An important aspect of CaSa-compost is its comparatively high nutrient content (Krause et al. 2015). Contents of Ptot and Nmin, for example, are about three times higher in CaSa-compost than in Karagwe standard compost (ibid.). My findings are supported by considerable Ptot and Nmin concentrations in composts blended with faeces, as compared to compost without the addition of faeces, as per another experiment I took part in (Krause and Klomfaß 2015). Given that faeces are characterised by significantly higher P content than, for example, grass cuttings or kitchen waste (cf. Krause and Rotter 2018), the remarkably high P content in CaSa-compost can be attributed to co-composted human faeces. My model-based analysis shows that human faeces contribute about one-quarter of the P contained in CaSa-compost (ibid.). In view of the fact that P scarcity is a major soil constraint threatening farmers in Karagwe, this is a highly significant and beneficial aspect of utilising human faeces in agriculture.

#### **Faecal Compost Increases Crop Growth, but Its Use Is Not Recommended for All Crops**

In the field experiment, I tested the viability of CaSa-compost to effectively increase biomass growth and yields for maize, beans, cabbage, onion and carrots (Krause et al. 2016). The benefits observed for CaSa-compost, which uses locally available nutrients, match those of significantly higher inputs of synthetic N fertiliser. Likewise, Andreev et al. (2016) have observed a higher increase in maize grain yields when using faecal-biochar compost, in comparison to synthetic fertilisers or animal manure, in Moldova. Consequently, maize plants grown in soil amended with faecal matter-blended compost take up significantly larger amounts of P and N than plants grown using standard compost (Krause et al. 2016; Krause and Klomfaß 2015). Adequate concentrations of those macronutrients can, therefore, be found in plant tissue and seeds (ibid.). Meanwhile, composts which contain human faeces should, in general, not be used for crops which grow underground, such as for onion, carrots, beetroot, potatoes, etc. (e.g. Richert et al. 2010). Nonetheless, as shown in the field trial, CaSa-compost was especially beneficial for cultivating maize and beans (Krause et al. 2016). The demo plots of MAVUNO further indicate the appropriateness of CaSa-compost for growing tomatoes.

#### **Human Excreta Can Alternatively Be Used for Growing Perennial Crops or for Reforestation**

If the use of human excreta for the production of annual crops is undesirable for farmers, there are other options for its agricultural use. For example, faecal compost could be applied to fields used for growing bamboo, fodder grasses such as elephant grass (*Pennisetum purpureum*, *Miscanthus fuscus* or *Miscanthus violaceus*) or other grasses, which can be used as a fodder or energy crop. Another option for utilising human excreta is for growing bananas in shambas. This practice is called omushote in Swahili and was common in Karagwe until pit latrines were installed in the region through 'development cooperations' in the 1940s (Rugalema et al. 1994). It would be possible to adapt this method to modern practice in the following way. Faeces are first collected in a double-vault UDDT and then pre-composted inside the toilet for a period lasting from several weeks to months. Pre-composted solids are then applied, on rotational basis, to planting holes for banana plant cuttings. Similarly, faeces may be applied to the planting holes for trees, including fruit trees and trees for use as firewood or timber. To avoid transmission of diseases through direct contact or through flies, the hole needs to be covered ultimately with a layer of soil of about 30–50 cm in depth. Such reforestation could, for example, be realised on remote fields in the vicinity of settlements and thereby contribute to ameliorating degraded soils in these areas.

#### **Mixing Human Faeces with Other Organic Matter Ensures Adequate Composting**

However, when faeces are employed for composting, they should always be mixed with other kinds of organic residues, such as kitchen waste, harvest residues and also biochar or ashes. The aim of this is to sustain a well-functioning composting process with a balanced mixture of (1) C- and nutrient-rich material, (2) fractions of easily degradable organics and of stable matter suitable for humification and (3) dry and wet matter (e.g. Amlinger et al. 2008; Heinonen-Tanski and van Wijk-Sijbesma 2005; Niwagaba et al. 2009).

#### *5.4 Utilising Urine as Fertiliser and Compost Additive*

I identified the following potential opportunities and challenges for the practical use of urine in agriculture.

#### **Different Means of Treating Urine Prior to Application to Reduce Odour**

It is likely that the most common method of using urine is as a liquid fertiliser diluted with water (Richert et al.2010). Urine is diluted mainly (1) to avoid excessive application of urine and (2) to reduce odour. If urine is used undiluted, Richert et al. recommend applying it to a furrow or hole and closing the furrow/hole with soil thereafter. This can reduce odour and N losses through sub-surface volatilisation. Lactic acid fermentation of urine is another option to reduce odour (e.g. Andreev et al. 2017). During the fermentation process, the lactic acid produced inhibits urease and, thus, also inhibits the formation of ammonia, whilst still conserving urea (ibid.). In practice, the lactic acid bacterial inoculum should be added to the empty urine storage tank of the UDDT before urine collection starts (ibid.). This increases the efficiency of lactic acid fermentation. Another approach to using urine as a fertiliser is the addition of magnesium oxide to stored urine, which results in a crystalline product called 'struvite', or magnesium ammonium phosphate (MAP) (Winker et al. 2011).

#### **Fertilising with Urine, in General, Promotes Plant Growth**

The beneficial effects of using urine as fertiliser have often been demonstrated (e.g. Andersson 2015; Esrey et al. 2001; Richert et al. 2010; Schönning and Stenström 2004). Arnold and Schmidt (2012) found that both treatments, stored urine and struvite, show equally good fertilising characteristics and are thus valid substitutes to synthetic fertiliser for cultivating maize, beans, summer wheat or *Miscanthus*. When testing the use of urine specifically for Karagwe (Krause et al. 2016), the urine's qualities as a fertiliser were altered inside the UDDT by passing it through a deodoriser block in the urinal. For this reason, the true benefit of urine fertilisation was not easy to gauge in our experiment.

#### **Adding Urine Maintains a Well-Functioning Composting Process**

The benefits of adding urine to compost identified in this study are as follows: (1) urine contributes to moisture levels in the mixture; (2) urine enriches the compost product with N and P; and (3) adding urine to compost can reduce workload for farmers. In regard to the first point, practical experience from the CaSa case study showed that adding urine to the compost pit was highly effective in order to avoid the matter drying out in local climate conditions in Karagwe. As water is scarce in the region, utilising urine solves this problem without the need for extra (fresh) water. To maintain a well-functioning composting process and to minimise NH3 and N2O emissions from the process, Amlinger et al. (2008) recommend a stable moisture content in the mixture of between 50% and 60% of the total fresh matter. In regard to the second point, to maintain a fast and odourless process and also to minimise GHG emissions, C and N in the compost mixture should be in the range of 25–35 (i.e. C/N ratio) (ibid.). The optimal C/N range is determined by the needs of microorganisms, which require proportional content of C as an energy carrier and N for proteins (Finck 2007). Most materials added to compost tend to be rather rich in C, and so the C/N ratio of the resulting compost is often too high (ibid.), which slows down the process. According to my model, the C/N ratio in Karagwe standard compost is about 43 and in CaSa-compost about 38 (Krause and Rotter 2018). Hence, the C/N ratio in CaSa-compost is lower and therefore more proportional, presumably due to N input from urine. In regard to the third point, using urineblended compost can avoid an additional work step, when compared to applying compost prior to sowing or planting and then adding urine separately during plant growth.

#### **Enhancing Compost with Urine Potentially Decreases the Efficiency of N Recovery**

With regard to the overall efficiency of N recovery, I found that, theoretically, the N-recovery potential is higher for the direct field application of urine than for its use as a compost additive, with approximately 70% and 55% of total N recovered, respectively (Krause and Rotter 2018). From a practitioner's perspective, there is, thus, a trade-off between optimising the efficiency of N recovery, improving the composting process and managing or reducing workload. Finally, since biochar can capture NO3 and PO4 3- (cf. Sect.4.2), the combined use of urine and biochar for composting also has the potential to reduce nutrient loss during, and after, composting and thus to positively affect the turnover of N and P and to make the practice of blending compost with urine more effective.

#### **Factors Surrounding Pharmaceuticals and Hormones in Urine Are, as yet, Largely Unstudied**

Finally, there are existing challenges in relation to 'health and hygiene' that relate to unknowns and uncertainties about 'organic micropollutants' (OMPs) contained in human excreta, such as pharmaceuticals, hormones, etc. Most OMPs are contained in urine, whilst faeces contain the larger part of pathogens (Richert et al. 2010). The eventual fate of these hazardous substances and the risk they pose to local populations is an important issue, which is, however, neither especially relevant to Karagwe nor specifically related to EcoSan. To the best of my knowledge, it is still unclear on a global scale how we will deal sustainably with different OMPs that we continuously and increasingly emit into the ecosystem. OMPs are also released into the environment through water toilets and pit latrines (e.g. Ngumba et al. 2016), most often in an uncontrolled manner and without any further treatment. Similarly, little is known about methods to eliminate OMPs in the environment, the prevalence of OMPs in the soil, their uptake by plants, further consequences for human health through consumption, the eco-toxicity of metabolisms, etc. It is certain, however, that simply storing urine is not sufficient to completely remove pharmaceuticals from urine. Struvite, meanwhile, is a product free of pharmaceuticals and pathogens (Schürmann et al. 2012). Furthermore, according to the WHO (2006), 'the soil system is generally better equipped than watercourses for the degradation of pharmaceutical residues'. Further to this point, Arnold (2012) observed the successful degradation of hormones in the soil. With respect to pharmaceuticals, Arnold and Schmidt (2012) demonstrated that diclofenac (painkiller), atenolol (beta blocker) and verapamil (high blood pressure treatment) are not transferred to crops when present in urine used as fertiliser. Carbamazepine (an epilepsy treatment), however, can be determined in maize grains and stalks, but in relatively low concentrations (ibid.). Furthermore, nitrification is a suitable process for removing certain pharmaceuticals, whilst filtration of urine with activated carbon is a viable way to remove all pharmaceuticals from urine (Bischel et al. 2015). However, secure disposal of used activated carbon needs to be solved.

#### **6 Conclusions**

In order to be considered 'sustainable', soil fertility management should, amongst other factors, mitigate existing soil constraints, such as nutrient depletion and soil acidity. In the contemporary context, it should also promote resilience for agriculture in the face of climate change as a local and global threat. SOM, and the restoration of SOM, is of equal importance to climate adaptation measures, as it contributes to the soil's water-holding capacity and erosion resistance. Ultimately, soil fertility management is applied in order to maintain or improve crop productivity. With respect to the potential identified for capturing residues from cooking and EcoSan for recycling-driven soil fertility management, I conclude that recovering and processing residues from smallholder households provides a significant opportunity to increase access to fertiliser and soil improvers through subsistence production. All treatments analysed are viable as substitutes for synthetic, commercial fertilisers, but CaSa-compost displays benefits over and above the alternatives. The potential of CaSa-compost for 'sustainable' soil fertility management is superior to that of standard compost, especially with respect to liming and potential SOM restoration. Biogas slurry gives inferior results in all aspects when compared to compost amendments, but especially for liming, potential SOM restoration and GHG emissions. Moreover, even when the strong P-retention characteristics of the local Andosol are

taken into consideration, further gradual increases in soil P are possible with regular applications of CaSa-compost. Both prevailing challenges for agricultural production in Karagwe – namely, P scarcity and soil acidification – can be mitigated through sufficient application rates of CaSa-compost, as the analysed case studies showed. Whether, and how, CaSa practice can also serve as a mitigation measure in relation to climate change could be the focus of future research. The demonstrated potential to increase yields is theoretically sufficient to enable food sovereignty for smallholder households, whilst the corresponding nutrient requirements are adequately compensated for by locally available residual matter. Therefore, this practical approach of recovering biochar and human excreta for soil fertility management represents an exit strategy from the vicious circle of poor soil quality and insufficient production of food crops and residual matter in the context of smallholdings in sub-Saharan Africa. Overall, my results endorse the establishment of a clear link between cooking, sanitation and agriculture and, therefore, an 'intersectional resource management' approach around the energy-sanitation-agriculture nexus. This is due to the fact that recyclable matter from energy and sanitation facilities has complementary benefits. For example, biochar from microgasifiers promotes the recycling of C for restoring SOM, whilst those residues collected from EcoSan facilities contribute to capturing nutrients for fertilisation.

