UDC 631.51:631.445.4:633.11
INFLUENCE OF BIOLOGICAL TECHNIQUES FOR RESTORING SOIL FERTILITY AND METHODS OF SOIL TREATMENT ON THE FERTILITY OF TYPICAL CHERNOZEM AND YIELD OF WINTER WHEAT
Dedov A.V., Doctor of Agricultural Sciences, Professor Boluchevsky D.A., Post-graduate Voronezh State Agrarian University named after Emperor Peter the Great, Voronezh, Russia
E-mail: dboluchevskiy@bk.ru
ABSTRACT
Influence of various methods of soil treatment and biological techniques for restoring soil fertility on the fertility of typical chernozem and yield of winter wheat in the conditions of forest-steppe the Central Black Earth region has been studied. Research was conducted in the repeated stationary experiment of the Agriculture Department of Voronezh State Agrarian University n.a. Emperor Peter the Great. Object of research - typical chernozem and cultures of a crop rotation. This article discusses the following indicators: soil hardness, which was defined by using the Revyakin's hardness tester up to 25 cm in three terms - sowing, earing, harvesting; aggregate composition of soil by Tyulin-Savvin's method before sowing and harvesting; yield of winter wheat at various soil treatment methods. Studies have shown the advantage of green-manure fallow with sweet clover and binary sowing of winter wheat with blue alfalfa. During the years of researches, hardness of the soil was less (within the optimum) at variants using biological techniques; the number of structural aggregates in the binary sowings was greater by 25 - 38% compared with the control. The use of various methods of soil treatment and biological techniques for restoring soil fertility allowed to harvest from 35.8 to 54.9 t/ha of winter wheat in 2011 - 2013. Thus, sowing winter wheat at green-manure fallow with sweet-clover and alfalfa contributed to sustain and improve the fertility of typical chernozem and creating conditions for obtaining high grain yield.
KEY WORDS
Binary sowing with perennial grasses; Soil treatment methods; Soil hardness; Green manure; Agrophysical properties.
Saving and improvement of soil fertility has been and remains the main task of agriculture, especially now with dramatically reducing the use of organic and mineral fertilizers [6-9].
One of the main problems of modern agriculture - increasing grain production at projection and learning of science-based agriculture systems [3,13,15].
The main parts of the agriculture system are fertilizers and soil treatment. Lack of material and technical resources forces us to search for low-cost technologies in agricultural production. For solving this problem is important to use energy-saving soil treatments and biological techniques for restoring soil fertility ensuring sustainable high grain yields. The urgency of this task increases and continues to be under discussion because of the insufficient study of this question [5,12,14].
The purpose of researches - to study influence of basic soil treatment methods and complex biological techniques for restoring soil fertility on the indicators of the fertility of typical chernozem and productivity of crop rotation cultures.
Research was conducted in a repeated stationary experiment of the Agriculture Department of Voronezh State Agrarian University n.a. Emperor Peter the Great, which was carried out at the peasant farm "I.P. Palihov" in Khokholsky District of the Voronezh Region [6-9].
Placing of crop rotation cultures in stationary experiment was systematic, replication -three times. Except studied techniques, technology of crops cultivation in experiment was generally accepted for forest-steppe zone of the Central Black Earth region.
In this experiment, the following parameters were determined: soil hardness, its structural state, the yield of winter wheat [10].
Hardness - the ability of the soil with a natural texture to resist compression and wedging. It provides mechanical resistance to the development of the root system of plants, affects the germination of seeds, water, air and thermal soil regimes, traction resistance of tillage machines and implements.
Our researches have shown (Fig. 1) that before sowing of winter wheat, soil hardness in the layer of 0-25 cm in all variants of the experiment was in the optimal range.
50
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■ Sowing «Earing ■ Harvesting
Note: 1 - clean fallow (control, plowing), 2 - sweet-clover green-manure fallow (plowing), 3 - binary sowing with blue alfalfa (plowing), 4 - clean fallow (disking), 5 - sweet-clover green-manure fallow (disking), 6 - binary sowing with blue alfalfa (disking), 7 - clean fallow (subsurface cultivator), 7 - sweet-clover green-manure fallow (subsurface cultivator), 8 - binary sowing with blue alfalfa (subsurface cultivator).
Figure 1 - Soil hardness under crops of winter wheat in the layer 0-25 cm depending on precursors at the background of the main soil treatment (2011-2013), kg/cm2
Soil hardness was lower (18.7 kg/cm2) in the variant of the binary sowing of winter wheat and blue alfalfa with subsurface processing.
In the earing phase of winter wheat, soil hardness increased compared to its value on the day of sowing. On the background of subsurface and surface treatments, the density of clean fallow soil exceeds the optimal value by 8 - 20% from a depth of 10 cm and less.
By the time of winter wheat harvest, soil hardness increased in all variants of the experiment and all soil layers. Under the crops of winter wheat on the clean fallow at all types of soil treatment, there was a trend of exceeding the limit of the optimal hardness values in soil layers 0 - 10 cm, 10 - 20 cm, 20 - 25 cm, 0 - 25 cm.
In 2011 under the crops of winter wheat on plowed fallow, hardness of topsoil was less
than in 2012 - 2013 on average by 40 - 44% in earing and harvesting period.
In green-manure fallow with sweet-clover and binary sowing of winter wheat with blue
alfalfa, soil hardness decreased due to the high efficiency of perennial grasses that formed a strong root system, which saturated the soil by organic matter in layers as well as throughout the arable horizon.
