera spp.

Some of the most promising agroforestry techniques for root and tuber crops include: (a) Scattered farm trees, this simply involves the increase in number of trees in the middle of crops and alongside the farm boundaries. The trees might have greater value than the crops they displace. Alternatively, the trees might actually increase the productivity of these crops by replenishing the soil and helping reduction of soil erosion. (b) Improved fallows, which involves fallows being enriched with fast-growing trees, vines, or shrubs. This is required by the fact that the fallow periods in many areas needs to be shortened considerably. (c) Buffer strips, which are areas of land maintained in permanent vegetation that helps control soil, air, and water quality. Root and tuber crops can therefore serve as buffers against soil erosion when planted along contour lines of slopes. In complicated systems, these root and tuber crops buffer strips can include other crop, such as grasses, trees, shrubs, and fodder legumes.

#### Clean Seed Production Technologies

Policy makers acknowledges that seed security is pivotal for global food security. This is because seeds serves as the primary farm input in crop production and is also a means for conveying agricultural innovations to the farmers. Forasmuch as seeds are among the main factors that impediment crop production, these seeds must therefore be in good quality by the time they are distributed to the farmers. Actually availability, accessibility, and use of quality seeds that are adapted are of essence in increasing agricultural productivity and improving farmers livelihoods.

For clean seed production of root and tuber crops, cases reviewed encouraged seed stakeholders to emerge as permanent seed producers (Bentley et al. 2018). This would enable clean seed to flow through the value chain constantly. Methods of clean seed production include:

(a) Commercial farms being contracted for one season, even though the method has demonstrated that it is labor intensive, it is susceptible to pests and diseases, and it is time consuming.

#### Nutrient Use Efficiency (NUE)

Nutrient use efficiency indicates the ability of crops to take up and utilize nutrients for yield. The concept entails three major processes in plants: uptake, assimilation, and utilization of nutrients. The nutrient uptake and fertilizer recommendation of important root and tuber crops are presented in Table 4. This is an indicator that root and tuber crops have a higher NUE. This is support by Nieto, C. O. (2016) who

Table 4 Nutrient uptake and fertilizer recommendation of important root and tuber crops

Source: Mohan Kumar et al. (2000)

reported that NUE of potatoes under low nitrogen input was higher than under high nitrogen input, and higher for late cultivars than for early cultivars.

#### Conclusion

There is an urgent need to broaden the food basket of the Sub-Saharan Africa by supporting root and tuber crops cultivation through boosting their capacity to adapt to climate change. Even though these crops have been neglected, there is evidence that the crops have greater adaptability to extreme climatic conditions and that they are more resilient to both biotic and abiotic stresses. Therefore, the suggested innovations and/or adaptation measures will help in enhancing their adaptability to climate change and also to enable them to produce more harvestable yields where major crops have failed.

#### References

Purseglove W (1975) Tropical crop monocotyledonous. Longman Group, Britain

Wiyo A, Kasomekerab M, Feyen J (1999) Effect of tied-ridging on soil water status of a maize crop under Malawi conditions. Agric Water Manag 45(2000):101–121

Woolfe A (1992) Sweet potato, an untapped food resource. Cambridge University Press, Cambridge, UK

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# Farmers' Adaptive Capacity to Climate Change in Africa: Small-Scale Farmers in Cameroon

Nyong Princely Awazi, Martin Ngankam Tchamba, Lucie Felicite Temgoua, and Marie-Louise Tientcheu-Avana

## Contents

This chapter was previously published non-open access with exclusive rights reserved by the Publisher. It has been changed retrospectively to open access under a CC BY 4.0 license and the copyright holder is "The Author(s)". For further details, please see the license information at the end of the chapter.

