Soil-protective complex of measures is an integral part of farming system aimed at protection of soil from erosion and prevention of development and spreading of erosive processes.. It includes agro-forestry reclamation, agrotechnical, organizational, water management measures, application of soil-protective methods in crop rotation, soil tillage system, fertilizer system, etc.
The importance of soil-protective complex of measures increases with intensification of agriculture and increasing loads on soil. In conditions of Russia, where in each region water or wind erosion is observed to a greater or lesser degree, farming systems should take into account the system of soil protection.
An important condition for creating erosion-resistant agrolandscapes is a systematic approach, adaptability to local conditions, comprehensiveness, environmental sustainability, economic and technical feasibility, environmental and socio-economic expediency.
Development of a soil-protecting complex
Soil-protective complex of measures is developed for each soil-climatic zone taking into account local peculiarities, type and degree of erosion, natural ecological and erosion situation:
- the general condition of the land area (landscape) of the land, district, region, territory, republic in terms of exposure to erosion;
- nature of soil cover and potential erosion hazard;
- features of the terrain;
- vegetation cover, e.g. afforestation, availability of natural hayfields and pastures, sodding, structure of areas under crops;
- climate features;
- human activities, i.e. specialization, farming systems, tillage practices, fertilizer use, machinery, etc;
- economic, social and environmental consequences.
When developing a complex of measures to control soil erosion, one should be guided by the Methodological instructions “Anti-erosion organization of the territory of an agricultural enterprise” (Russian normative document).
In zones of water erosion manifestation soil protective measures are designed and implemented within the boundaries of water-collecting basins in the following sequence: from watershed to the foot of slope, from watershed line of gully and gully system to the mouth. In the zones of manifestation of wind erosion complex of measures covers the entire erosion area, including a group of agricultural farms or administrative districts. In zones of joint manifestation of water and wind erosion both requirements should be met.
The question of the necessity of using a particular erosion control measure should be decided on the basis of comprehensive consideration of conditions: climate, topography, soil cover features and economic opportunities of the farm. Cost-effectiveness of soil protection measures – achievement of the maximum efficiency of techniques and their complex with the minimum exclusion of valuable lands and the least expenditure of resources for their implementation.
Design of erosion control measures shall include:
- drafting of general schemes of the complex of anti-erosion measures for the republic, territory, region;
- drafting of erosion control schemes by soil-erosion zones, including interrelated agricultural farms and administrative districts;
- development of erosion control complexes for the enterprise;
- development of design and estimate documentation for the construction of hydrotechnical, water management constructions and the creation of protective plantations.
Development of a scheme of a complex of anti-erosion measures for the republic, territory, region includes soil-erosion zoning, selection of zones and areas similar in the nature of erosion processes and a set of planned soil protective measures. Types, volumes, terms of performance and cost of works on soil protection shall be determined.
Annual plans of erosion control measures shall be developed on the basis of the scheme. Each enterprise shall have a project and a long-term plan of soil protection measures and measures to improve the fertility of eroded lands. Specialists and managers of enterprises should organize control over implementation of these measures.
Project of complex of soil protective measures is prepared on the basis of: documentation of on-farm land management, soil and agronomic maps, maps of relief and steepness of slopes, data on amount and character of precipitation, data on the size of meltwater runoff, development of wind and water erosion.
The design takes into account:
- the influence of the degree of washout and dispersion of the topsoil on crop yields;
- possibility of using soil-protective, humus and symbiotic role of certain crops;
- the amount of time the soil is not occupied by plants or plant residues;
- peculiarities of each land plot;
- possibility of application of erosion control measures in specific conditions.
The design of erosion control measures is carried out in the following order:
- The relief, steepness, length, shape and exposition of slopes, climatic conditions (amount, distribution and character of precipitation, wind speed and direction, temperature regime) are studied. Water reserves of snow cover, intensity of melting and condition of soil by the period of snow melting are taken into account. The period of occurrence of erosion danger is determined. Data of soil conditions such as granulometric composition, texture, thickness of humus layer, soil density and moisture, degree of washing out and blowing out are analyzed.
