KAPSHTYK Mykhailo (1), SHYKULA Mykola (1), BALAJEV Anatoliy(1), KRAVCHENKO Yuriy(1), BILYANOVSKA Tetyana (2)

Transcription

1 Scientific registration n 0 : 2568 Symposium n 0 : 14 Presentation : poster The ways for an extended reproduction of soil fertility in chernozems of Ukraine Les voies d'une restauration durable de la fertilité des chernozems d'ukraine KAPSHTYK Mykhailo (1), SHYKULA Mykola (1), BALAJEV Anatoliy(1), KRAVCHENKO Yuriy(1), BILYANOVSKA Tetyana (2) (1) National Agricultural University, 15 Geroyiv Oborony Street, Kyiv, Ukraine (2) Scientific- Engeneering Centre ACSO, 50 Kharkivske shosse, Kyiv, Ukraine Ukraine has a great potential for the development of agriculture with an area of farmland 43 mln ha and chernozems (rich mollisols) reaching 68% of the total area of soils. These soils are very rich but ecologically unbalanced systems of farming and irrational techologies based on mouldboard plowing caused a considerable soil degradation. Soil organic matter (SOM) status was the first to degrade severely. There is a considerable correlation between the content of humus and other soil regimes (r= ), humus being a matrix which determines other indices of soil fertility. Many centuries of soil dehumification were caused by the violation of the principle of returns in farming. Less residues means a lower intensity of soil formation and biogeochemical cycles of elements and energy which reproduce soil fertility. Lower fertility and bioproductivity of cultivated chernozems, as compared with virgin and long-fallow soils, is caused not only by the losses of organic matter and nutrients but also by the changes in organic matter composition and its inability for reproduction in the seasonal cycles of transformation. Our research results have shown how difficult it is to ensure a non-deficit ballance of SOM using conventional tillage based on mouldboard plowing (Table 1). In crop rotation with 40 percent of intertilled crops during 17 years of experiment the most drastic reduction in SOM and total nitrogen content occurred on unfertilized plots, reaching 0.31 percent and 35 ppm respectively in 0-40-cm layer. Farm manure (6 t/ha) and mineral fertilizers (N 28 P 28 K 28 ) have reduced the losses of SOM to 0.24 percent and total N to ppm. But such a fertilizing has not ensured the non-deficit balance of SOM and N. Our calculations have shown that it is necessary to apply t/ha of farm manure to ensure a non-deficit balance of SOM in the soil subject to mouldboard plowing. Agricultural enterprises of Ukraine are unable to produce such an amount of farm manure, especially in present-day economic situation. Therefore, it is necessary to introduce more up-to-date technologies in the systems of crop production. 1

2 With this purpose we introduce a conservation system of farming with an increased reproduction of soil fertility. This system not only ensures higher and stable yields of crops but reproduces the potential fertility of chernozems and function of selfregulation making them like their virgin counterparts. Minimum non-plow tillage and plant residues management are the corner stones of a new conservation system. Crop residues will maintain a high level of the energy of soil formation as a means of soil protection against degradation. Our research has shown that non-plowing technologies increase nutrient element contents in the soil and instigate the self-regulation of soil productivity. Soil renovation mechanism lies in an increased intensity of seasonal and annual cycles of SOM and biogeochemical cycles of byogenic elements and energy. Higher seasonal changes in SOM content and higher level of soil and agroecosystem self-regulation increase soil fertility and crop yields which become less dependent on weather conditions, rates of fertilizers and chemicals. Also, the ecological stability of agrolandscapes becomes higher. Seasonal cycles of SOM in Chernozems can be explained by the mechanism of soil fertility self-regulation. In the period of intensive growth and development of plants a part of SOM is mineralized due to tearing-off of lateral nitrogen-containing radicals and consumption by the roots of plants of the nutrients released into soil solution. In the next period, plant residues decompose and supply SOM with the fragments of macromolecules lost in the first period. SOM mineralization is more intensive in the period of intensive growth and development of plants because of a more favorable conditions for the development of oxidation. Such conditions favor the destruction of lateral chains in the molecules of humus substances. There is also a parallel process of the synthesis of new molecules and the complication of older ones. This process requires much energy and has to take place only in aerobic conditions (B.Novak,1964). After harvesting the soil is saturated with water and oxidation processes are impeded. In this period of plant residue decomposition intermediate compounds are formed with carboxyl and other functional groups, such as aminoacids, amines and amides. Carboxyls of some earlier formed humic acids are substituted by nitrogen-containing functional group. At the same time there is an accumulation of newly-formed humic substances in autumn, spring and winter when no free energy comes to the soil. Conservation tillage incorporates crop residues in the upper, 5-7 cm - thick and well aerated layer of the soil. This layer has the greatest humification coefficient. We have found out that there is by one-third more humus formed when the residues are incorporated no deeper than 10 cm, as compared with their incorporation below 15 cm. A shallow placement of residue drastically reduces organic carbon losses. A mechanism of SOM formation and self-regulation was employed by us in the development of practices for an increased reproduction of soil fertility. These practices were included in soil - protective crop production systems. All this makes it possible to control soil fertility in crop rotations. Taking into account the natural laws of soil formation made it possible to obtain higher yields of crops at lesser expenditures of the means of production. Soil-protective technologies developed by us are based on the functioning principles of natural ecosystems, where there is no tillage and plant cover is renewed by the way of Nature. Soil formation and production processes in virgin ecosystems allows to obtain 5 to 6 times more biomass than a man obtains in crop rotations. Conservation technologies based on a self-regulation principle in soil formation 2

