In modern agriculture, a number of erosion control measures have been developed and applied to protect the soil from erosion and prevent its development and spreading. The erosion control techniques (measures) are the components of anti-erosion complex of measures.
Integrated application of organizational, agrotechnical, agrochemical, ameliorative and hydro-technical erosion control measures is the most effective. It ensures the preservation of land fertility, growth of crop yields, stability and profitability of agriculture.
- The main methods of soil-protecting complex
- Forest reclamation techniques
- Phytomeliorative techniques
- Soil protection crop rotations
- Buffer strips
- A system of soil protection tillage
- Fertilizer application on eroded soils
The main methods of soil-protecting complex
The main methods of soil-protecting complex:
- Anti-erosion measures:
- grassing of heavily washed out slopes;
- soil-protective crop rotations;
- forest reclamation;
- hydro-reclamation structures, e.g. dams, water-regulating swale
- systems, swift-flowing streams;
- strip rolling and snow blanketing, use of snow retention shields.
- Anti-deflation measures:
- cereal-fallow, cereal-row crop rotations with a short rotation;
- buffer strips of perennial grasses;
- strip planting of bare fallows and row crops;
- strip-till farming;
- flat-cutting tillage;
- sowing cereals with stubble seeders;
- wood reclamation;
- regular irrigation.
- Anti-erosion and anti-deflationary measures:
- soil and water conservation land management of the territory;
- grassing of heavily washed out slopes;
- cereal-grass, cereal-fallow and cereal-row crop rotations;
- strip-tillage placement of bare fallows, row crops and perennial grasses;
- flat-cutting across the slopes after cereal crops;
- hollowing, for example, after perennial grasses and corn, ploughed land and fallows;
- slitting of perennial grass;
- mulching the soil with chopped straw;
- forest reclamation;
- hydrotechnical constructions;
- agrohydromeliorative soil-protective complex in the watershed.
The leading role in erosion control is given to the systems of tillage of soils subject to water erosion and tillage of soils subject to wind erosion.
Forest reclamation techniques
Forest plantations in erosion-prone areas, depending on their purpose, are divided into:
- pasture protective.
In addition, there are water-protective plantings located near rivers, ponds and reservoirs, as well as group and cluster plantings. In some cases there is continuous afforestation of slopes, sands, wash and gullies.
In open steppe and forest-steppe regions with active and strong winds the main purpose of forest belts is to reduce the speed and turbulence of erosive wind flows. Wind weakening contributes to protection of soils from blowing out in summer and winter periods, snow retention, increase of soil and air moisture, improvement of microclimate.
According to VNIALMI data, the system of forest belts allows to accumulate 1.5-2 times more snow on the fields, air humidity in the ground layer increases by 5-10%, moisture losses from evaporation decrease by 20-30% than in the open steppe.
The anti-erosion and reclamation efficiency of forest plantations depends on their design. In steppe areas, openwork and blown narrow-row strips of 3-5 rows are used.
When forest reclamation measures in areas of water erosion development it is important to take into account peculiarities of terrain, as incorrect placement of forest strips may lead to increased runoff, increased washout and erosion of soil, gully formation.
Water-regulating forest strips are created on relatively steep slopes with a slope of more than 2-3°. Their main purpose is to disperse and absorb surface runoff of meltwater and stormwater. They are placed in strips in 4-7 rows across the slope or horizontally, with a distance of 200-350 m between strips, depending on steepness and susceptibility of soil to erosion.
Near-wash forest belts are designed to protect the adjacent arable land from the destructive action of erosion processes and for more effective snow distribution and moistening of fields. As a rule, they are designed in openwork design with width of 12-21 m.
Near-gully forest belts are created to strengthen the growing tops of gullies. They can cover the whole systems of gullies and tops. Gully tops are secured by diking in advance.
Pasture protection forest strips are placed on slopes, taking into account the relief, soil damage by erosion, the direction of runoff and prevailing winds. Design of strips is openwork and openwork-blown with width of 9-18 m and distance between main strips from 200 to 350 m.
Cluster-group and continuous afforestation is carried out if the territory is very indented by ravines and on sands.