#### **References**

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## **Chapter 6 Urban Waste as a Resource: The Case of the Utilisation of Organic Waste to Improve Agriculture Productivity Project in Accra, Ghana**

**Dzidzo Yirenya-Tawiah, Ted Annang, Benjamin Dankyira Ofori, Benedicta Yayra Fosu-Mensah, Elaine Tweneboah- Lawson, Richard Yeboah, Kwaku Owusu-Afriyie, Benjamin Abudey, Ted Annan, Cecilia Datsa, and Christopher Gordon**

**Abstract** Poor municipal solid waste management continues to be a daunting issue for municipal authorities in Ghana. Major cities generate 2000 tonnes of mixed municipal waste per day, of which about 80% is collected and disposed of at open dump sites and/or at the limited number of landfills available. About 60% of this waste is organic. The Utilization of Organic Waste to Improve Agricultural Productivity (UOWIAP) project sought to co-create knowledge through a privatepublic engagement for the development of organic waste value chain opportunities to sustainably manage municipal organic waste and, at the same time, improve urban farm soils and increase food productivity in the Ga-West Municipal Assembly in the Greater Accra Region of Ghana. Through the project, identified key stakeholders in the waste and agricultural sectors, such as market traders, informal waste collectors, unemployed persons, farmers, landscapers, media, agricultural extension

R. Yeboah · K. Owusu-Afriyie Management for Development FoundationTraining and Consultancy, Accra, Ghana e-mail<EMAIL_ADDRESS><EMAIL_ADDRESS>
B. Abudey Ga-West Municipal Assembly, Local Government Office, Accra, Ghana

T. Annan Ministry of Food and Agriculture, Accra, Ghana

D. Yirenya-Tawiah (\*) · T. Annang · B. D. Ofori · B. Y. Fosu-Mensah E. T. Lawson · C. Datsa · C. Gordon

Institute for Environment and Sanitation Studies, University of Ghana, Accra, Ghana e-mail<EMAIL_ADDRESS><EMAIL_ADDRESS><EMAIL_ADDRESS><EMAIL_ADDRESS><EMAIL_ADDRESS><EMAIL_ADDRESS><EMAIL_ADDRESS>
officers, Municipal Assembly officers and the general public, were engaged and made aware of sustainable organic waste management processes, including organic waste segregation from source, collection and compost production. Four formal markets were selected for the piloting of organic waste segregation from source. Interested persons were trained in organic waste collection, compost production and entrepreneurship. The lessons learned draw attention to the need for a massive effort to generate demand for compost use as this will invariably drive removal of organic waste from the unsorted waste stream.

**Keywords** Market waste · Waste to resource · Waste segregation · Community project · Compost · Pollution prevention

#### **1 Introduction**

The challenge of municipal solid waste management continues to be a daunting issue and is of global concern. Increasing population and urbanisation, and the accompanying high rate of waste generation, have engendered serious concerns regarding the attainment of the Sustainable Development Goals. According to the World Bank, the global urban population in 2012 was about 3 billion, generating about 1.3 billion tonnes of solid waste annually (Hoornweg and Bhada-Tata 2012). Waste generation in sub-Saharan Africa was estimated to be approximately 62 million tonnes annually, reflecting an average of 0.65 kg/capita/day (Hoornweg and Bhada-Tata 2012). With a projected urban population of about 4.3 billion by 2025, municipal solid waste generation is estimated to exceed 2.2 billion tonnes (Hoornweg and Bhada-Tata 2012). The estimated projections raise concerns about the anticipated exponential increase in the volume of waste that will be produced in the near future.

The end-of-pipe approach to waste management in the twentieth century can be blamed for the outcomes and the impact of waste management observed today. The release of greenhouse gas emissions from waste landfills and its effect on climate change, the burden of gastro-intestinal diseases, the indiscriminate dumping of waste especially in developing countries and the heavy financial cost of waste management have been overwhelming (Starovoytova 2018). Faced with this daunting situation, global efforts have been directed towards reversing this trend and finding sustainable approaches to waste management.

Recent global trends in city waste management have seen a focus on managing waste in a socially and environmentally acceptable manner (Vergara and Tchobanoglous 2012), to promote public health and enhance resource use efficiency. Various frameworks and concepts have been developed to guide the sustainable management of waste. Examples include the waste hierarchy framework which outlines the most preferred waste management strategies, such as waste recovery, reduction, reuse and prevention, towards the apex of the pyramid, and the unwanted methods, such as landfilling, at the base of the pyramid. Zero waste and circular economy concepts are nowadays driving the international waste management approaches.

Waste governance is also becoming regionalised (Vergara and Tchobanoglous 2012). In developed nations, where citizens produce far more waste, the waste generated is often managed formally at a municipal or regional scale. In developing nations, where citizens produce less waste, most of which is organic, a combination of formal and informal actors is often involved in the management of waste. Thus, effective waste management strategies should vary depending on the local waste characteristics, which vary with cultural, climatic and socio-economic variables and institutional capacity.

In Ghana, solid waste generation currently ranges between 0.2 and 0.8 kg/person/day, with an estimated volume of 13,500 tonnes of solid waste being produced daily nationwide (Miezah et al. 2015). The waste composition of Ghana is predominantly organic (60%), followed by plastics (14%), paper (5%), metals (3%) and glass (3%). Major cities in Ghana generate 2000 tonnes of mixed municipal waste per day, of which 80% is collected (Cofie et al. 2009). Collected waste is disposed of either by open dumping or in the few available landfills. Ghana currently has only five engineered landfills; however, most of them are dysfunctional. Accra, for example, has no landfill site; therefore, most of the waste collected from the city is taken to Kpone in Tema, a city 24 km from Accra.

In line with recent global trends, Ghana is working on promoting waste recovery for reuse and recycling. The informal sector is actively involved in this approach to waste management. Waste pickers often collect plastics, metals and cans from the municipal waste stream and sell them to recycling companies or for reuse purposes. In Ghana, there is the potential of harnessing large volumes of organics from the municipal waste stream: compost production can divert organic waste away from landfill. Compost production can create employment and revenue opportunities for the unemployed population, farmers and waste pickers who may take part in the recovery, processing and utilisation (Gabbay 2010). Nevertheless, composting as a waste management tool is only feasible in cases where there is a strong and stable demand for compost at the local level.

The Institute for Environment and Sanitation Studies at the University of Ghana, the MDF West Africa Training and Consultancy, the Ministry of Food and Agriculture (MOFA) and the Ga-West Municipal Assembly partnered, with the funding support of the Ministry of Foreign Affairs of the Netherlands, through the Netherlands Organisation for Scientific Research (NWO) and the Food and Business Applied Research Fund, to co-create knowledge and demonstrate organic waste valorisation in an urbanised location in the city of Accra. The overall goal of the UOWIAP project was to co-create knowledge in order to promote the development of organic value chain opportunities, to enhance the food security and livelihoods of the peri-urban poor in the Ga-West Municipality. The project's objectives were to:

#### **2 The Context**

The project was implemented in the Ga-West Municipality, which is located within latitudes 50°48′ north and 5°39′ north and longitudes 0°12′ west and 0°22′ west and which covers a land surface area of 299.578 km2 (Ghana Statistical Service 2014). The municipality is bordered to the north by the Akwapim South Municipality and to the south by the Ga-South Municipality. It is bordered to the north-south by the Ga-Central Municipality and to the east by the Accra Metropolitan Area and the Ga-East Municipality (Fig. 6.1).

The Ga-West Municipality has a population of about 219,800 inhabitants, made up of 51% females and 49% males. About 63% of the population is between the ages of 15 and 60 (Ghana Statistical Service 2014). The overspill of the urban

**Fig. 6.1** Map of the Ga-West Municipality showing the study areas

population into the peri-urban Greater Accra Metropolis has created severe challenges in waste management, urban agricultural productivity, land management and general socio-economic development. Population inflows into the study area, the Ga-West Municipality, have brought the population density to the unprecedented level of 711 persons/km2 , compared to the population density within the city of Accra of 90/km2 and the national density of 79/km2 (Ga-West Municipal Assembly 2010). A significant number of the population live in scattered rural settlements covering about 60% of the land area of 462 km2 . The municipality is noted for intense agricultural activities. Today, cultivated farmlands and rural neighbourhoods are gradually becoming small towns, with increasing commercial activities.

The municipality is faced with many challenges. These include farmers losing their farmlands to commercial and residential developers and sand winners. The situation has resulted in a reduced land area for farming, loss of soil fertility because of continuous cropping and increased inorganic fertiliser usage, leading to low agricultural productivity. The municipality also faces waste management challenges where volumes of uncollected municipal waste, often left in the open, are burnt amongst open-air residences or clog up natural and artificial waterways.

Agriculture remains the main occupation in the municipality, supporting around 55% of the economically active population. Within this context of declining agricultural productivity, loss of livelihoods and poor environmental sanitation in the Ga-West Municipality, there are existing opportunities to:

#### *2.1 Strategic Focus and Methods Used*

The project addressed four strategic areas:

Prior to project implementation, a baseline study was conducted to ascertain the prevailing situation regarding the profile of vulnerable groups in the municipality, waste management practices in the local markets and compost production and use in the municipality amongst farmers. Community fora were held at different levels within the municipality to create awareness of the project, to solicit community support and to seek ideas for sustainable strategies needed to facilitate its implementation and the recruitment of unemployed youth for skills training. Media coverage (television, radio and news print) of community engagement activities was also used to create awareness of the project amongst the public. Findings from the baseline study informed the project implementation direction, subjects and study markets and the selection of farms. The project implementation plan was structured as follows:

	- (a) Project implementation planning.
	- (b) Assess and receive input during various stages of project, including results dissemination.
	- (c) Knowledge co-creation sections.
	- (a) Develop curriculum and content for compost production and entrepreneurship training.
	- (b) Recruit and train the unemployed in organic waste collection and compost production.
	- (c) Conduct compost production training for farmers' groups and agricultural extension officers.
	- (d) Closely monitor farmers' progress and obstacles.
	- (a) Acquire land to use as a composting site.
	- (b) Collaborate with partners to obtain the materials and infrastructure necessary to pilot the waste collection and composting.
	- (c) Train youth on waste separation and how to educate their customers, on collection and on processing/reselling.
	- (d) Build capacity for groups to manage and maintain composting facilities, produce quality compost and appropriately price and market it.
	- (a) Conduct advocacy campaigns for waste separation from source and organic fertiliser usage.
	- (b) Develop strategies to involve local media, markets and schools in the promotion of organic foods (e.g. posters, leaflets and community FM stations).

The project was implemented for 3 years. The first year was used for sensitisation, study subject engagements, knowledge co-creation activities, developing methodologies and training, pilot testing and improvement of methodologies. In the second year training continued and field experimentation was conducted to

demonstrate the value of crops and organic waste opportunities. Feedback loops were also implemented to improve the methodologies employed. The third year was for the establishment of a small-scale business venture by the trained groups. The project was structured as a trans-disciplinary pilot study.

#### *2.2 Project Actors*

The main project actors were all located within the municipality. Different key stakeholders were involved based on the different roles they play in the development of the waste value chain. These included the governmental agency staff, such as the Environmental Health Officers, Planning Officer and Youth Employment Officer of the Municipal Assembly, the Director of the MOFA and his extension officers. Others included local community leaders, community members, market queens and leaders and traders, waste pickers and caretakers of skips for waste collection, farmer groups and individual farmers, youth groups, schools and local radio stations. External stakeholders comprised the project team from the University of Ghana and MDF West Africa Training and Consultancy, the media and the general public.

#### **3 Data Collection and Analyses**

The study design was cross-sectional and it employed the use of both quantitative and qualitative methodologies. Various methodologies were adopted and tailored for the specific components of the project. For example, in order to assess the foodinsecure in the study communities, participatory maps, focus group discussions, semi-structured individual interviews and key informant interviews were used.