3 allow to create soil conditions which are the most favorable for plant growth and development. The effectiveness of our technologies has been proved in practical farming. They were used in a cooperative farm Obriy, Poltava region where mould board plow is not used for 21 year and agricultural chemicals are used for 18 years only by least quantities. Minimum non-plow tillage (10-12 cm deep) is employed in all crop-production systems. Yields of crops became 2 times higher. Developing conservation technologies of crop production we discovered in stationary field experimental plots a hyerarchical discreteness of changes in soil fertility occurring under the influence of soil-protecting systems of farming. Figure 1 shows the seasonal cycles in SOM content in typical chernozem for different technologies of crop production with the application of 12 t/ha farm manure and N 80 P 75 K 65. Even in the first 3 years the conservation technology with minimum nonplow tillage instigates the renewal of the seasonal cycles of soil humus. SOM contents changed from spring (planting) to autumn (harvesting) under sugar beets in 0-20 cm layer only by 0.11 percent on the plots with mold board plowing, while on the non-plow tilled plots the amplitude of its changes reached percent. The first change in the quality of soil fertility occurs after 5 years of systematic non-plow tillage when the soil renews the internal connections which were destroyed by the furrow inversion. Humus content becomes 0,10 to 0,12 percent higher. Amplitude of SOM fluctuations increases. Figure 2 shows the soil-protective non-plow technologies decreased the content of humus in a crop rotation sugar beets peas winter wheat from April to August by 0,24 percent, while on plowing it decreased only by 0,16 percent. In the next period there was a gradual recompensation of humus. Maximum amplitude of seasonal changes in humus content was characteristic for the typical chernozem under a long- term grassland (0.31 percent). By the character of seasonal cyclicity of SOM soil- protective technologies approach a long- term grassland. So the processes of soil formation become more natural. After 9 years of non-plow soil-protective technologies the soil acquires the ability for the self-regulation of its fertility. Hyerarchical changes of soil fertility affect the bioproductivity of soils. Within 5 years of the use of soil-protective technologies the yields of crop become higher by t/ha in grain units, compared to the technologies with conventional tillage (Table 2). After 5 years the increments of yields reach t/ha in grain units. After 9 years yield increments increase by t/ha, compared with conventional technologies. Crop yields become less dependent upon whether conditions and the application of mineral fertilizers and chemical means of plant protection. The third hyerarchical change in the fertility of the soil occurs after 15 years of systematic non-plow technologies when the soil restores completely the natural processes of soil formation. Yields of crops become by percent higher compared with the initial yields and become ever less dependent upon weather conditions and agricultural chemicals. Thus, the use of conservation systems of crop production is a prerequisite for an increased reproduction of soil fertility in chernozems. A process of soil formation becomes more similar to its natural counterpart, which ensures stability and considerably higher yields of crops. 3

4 Keywords : chernozem, soil fertility, soil conservation, self- regulation, hierarchical discreteness Mots clés : chernozem, fertilité des sols, conservation des sols, auto-régulation 1. Changes in humus and nitrogen contents in typical clay loamy Chernozem under influence of various systems of fertilising applicated for 17 years. Stationary field experiment in Poltava region. Layers, Variants sm Non fertilized Manure 6 t/ha+npk Manure 9 t/hà+npk 1* 2* Humus, % ,44 4,71 5,28 4,72 5,27 4, ,19 4,30 4,11 4,20 4,14 4, ,82 4,51 4,70 4,46 4,71 4,56 ± to initial -0,31-0,24-0,15 LSD 05 0,24 0,19 0,22 Total nitrogen, mg/kg ± to initial Note: 1* - until experimental plots are not laid out 2* - after 17 year period of experiment 4

5 2. Increase of crops yield in farm Obriy of Poltava region from 1966 to 1994 years under influence of soil consevation crop production systems applicated for various periods of time. Unit of Crop yields and its increase Years measure- grain for kinds of crops Crop yield Increase of yield for : ment metric centner per ha crops a whole winter wheat spring barley oats peas corn sunflower sugar beets 28,1 29,2 25,2 27,1 15,9 24,3 16, m.c/ha 4,1 9,0 3,4 0,8 14,0 2,4-3,6 124 % m.c/ha 7,2 5,3 5,4 10,3 2,0 25,8-4,2 67 % m.c/ha 28,2 34,3 28,4 38,3 5,5 34,8 12,2 140 % m.c/ha 25,2 33,9 27,6 31,1 12,5-11,9 159 %

6 6.10 % april june august november 5.47 Cropping system based on: plow tillage minimum non-plow tillage long-term grassland Figure 2. Seasonal cycles of humus in layer 0-10 cm of typical chernozem influenced by various cropping systems applicated for more than 5 years. 6

7 april may july october tecnology based on plow tillage tecnology based on minimum non-plow tillage april may july october tecnology based on plow tillage tecnology based on minimum non-plow tillage Figure 1. Seasonal cycles of humus in layer 0-20 cm of typical chernozem under influence of different cropping systems applicated for first three years of experiment, % april may july october tecnology based on plow tillage tecnology based on minimum non-plow tillage 7 Stationary field experiment NAU in Poltava region 1. Sugar beets (first year) 2. Sunflower (second year) 3. Annual grasses (third year)