N. P. Awazi (\*) · M. N. Tchamba · L. F. Temgoua · M.-L. Tientcheu-Avana Department of Forestry, Faculty of Agronomy and Agricultural Sciences, University of Dschang, Dschang, Cameroon

#### Abstract

Small-scale farmers' limited adaptive capacity confronted with the adversities of climate change is a major call for concern considering that small-scale farms feed over half of the world's population. In this light, small-scale farmers' adaptive choices and adaptive capacity to climate change were assessed. Data were collected from primary and secondary sources using a mixed research approach. Findings revealed that extreme weather events have been recurrent and small-scale farmers perceived access to land, household income, and the planting of trees/shrubs on farms (agroforestry) as the main factors influencing their capacity to adapt to climate change. Agroforestry and monoculture practices were the main adaptive choices of small-scale farmers confronted with climate change. T-test and chi-square test statistics revealed a strong non-causeeffect relationship ( p < 0.001) between small-scale farmers' capacity to adapt to climate change and different socio-economic, institutional, and environmental variables. Parameter estimates of the binomial logistic regression model indicated the existence of a strong direct cause-effect relationship ( p < 0.05) between small-scale farmers' capacity to adapt to climate change and access to credit, household income, number of farms, access to information, and access to land, indicating that these variables enhance small-scale farmers' capacity to adapt to climate change. It is recommended that policy makers examine the adaptive choices and determinants of farmers' adaptive capacity unearthed in this chapter when formulating policies geared towards enhancing small-scale farmers' capacity to adapt to climate change.

#### Keywords

Climate change · Small-scale · Farmers · Adaptive capacity · Africa · Cameroon

#### Introduction

#### Background of the Study

The fight against climate change features prominently among the seventeen (17) United Nations Sustainable Development Goals (SDGs) – 2030 Agenda, demonstrating the desire of the global policy making community to tackle climate change, one of the foremost existential threats facing humanity today, head-on (IPCC 2018; Chanana-Nag and Aggarwal 2018; Niles and Salerno 2018). This comes in the wake of unprecedented levels of global warming caused mainly by increasing concentrations of carbon dioxide, methane, nitrous oxides, and other greenhouse gases (GHGs) in the atmosphere (Aggarwal et al. 2015; IPCC 2018). Anthropogenic activities especially excessive fossil fuel combustion, deforestation, and degradation of tropical forests have been singled out as the principal causes of the increasing emissions of greenhouse gases into the atmosphere (Biermann 2007; IPCC 2007; The Royal Society 2010; NAS and RS 2014). With the present climatic variations and changes, humanity has just two choices: adaptation and/or mitigation. With mitigation being a long-term option, adaptation becomes incumbent for different sectors of economic life especially the agricultural sector (Adger et al. 2007; Challinor and Wheeler 2008; Challinor 2009; World Bank 2013; FAO et al. 2018). With the most vulnerable actors in the agricultural sector being small-scale farmers, there is absolute necessity to promote measures that foster adaptation and enhance adaptive capacity to the adversities of climate change.

 In 2016, studies demonstrated that small-scale farmers will be adversely affected by changes in climate patterns owing to their limited adaptive capacity (FAO 2016). Small-scale farmers' limited adaptive capacity when confronted with the adversities of climate change is a major call for concern considering that small-scale farmers – who in the majority are found in developing countries – contribute to the nourishment of over half of the world's population (FAO 2016). It is estimated that the developing world has roughly 500 million smallscale farms supporting about two billion people, and these small farms produce about 80% of the food consumed in Asia and sub-Saharan Africa (IFAD 2012). With the number of small-scale farms across the developing world rising (FAO 2010a, b; IPCC 2014; FAO et al. 2018), it becomes necessary to examine the capacity of smallscale farmers to adapt to climate change adversities and to examine the factors influencing the capacity of small-scale farmers to adapt to the negative effects of climate change.

Cameroon like other developing countries is dominated by food-based agricultural systems. These food-based farming systems owned in the majority by smallscale farmers (who constitute over 90% of the farming population) have been adversely affected by climate change (Molua 2006, 2008; Tingem et al. 2009; Azibo and Kimengsi 2015; Awazi 2018). Small-scale farmers' capacity to adapt to climate change could be enhanced if human, material, logistic, and financial resources are placed at their disposal (Molua 2008; Azibo et al. 2016; Innocent et al. 2016). From this perspective, this chapter sought to assess small-scale farmers' adaptive choices and the determinants of small-scale farmers' capacity to adapt to climate change, in the hope that the findings will go a long way to influence policy and alleviate the plight of small-scale farmers.