- The erosion danger of crops in crop rotations is assessed. For this purpose coefficients of erosion danger of field crops determined by A.S. Stantsyavichyus for north-western regions of Non-Black Earth zone on sloping lands are used. The following crops are considered erosion hazardous: black fallow – 1,0, root crops – 0,8, corn for silage – 0,5, spring cereals – 0,5. Soil protection level includes: leguminous-cereal mixtures – 0.4, spring crops with undersowing of perennial grasses – 0.3, winter rye – 0.2, winter crops with undersowing of perennial grasses – 0.1, perennial grasses of the first year of use – 0.05, perennial grasses of the second year of use – 0.03, perennial grasses of the third year and more – 0.01.
- Methods of placement of crops on sloping lands or on soils at risk of wind erosion, such as striped, continuous, contour-striped, with creation of buffer strips, etc., are established. The composition and order of alternation of crops in crop rotations at their strip arrangement should ensure protection of soils during the whole erosion hazardous period.
- The system of fertilizers in crop rotation is built, taking into account soil-protection requirements.
- The anti-erosion methods of tillage for each crop are determined.
- Methods of sowing and methods of care of crops for each crop are determined.
- Soil tillage, sowing and harvesting aggregates and the direction of their movement are determined.
- Measures for accumulation and regulation of snowmelt are envisaged.
For a more detailed study, a field complex survey of the territory is carried out.
Classification of lands by erosion hazard
According to the Methodological Guidelines, all lands are divided into 4 groups, including 9 categories, of which 5 are suitable for cultivation:
1.Land suitable for intensive use in farming.
I category. Land not subject to erosion, located on watersheds and near-watershed slopes with a slope of up to 1° and a runoff line length of up to 200m. Potential intensity of soil washing out not more than 3 t/ha per year.
Category II. Land subject to slight erosion. Upper gentle areas of slopes with a slope up to 3° and runoff line length up to 300 m. Potential intensity of washout 3.1-10 t/ha per year.
Category III. Lands prone to erosion. Middle and partly lower parts of slopes with slope up to 5°. Length of runoff line is from 300 to 600 m. Potential washout of 10.1-20 t/ha per year.
2. Land limited suitable for tillage but unsuitable for cultivation of row crops.
IV category. Lands subject to severe erosion. Middle and partly lower parts of slopes with steepness up to 8°. Length of runoff line is from 800 to 1000m. Potential intensity of washout 20,1-40 t/ha per year.
V category. Lands very prone to erosion. Lower parts of slopes with steepness more than 8° adjacent to gully banks. Potential intensity of washout more than 40 t/ha/year.
3. Land unsuitable for cultivation.
VI category. Land of gullies, their upper parts adjoining arable lands, with steepness from 10 to 15°. Length of drain line is from 1000 to 1500 m. Grass vegetation is thinned and there are washouts. Amount of washout at plowing can reach 100-150 t/ha per year.
VII category. Lands of lower parts of gully slopes, 15-17° steepness. Length of runoff line is from 1500 to 2000 m. Potential intensity of washout at plowing can reach 150-200 t/ha and more.
4. Lands unsuitable for agricultural use.
Category VIII. Gully slopes rugged with frequent scour, steepness over 8-10°, located between ravines with depth over 10 m, distance between ravines up to 150-200 m. Narrow gullies of less than 200-250 m, with steep slopes of more than 17-20°, their bottoms are exposed to erosion.
Category IX. Gullies not subject to flattening, outcrops of chalk, gravel, stony talus, sands and others.
Depending on the degree of risk of wind erosion, a complex of anti-erosion measures may be built according to the following recommendations:
- Land not subject to wind erosion. No measures are taken.
- Land slightly exposed to the risk of wind erosion. Simple anti-erosion measures are used: conduct of tillage in optimal terms, use of fertilizers, snow retention, use of non-moldboard tillage and sowing with stubble remaining on the surface, strip planting of crops and fallows by 100-150-200 m wide strips perpendicular to wind direction, creation of a network of field-protection forest strips.