A two-stage sampling technique was used. The first stage involved a purposive sampling of eight communities after reconnaissance visits to the district: this is where the researchers chose specific people who had knowledge of waste separation and composting to participate in the project. Two focus group discussions were organised in each of the selected communities, separate ones for men and women. Participants in focus group discussions were also selected voluntarily to obtain a good representation of key members within the communities. The results of the focus group discussions were important in developing the questionnaire for the individual interviews. Transect walks were organised with some community members to identify key locations within the communities, as well as settlement patterns. The second stage of data collection considered a random sampling to select the households for the interviews. According to the United Nations Food and Agriculture Organization (FAO) (2004, p. 50), households normally "comprise individuals who live in the same dwelling and who have common arrangements for basic domestic

and/or reproductive activities such as cooking and eating". In each household, the head of the household and one other adult, in most cases the wife, were interviewed.

For market surveys, three formal markets (designated sites and markets approved by the Municipal Assembly) in the municipality and one other market in a neighbouring municipality market were engaged. Visits were conducted to the neighbouring markets to identify market leaders in order to engage and observe first-hand the state of waste management in the selected site. A survey was also conducted amongst the traders to solicit their views for, and inputs to, the project. Questionnaires were also developed to assess the waste generated from the markets and the willingness of traders to engage in waste segregation. The questionnaires consisted of both open-ended questions and closed-ended questions and centred on demographics and socio-economic characteristics, solid waste management practices and willingness to segregate and pay for segregated waste to be collected.

Another survey was also carried out to assess the profile of the farmers in the municipality. Data was collected by conducting a face-to-face interview with farmers. A pre-tested structured questionnaire and an unstructured questionnaire were developed and administered to 155 farmers (four zones), to collect data on household characteristic, types of crops cultivated in the district, land size, crop yield and source of capital for farming. The sampling method used was purposive random sampling: the researchers identified specific farmers who were willing to answer the questions.

All data was entered into SPSS version 20 (SPSS, Chicago, IL, USA) and analysed using descriptive and logistic regression statistics. Actual counts and percentages were used to describe the characteristics of the sample. Inferential statistics were set at *P* < 0.05.

#### **4 Baseline Situation**

#### *4.1 Profile of Vulnerable Groups in the Municipality*

The profiling of vulnerable groups was carried out to help target groups who could be engaged in organic waste business. The study therefore sought to understand the characteristics of the vulnerable groups in the municipality. Perceived vulnerability and poverty are context-specific. In some communities, participants indicated that a poor person is one "who cannot afford three square meals a day". In some areas a person was presumed to be poor if they do not own land. Especially in rural areas, a person was deemed to be poor if they do not own their house. According to some respondents, some people cannot afford three square meals a day and cannot care for their dependents and therefore are classified as poor people. These include the unemployed, lazy, disabled, weak or aged people.

Men were perceived as being more vulnerable to poverty. Almost 48% of study subjects believed that men form the majority of poor people, as compared to women,

because men often have fewer livelihood options. In one of the study communities, everyone in the community, including the chief, classified themselves as poor. According to the participants, both the youth and the aged face similar problems because they have no lands on which to farm. Results from the interviews showed that the majority of the poor are identified to be mainly farm labourers, unemployed and beggars.

#### *4.2 Waste Management Practices in Local Markets*

A total of 108 questionnaires were administered in the three selected markets. The respondents included 88 females and 20 males. The majority of them were within the age group of 21–40 years. Most of the respondents were married. A substantial number of them (20%) had no formal education. Out of those with some form of education, the majority of them (36%) had attained middle school/junior high school level. Most of them were traders but a few (12%) were artisans who engaged in vocations such as hairdressing and sewing.

Regarding their waste management practices, the study revealed that over 90% of the interviewees dump the waste they generate into a communal skip in the markets. A few of them (7.5%) burn the waste and (0.9%) dump it indiscriminately. Those who dump at the communal skip pay to do so. The survey also revealed that only 20.8% of market women segregate their waste. Segregated wastes – mainly cassava and plantain peels – are given out for animal feed. The majority of the market traders also indicated that they have no education in waste management. Key stakeholders who were identified as being involved in market waste management included the skip supervisors, waste pickers, private service providers and market traders.

All market traders dump their mixed waste in skips provided by the Municipal Assembly. However, in two of the markets, the traders had engaged individuals who help to maintain the dump site. There was no waste dump site in the third market; as a result the traders use a communal skip placed a few metres away from the market. There was a female leading the waste dump site management in one of the markets. This woman engages young men, who support her in maintaining the dump site.

Engagement with the dumpsite managers revealed their willingness to support the project with any waste segregation effort, such as maintenance of bins for only segregated waste. However, their major challenge was the difficulty in controlling the type of waste dumped as many of the neighbouring households do not have toilets. After several consultations with stakeholders, it came out clearly that to achieve success in the area of segregated waste, the market women need to find their own designated location to position bins solely for the collection of organic waste. This site should not be close to the official dumpsite, so the market women can manage the waste collection process.

#### *4.3 Farmers' Profile*

From the survey data, the majority (63.9%) of the farmers interviewed were males, with only 36.1% being female. The results show that the majority of the farmers were within the 31–60 years age group. The 51–60 years age group (30%) formed the majority, followed by the 41–50 years age group (24%) and the 31–40 years age group (23%), with farmers above 70 years forming the smallest age group, at 2%. The majority of the farmers had no formal education (34.2%), with most of them having a basic school level of education. Only 15% of them had a secondary education. Larger part of farmers within the municipality rent (32%) and lease (32%) their farmlands. Another 31% of respondents indicated that they inherited their land; 4% reported that they clear freely available lands, whilst only 1% indicated that they bought their land strictly for farming (Fig. 6.2). When questions about the number of years allowed to cultivate on rented lands were posed, the majority (47%) of respondents indicated that they are allowed to cultivate on the land for more than 5 years, whilst 35% indicated that they are allowed to cultivate for 1–2 years; the smallest group (18%) said that they are allowed to cultivate for between 3 and 4 years.

Generally, farmlands are small and fragmented. Cumulatively, the majority (35%) of the farmers have between 4000 and 8100 m2 of farmlands, followed by farm size of 12,000 and 16,200 m2 (29%). Only 6% of the respondents indicated that they have farms sized <4000 m2 (Fig. 6.3).

#### **UOWIAP Field Work Progress Report 2016**

Most farmers (36.1%) cultivate at least two crops in a year, whilst 33% indicated that they cultivate three crops per season. Only 2.5% of farmers cultivate more than five different crops per season, whilst 5.1% and 22.5% produce one and four crops per season, respectively. From the survey, the major crops/vegetables cultivated in the area are maize (*Zea mays*), pineapple (*Ananas comosus*), okra (*Abelmoschus esculentus*), cassava (*Manihot esculenta*), tomatoes (*Solanum lycopersicum*), pepper (*Capsicum*), garden eggs (*Solanum melongena*), lettuce (*Lactuca sativa*) and cabbage (*Brassica oleracea* var. *capitata*).

#### *Farmers' Knowledge and Utilisation of Compost*

When the question of the use of compost was posed to farmers, it was found that only 12% of them acknowledged its use. More than a half of the farmers (63%) indicated that they do not use any form of organic fertiliser on their farms, whilst 37.4% indicated that they apply some form of organic manure, which is mainly animal droppings. Danso et al. (2006) earlier reported that very few urban farmers in Ghana make use of compost.

Surprisingly, the municipality is home to one of the largest compost manufacturing companies in Accra, yet its patronage by the farmers remains low. Composting at the small-scale level is non-existent in the municipality. The willingness of farmers to use compost observed in this study reveals that the Ga-West Municipality has the potential to be a major compost hub, in both production and utilisation. Many of the farmers interviewed complained about the loss of soil fertility and acknowledged the fact that compost is likely to improve their soil quality. However, when presented with a maximum price scenario, this study found a variation in the willingness to buy. Since most farmers are producing on less than 18,000m2 farm plots, it is not surprising that they expressed an unwillingness to pay anything above a GH¢ 40.00 (about 8 USD – at an exchange rate of 1 USD to 4.9 GH¢) for 50 kg. Doing so would increase their cost of farming and, inevitably, produce a perceived reduction in their profit margins. The lack of experience with compost or previous exposure to compost use could also account for the reservation in committing much money to it, because of the fear of not getting the expected income from using compost. Cofie et al. (2009) also identified the lack of a ready market as one of the major constraints to the successful operation of composting projects.

#### *4.4 Public Views on Compost-Grown Foods*

The success of organic agriculture, and by extension compost use, depends to a large extent on consumer demand (Bonti-Ankomah and Yiridoe 2006). This study revealed that all consumers were willing to buy compost-grown crops. These decisions were based on the assumption that organic crops taste better and are preferred, health-wise, to those grown with inorganic fertiliser. This supports the conclusion of Bonti-Ankomah and Yiridoe (2006) that consumer preference for organic crops is

influenced by inherent product characteristics, such as the taste and appearance of the product.

About 73% of the youth in the municipality were willing to go into composting as a source of income. Analysis revealed that the need for income and composting knowledge were factors that significantly influenced the decision to go into composting. It is expected that the monetary benefit of composting would be a motivating factor that would draw people to composting, including those already engaged in some other forms of economic activity. It is therefore reasonable for the aforementioned percentage of the respondents to express a willingness to go into composting as an economic venture, even when 49% were already economically active.

Knowledge of the composting process, as a factor influencing the decision to go into composting, is significant, considering the observation that there was no previous knowledge of composting amongst the participants of the study. This confirms the study by Nartey (2013) that people are willing to go into composting when they are equipped with the necessary training. The labour required during composting, the duration of composting and the space for composting are identified as factors that are likely to deter youth from going into composting. Since income is a significant factor in the decision to go into composting, the lengthy composting period and the labour-intensive nature of the process will deter people from engaging in it. Also, space for composting is a likely deterring factor due to the likely hostile reaction of neighbours to the idea of waste being accumulated in their neighbourhood and the contentious issues normally related to land.

#### *4.5 Exploration of Business Models*

The project partner, MDF West Africa, conceptualised four business models that could potentially be implemented by the project. These models are presented in Fig. 6.4. Box 6.1 explains the money-making opportunities for the four models. In

**Fig. 6.4** Proposed business models for organic waste valorisation for unemployed youth

#### **Box 6.1 Business model options**

general, the four models differed based on the capacity of the entrepreneur (in terms of planning, organisation and funding). Option 1 explored the situation where the trained personnel could focus on promoting and collecting only segregated waste from the market and delivering to a producing plant for a fee. Whilst this was a potential option for the trainees, since there was an already existing plant, this option could not be implemented because the compost plant already had its staff and system of operation. Option 4 was also not an option to consider since it required substantial investment. Options 2 and 3 were therefore potential options that were tested with project support.

#### **5 Observations from Project Implementation**

#### *5.1 Knowledge Co-creation*

Knowledge co-creation was a key strategy employed to gain community support for the project, to facilitate implementation and to promote sustainability. The strategy was developed by the relevant actors. For instance, dealings with market traders were led by the traders' leadership, who engaged their colleagues, Municipal Assembly staff, waste pickers in the markets and waste collectors and with the project team devised their own workable strategies. Similarly, farmer engagement was based on open fora and several group meetings held with farmers and extension services of MOFA. This promoted ownership of the project and enhanced implementation process management and the acceptability of the project.

#### *5.2 Youth Engagement and Skill Training*

Youth engagement was quite challenging, even with the support of the Youth Employment Officers at the Municipal Assembly and radio and community fora. The youth were generally not interested in the waste business because it was viewed as a lower-level, dirty job, with minimum returns. They complained about stigmatisation and that the general public did not respect persons engaged in waste business, especially waste pickers.

To encourage participation, the criteria for selection were enhanced to include interested persons rather than a focus on youth. Some financial incentives were given to support trainees' travel to the training centre. In this way, the project attracted diverse groups of persons, which included some unemployed youth, retirees and persons seeking to learn skills for self-reliance. It was also interesting to observe that about 60% of those that enrolled to participate in the 3-month programme were women. Compost production trainings were also held in several communities within the municipality, with the support of project staff and the extension officers of MOFA; the main participants in these community trainings were men. Persons enrolled at the training centre undertook three modular curricula that entailed knowledge and skills learning in relation to organic waste collection, compost production and entrepreneurship (Figs. 6.5 and 6.6). The project registered a total of 65 persons who reported voluntarily to the training centre to be trained.