#### Review of Literature

#### Perceptions of Climate Change by Small-Scale Farmers in Africa

Africa's small-scale farmers are increasingly perceptive of climate change, although their perceptions vary on a country-by-country basis as shown by different studies carried out in Africa. In a study carried out by Belaineh et al. (2013) in the Doba District, West Hararghe, Ethiopia, it was found that all male-headed and femaleheaded households perceived the occurrence of climate change. Boissière et al. (2013) on the contrary, in a study carried out in Indonesia – the tropical forests of Papua – found that the local population's perceptions of adverse climatic variations and changes differed significantly across the studied villages. They concluded that these differences in perception of climate change could be due to the different agroecological conditions of the villages. Mtambanengwe et al. (2012) on their part found respondents unanimous that the total quantity of rainfall had declined. The findings of Mtambanengwe et al. (2012) corroborate those of De Wit (2006) and Anderson (2007) who revealed that Southern Africa is becoming increasingly drier, threatening agricultural sustainability, as rainfall distribution within the season fluctuates tremendously.

Maddison (2006), however, found that Zimbabwe's small-scale farmers' perception of climate change varied with respect to the number of years of experience in farming. According to Maddison, small-scale farmers with more than 20 years of experience in farming were more likely to notice significant changes in normal weather patterns compared to their less experienced counterparts. This is corroborated by Mtambanengwe et al. (2012) who also found that 3–4% of small-scale farmers who claimed not to have noticed any shift in climate in the two communities studied in Zimbabwe were young farmers or farmers mostly involved in off-farm activities.

In a study undertaken in South Africa, Benhin (2006) found that about 72% of farmers sampled were of the opinion that climate change has been occurring over the years, with delays in the timing of the rain, a drastic drop in the quantity of rain, and higher temperatures. The farmers' perceptions, however, varied slightly across the nine provinces in which the study was carried out. In the semiarid areas of Tanzania, Mary and Majule (2009) found that 63.8% of farmers sampled in Kamenyanga village and 73.8% of farmers sampled in Kintinku village perceived an increase in temperature. Farmers reported that the months of September to December were becoming extremely hot and the nights were generally becoming very cold. It was also found that most of the farmers sampled perceived a decrease in precipitation and changes in onset of rains as well as an increase in drought frequency in Kamenyanga and Kintinku districts, respectively. Most of the farmers stated that the onset of rainfall has changed because crops were usually planted in the months of October/ November but lately crops are being planted in the months of December/January.

In a study undertaken in eleven (11) African countries, Maddison (2006) found that a large majority of farmers believed that precipitation is declining and temperature is on the rise. Majule et al. (2008) also reported similar findings. Tessema et al. (2013) in a study undertaken in the East Hararghe zone of Ethiopia found that farmers' perceptions differ with respect to changes in precipitation and temperature. A large majority (91.2%) of the farmers perceived a rise in temperature, whereas 3.5% and 5.3% of the farmers perceived a decrease in temperature and no change, respectively. Most of the farmers (90.3%) perceived a drop in the quantity of precipitation; meanwhile 2.6% and 6.2% of the farmers perceived an increase in the quantity of precipitation and no change, respectively. Only a small percentage (0.9%) of the farmers indicated that precipitation is variable rather than agreeing either on an increase or decrease in the quantity of rainfall.

In the same line of thought, studies undertaken across different parts of Africa have shown that small-scale farmers perceive climate change through variations in climate elements. Studies undertaken by Ishaya and Abaje (2008) in Kaduna state, Nigeria; Gbetibouo (2009) in the Limpopo Basin of South Africa; Mertz et al. (2009) in the Rural Sahel; Deressa et al. (2011) in the Nile Basin of Ethiopia; Nyanga et al. (2011) in Zambia; Nzeadibe et al. (2012) in the Niger Delta Region of Nigeria; Tambo and Abdoulaye (2012) in Nigeria; Yaro (2013) in Ghana; Juana et al. (2013) in sub-Saharan Africa (synthesis of empirical studies); Temesgen et al. (2014) in Ethiopia; Mulenga and Wineman (2014) in Zambia; and Aggarwal et al. (2015) in the Kullu District of the western Himalayan region all found that small-scale farmers were increasingly perceptive of climate change. Based on the findings of all these studies, a conclusion could be drawn to the effect that small-scale farmers' perceptions of climate change are quasi-unanimous across Africa.