Hydrotechnical anti-erosion structures primarily include:
- earthen water-retaining, water-regulating shafts and ditches used for water retention and diversion to reinforced water receptors, hollows, etc.;
- apical (head) structures in the form of concrete, wooden, brick and other flumes, swift currents, drops, cantilevers, etc.;
- bottom structures along the beds of hollows and gullies, preventing further erosion of the bed;
- bank protection and mudflow prevention structures;
- ponds and reservoirs.
The natural vegetation cover and dense cover of cultivated plants can serve as effective soil protection against water and wind erosion. Cultivated plants with high soil-protective properties include perennial and annual grasses, winter and spring cereals, buckwheat, peas and other continuous crops. To enhance soil-protective effect, the seeding rate is increased, and cross-row and narrow-row sowing methods are used.
On steep slopes, perennial grasses are grassed. For example, in the Belgorod experimental station, when grassing steep slopes of 10-12°, the hay yield is 2.5-3 t/ha. In Liskinsky and Ostrogozhsky districts of Voronezh region, the hay yield on steep slopes is up to 4 t/ha. In Belgorod Region, grass mixtures of alfalfa, Onobrychis, awnless bromegrass (Bromus inermis) and meadow fescue (Festuca pratensis) are most productive on sloping lands.
In eastern Russia, Agropyron ? (broad-banded) and narrow-banded (Agropyron desertorum), Melilotus officinalis and Sainfoin (Onobrychis arenaria). Their mixtures yield large harvests of high-quality hay or green mass.
Perennial grasses and sprouted winter crops have high soil-protecting ability against blowing out; to a lesser extent, it is manifested in early spring crops, and the lowest – in late row crops.
Soil-protective crop rotations are crop rotations designed to protect soils from water erosion on slopes greater than 5°, where soil washout can reach 15 t/ha per year, and wind erosion, for example in open steppe where wind speed near the surface is more than 3-4 m/s.
On lands subject to water erosion, crop rotation fields are placed with the long side across the direction of the slope in order to cultivate the field across the slope.
Soil-protective crop rotations are based on the property of some crops in combination with special methods of tillage and placement of crops to protect the soil from erosion.
Buffer strips are a method of sowing crops that serves to accumulate snow in winter and reduce runoff and the development of water and wind erosion in spring. Sowing of perennial and annual grasses, winter and spring cereals, sunflower, Sudan grass and other crops is used for buffer strips. Width of buffer strips and distance between them is determined by steepness of slope, degree of manifestation of erosion processes.
In practice, on slopes of 6-8° the width of buffer strips is 4-6 m (3.6-7.2 m), with the distance between them 30-40 m. On slopes of lesser steepness the distance is up to 50-100 m and on steeper slopes it is 10-30 m with the width of strips of 10.8 m. To prevent wind erosion, the width of buffer strips is determined depending on the degree of soil deflation and wind speed.
A system of soil protection tillage
The tillage system should provide each field and plot with soil protection from erosion processes and high and sustainable yields of crops throughout the year.
General and special (additional) tillage methods are referred to soil-protecting practices.
Examples of common anti-erosion methods of main tillage:
- plowing across the slope;
- stepped plowing with the use of plows, where even bodies are set 10-12 cm deeper;
- plowing with simultaneous formation of anti-erosion nanorelief on the field, such as furrows, ridges, holes, intermittent furrows;
- plowing with a deepener or a plow with notched bodies;
- non-moldboard plowing;
- flat-cutting, deep loosening with stubble retention;
- combined mouldboard and non-moldboard plowing;
- strip loosening;
- slitting of winter crops, perennial grasses, natural hayfields and pastures;
- minimum tillage;
- mole tilling;
- contour tillage;
- cultivation with deep looseners, flat-cut cultivators, needle harrow, rod
- cultivators and other erosion control tools.
The above list is not limited to the listed techniques, which can be supplemented by others, taking into account soil and climatic conditions of each zone.
According to studies conducted in erosion-prone zones of Russia, deep autumn plowing allows increasing water reserves by 20-30 mm by reducing surface and subsurface runoff and increasing crop yields by an average of 10-15%, especially in years of drought and in areas with insufficient moisture.
Alternating tillage methods
Alternation of non-moldboard tillage at a depth of 30-32 cm with plowing at a depth of 20-22 cm with creation of rollers on the surface of plowed soil is an effective method of erosion control tillage.
Alternation of deep plowing at 30-32 cm, if the humus horizon allows, with ordinary plowing at the depth of 20-22 cm is also effective.