However, only 31 completed the training and were awarded certificates. The high dropout rate was a result of various issues. Some of the attendees thought the process was tedious, but many of them dropped out because they were not satisfied with the financial incentive given to them to support their travel to and from the training centre.

**Fig. 6.5** Trainees using tricycle for waste collection

**Fig. 6.6** Trainees undergoing compost production training

#### *5.3 Engagement of Market Traders and Waste Segregation*

With the support of the Environmental Health Officer of the municipality, the market queens took the lead in mobilising and identifying the best locations to site waste bins for temporary storage of their segregated food waste generated in the market. In one of the markets, the leaders took full responsibility for the protection and maintenance of the bins. They also made sure recalcitrant traders were not allowed to dump mixed waste into the bins. The commitment levels of the market women were impressive and within a few months of project implementation, many of the traders began to show consistency in segregating organic waste from their waste stream, though a few still remain reluctant to change their practice. The waste segregation is continuing in two of the markets, with the programme being disrupted in one of the markets due to market reconstruction and the other market dealing with leadership challenges.

#### *5.4 Farmer Engagement and Training*

Over 1750 farmers were provided with the technology for composting farm waste by the agricultural extension officers.  However, the purchase of compost by farmers is currently low. Farmer engagement and training activities were led by the agricultural extension officers. A household survey was conducted in October 2017: 175 farmers were randomly sampled from four working zones of the district office of MOFA using the purposive random sampling method, to assess farmers' perceptions of compost and its adoption level.

Almost one-third of the farmers surveyed (29%) were of the ages of 51–60 years, with only 2% of them above 70 years. The major crops cultivated by the farmers are cassava (*Manihot esculenta*), maize (*Zea mays*), garden eggs (*Solanum melongena*), pineapple (*Ananas comosus*), okra (*Abelmoschus esculentus*), tomatoes (*Solanum lycopersicum*) and pepper (*Capsicum*). The study revealed that over 80% of farmers

were aware of the benefits of the use of compost. They stated benefits such as soil moisture retention, improvement of soil nutrients and increase in crops' shelf lives, amongst others. However, out of a total of 175 farmers interviewed, only 23.4% of them have adopted and are using compost, with the majority not using it. Questions on why they were not using compost were posed to people who had not adopted compost. Analysis of the factors influencing the low compost adoption and utilisation rate by farmers revealed factors such as the labour-intensive nature of compost preparation, a general lack of interest, the use of fertiliser and a lack of water for making compost, raw materials and knowledge on compost preparation. Also, access to extension services and land size were found to significantly influence compost adoption.

#### *5.5 On-Farm Experimentation*

Two field experiments were conducted at the University of Ghana research farm to evaluate the influence of compost and nitrogen fertiliser on plant height yield and biomass of maize (*Zea mays* L.). The study area was within the coastal savannah ecological zone of Ghana. The experiments were run during the minor season in 2016 and major season in 2017. The test crop was maize (Fig. 6.7). Four concentrations of nitrogen (N) were considered with three levels of compost during the major season (Table 6.1). However in the minor season, two levels of compost were applied (0 and 4000 kg/ha). Basal application of phosphorus (P) and potassium (K) was carried out for all plots; N was split-applied to respective plots and compost was applied to respective plots. Initial soil sampling was carried out before the establishment of trail.

The experimental design was a randomised complete block design, with 12 and 8 treatments and 3 replications during the major and minor seasons, respectively. Each treatment was separated from the other with a 1 m buffer strip (alley) between plots and a 1.5 m buffer strip between replication, to prevent cross-contamination between treatments.

**Fig. 6.7** Farm experimentation

N4C2 120 6000

The results of the field experiments showed that the application of compost increased plants' growth, with a greater plant height in plots which received compost compared with those without compost application. The increase was greater during the major season compared to the minor season.

Generally speaking, nitrogen significantly (*P* < 0.05) increased the grain yield of maize up to 80 kg N/ha. Grain yield responded positively to N application, with yields ranging from 1124 kg/ha in N1C1 (control) to a maximum yield of 3651 kg/ ha in N4C3 (120 kg N/ha and 6000 kg C/ha) during the major season. There was a significant increase (*P* < 0.01) in grain yield when N was applied, irrespective of the application of compost. Significant (*P* < 0.05) interactive effects of N and compost on grain yield were also observed. Similarly, nitrogen fertiliser and compost significantly increased the total biomass accumulation. The application of 6000 kg compost increased total biomass by 28% compared to treatment without compost application. In addition, compost significantly increased the total nitrogen uptake. The logistic (logit) model was employed to analyse the data due to the nature of the variable: whether farmers perceived compost to be good and had adapted or otherwise. For such a dichotomous outcome, the logit model is the most appropriate analysis tool. The logit model considers the relationship between a binary dependent variable (compost adoption) and a set of independent variables, whether binary or continuous.

#### *5.6 The Business Model*

Based on the assumption that the trainees had received comprehensive training in waste collection, composting and entrepreneurship, Business Model 2 was selected by the first batch of trainees for experimentation. They were responsible for

**Fig. 6.8** Youth group busy sieving and bagging compost for delivery

collecting, processing and producing compost, creating awareness of the product and marketing the product. After 3 months of experimentation it was difficult for them to sell their product because the farmers who were the initial target customers were not eager to use compost, i.e. there was no demand for the compost. Based on the experience of the first batch, the second batch of trainees experimented with Option 3.

A small-scale compost production business venture was set up by a six-member group of trainees, who have taken it up as an income-generating activity (Fig. 6.8). Also, one of the trainees also set up a production unit in his home. The project provided support for the trainees by offering them tricycles on hire purchase and providing them with basic tools and technical support. To date, they have produced about 78 tonnes of compost and have sold compost worth about 2500 USD.

#### **6 Key Outcomes and Achievements**

Through the UOWIAP project, organic waste value chain opportunities have been created in the municipality, particularly amongst the public. Youth groups who engaged in the compost production and sale are enthused about the opportunities.

**Fig. 6.9** Weight of waste collected by youth group over a 6-month period between October 2017 and March 2018

Between October 2017 and March 2018, one of the groups had diverted about 62 tonnes of organic waste from landfill to compost production (Fig. 6.9).

The general feedback from clients who purchased compost was very positive. The following are examples of comments received:

The visibility of the project is also increasing as various stakeholders continue to pay visits to the project site to see the project. Visitors to the sites include a pawpaw exporters association, real estate agencies, other university units such as the West African Centre for Crop Improvement and a group of 12–15 participants of the Valorisation and Innovation in Africa (VIA Water) project from about six countries.

The fact that a few farmers have begun experimenting with compost production on their farms is a success story for the project. Farmers in the municipality have been trained on the benefits of compost use for soil health and nutrient. The project has also increased the number of farmers who have adopted compost use and production. Farm experimentation increased by between 12% and 20%.

Knowledge co-creation efforts were very helpful in strategy development, especially with the waste collection and awareness creation components of the project. The direction given by traders informed collection frequency and time and the establishment of a cordial working relationship between the youth group and the traders.

#### **7 Challenges**

Driving behavioural change towards good environmental sanitation is a complex issue that needs innovative strategies and intense stakeholder engagement to achieve success. Outlined below are some pertinent challenges faced in the implementation of the project.

#### *7.1 Stakeholder Engagement with Government Agencies*

The experience with engaging governmental agencies faced challenges, which varied from issues with project staff mobility to the business-as-usual approach to work. Within the project period, about four government agency representatives on the project were transferred to other jurisdictions and this hindered project activity continuity, especially in the area of monitoring and supervision and further engagement. Secondly, certain components of the study were to be incorporated into government staff's normal programmes of work, which also significantly delayed implementation. For instance, the Agricultural Extension Services for many months did not receive their budgetary allocations and hence on many occasions did not have funds to fuel their vehicles and motorbikes to engage in their routine jobs. The bureaucracy and the general business-as-usual approach to work within the governmental institutions also delayed processes.

#### *7.2 The Low Level of Awareness of the Value of Compost*

There were misconceptions amongst the farmers about compost value as regards soil quality. Many of the farmers considered the compost's effect on soil to be slow and did not support the fast yields expected, as with the application of chemical fertilisers. The value of compost as a soil conditioner was only marginally appreciated. The adoption of new technologies by farmers generally takes time. Likewise, the practicality of composting on farms needs further investigation. One of the major concerns raised by farmers in relation to composting is the availability of water. Farm composting can be practised during the non-farming season and this coincides with the dry season.

Because of the low level of awareness and use of compost nationwide, there is low demand for compost. Also, the limited market space for organically produced foods is a disincentive, and farmers are forced to sell at the same price as inorganic fertilised food. This situation needs to be addressed through massive campaigns (education and awareness creation) to create demand for organic foods.

#### *7.3 Practice of Non-segregation of Waste from Source*

Non-segregation is a major drawback to waste valorisation. In Ghana, the practice of waste segregation occurs on a very limited scale and the large volumes of municipal waste generated are mixed. This problem is related to the fact that municipalities have no systems in place that promote waste segregation from source and the behaviour of producing mixed waste is entrenched in many Ghanaians.

#### **8 Sustainability Pathways**

To ensure project sustainability, a strong commitment to promote waste segregation is required from the Municipal Assembly. The Municipal Assembly is responsible for waste management and has the mandate to create an enabling environment to promote the expected behaviour in order to promote sustainable waste management. They must invoke their powers to set the necessary by-laws for waste segregation from source, and they must enforce them. The Municipality Assembly engages the private sector to collect waste from the municipality and therefore can direct the private sector through contractual agreements to begin the collection and treatment of segregated waste, whilst providing the necessary support for them.

There is also a need to create demand for compost products, such as organic foods. The post-project implementation phase is ongoing, with efforts taking place to develop a national compost use campaign. Through a partnership with the University of Oregon advertising team and other stakeholders, a prototype campaign has been developed to target middle-income urban dwellers to demand organic foods. Farmer education and sensitisation to use compost is also ongoing through the MOFA extension services. The project is also working to engage further with MOFA on the government's "planting for food and jobs" initiative.

#### **9 Conclusions**

The educational and awareness programme undertaken by the project, against the backdrop of the current knowledge and experiences of the stakeholders with respect to the mounting municipal waste menace, has heightened the need to find appropriate solutions to the waste challenge. This, together with the right support for composting, would help in addressing the problem. The experiences of the project suggest the need to build the capacities of compost producers, farmers, market participants and other parties on sustainable municipal organic waste management. The following measures are necessary:

**Acknowledgements** The authors are sincerely grateful to the Ministry of Foreign Affairs of the Netherlands Government, through the Netherlands Organisation for Scientific Research (NWO-WOTRO), for funding this study. We are also thankful to all stakeholders engaged, whose contributions have impacted on the success of this project. Our sincere gratitude goes to the University of Oregon advertising faculty and students, who have partnered with the project to develop a compost campaign. Also acknowledged are the support staff of the Institute for Environment and Sanitation Studies, particularly Mr. Logosu, Mr. Lar and Mr. Acheampong, and the laboratory technicians who worked tirelessly on this project.

#### **References**

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## **Chapter 7 Organic Waste Composting at Versalles: An Alternative That Contributes to the Economic, Social and Environmental Well-Being of Stakeholders**

**Luis Fernando Marmolejo-Rebellón, Edgar Ricardo Oviedo-Ocaña, and Patricia Torres-Lozada**

**Abstract** Composting is one of the most widely used technologies for the recovery and use of organic waste from municipal solid waste (MSW); however, its implementation in some developing countries has mostly been ineffective. This chapter documents the experience of the composting of municipal organic waste in the urban area of the municipality of Versalles, Valle del Cauca, Colombia. Within the locality, composting of organic waste occurs at an MSW management plant (SWMP), after being separated at the source and selectively collected. The information presented was generated through collaborative research projects, conducted with the cooperation of Camino Verde APC (a community-based organisation providing sanitation services) and Universidad del Valle (Cali, Colombia). The evaluations undertaken show that (i) within the locality, high rates of separation, at the source, in conjunction with selective collection and efficient waste sorting and classification processes in the SWMP, have significantly facilitated the composting process; (ii) the incorporation of locally available amendment or bulking materials (e.g. star grass and cane bagasse) improves the physicochemical quality of the processed organic waste and favours development (i.e. a reduction in process time), leading to an improvement in product quality; (iii) the operation, maintenance and monitoring of the composting process can be carried out by previously trained local human talent; and (iv) revenues from the sale of the final product (compost) are not sufficient to cover the operating costs of the composting process. Despite this current lack of financial viability, the application of technology entails environmental benefits (e.g. a reduction in the generation of greenhouse gases) and social benefits (e.g.

