**3. Conclusion**

The systematic mineral fertilization for a period of 40 years with different norms and at different ratios between nitrogen, phosphorus and potassium had high effect on the agrochemical condition of slightly leached chernozem (Haplic Chernozems) down the soil profile.

The soil acidity forms, averaged for the investigated depth of the 0-400 cm profile, were significantly affected by the type of fertilizer combination. The depth was the factor with decisive effect in all forms of soil acidity. Influence of mineral fertilization was higher on exchangeable Al3+, Ca2+ and the ∑Са+Mg, and significantly lower - on the values of residual hydrolytic acidity and the rate of alkali saturation. The amount of exchangeable Mg2+ had a clear tendency toward increasing down the soil profile

Independent long-term mineral fertilization with 180 kg N/ha and with N180P60K60 caused the occurrence of exchangeable Al3+ in the soil absorption complex in the surface layers 0-10 and 10-20 cm. It was not present further down the profile.

The variant with independent nitrogen fertilization with 180 kg/ha has also the lowest ∑Са+Mg and the lowest value of sorption capacity. Intensive mineral fertilization with N180P60K60 caused decreasing of degree of saturation with bases.

The value of the pH, sorption capacity, acidity on strongly acid positions and degree of saturation with bases showed a tendency of decreasing at the end of 40th year of trail beginning comparing the end of 30th year. In the same way independently of fertilizer variant the acidity on the slightly acid positions is strongly increased.

The mineralization ability down the soil profile was affected to a maximum degree of significance by the mineral fertilization and the incubation. Depth had decisive effect on the value of the index. The maximum effect of this factor was registered after 28-day incubation – 92.3 %. The role of mineral fertilization on nitrogen mineralization according to the incubation period was significantly less expressed – 9.2 %, 3.2 5 and 4.0 %, respectively. The amount of nitrified nitrogen increased with the longer incubation periods with 52.7 % (28 days) and with 118.8 % (56 days), respectively, in comparison to 14-day incubation. The long-term mineral fertilization with N180P60K60 had the highest values of mineralization ability for all three incubation periods. The established strong effect of systematic mineral fertilization regardless of the norm and ratios of nitrogen, phosphorus and potassium on the mineralization ability of soil in comparison to the check variant was highest at depths 0-100 cm and 300 – 400 cm.

Systematic mineral fertilization carried out for 40 years in two-field crop rotation (wheat – maize) affected the content of Ctotal deep down the profile of the slightly leached chernozem

Soil depth, cm N0P0K0 N60P0K0 N120P0K0 N180P0K0 N0P180K0 N60P180K0 N120P120K120 N180P60K60 0 – 10 1,659 1,762 1,955 2,262 2,250 2,162 2,069 1,801 10 - 20 2,323 2,104 2,301 2,397 2,446 2,080 2,127 2,240 20 - 40 3,694 4,233 4,593 4,384 4,754 4,891 4,548 4,645 40 - 60 3,161 3,957 2,981 3,161 3,807 3,677 4,333 4,005

The systematic mineral fertilization for a period of 40 years with different norms and at different ratios between nitrogen, phosphorus and potassium had high effect on the agrochemical condition of slightly leached chernozem (Haplic Chernozems) down the soil

The soil acidity forms, averaged for the investigated depth of the 0-400 cm profile, were significantly affected by the type of fertilizer combination. The depth was the factor with decisive effect in all forms of soil acidity. Influence of mineral fertilization was higher on exchangeable Al3+, Ca2+ and the ∑Са+Mg, and significantly lower - on the values of residual hydrolytic acidity and the rate of alkali saturation. The amount of exchangeable Mg2+ had a

Independent long-term mineral fertilization with 180 kg N/ha and with N180P60K60 caused the occurrence of exchangeable Al3+ in the soil absorption complex in the surface layers 0-10

The variant with independent nitrogen fertilization with 180 kg/ha has also the lowest ∑Са+Mg and the lowest value of sorption capacity. Intensive mineral fertilization with

The value of the pH, sorption capacity, acidity on strongly acid positions and degree of saturation with bases showed a tendency of decreasing at the end of 40th year of trail beginning comparing the end of 30th year. In the same way independently of fertilizer

The mineralization ability down the soil profile was affected to a maximum degree of significance by the mineral fertilization and the incubation. Depth had decisive effect on the value of the index. The maximum effect of this factor was registered after 28-day incubation – 92.3 %. The role of mineral fertilization on nitrogen mineralization according to the incubation period was significantly less expressed – 9.2 %, 3.2 5 and 4.0 %, respectively. The amount of nitrified nitrogen increased with the longer incubation periods with 52.7 % (28 days) and with 118.8 % (56 days), respectively, in comparison to 14-day incubation. The long-term mineral fertilization with N180P60K60 had the highest values of mineralization ability for all three incubation periods. The established strong effect of systematic mineral fertilization regardless of the norm and ratios of nitrogen, phosphorus and potassium on the mineralization ability of soil in comparison to the check variant was highest at depths 0-100

Systematic mineral fertilization carried out for 40 years in two-field crop rotation (wheat – maize) affected the content of Ctotal deep down the profile of the slightly leached chernozem

Table 15. Reserves by depth up to 60 cm according to fertilization, C – kg/m2

clear tendency toward increasing down the soil profile

and 10-20 cm. It was not present further down the profile.

N180P60K60 caused decreasing of degree of saturation with bases.

variant the acidity on the slightly acid positions is strongly increased.