The fertile soil along with the optimum content of nutrients has to have the favorable agrophysical conditions for growth and development of crops. According to some researchers, perennial grasses and fallow becomes more important in restoring agrophysical soil properties as one of the conditions of its fertility [1,11,12,14].
As a rule, long agricultural use of the soil leads to the considerable deterioration of soil structure and water-physical properties. The main causes of the physical degradation of the soil are: decrease in the content of organic substance and deterioration of its quality and composition as well as a strong compacting effect on the soil by modern agricultural machinery. The problem of physical degradation of the soil cannot be solved only by the introduction of perennial grasses (and fallow). The solution of this complex challenge
possibly only on the basis of systems approach. Biological agricultural methods have to reach priority position in this complex [2-4].
At air-dried sifting, soil texture depended not only on predecessors, but also on basic soil treatment.
Our researches have shown (Table 1) that the binary sowing of winter wheat with blue alfalfa increased the content of structural aggregates by 13.4% - 14.6% compared with the control. Fewer of them were in the soil of clean fallow when using different methods of soil treatment. During the time from sowing to harvesting of winter wheat an increase of soil structure was observed.
In contrast, the content of water-stable aggregates decreased over the period from sowing to harvesting, except the variant of binary sowing with subsurface processing, where this rate increased.
Table 1 - Condition of the soil structure in 0-30 cm layer under the crops of winter wheat depending on precursors and soil treatment methods (2011 - 2013)
Precursors of winter wheat Soil treat ment Content of aggregates in weighed portion, % Structure coefficient
Structureless aggregates >10 mm Structu ral aggreg ates from 10 to 0,25m m Structureless aggregates < 0,25 mm Water- stable aggreg ates
1. Clean fallow (control) Plowing 20-22 cm 22 70.5 74.6 49 4,3 50,41 55,88 2,39 2,93
2. Green-manure fallow (yellow sweet-clover) 24,9 9,6 -HCD 78 36 3,9 54,46 59,37 2,50 6,40
3. Binary sowing with blue alfalfa 14,6 5,7 81,6 89 3,8 5,3 59.58 57.59 4,44 8,13
4. Clean fallow Disking 8-10 cm 12 66 67,4 80 4,0 4,4 53,08 59,07 2,07 4,01
5. Green-manure fallow (yellow sweet-clover) 22.4 14.4 73,3 82 4,2 3,6 54.59 62.59 2,75 4,56
6. Binary sowing with blue alfalfa 15,4 5,7 98 plO 59 3.7 3.8 57,34 67,15 47 cn]^ 49
7. Clean fallow Subsurface processing 20-22 cm loIco 21 77 Pp 19 4,0 3,8 54,85 60,08 2,44 3,56
8. Green-manure fallow (yellow sweet-clover) 20,4 9,7 76,1 87 3,5 3,3 57,55 65,75 87 Hco 36
9. Binary sowing with blue alfalfa 14,4 10,1 82,0 87,0 3,5 2,9 61,90 70,27 4,56 6,67
HCP05 - 2,3-2,6 2,0-2,6 2.3-2,4 2.4-5,1 0,3-0,4 0,4-0,5 38 3,4
Note: Numerator - sowing; denominator - harvesting
Content of water-stable aggregates in the soil is of great importance for improving soil fertility and its resistance to erosion processes. In binary sowings their quantity was greater by 25 - 38% compared with the control. The use of biological techniques for restoring soil fertility increases the content of water-stable aggregates during vegetation of winter wheat for all types of soil treatment. Formed during the decomposition of plant residues, readily degradable organic matter promotes bonding of soil particles and the formation of structural soil aggregates. There is a strong correlation (k = 0.76 - 0.97) between the readily degradable organic matter and content of structural aggregates [2]. Improving the structure of topsoil under yellow sweet-clover and blue alfalfa associated with the development of their strong root system which actively releases substances that contribute to the formation of soil aggregates [2, 4]. The use of various methods of soil treatment and biological techniques for restoring soil fertility (Table 2) allowed to harvest from 35.8 to 54.9 t/ha of winter wheat in 2011 - 2013.
Table 2 - Dependence of the yield of winter wheat from precursors and method of soil treatment, c/ha
Precursor, method of soil treatment 2011 г. 2012 г. 2013 г. Average
1. Binary sowing with alfalfa: plowing 20 - 22 cm - 39,8 50,3 45,1
2. Disking at 8 - 10 cm - 39,4 48,7 44,1
3. Subsurface processing 20 - 22 cm - 39,9 49,4 44,7
4. Green-manure fallow with yellow sweet-clover: plowing 20 - 22 cm - 41,5 52,2 46,9
5. Disking at 8 - 10 cm - 41,3 53,8 47,6
6. Subsurface processing 20 - 22 cm - 41,6 54,9 48,3
7. Чистый пар, вспашка 20 - 22 см 44,5 43,3 50,0 46,6
8. Disking at 8 - 10 cm 43,1 49,4 46,2
9. Subsurface processing 20 - 22 cm - 43,3 49,7 46,5
10. Oilseed radish 35,8 - - -
11. Common vetch 42,4 - - -
НСР05 1,1 3,7 4,5 -
The highest average yields of winter wheat (48.3 c/ha) was obtained at green-manure fallow with yellow sweet-clover at subsurface processing. In other experiment variants the difference in the yield of winter wheat was not significant. Thus, the use of green-manure fallow with sweet-clover and binary sowing of winter wheat with blue alfalfa enhances agrophysical fertility indicators of typical chernozem, creates favorable conditions for obtaining high yields of winter wheat grain.
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