L. F. Marmolejo-Rebellón (\*) · P. Torres-Lozada

Faculty of Engineering, Universidad del Valle, Cali, Colombia e-mail<EMAIL_ADDRESS><EMAIL_ADDRESS>
E. R. Oviedo-Ocaña

School of Civil Engineering, Universidad Industrial de Santander, Bucaramanga, Colombia e-mail<EMAIL_ADDRESS>
employment opportunities), which, given the conditions in the municipality studied, highlight the relevance of this technological option.

**Keywords** Amendment materials · Bulking materials · Selective collection · Source separation · Zero waste

#### **1 Introduction**

Composting has become one of the most popular (and frequently utilised) technologies for the recovery and use of organic waste, which is the predominant fraction of municipal solid waste (MSW) in smaller municipalities in developing countries. The main advantages over other technological options are its low cost and operational simplicity (Li et al. 2013, Sundberg and Navia 2014). In addition, compost contains nutrients which can help improve levels of soil organic matter and soil fertility status (Hargreaves et al. 2008). However, experiences in developing countries (Barreira et al. 2006, Ekelund and Nyström 2007, Organización Panamericana de la Salud (OPS) 2005, Zurbrügg et al. 2005), including studies from Colombia (Marmolejo 2011, Superintendencia de Servicios Públicos Domiciliarios 2008), show that the implementation of composting has so far been ineffective. Smaller municipalities, i.e. those with less than 15,000 inhabitants as classified by OPS (2010), present the most critical conditions, which can even lead to the generation of negative environmental and health impacts (e.g. gaseous emissions, odours and soil contamination when the product is applied), ultimately leading to the closure of composting facilities, putting investments at risk.

This chapter details the experience of organic waste management in the minor Colombian municipality of Versalles (Valle del Cauca, Colombia). The focus of the chapter is on the local community's experience, as documented, and the partnership between the company providing waste management services and the research group 'Estudio y Control de la Contaminación Ambiental' (Study and Control of Environmental Pollution) at Universidad del Valle, Cali.

This chapter includes four sections: Sect. 2 describes the municipality's location (i.e. geographic position, size, climate); Sect. 3 presents the management of the MSW within the locality (i.e. generation and composition of MSW, storage, collection and transport, recovery and recycling and final disposal in a landfill site); Sect. 4 focuses on documenting the composting experience of organic waste in the locality, highlighting the technical aspects, technical improvement strategies and the social and economic aspects related to the MSW management; and Sect. 5 presents final considerations arising from the study.

#### **2 General Aspects of the Locality**

Versalles is a Colombian municipality, located in the department of Valle del Cauca, at 1860 m above mean sea level, on the western branch of the Andes. Its geographic coordinates are latitude 4°, 34′,43′ and longitude 76°, 12′,23′. The average temperature is 18 °C, with a maximum of 24 °C and a minimum of 12 °C, and it covers an approximate area of 352 km2 , of which 246 km2 corresponds to the urban area. Versalles is approximately 205 km from Santiago de Cali, the capital of the Valle del Cauca department and Colombia's third largest city in terms of population. The municipality has an urban population of approximately 3831 inhabitants. Figure 7.1 presents the location of the municipality.

Rooted within its population, Versalles has a broad participatory culture, as reflected in events and initiatives promoting community consolidation. An example of this was the opening of an access road at the beginning of the twentieth century, which resulted from so-called 'minga' activities – an ancient tradition of collective work for the purpose of social utility. This culture was also promoted by the operation of an educational institution which offered a modality of social promotion, in which many of the social leaders, who have been promoting local development in the last 25 years, were trained.

Additionally, in the 1980s, under the leadership and guidance of initiatives such as the Committee of Community Participation in Health, the municipality advanced

**Fig. 7.1** Location of the municipality of Versalles, Valle del Cauca, Colombia

planning processes aimed at addressing urgent needs in the fields of health, education and culture, agricultural development and the environment, infrastructure and public services, business management, security and peaceful coexistence. Improvements made in these areas have earned Versalles recognition, such as the distinction of 'Healthy Municipality for Peace', awarded by the Pan American Health Organization in 1993 (Restrepo 2002).

Another example of a social scheme of local empowerment is the provision of public water, sewerage and sanitation services, provided by the Administracion Pública Cooperativa (APC) Camino Verde Company, an organisation whose board of directors consists of 51% of members from community-based organisations and 49% from the mayor's office. The internal organisation of the company with respect to both administrative and operational functions is clearly differentiated and interrelated. For example, its personnel plant is made up mainly of people from the locality, who actively participate in continuous improvement programmes promoted by the company, thereby leading to high levels of company service and user satisfaction.

#### **3 Management of MSW**

The waste management service in Versalles has a significant connotation for the country, because the management scheme is oriented towards both a reduction in MSW generation and the subsequent recovery and recycling of any MSW generated. This scheme results in the recovery of approximately 80% of all the MSW generated and, in comparison to populations with similar conditions, leads to a lower per capita generation of MSW (Marmolejo 2011). The following is a description of the waste management scheme in the locality, focusing on the recovery and use of organic waste, which is the subject of this chapter.

#### *3.1 Generation and Composition of the MSW*

In sampling and characterisation studies conducted by Erazo and Pereira (2010) and Vélez (2016), the production per capita (ppc) of MSW was estimated to be 0.29 kg/ inhabitant-day in the urban area of the town. In the first study, it was established that the ppc in the residential sector was 0.27 kg/inhabitant-day, a value similar to that found in later studies of the same locality, also focused on the residential sector (0.29 and 0.24 kg/inhabitant-day), by Pérez and Reina (2015) and Maldonado (2015), respectively. These ppc values are lower than the suggested minimum value for Colombian populations (0.30 kg/inhabitant-day) with conditions similar to those of Versalles, as documented in Title F of the 'Reglamento Técnico del Sector Agua

Potable y Saneamiento Básico' (Technical Regulations for the Drinking Water and Basic Sanitation Sector) – RAS (Ministerio de Vivienda Ciudad y Territorio 2012).

Research carried out seeking to explain this situation found that the majority of local waste management service users had a zero waste-oriented culture, associated with (i) rural cultural practices, such as the re-use of food waste (e.g. for animal feed, or as soil fertiliser); (ii) the existence of other strategies for the recovery and in situ valorisation of recyclable materials, promoted by Camino Verde APC and by educational institutions; and (iii) the establishment of 'responsible consumption' practices by some of the residents.

In relation to the physical composition of MSW, organic waste predominates, accounting for 65.8%, followed by recyclable materials, accounting for 17.2% (i.e. paper, cardboard, plastic, metals and glass), and finally, non-usable or rejects (i.e. hygienic material, sweepings and others not recyclable) that reach 17.0% of the MSW (Table 7.1). This composition is similar to that reported by Marmolejo et al. (2009) for other municipalities near to the town studied and is consistent with the trend found in other developing countries (Aalok et al. 2008; Thi et al. 2015).

#### *3.2 Storage of MSW*

Source separation of waste is a common practice in the locality, applied by a high proportion of users (i.e. varying between 60% and 90% of users). This variation is associated with factors such as (i) the discontinuity of the awareness activities developed by Camino Verde APC, which on occasion have been reduced due to budget cuts, and (ii) the hosting of large-scale community events, such as festivals and municipal parties, during which there is an influx of visitors from outside, who are unaware of the social and environmental process commitments existing in the town.

In an evaluation conducted in 2015, Cardona and Pinto (2015) found that 0.9% of residential users stored their waste in only one container, 18.5% in two and the remainder in three or more. Plastic bags, and a combination of plastic bags and containers, are the most used storage options. It is also common to find waste stored in roofed places which limit the conditions required for decomposition and therefore do not affect the quality of the stored materials. Waste is generally put out by the user at the time of the garbage truck collection, or 10 min before.

#### *3.3 Collection and Transport*

Waste is regularly collected on the curb of homes or establishments, twice a week, on Mondays and Thursdays. For each solid waste collection day, two trips are usually made to a solid waste management plant (SWMP). A dump truck is used for the collection, which has two uncovered compartments of the same size (organic waste is collected in one compartment and recyclable waste and rejects in the other). The collection is carried out by four operators, two of whom advance through the streets, whilst the other two receive and accommodate the waste in the respective compartments of the dump truck.

#### *3.4 Recovery and Recycling*

Once the collection route is concluded, the vehicle goes to the SWMP, where activities are carried out for the recovery and recycling of the MSW. The SWMP is located 1 km from the urban limits. The SWMP has an area of 1.5 hectares (ha), with slope inclination ranging between 5% and 50% (Oviedo 2015). The operating scheme of the SWMP is shown in Fig. 7.2.

The waste management in the SWMP is conducted in the following steps:

(a) Reception of materials: Includes the weighing of the loaded and unloaded collection vehicle and the emptying of the solid waste in the areas destined for recovery or temporary storage.

**Fig. 7.2** Scheme of operation of the SWMP

Figure 7.3 presents the waste stream in the locality. It can be observed that organic waste is the largest fraction that enters the SWMP (65.8%). Recyclable materials, despite representing 17.2% of the generated MSW, enter the SWMP in a smaller amount (5.0%), due to the fact that 12.2% (1.26 t/week) is being taken by local waste pickers. Of the total MSW received in the SWMP, only 17.5% is transported to the final disposal site. These yields are associated with the quality of the raw materials of the different processes, which come from source separation

**MSW generation:** 10,3 t/week

**Fig. 7.3** MSW flow in Versalles. (Source: Adapted from Erazo and Pereira 2010)

practices and selective collection of MSW, as well as efficient waste sorting and classification processes in the SWMP.

#### **4 Composting of Organic Waste**

In 2008, Camino Verde APC and Universidad del Valle established cooperation links that had the purpose of contributing to the improvement of the waste management service in the population. The evaluation of SWMP functioning was included amongst the jointly agreed priorities, and within this priority, the evaluation of vermicomposting (the organic waste transformation process applied at that time) was included, in order to comply with the regulations and standards in Colombia and to obtain the necessary approvals to market the compost product.

The evaluations conducted showed that the vermicomposting, as carried out, did not meet the necessary operation and maintenance requirements. This was reflected in the product quality analysis: the physiochemical and microbiological characteristics did not satisfy the requirements of the Colombian regulations associated with this type of material (i.e. NTC 5167) (Instituto Colombiano de Normas Técnicas y Certificación (ICONTEC) 2004, Marmolejo 2011). Additionally, the technical evaluation showed that, given the waste generation context and conditions at that time, the area of land available in the SWMP for the processing of organic waste was insufficient for vermicomposting. For these reasons, the possibility of utilising composting was evaluated and validated, and research projects were conducted jointly by Camino Verde APC and Universidad del Valle. Within the framework of these projects, technical, economic and social studies have been carried out, evaluating the improvement and sustainability of the process. The main aspects evaluated and the respective results obtained are discussed in Sect. 4.1.

#### *4.1 Technical Aspects*

Taking into account the fact that organic waste is the raw material of the composting process (substrate) and that the raw material quality is highly variable, sampling and characterisation activities were carried out to evaluate both the variability of quality and its effect on the process.

The results showed that there was a need to use co-substrates (amendment and/ or bulking materials), in order to improve both the quality of the substrate, alongside the operation and maintenance conditions, and the quality of the product. Given that the completed research sought to contribute to the sustainability of the system, it was essential that the co-substrates could be sourced from the local region, within easy reach of Camino Verde APC, in order to improve the product quality without risking the economic sustainability of the technology.