#### Adverse Effects of Climate Change on Africa's Small-Scale Farmers

Africa's small-scale farmers are increasingly being affected by climate change. Scholarship indicates that climate change has mainly adverse effects on Africa's small-scale farming communities. In a study carried out in Kenya, Herrero et al. (2010) found that climate change adversely affected small-scale farmers through recurrent droughts. Mary and Majule (2009) carried out a study in Tanzania, revealing that the recurrence of extreme climate events (changing rainfall and temperature patterns) led to increased risk of crop failure owing to the washing away of seeds and crops, stunted growth, poor seed germination, and withering of crops. It was equally found that, in the case of livestock, variations in rainfall patterns (decreased rainfall–drought and increased rainfall–floods) led to a decrease in pasture and an increase in parasites and diseases. Similar findings have been reported by other studies carried out in Africa. Mortimore and Adams (2001), for example, found that the timing of the onset of the first rains and other intra-seasonal factors such as the effectiveness of the rains in each precipitation, and the distribution and length of the period of rain during the growing season, seriously affect cropplanting regimes as well as the effectiveness and success of farming. According to the IPCC (2007), changes in rainfall patterns and the quantity of rainfall affect soil moisture and the rate soil erosion, both prerequisites for crop growth and crop yields. All these negatively affect small-scale farmers.

In a study assessing the economic impact of climate change on agriculture in Cameroon, Molua and Lambi (2006) found that as temperature increases, and precipitation decreases, net revenue dropped across all the surveyed farms. The study equally revealed that an increase in temperature by 2.5 °C will lead to a drop in net revenues from agriculture in Cameroon by \$0.5 billion. A 5 °C increase in temperature on its part will lead to a drop in net revenues by \$1.7 billion. A 7% decrease in precipitation will lead to a drop in net revenues by \$1.96 billion, and a 14% decrease in precipitation will lead to a drop in net revenues from crops by \$3.8 billion. The study, however, found that increases in precipitation will lead to an increase in net revenues. Based on these findings, small-scale farmers in Cameroon will be adversely affected by climate change through a fall in farm revenue.

On their part, Tabi et al. (2012), in a study carried out in the Volta region of Ghana, found that climate change adversely affects rice farmers. These adverse effects were death of animals, loss of farming capital, heat stress, increase in social vices, shortage of water, slow development, and increased poverty and food insecurity. From these findings and those of other studies aforementioned, it could be said that climate change has mainly adverse or negative effects on small-scale farmers in Africa.

#### Drivers of Small-Scale Farmers' Vulnerability to Climate Change in Africa

In the face of climate change adversities, small-scale farmers in Africa are the most vulnerable actors involved in the agricultural sector (Rurinda 2014). Small-scale farmers' vulnerability to climate change adversities could be attributed to several factors. In a study carried out to examine the vulnerability of small-scale farming systems of Zimbabwe to climate change, Rurinda (2014) and Rurinda et al. (2014) found that the main causes or sources of vulnerability of small-scale farmers to climate change were lack of knowledge, lack of draught power, increased rainfall variability, lack of seed, lack of fertilizer, and declining soil fertility. Following Rurinda's findings, the single most important source or cause of small-scale farmers' vulnerability to climate change was increasing variability in rainfall.

In a study assessing rice farming in the Volta region of Ghana, Tabi et al. (2012) showed that the main sources or causes of rice farmers' vulnerability to climate change were low price of rice in the local market, difficult land tenure system, limited or no access to credit facilities, few farmers engaged in off-farm activities, poor soils, and lack of insurance in times of crop failure.