Application of non-moldboard implements on sloping lands allows to reduce dramatically melt water runoff and soil washout. At the same time cereal crops yield increases by 0.2-0.4 t/ha. Deep loosening (chiseling) and plowing across the slopes is used on heavy soils.
In the Non-Black Soil Zone, sod-podzolic soils usually use mouldboard tillage combined with surface tillage, in the rest of the European part of Russia – combined tillage combining mouldboard tillage with surface and flat tillage, in Siberia – flat tillage combined with surface tillage.
Contour tillage – tillage in the direction close to the course of the horizontals with the transverse movement of aggregates, is a part of the contour organization of the territory.
The Research Institute of Agriculture of the Central Black Earth Belt named after V.V. Dokuchaev and Voronezh State Agrarian University proposed a contour-buffer system consisting in strip alternation of crops and buffer strips of perennial grasses in soil-protective crop rotations.
The works of Y.I. Potapenko of the All-Russian Research Institute of Viticulture and Winemaking, who proposed a set of anti-erosion measures on the contour-belt basis, were widely spread.
Special (additional) methods of anti-erosion tillage include: furrowing, hollowing, mole cutting, creation of rollers, slitting, etc.
Creation of rolls and furrowing of ploughed soil are used on one-sided and levelled sloping lands without troughs. Creation of rollers is carried out simultaneously with plowing with the use of the extended mouldboard mounted on one of the plough bodies. Simultaneously with plowing of furrow it is possible to perform intermittent furrowing. For this purpose, ploughs with special three-blade bridging-makers mounted on them are used. For intermittent furrowing, ploughs are equipped with ПРНТ-70000 and ПРНТ-90000 devices.
The depth of the furrows on the cultivated field is 25-30 cm and the distance between them is 4-10 m. The steeper the slope, the more often make furrows.
According to the data of experimental institutions in Bashkortostan, furrowing of the furrow reduces soil washing out, increases its moisture and the yield of spring wheat by 0,15-0,4 t/ha.
On many agricultural enterprises of the Central Black Earth zone, the Volga region, Northern Caucasus and Bashkortostan on slopes steep to 2-4° use plowing with making rolls height of 15-30 cm across the slope, which is carried out by lengthening the penultimate blade on the body plow.
On slopes up to 3.5-4° for water erosion control in Rostov oblast, furrow ploughing with breaker furrows of ППБ-0,6 type has proved to be a good solution. For intermittent furrowing, a key plough is also used, equipped with movable sections of plough bodies, each of which, rising and falling, creates intermittent furrows.
Creation of microlimans on the surface of cultivated soil contributes to retention of melt water. For their arrangement on slopes, bridge-maker is installed on a plough with extended mouldboards.
On ploughed and fallow fields in autumn it is applied hollowing with the help of six-section disc hollows-formers ЛОД-10 or special devices, which allow to create on the field about 13 thousand hollows, 130 cm long, 40-50 cm wide and 10-20 cm deep, with total capacity to 250-300 m3/ha of water. However, under conditions of periodic thaws and frosts, a stable snow cover is not formed, and ice lenses arise at the bottom of the wells, preventing the absorption of melt water. As a result, runoff not only does not decrease, but increases. In this regard, technical improvement of anti-erosion aggregates, which form rolls, holes and slits in one pass, absorption capacity of such holes increases due to location of holes above the slits, has received as an agrotechnical technique.
To reduce subsurface runoff a stepped multi-depth plowing is used, which is carried out across the slope by a plough, with even bodies exposed to normal depth and odd bodies exposed to a depth of 12-15 cm more. As a result the plow pan acquires a stepped configuration reducing subsurface runoff.
On highly sloping soils, where the efficiency of furrowing and hollowing is significantly reduced, slitting, chiseling and mole cutting are used. Slitting is carried out on winter crops, perennial grasses, bare fallow, natural hayfields, pastures and orchards, especially on early fallow lands. This method consists in making slits up to 40-60 cm deep, 3-5 cm wide and 100-400 cm wide with the help of slitters or other implements. The slits are usually cut in late autumn, when the soil is frozen, which ensures preservation of the slits until spring.
Mole-cutting is the creation of cavities-moles 6-8 cm in diameter at a distance of 0.7-1.4 m at a depth of 35-40 cm with the help of special devices. This method improves water permeability, moisture distribution along the soil profile, and removes excessive moisture in conditions of excessive moisture.