**Table 7.2** Physicochemical characteristics of organic waste composting substrates

Note: a Oviedo et al. (2015), obtained from monitoring 39 sessions in the locality under study, b on wet matter basis, c on dry matter basis

**Fig. 7.4** The compost management process of organic waste in the SWMP

#### **Substrate Conditions**

The local organic waste is characterised by a high content of food waste, with 92.9% (±4.3%) being unprocessed foods, amongst which bananas, tubers (32.6%) and citrus fruits (15.5%) are in greater proportion. This waste is characterised by having rapidly degradable organic matter that makes it complex to manage. Regarding the physicochemical composition of organic waste, it can be observed that it presents critical conditions for composting (Table 7.2), such as acid pH, excess moisture, deficiencies in total organic carbon (TOC) and total phosphorus (total P) and a lower carbon/nitrogen (C/N) ratio than that recommended at the start of composting.

#### **Process Conditions**

Figure 7.4 presents the manual composting process stages carried out in the SWMP. The waste is discharged in the organic waste area. The operators sort through the waste and extract any impurities or rejects. Then, using tools such as machetes and shovels, the size of some thick materials is reduced. Subsequently, compost piles are formed conically from the waste that enters from each collection day (i.e. Monday and Thursday).

The composting piles are operated (i.e. by manual turning and wetting) and, depending on the operator's time span availability, variables such as temperature, pH and moisture are controlled. The process takes approximately 120 days (i.e. about 90 days in active phase and 30 days in maturation). To establish when the process is complete, the operators perform visual and odour tests on the material; no

**Photo 7.2** Operational turning activities

other tests are carried out to determine the level of stability or maturity of the processed material. Finally, the material received from the maturation area of the composting process is manually sifted, packed and stored until use. Photos 7.1 and 7.2 show details of the manual composting process carried out in the study area.

#### **Product Quality**

The evaluation of product quality, as carried out in organic waste composting experiments on a pilot scale in developing countries such as Nigeria, Brazil and India (Adekunle et al. 2010; Saha et al. 2010), has shown that the composting of municipal organic waste without the use of co-substrates is characterised by high pH and ash values and limited content of TOC and nutrients such as total P, which ultimately restricts product commercialisation. Table 7.3 presents the results of two

**Photo 7.1** Area of the composting process

**Table 7.3** Evaluations of the product quality in the SWMP

Note: a Average values of three replicates, b Colombian Standard Technique referring to organic products used as soil conditioners, c MPN: most probable number

typical product quality evaluations at the SWMP and also compares the results with the values established for the use of the product as an organic amendment in the Colombian Technical Standard, NTC 5167 (ICONTEC 2004).

#### **Improvement Strategies**

Given the natural limitations of organic waste for effective composting and the necessity to obtain a final product which satisfies both the regulatory requirements and that of the user within the locality, substrate conditioning options were evaluated. The studies of Marmolejo (2011) and Oviedo et al. (2015) identified potential amendment or bulking materials, including (i) fruit harvest residues, (ii) cane bagasse (CB), (iii) star grass (SG), (iv) material in process (MP), (v) wood ashes (WA), (vi) bovine manure, (vii) pig manure and (viii) chicken faeces.

The selection criteria included the consideration of variables such as quality and quantity of required material, acquisition costs, access and distance to the site of material generation, provision for material delivery and material handling facilities. The amendment or bulking materials chosen were (i) WA, (ii) MP, (iii) BC and (iv) SG, which were evaluated in experiments on a pilot scale of organic waste composting. The evaluation processes are described as follows:

• Addition of WA (proportion of 2%, 4% and 8%): It was favourable to increase the initial pH, improve the nutrient content of the substrates and dampen the acids generated in the first phase of the process. However, it had no effect on accelerating the start of the process, and an excessive increase in pH was observed with the addition of 4% and 8% WA, which, associated with thermophilic temperatures, could cause greater total N losses. The germination tests in the products with WA showed the presence of phytotoxic agents (e.g. presence of salts) that compromised the use of the product (Oviedo et al. 2014a).

On the other hand, to counteract the high moisture content of the organic waste, the effect of the increased turning frequency in the composting process was also evaluated (i.e. six times per week during the first 4 weeks, compared to a pile with a turning frequency of twice per week; at least one flip per week was performed on each type of pile). This study showed a decrease in the processing time of 20% in

**Table 7.4** Product quality in experiments evaluating the incorporation of SG and CB

Note: a A, 34% SG + 66% organic waste; b B, 22% CB + 78% organic waste the mesophilic, thermophilic and cooling phases. However, a decrease in product nutrient content (i.e. nitrogen and phosphorus) was observed. The results also made it possible to demonstrate that control and monitoring schemes, in accordance with local conditions, can be effective in improving the performance of the process. Additionally, the results pose new research challenges, such as the joint evaluation of the effect of the increase in the turning frequency and of the addition of bulking materials (or of amendment) for the composting process and quality (Oviedo et al. 2014b).

#### *4.2 Economic and Social Aspects*

The SWMP operation and maintenance is carried out by four workers, who in turn are part of the collection crew (an activity on which they spend approximately 25% of their time). These workers are part of the Camino Verde APC hourly employee crew, and their employment relationship is carried out in strict compliance with the requirements of Colombian labour legislation. This is an aspect that represents an important added value, since the linkage with local participants in the use and valorisation of the MSW constitutes a source of formal employment in a locality that has few employment options, which is one of its biggest social problems and one of the causes of out-migration of its native population.

The implementation of composting brought with it an increase in the labour requirements, relating to monitoring, operation and maintenance activities, and therefore an increase in costs. With resources obtained through the research projects funded by the Universidad del Valle and Camino Verde APC, the four operators at the plant were trained in aspects related to the composting monitoring and operation process. When reviewing the work assignment of these workers, it was identified that they had time to support the turning and wetting, but not for the monitoring of the process, for which it was necessary to train and link an additional full-time operator (now no longer employed). For a period of time, this last operator was responsible for the monitoring and recording of temperature, pH and pile moisture. Following parameter interpretation and evaluation, the operator was required to make decisions on fundamental aspects of the process such as turning and wetting. The execution of these last activities (i.e. the turning and wetting) was/is the responsibility of the entire team of workers.

In general, because of the substrate's characteristics, during the first 5 days in which the piles are made, they have to be turned over between two to three times a week. At the same time, a space was established in the SWMP for a laboratory, in which the operator responsible for monitoring was able to perform moisture and pH determinations using field equipment facilitated by the university and was able to register information about the process. This was successful: the operator responsible for this function took the knowledge into his own hands and made correct decisions, as reflected in product quality improvement in terms of variables such as moisture, pH and C/N ratio, a decrease in offensive odours and a reduction in the

**Photo 7.4** Final product storage area

process time. Nevertheless, once the investigation project budget – financed by Universidad del Valle – had been used up, the enterprise was unable to sustain the funding of this operator, and thereafter the activity was suspended. The operators responsible for the maintenance of the plant continued with the turnover and watering, insofar as the piles were being moved (Photos 7.3 and 7.4).

In a cost evaluation of the sanitation service performed by Yusti (2017) it was estimated that the monthly cost associated with the payment of an employee's salary was \$1,134,383.00 Colombian pesos (COP) (approximately US\$384.40).

The COP monthly cost of endowment was \$15,542 (US\$5.30) and the COP provision of security elements amounted to \$58,667.00 (US\$19.90).

The cost associated with the use of supplies was \$62,333.00 COP (US\$21.10). According to this information, the monthly operation and maintenance costs of the SWMP would sum up to about \$5,083,700 COP (US\$1723.00).

The final composting product is not currently for sale, since an authorisation for use has not been requested from the competent government agency, and therefore

**Photo 7.3** Process monitoring

the product is used in internal activities at the SWMP, or for the recovery of eroded soils. In the region, the sale price of a bulk of 40 kg of compost is approximately \$8000.00 COP (US\$2.71). If the total monthly production of compost (approximately 8360 kg) were to be sold, the income would be approximately \$1,672,000.00 COP (US\$566.60). With respect to the monthly income from the sale of recovered recyclable materials, Yusti (2017) reported it was in the order of \$1,415,525.00 COP (US\$479.70). As can be observed, even if all the compost produced was marketed, the SWMP would not be financially sustainable. However, it is important to take into consideration that composting the organic waste at the SWMP reduces the costs of final disposal. Specifically, it avoids four monthly solid waste collection trips, which represent a monthly saving of \$696,000.00 COP (US\$235.80) in terms of fuel costs and tolls and \$728,295.00 COP (US\$246.8) in final disposal fee payments.

In 2017, Flórez (2017) carried out a comparison of the environmental impacts generated by the composting of organic waste in the locality, versus the shipment to final disposal at a regional landfill site, using the software SimaPro 8.0 (developed by the company PRé). Overall, Flórez found that in terms of climate change, the impact of final disposal in landfill was approximately 7.5 times that of composting, due to the negative environmental effects of the eutrophication of water (2×) and particulate material formation (5×). In accordance with the above, the use and recovery of waste generated are the most convenient strategies for the municipality of Versalles. Emphasis is placed on this result, specifically in relation to (i) a reduction in generation, (ii) separation at source, (iii) selective collection and (iv) the encouragement to use and enhance MSW.

#### **5 Final Considerations**

The integration of key elements of solid waste management, such as community participation and business development in the provision of public services, and the implementation of technologies adapted to the local context have been fundamental pillars of the experience of waste management in the urban area of Versalles.

The predominant fraction of MSW is organic waste, which has a high potential for biological treatment. However, the quality of the organic waste itself presents deficiencies for the composting process, generating products that do not meet quality standards, limiting their use and marketing. Therefore, strategies adapted to the context, such as the incorporation of amendment and bulking materials, can contribute to improving the quality of both the substrate and product, as well as process efficiency. However, it is necessary to continue to strengthen research and development on pilot-scale projects in the context of smaller populations, which can contribute sustainable improvements to the operation of organic waste composting facilities.

In spite of the difficulties of using MSW in the locality in regard to financial feasibility and in particular the valorisation of the use of organic waste, the evaluations carried out highlight the social pertinence of these options: they generate employment opportunities at the local level and reduce environmental impact. The evaluations also highlight the generation of a product that has potential in regard to supplying organic matter and nutrients to the soil in the local context.

**Acknowledgements** The authors thank Universidad del Valle, for financing the research projects; the Cooperativa de Servicios Públicos de Versalles, Camino Verde APC, for the support provided in the experimental activities; and the undergraduate and MSc students at Universidad del Valle, who participated in the projects.

#### **References**

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## **Chapter 8 Traditional and Adapted Composting Practices Applied in Smallholder Banana-Coffee-Based Farming Systems: Case Studies from Kagera and Morogoro Regions, Tanzania**

#### **Anika Reetsch, Didas Kimaro, Karl-Heinz Feger, and Kai Schwärzel**

**Abstract** In Tanzania, about 90% of the banana-coffee-based farming systems lie in the hands of smallholder farmer families. In these systems, smallholder farmers traditionally add farm waste to crop fields, making soils rich in organic matter (humus) and plant-available nutrients. Correspondingly, soils remained fertile during cultivation for over a century. Since the 1960s, the increasing demand for food and biofuels of a growing population has resulted in an overuse of these farming systems, which has occurred in tandem with deforestation, omitted fallows, declined farm size, and soil erosion. Hence, humus and nutrient contents in soils have decreased and soils gradually degraded. Inadequate use of farm waste has led to a further reduction in soil fertility, as less organic material is added to the soils for nutrient supply than is removed during harvesting. Acknowledging that the traditional use of farm waste successfully built up soil fertility over a century and has been reduced in only a few decades, we argue that traditional composting practices can play a key role in rebuilding soil fertility, if such practices are adapted to face

A. Reetsch (\*)

Institute for Integrated Management of Material Fluxes and of Resources (UNU-FLORES), Dresden, Germany

Sebastian Kolowa Memorial University, Lushoto, Tanzania e-mail<EMAIL_ADDRESS>
K. Schwärzel Thünen Institute of Forest Systems, Eberswalde, Germany e-mail<EMAIL_ADDRESS>
the modern challenges. In this chapter, we discuss two cases in Tanzania: one on the traditional use of compost in the Kagera region (Great African Rift Valley) and another about adapted practices to produce compost manure in the Morogoro region (Uluguru Mountains). Both cases refer to rainfed, smallholder banana-coffee-based farming systems. To conclude, optimised composting practices enable the replenishment of soil nutrients, increase the capacity of soils to store plant-available nutrients and water and thus, enhance soil fertility and food production in degraded banana-coffee-based farming systems. We further conclude that future research is needed on a) nutrient cycling in farms implementing different composting practices and on b) socio-economic analyses of farm households that do not successfully restore soil fertility through composting.