**3. Conclusion**

cm and 300 – 400 cm.

profile.

soil. Systematic use of N180P60K60 contributed most for the increase of its content at average depth 0-400 cm. Fertilizer variants N180P60K60 and N120P120K120 led to lower amount of HA-Ca, below the level of the check and all other investigated fertilization variants. There was a well expressed tendency towards increase of carbon in HA-Ca as a result from the independent phosphorus and nitrogen fertilization, regardless of the nitrogen norm.

The ratio CHA/CFA putted under average for the 400 cm profile to distinct differentiation between the fertilization variants.Variation was within a wide range: from 1.72 to 3.75. The long-term systematic nitrogen fertilization with 180 kg N/ha in combination with low fertilization norms of phosphorus and potassium determined the type of humus as fulvichumic, averaged for the investigated depth 0-400 cm. In all other fertilization variants, regardless of the norms and ratios between the macro elements and in the check variant, the values of this ratio were above 2, which determined the type of humus as humic. Independent nitrogen fertilization, especially with annually applied high norms, had a strong negative effect on the mobility of the organic substance and caused serious decrease of the percent of carbon in the insoluble residue.

As a result from the systematic mineral fertilization in the 20-40 cm layer, higher reserves were formed by the layers lying above and below. Triple NPK combinations (N120P120K120 and N180P60K60) enriched organic mater reserves in 40-60 cm layer.

These results showed that regardless of the intensive agricultural activities and changes of some agrochemical characteristics, slightly leached chernozem soil (Haplic chernozems) in Sough Dobrudzha region in Bulgaria preserved its main genetic characteristics at the lower depths of the soil profile.

The effect of long-term fertilizer treatments on detail nutrient balances, technological quality of crops, concentration of available forms of macro elements and trace elements in soil and plant biomass dynamics and many other aspects of this experiment await detailed analysis.


*2.2. Growth Parameters*

For the measurement of growth parameters, two uniform plants were randomly selected from each biological replicate. Plant height and root length was measured using a meter rod from the surface of the soil to the tip of the plant. Pots were filled with water to gently uproot the randomly selected plants and averaged. The length of five roots was taken by using a meter rod from the uprooted plants and averaged. These samples were cleaned and washed with distilled water, and root and shoot were separated by a pair of scissors. After cleaning, the fresh weight of root and shoot was taken by using a digital balance (Uni Block AUX220, Shimadzu Corporation, Kyoto, Japan). These samples were oven-dried (Memmert-110, Schawabach, Germany) at 70 ◦C for 72 h to take dry weight by using a digital balance.


**1. Introduction**

Due to climate change, glaciers are shrinking worldwide [1–3]. Simultaneously, 'waves' of different organisms try to colonise the newly exposed land. Glacier forelands give unique

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2017 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

possibilities for studying primary succession. Instead of monitoring changes within a fixed plot over time, which indeed would be a very time-demanding approach, successions can be described by studying sites with known ages. Such a gradient in the terrain, where space is used as a substitute for time, is called a chronosequence [4, 5].

Most studies in glacier forelands have dealt with plant succession, and a thorough and longlasting one has been performed near the glacier Storbreen in Norway [4]. A main conclusion is that age alone cannot predict the plant community. Local variations in microtopography, moisture, nutrients, substrate and exposure contribute in shaping the species composition. Instead of ending up with a 'monoclimax', the succession produces a 'polyclimax' with a mosaic of plant communities. A 'bulk' succession related only to the age of the ground contains 'noise' from a mixture of successional pathways. It has been argued for a 'geo-ecological' view on primary succession, where both biotic and abiotic factors were taken into considerations [4]. A recent study from Nigardsbreen foreland in Norway confirmed the modifying effect of microtopography on the floral succession [6].

Studies on animal succession near receding glaciers are fewer, and are mainly focusing on arthropods. In addition to the present case study, there are studies on arthropod succession in glacier forelands from the Alps [5, 7–11], from Svalbard [12–15], from Iceland [16] and from Norway [17–23].

In the following presentation, we have adopted the geo-ecological perspective. In other recent studies of invertebrate successions in Norwegian glacier forelands, a geo-ecological perspective has been successfully applied, when comparing succession patterns at different altitudes and climatic conditions [19, 20, 22, 23].

Hardangerjøkulen glacier in Southern Norway has been receding since the end of 'the little ice age' for about 250 years ago. The melting rate has been especially high during the last two decades, with about 20-m retreat yearly at one glacier snout near Finse (Midtdalsbreen). We have good data on earlier positions of the ice edge in this glacier foreland due to dated moraines. Since 2001, extensive zoological studies have been performed here to describe and understand arthropod succession patterns (**Figure 1**). These studies include soil-living microarthropods [24, 25], surface active beetles, spiders and harvestmen [26, 27], aerial transport of arthropods [28], studies on ancient carbon released by the glacier [29, 30], food choice of pioneers [31], as well as a special focus on early succession [32].

Time has come to combine these fragments into a holistic story about animal succession near a melting glacier. In addition to summing up the main results from these nine papers, the present syntheses will discuss some general aspects of succession:

Animal Successional Pathways for about 200 Years Near a Melting Glacier: A Norwegian Case Study http://dx.doi.org/10.5772/intechopen.68192 149

**Figure 1.** Sampling of soil for the extraction of microarthropods (springtails and mites). This snow bed habitat was 180 years old and situated 1 km from the glacier (plot no. 18). It had a well-developed *Salix herbacea* vegetation and a 2-cm thick organic soil layer. Microtopography in the surroundings created gradients from dry ridges to moist depressions.