Methods of pre-sowing and post-sowing tillage
Sowing across the slope, at an angle or horizontally is used as soil protection measures for pre-sowing and post-sowing tillage. This method of sowing allows to reduce the velocity of water flow, increase the duration of water contact with the soil and moisture absorption.
The system of tillage in the areas of wind erosion is based on the preservation of the limiting factor of yield – moisture. For this purpose, non-moldboard – flat-cutting and chisel tillage are used.
Non-moldboard tillage or plowing with ordinary plows with moldboard removed and stubble left at a depth of 27-32 cm across the slopes is good at preventing runoff and erosion. Soil-protective non-moldboard tillage allows to increase the reserves of moisture available for plants in one meter layer of soil by 20-40 mm and to increase the grain yield by 0,2-0,6 t/ha.
In cereal-fallow rotations with a short rotation, for example, 1 – bare fallow, 2-4 – crops, flat-cutting is used on all fields. Sometimes after perennial grasses in cereal-grass and cereal-row rotations, more often 2-3 years of use, the ordinary ploughs are used for cutting the layer with 23-25 cm of ordinary ploughs. In the presence of weak (Agropyron, Onobrychis) turf for greater conservation of moisture and prevention of wind erosion, plowing can be replaced by a preliminary discing with subsequent flat-cutting, chiseled cultivation or deep loosening.
Plowing of perennial grasses in all cases is carried out in strips. Width of cultivated and sown strips multiple of 50 m depends on the power of prevailing winds, steepness of slope and granulometric composition of soil.
In moist forest-steppe areas with 350-450 mm of precipitation with black earth soils for row crops depending on the type and density of soil, the use of organic fertilizers, weediness of the field can be used ordinary plowing to a depth of 23-25 cm.
In areas of wind erosion, non-moldboard tillage is mainly used.However, if necessary, for example, for the embedding of organic fertilizers and turf of perennial grasses, reclamation treatments of irrigated or saline soils, different types of mouldboard tillage are used.
Fertilizer application on eroded soils
Indirect erosion control measures include the application of organic, mineral fertilizers, micro- and bacterial fertilizers, liming and cultivation of siderats. Due to their effect on improving the development of aboveground and root mass, density of crops and a positive role in creating erosion-resistant soil structure, the protective effect of fertilizers and ameliorants is manifested.
The need of crops on eroded soils in nitrogen and phosphorus fertilizers is higher than on non-eroded soils. Therefore, fertilizer doses on medium eroded soils are increased by 20%, on highly eroded – by 50%. At the same time, measures to reduce runoff significantly increase the effectiveness of fertilizers.
On eroded soils of Bashkortostan yield of winter wheat from application of 20 tons of manure increased by 0.4 t/ha, 40 tons – by 0.5-0.6 t/ha.Complex application of manure and superphosphate increased the yield by 1.1 t/ha, against the control – 1.3 t/ha. According to the Research Institute of the Central Black Earth Strip named after V.V. Dokuchaev, the application of 10 t of manure and 60 kg of nitrogen fertilizers on eroded soils increased barley yields by 48%. V.V. Dokuchaev Research Institute, the application of 10 t of manure and 60 kg of nitrogen fertilizers on eroded soils increased barley yields by 48%.In Tatarstan the application of peat and manure compost and mineral fertilizers increased the yield of green mass of corn from 8.2 to 17.3 t/ha.
Eroded soils are characterized by low content of microelements, especially zinc, boron, molybdenum, bromine, cobalt, so the application of microfertilizers shows greater efficiency.
Of great importance is the use of green fertilizers as an organic fertilizer. For this purpose can be used: annual and perennial lupine, clover, alfalfa, fodder beans, white mustard, bittercane, rape, vetch, seradella and others.
Syderal crops may be cultivated as intermediate, post-mowing, stubble or fallow-seeded crops. Plowing green matter as fertilizer has the same effects as applying manure.
Doses of organic and mineral fertilizers for eroded soils, determine by the formula:
where F is the dose of manure and nitrogen fertilizers, t/ha; Fm is the dose of manure and nitrogen fertilizers on unwashed soil, t/ha; K is the reduction of humus in washed out soils, % of unwashed.
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