**Keywords** African smallholder agriculture · Banana-coffee-based farming systems · Reuse of farm waste · Composting · Soil fertility and conservation

#### **1 Introduction**

Increasing yield gaps for almost all crops and decreasing food security are exacerbating poverty in rural areas in Sub-Saharan countries (Tittonell and Giller 2013). In many cases, low biomass production results from soil and land degradation, which in turn are driven or accelerated by three factors: firstly, the growing demand for food of an increasing population; secondly, poor soil and land management; and thirdly, the increasing variability of rainfall pattern due to climate change (Masawe 1992; FAO 2017a; Gebrechorkos et al. 2018).

In banana-coffee-based farming systems in mountainous regions in Tanzania, smallholder farming contributes up to 95% of agricultural production (cf. FAO 2017a). Mountainous regions in Tanzania are densely populated and intensively used to produce banana (mainly fruit banana and plantain, *Musa* spp.), coffee (mainly *Coffea caneophora*), maize, roots, tubers, pulses, and legumes. Since the 1960s, agricultural production in these regions has increased, often in unsustainable ways. For instance, omitted fallows, intensive use of woody biomass in threestone fires, missing awareness concerning soil erosion measures, frequent tillage, and lack of composting and mulching have resulted in the exploitation of vegetation, land, and soils. In rural areas of Tanzania, such as the Kagera region, more than 90% of the rural households' cooking energy relies on firewood (unprocessed woody biomass) and charcoal (processed woody biomass), and improved stoves are not widely utilised (URT 2012). Due to the poor soil and land management, the amount of organic material added to the soils has reduced compared to the soil status in the 1960s and 1990s (Copeland Reining 1967; Touber and Kanani 1996). This led to a reduction of humus content and plant-available soil nutrients and thus, decreasing agricultural production. Since the extraction of biomass is not compensated by measures to improve soil fertility and nutrient recycling, significant degradation of vegetation and soil, and thus, accelerated soil nutrient depletion and declining water resources occur in the mid and long terms (Schwärzel et al. 2017). Furthermore, East African countries have experienced increased unreliability in rainfall patterns in the last decade, and future scenarios show that higher temperatures, less rain, and changes in rain pattern are very likely for some regions in Tanzania (Gebrechorkos et al. 2018). Smallholder farmers in mountainous regions in Tanzania, however, depend on rainfed agriculture, and we experienced that only a few farm households have experience with or the capacity of long-term water harvesting to feed the family's demand for drinking water and to irrigate the main farmland. Food production is therefore severely jeopardised.

Traditionally, smallholder farming practices in banana-coffee-based farming systems ensured that a sufficient amount of organic material returns to the soils to produce a thick, dark-coloured, humus-rich, and thus, nutrient-rich topsoil (Copeland Reining 1967; Masawe 1992; Touber and Kanani 1996). As introduced above, unsustainable agricultural practices since the 1960s have led to a continuous reduction in the addition of organic material to the topsoil, and thus, to a reduction of humus content in the soil. With less humus that is able to store and release nutrients, the productivity of these farming systems has diminished. A change in reuse and recycling of organic material from farms is thus needed. Research has shown that the potential of farm waste as a soil fertiliser and soil conditioner is not yet exhausted in banana-coffee-based farming systems because adapted composting practices are not frequently applied (cf. Kimaro et al. 2011). Furthermore, nutrients contained in human excreta are not widely maximised (Krause et al. 2015, 2016). Acknowledging that the traditional use of farm waste successfully built up soil fertility over at least one century and has been reduced in only a few decades, we argue that traditional composting practices will have to play a key role in rebuilding soil fertility in degraded banana-coffee-based farming systems. To transform degraded banana-coffee-based farming systems into sustainable agroforestry or agroecology systems that meet regional and global challenges, the understanding of traditional uses of farm waste is as important as the integration and adaptation of these practices (Gliessman 2015, 2016; FAO 2015, 2017b).

In this chapter, we focus on traditional and adapted composting practices in banana-coffee-based farming systems to highlight the positive properties of organic farm waste as a soil fertiliser and soil conditioner. In the following, we first describe the characteristics of banana-coffee-based farming systems, and secondly, illustrate traditional and adapted composting practices that are typical for these farming systems. Then, we present two cases where these composting practices are applied. The first case introduces the work of the farmer initiative Mavuno Project in the Kagera region in north-west Tanzania (Great African Rift Valley, Lake Victoria Basin; Fig. 8.1). In the Mavuno Project, about 750 smallholder farm families have been trained in implementing adapted composting practices to restore degraded bananacoffee-based farming systems. The second case presents the work of a farmer field school established by the Sokoine University of Agriculture (SUA) in the Uluguru Mountains, in the Morogoro region in central Tanzania (Kimaro et al. 2011). Among the skills trained, farmers learnt how to produce adapted in-situ and on-surface composting. In the discussion, we compare degraded banana-coffee-based farming

**Fig. 8.1** Map of the Kagera, Kilimanjaro, and Morogoro regions in Tanzania. (Vector files used from Map Library 2007)

systems with densely cropped and well-managed systems in the Kilimanjaro region (north Tanzania), discuss the advantages and disadvantages of the composting practices introduced, and consider their limitations.

#### **2 Banana-Coffee-Based Farming Systems in the Highlands of Tanzania**

The banana-coffee-based farming system is a typical smallholder, usually rainfed, subsistence farming system based on agroforestry in a tropical, mountainous environment, covering the dominant perennial crops coffee and banana, several annual crops, and native trees (Rugalema et al. 1994). Garrity et al. (2012) classified it as a typical Sub-Saharan African farming system, namely, the 'highland perennial', indicating that perennial crops—in this case, banana and coffee—are the core of the agricultural production. In Tanzania, traditional banana-coffee-based farming systems are mostly cultivated by smallholder farmer families and consist of up to four subsystems: the homegarden called *Kibanja* (in other Bantu languages named '*Kihamba*', '*Shamba*', or '*Chagga*'), new farmland or land in transition from

**Fig. 8.2** The subsystems of a banana-coffee-based farming system in the Kagera region, northwest Tanzania: (**a**). *Kibanja*, (**b**) *Kikamba*, (**c**) *Rweya*, (**d**) *Kabira*

grassland to farmland called the *Kikamba*, grassland called the *Rweya*, and woodland, the *Kabira* (Copeland Reining 1967; Rugalema et al. 1994; Baijukya et al. 2005; Hemp and Hemp 2008; Dancer 2015; Fig. 8.2).

Depending on the region, the naming of these subsystems differs according to the local Bantu language. In the Kilimanjaro region, the banana–coffee-based farming system is known as the *Chagga* (Hemp and Hemp 2008), named after the dominant tribe, the Chagga, that settled on the slopes of the Mount Kilimanjaro. Chagga landowners create and maintain densely intercropped and productive homegardens known as *Kihamba* where cultivation is well established. Around the *Kihamba* a small area is set aside for women to grow a variety of vegetables, which include amaranth, cabbage, peas, and tomatoes. A multilayered vegetation structure (Fig. 8.3), which corresponds to that of a tropical mountain forest with trees, shrubs, and herbs can be found within the *Kihamba* (Akinnifesi et al. 2008). Comparable to the *Kihamba* in the Kilimanjaro region, the *Kibanja* in the Kagera region is the heart of the farming system (Fig. 8.2a). In these fields, which usually are the closest to the

**Fig. 8.3** Multilayered vegetation in the traditional banana-coffee-based farming system—the *Kibanja* or *Kihamba—*in Tanzania. (Based on Rugalema et al. 1994 and Akinnifesi et al. 2008, Design: Claudia Matthias)

farmers' homes, biomass production is the highest and thus secures the livelihood of the farm families (Copeland Reining 1967; Rugalema et al. 1994).

In very densely cropped homegardens under favourable soil conditions, the vegetation corresponds to that of a tropical mountain forest and consists of multiple layers: annual crops (first layer), coffee shrubs and very young fruit trees (second layer), banana plants and younger fruit trees (third layer), and older trees (fourth layer) (Copeland Reining 1967; Rugalema et al. 1994; Akinnifesi et al. 2008; Hemp and Hemp 2008; Fig. 8.3). The first layer is up to 1 m high. Here, beneath a canopy of coffee bushes and banana plants, a variety of shade-tolerant annual food crops grow, such as beans, cassava, maize, yams, sweet and Irish potato, and also fodder, herbs, and grass. Coffee, medicinal plants and shrubs, and a few species of young trees are found within the second canopy zone, which lies approximately between a height of 1 and 2.5 m. Less commonly cultivated are the perennial crops vanilla, cotton, and sugarcane. The third vegetation layer, with the banana canopy along with other kinds of fruit and fodder trees, is located above 2.5 m and approximately reaches a height of 5 m. Here, various banana varieties are grown, of which plantain, the cooking banana is the primary staple food for the farm households; the sweet finger banana is cultivated as a fruit; and the brewing banana to brew local beer. Above this, the fourth layer is less distinct and more blended together. It contains various kinds of trees delivering shade and fruit crops, for example avocado, mango, pawpaw, jackfruit, and citrus fruits, as well as fodder, timber, and firewood. The shade provided by the trees plays an important role in reducing soil evaporation. The response of bananas to droughts is complex; drought effects are associated with low yields notably 6–8 months afterwards. Besides, stall-fed livestock activities and the cultivation of vegetables in kitchen gardens are common practices in this farming system. The farmer families keep mainly goats, pigs, sheep, and chicken in the homegardens, and in a few cases, improved cattle for milk production (Fig. 8.4).

**Fig. 8.4** Livestock rearing in smallholder farming: (**a**) traditional, free-range indigenous cattle in the *Rweya*, (**b**) integrated livestock management with cowshed for improved cattle in the *Kibanja*, (**c**) tied goats under a roof in the *Kibanja*, (**d**) free-range pigs in the *Kibanja*

As local weather conditions vary, several combinations of water-harvesting practices can be considered in agricultural production. In the Kagera region, for example, some farmers gather rainwater in clay containers from the roofs of their houses to irrigate the kitchen gardens, whereas a series of interlinked canals carrying water harvested in the forest on Mount Kilimanjaro, called *mfongo*, helps irrigate the homegardens of the *Chagga* people in the Kilimanjaro region. There, the canals deliver a convenient source of water for domestic use as well as for irrigation purposes. As coffee and banana require between 900 and 1050 m3 water ha-1 month-1 (Baulme 1993), irrigation water is supplied via the canals at intervals of 5–8 weeks, in the case of insufficient rainfall.

The other three subsystems are less fertile and diverse. The *Kikamba* (Fig. 8.2b) refers to land transitioning from *Rweya* towards *Kibanja* (cf. Baijukya 2004). The original vegetation is gradually replaced by young banana seedlings and some annual crops. Very often, the soils are uncovered and particularly exposed to soil erosion. The *Rweya* (Fig. 8.2c) is grassland and shrubland, which are often used for free-range livestock-rearing (Fig. 8.4). Traditionally, livestock rearing is an essential strategy against food shortage in dry seasons and an additional source of income (Lichtfield and McGregor 2008). The fourth subsystem is the *Kabira* (Fig. 8.2d), a land parcel with trees for firewood, charcoal, and timber production (Copeland Reining 1967).

#### **3 Composting Practices**

In the banana-coffee-based farming system, the following kinds of organic farm waste are produced: crop residues, livestock urine and manure, kitchen and food waste, litter, dead wood, ashes (inorganic), animal bones, and human urine and faeces; however, not all kinds of farm waste are used to produce compost, particularly not human excreta (Krause et al. 2015, 2016). Since open defaecation is prohibited, human excreta are collected in pit latrines, which are not sealed at the bottom and from which the excreta can easily leak into the underlying groundwater aquifer. Human excreta or pit latrine sludge is not redistributed to the fields. The subsystems of a banana-coffee-based farming system play an essential role in the composting process because farm waste and biomass (grass and wood)—and thus, plant nutrients—circulate within the *Kibanja* and also between *Kibanja*, *Kikamba*, *Rweya*, and *Kabira* (Fig. 8.5).