The CDCCP (2009), in a study undertaken in the Chiredzi district of Zimbabwe, found that the main causes of small-scale farmers' vulnerability to climate change were as follows: poor farming practices, high frequency of drought, inherent dryness, limited use of climate early warning systems, over-dependence on monocropping especially maize, high incidence of poverty, population pressure, skewed ownership and access to drylands' livelihood assets such as livestock and wildlife, lack of drought preparedness plans, limited alternative livelihood options outside agriculture, and low access to technology (irrigation, seed), markets, institutions, and infrastructure (poor roads, bridges, modern energy, dams and water conveyance).

These findings therefore demonstrate that small-scale farmers in Africa are highly vulnerable to the adverse effects of climate change.

#### Adaptation Options Implemented by Small-Scale Farmers in Africa Confronted with Climate Change

In Africa, small-scale farmers have adopted different adaptive options in order to improve their adaptive capacity confronted with climate change. Tabi et al. (2012) while assessing rice farming in the Volta region of Ghana found that rain-fed lowland rice farmers practiced different adaptive choices among which were the application of fertilizers, water management control practices, alternation of planting dates, herbicide use, and the use of high-yielding and disease-resistant varieties. On their part, Kuwornu et al. (2013) in a study carried out in northern Ghana found that smallscale farmers adopted both indigenous and introduced (modern) adaptive options to improve their adaptive capacity to climate change.

Molua and Lambi (2006), in a study undertaken in Cameroon, found that the main indigenous adaptation strategies implemented by small-scale farmers in the face of climate change were changing timing of farming operations, increasing planting space, undertaking traditional and religious ceremonies, change of crops, varying area cultivated, and cultivation of short season local varieties. The FAO (2006) found that the major indigenous adaptation strategies practiced by small-scale farmers were reducing food intake, change of crops, reducing personal expenditures, mortgaging land, homestead gardening, disposing of productive harvests, and re-sowing or replanting.

Different authors have carried out studies across Africa with varying findings as far as indigenous adaptive choices implemented by small-scale farmers confronted with climate change adversities are concerned. For example, studies carried out by Hassan and Nhemachena (2008), the FAO (2008, 2009b), Gbetibouo (2009), and Deressa et al. (2010) showed that diversification of crops is a major indigenous strategy practiced by small-scale farmers confronted with climate change adversities. Studies carried out by Easterling et al. (2007), Boko et al. (2007), Gbetibouo (2009), the FAO (2009a, 2010c), and Deressa et al. (2010) showed that the integration of livestock to crop production is a key indigenous strategy practiced by small-scale farmers confronted with climate change. Studies undertaken by Molua and Lambi (2006), Easterling et al. (2007), Boko et al. (2007), Hassan and Nhemachena (2008), Gbetibouo (2009), and the FAO (2009b) revealed that changing the timing of farm operations is one of the most important indigenous strategies adopted by small-scale farmers in the face of climate change. The FAO (2006, 2009b), Molua and Lambi (2006), and Gbetibouo (2009) found that changing of crops was a major adaptation strategy used by small-scale farmers to adapt to climate change. The FAO (2006) and Altieri and Koohafkan (2008) found that home gardening was a major indigenous strategy practiced by smallscale farmers confronted with climate change adversities.

The FAO (2010a), Thorlakson (2011), Rao et al. (2011), Mbow et al. (2013), Bishaw et al. (2013), Mbow et al. (2014), Kabir et al. (2015) and Awazi and Tchamba (2019), found that agroforestry practices like scattered trees on croplands, improved fallows, home gardens, and cocoa, coffee, and banana agroforests were sustainable and climate-smart adaptive choices practiced by small-scale farmers across Africa in the face of climate change.

From the foregoing, small-scale farmers are adopting both indigenous and introduced adaptive measures to adapt to the adverse effects of climate change across Africa. However, very little has been done to assess the adaptive capacity of smallscale farmers in the face of climate change.

#### Determinants of Small-Scale Farmers' Choice of Adaptive Measures Confronted with Climate Change