- The lands are moderately exposed to wind erosion. The measures applied to the previous category are supplemented by non-moldboard tillage and sowing with maximum preservation of stubble, in arid areas – use of strip seeded fallow and strip planting in combination with buffer strips of perennial grasses.
- Land highly exposed to wind erosion. The full set of available erosion control measures is used: introduction of soil-protective crop rotations with high specific weight of perennial grasses, non-moldboard tillage, sowing with maximum preservation of stubble, sowing of crops, fallows and buffer strips of perennial grasses in strips 50-100 m wide, perpendicular to wind direction, continuous grassing of wind-affected slopes, creation of thickened network of forest strips.
- Land very much exposed to wind erosion. Not suitable for permanent crop cultivation. Can be used for full grassing of hayfields and pastures with surface and radical improvement. In some cases can be allocated in soil-protective crop rotation with 1-2 fields of cereals and 3-5 fields of perennial grasses under the condition of protection by forest strips.
Effectiveness of a complex of erosion control measures
At Novosilsk zonal agromeliorative experimental station of Orel oblast, with the area of 700 ha of lands, experience in application of complex of measures against water erosion, including organizational-economic, hydraulic, forest-meliorative and agrotechnical measures, has been accumulated. Soil erosion was stopped on the whole area, cereal crops yield increased 3 times. The lands of this station are divided into categories depending on washout and slope. Field crop rotations were introduced on slopes with unwashed and slightly washed away soils, and soil-protecting ones on strongly washed away soils. Hollows and gullies are grassed and used for pastures with justified rational pasture rotation. The autumn tillage is carried out by mouldboard and non-moldboard ploughs in 27-30 cm across the slopes. Harrowing, cultivation and sowing are also carried out across the slope. Organic and mineral fertilizers are widely used.
In Stavropol Krai, much attention is paid to special soil-protective crop rotations on slopes, where more than half of the fields are allocated for perennial grasses. As a rule, row crops are excluded or occupy small areas. Soil-protective measures include tillage and sowing across the slope, strip planting, cutting rolls horizontally, tillage with stubble remaining, and grassing of gullies and ravines.
In the farm “Giant” in the Rostov region, with characteristic dust storms that recur every 2-3 years, and the duration of winter snowstorms is 10-12 days, and wind speed 15-20 m/s. To control erosion, field protective plantations, reasonable alternation of crops in crop rotations, and special agrotechnical measures are successfully used.
At the Pavlodar experimental station on soil erosion protection (Kazakhstan), a complex of anti-erosion measures, including soil-protective crop rotations with strip arrangement of crops, in which strips of annual crops and strip fallow alternate with strips of perennial alfalfa or Onobrychis in mixture with Agropyron. Width of strips is the same for sandy soils – 50 m, light loam – 100 m. Stripes are located across the prevailing winds. The flat-cutting tillage of the soil with stubble left on the surface is used. On fallow fields, mustard strips are grown for snow accumulation and protection against blowing. When harvesting cereals, high stubble is left and straw is scattered across the fields. Drought-tolerant crops and varieties are used in crop rotations, herbicides are widely used, and the number of mechanical treatments is minimized. Areas unsuitable for growing annual crops are grassed.
A scientifically sound complex of erosion control measures, adapted to local conditions, can significantly reduce or completely prevent the risk of soil erosion development.The experience of enterprises in Siberia, Altai, Trans-Urals, Volga region shows that even in severely dry years in the steppe regions of Siberia the application of soil protection measures allows to get 1.1-1.2 t/ha of grain, in years with sufficient moisture – up to 2 t/ha.
Sources
Farming. Textbook for universities / G.I. Bazdyrev, V.G. Loshakov, A.I. Puponin et al. – Moscow: Publishing House “Kolos”, 2000. – 551 с.
Fundamentals of agricultural production technology. Farming and crop production. Edited by V.S. Niklyaev. – Moscow: Bylina, 2000. – 555 с.