In general, in the *Kibanja*, most parts of the farm waste usually return to the crop fields, except human excreta, which is gathered in pit latrines on the *Kibanja* land

**Fig. 8.5** Flows of significant farm waste, grass, and firewood in traditional banana–coffee-based farming systems. (Based on Baijukya and Steenhuijsen Piters 1998), Design: Claudia Matthias

and is not reused. To fertilise the *Kikamba* land and to protect its topsoil against erosion, farmers remove organic material originating from the *Kibanja* and add it to the soils of the *Kikamba* land. From the *Rweya*, grass and firewood are imported to the *Kibanja*. The grass is either used as fodder or as mulch. Leftovers of the burnt firewood usually stay in the *Kibanja*. Wooden biomass is imported from the *Kabira* into the *Kibanja* and leftovers of the use of wooden biomass usually stay in the *Kibanja*.

#### *3.1 Traditional Practice: In-Situ and Pit Composting*

In the *Kibanja*, different practices of composting have been developed over the centuries and are still applied by most of the smallholder farmers (Reetsch et al. 2020a). The primary practices of traditional composting are ring-hole composting, in-situ composting, and pit composting (Fig. 8.6). As indicated in Fig. 8.6a, farmers dig ring-holes around perennial crops, fill them with nutrient-rich farm waste, preferably livestock manure, and cover the filled plots with soil material (*ibid.*). Another way of composting is presented in Fig. 8.6b. In-situ composting comprises of farm waste, which remains in place or can be spread over the surface and left to decompose itself, without any amendments like layering, watering, or adding of ashes (Kimaro et al. 2011; Reetsch et al. 2020a). During the rotting process of the mulch, humus is accumulated in the topsoil. A third form of reusing farm waste is pit composting (Fig. 8.6c). Very often, farmers collect different kinds of farm waste in pits (Reetsch et al. 2020a). After filling these waste pits, they are covered with soil and, if available, grass (*ibid.*). Then, a new pit is dug. Over time, the farmland is spread with pits containing rotten organic waste material.

In the homegardens of banana-coffee-based farming systems, the farm waste is composted either in situ or in pits (Fig. 8.6). In particular, in-situ composting enables the replenishment of soil nutrients and the conservation of soil moisture throughout the farmland, whereas pit and ring-hole composting improves the soil nutrient status at selected sites.

**Fig. 8.6** Traditional composting practices in banana–coffee-based farming systems in Tanzania: (**a**) in-situ composting: ring-hole application of livestock manure around perennial crops (banana, coffee), (**b**) in-situ composting: crop field mulched with plant-based farm waste, (**c**) pit composting: farm waste mixed in a waste pit (Design: Claudia Matthias)

**Fig. 8.7** The production of on-surface compost in smallholder farmers in banana-coffee-based farming systems in Tanzania according to Kimaro et al. (2011). (Design: Claudia Matthias)

#### *3.2 Adapted Practice: On-Surface Composting*

Traditional composting practices have been modified and further developed as onsurface composting (heap method) by Kimaro et al. (2011). This aboveground technique facilitates the production of compost, especially by women and children. The compost pile consists of several layers of farm waste, which are piled on top of each other above the ground (Fig. 8.7). In the first step, the ground is covered with a plastic sheet to avoid leaching, followed by an approximately 10 cm thick layer of stalks and weed, which forms the base of the compost pile. The second layer consists of green leaves of leguminous plants (15 cm in height) to enrich the compost with nitrogen. The third layer preferably contains animal manure and the local, phosphorus-rich Minjingu rock fertiliser (5 cm in height) followed by a 2 cm soil layer that is moistened with water. The Minjungu rock is mined in the north of Tanzania. All four steps are repeated until a height of approximately 1 m is reached. Finally, the compost pile is covered with banana leaves to control evaporation. To promote the rotting process, the compost pile needs to be regularly turned over. During the rotting process, a wooden stick is pierced through the layers to estimate the core temperature of the compost pile. As long as the rotting process is ongoing, the stick is warm and moist. If it becomes cold and dry, the rotting process is completed.

#### **4 Case Studies**

In this section, we present two case studies on composting in smallholder bananacoffee-based farming systems in Tanzania (Fig. 8.1) that follow each composting practice introduced in the previous section. Both cases are from humid to semihumid mountainous regions with steep slopes. The first case is located in the Kagera region and the second in the Morogoro region. Both regions suffer from land degradation caused by human activities and climate change as outlined in the introduction (Masawe 1992; FAO 2017a).

#### *4.1 Traditional Composting in the Kagera Region*

The Kagera region lies in north-west Tanzania 1,200 m above sea level (a.s.l.) (Fig. 8.8). The predominant soils are Rhodic and (*Anthri-*) *Humic Ferralsols*, *Lithic* and *Mollic Leptosols*, *Humic Acrisols*, *Anthri-luvic Phaeozems*, and *Ferralic Cambisols* following the FAO-UNESCO soil classification of 1988 (Touber and Kanani 1996) and recently as *Andosols* by Krause et al. (2016). With an annual rainfall ranging between 800 and 1,000 mm, falling in two rainy seasons, which allows for two cropping seasons per year. However, changing rainfall patterns were reported to cause harvest shocks in the last two decades (Trærup and Mertz 2011). The soils in the Kagera region degraded due to increased rainfall variability, soil nutrient losses, and deforestation—and thus increased soil erosion (Baijukya and Steenhuijsen Piters 1998; Trærup and Mertz 2011; Wasige et al. 2013; FAO 2017b)—and changed since 1901 from tropical forest, woodland, and savanna, to cropland and pasture (Wasige et al. 2013).

Traditionally, the use of farm waste plays an important role in this region (Copeland Reining 1967; Katoke 1970; Ndege et al. 1995; Touber and Kanani 1996). Over at least one century, farmers continuously added organic plant material and livestock manure to the fields in the homegardens (Copeland Reining 1967). The warm-humid climate conditions of the region are favourable to decompose organic material within a few days or weeks. This promotes the formation of A-horizons in the soil with a thickness of 30 to 40 cm, rich in soil organic matter and plant-available nutrients (Touber and Kanani 1996). Nutrient levels are found to be especially high near the farmers' houses with a decreasing gradient to the borders of the farm (Baijukya and Steenhuijsen Piters 1998). The thickness of the A-horizons decreased over the last five decades because the fields have been intensively used for agricultural production to meet the increasing demand for food and biofuels of the fast-growing and refugee-hosting population (CARE and Overseas 1994; URT 2016, 2018; Fig. 8.9).

The farmer initiative Mavuno Project (https://mavunoproject.or.tz/wp/) has supported smallholder farmer families in restoring degraded traditional banana-coffeefarming systems and further transforming the *Kibanja* into sustainably intensified

**Fig. 8.8** Map of the Kagera region in north-west Tanzania with elevation contours. (Digital Elevation Model used from CGIAR-CSI (2017))

**Fig. 8.9** Population growth in Karagwe and Kyerwa districts, Kagera region. (Data extracted from Copeland and Reining (1967), Katoke (1970), and URT (2016))

and climate-resistant farming systems. The agricultural transformation was jointly developed with smallholder farmers acknowledging traditional composting practices, involving climate change adaptation measures, and land management practices that are also known in agroforestry (Wekesa and Jönsson 2014; Gliessman 2016; FAO 2017a). These measures involved nutrient management, soil and water conservation, the establishment of mixed crop-tree systems, adapted agricultural practices (crop rotation, intercropping, relay and contour strip cropping), tillage, residue management, integrated livestock management, sustainable energy use, and integrated pest management (Wekesa and Jönsson 2014).

Inspired by this smallholder farmer initiative, we investigated the implementation of traditional and adapted composting practices in five focus group discussions with 22 lead farmers working with the Mavuno Project (Reetsch et al. 2020b). The lead farmers were responsible for training and monitoring of 750 smallholder farm families in the Kyerwa and Karagwe districts (Fig. 8.8) in reintegrating traditional composting practices (Fig. 8.6) and optimising waste flows within the farmland (Fig. 8.5). According to the focus groups, the farm households began by establishing a plot of one acre (0.4 ha) where they planted perennial and annual crops intercropped with a few trees. In this early stage, optimised in-situ composting was already practised. With every rainy season, the plot got more diverse, and farmers started to establish further plots. In the discussions, the lead farmers indicated that soil fertility and biomass production increased in those farm households that implemented the composting practices that they were trained on, whereas they did not increase when a farm household did not properly apply the practices taught. As a side effect, humus enrichment counteracted with soil acidification, protected soil water from evaporation, and markedly reduced soil erosion. Increasing soil fertility led to higher yields and higher food availability for the entire farm household. Harvested crops could be stored either for consumption or for sale. However, the first results also indicated that not all farm households succeed in the same way.

#### *4.2 On-Surface Composting in the Morogoro Region*

In the Uluguru Mountains in the Morogoro region, the mean annual rainfall varies with altitude, from 900 mm at 550 m a.s.l. to 2,300 mm at more than 1,500 m a.s.l. In this area, mountain ridges are mainly used for the production of banana, vegetable, bean, and short rain maize while on the foothills long rain maize is the main crop (Kimaro et al. 2005). The topography is highly variable with dissected mountain ridges and foothills with very steep slopes of up to 80% and narrow valleys (Kimaro et al. 1999). Bedrock geology is dominated by metasediments mainly consisting of hornblende pyroxene granulite, with plagioclase and quartz-rich veins (Kimaro et al. 2005). Based on the FAO (2006), the soils on the mountain ridges are dominantly *Endoskeletic* and *Leptic Cambisols*, with accessory surfaces of *Haptic* and *Chromic Phaeozems* and *Orthi-eutric Regosols*. On the foothills, the dominant soils are *Chromic Lixisols* and *Profondic Acrisols* associated with *Hyperferralic*

**Fig. 8.10** Map of the Morogoro region in central East Tanzania. (Digital Elevation Model used from CGIAR-CSI (2017))

*Cambisols* and *Endoleptic Cambisols*. The soil covers are generally affected by severe erosion. Increased free-range livestock and human activity have led to the collapse of the soil conservation system and increased land degradation (including soil erosion). Therefore, strategies that aimed at combating land degradation through mechanical and biological measures such as reforestation activities, agroforestry, protection of watersheds, improved land husbandry, and environmental conservation were initiated in Tanzania in the late 1980s (Shetto 1999, Fig. 8.10).

The Sokoine University of Agriculture (SUA) initiated a soil and water conservation programme in the Uluguru Mountains to train smallholder farmers on the effect of conservational tillage on soil loss and plant nutrient status on their fields. To that end, a farmer field school was piloted in the north-eastern part (Kimaro et al. 2005). The farmers were trained on how to increase the productivity of their farming systems through composting. This included the application of in-situ and on-surface composting in combination with conservation tillage and terracing. The results showed that yields under in-situ composting and conservation tillage were the highest, presumably due to improved soil fertility and decreased soil losses in space and time (Kimaro et al. 2011, Fig. 8.11).

Seasonal yields of vegetable were measured in order to assess the following soil and water conservation practices: (1) conservational tillage and in-situ compositing, (2) traditional terrace and in-situ compositing, (3) conservational tillage and manure, and (4) traditional terrace and manure over traditional farming practices. In this

**Fig. 8.11** Training farmers on improved indigenous farming practices: (**a**) and (**c**) On-surface composting, (**b**) and (**d**) Traditional terraces (Kimaro et al. 2011)

case, adapted in-situ composting means a mixture of green manure (a mixture of *Gliricidia* and other farm residues at a rate of 5 t ha-1), farmyard manure (10 t ha-1), and Minjingu phosphate rock (MPR) 100 kg P ha-1 were left to decompose in situ on the soil (Msita et al. 2010). The results showed that conservation tillage with insitu composting followed by traditional terrace and in-situ composting gave a higher fresh yield of vegetables, presumably due to improved soil fertility and decreased soil losses in space and time, than conservation tillage and livestock manure alone, traditional terrace and manure alone, controlled conservation tillage, and controlled traditional terrace (Msita et al. 2010). It can be concluded for this case that integrating composting practices in conservation tillage for crop production on sloping land is the best practice for sustainable crop production, nutrient availability, and reduction of soil loss.

#### **5 Discussion**