Soil conservation in agriculture

Soil is the top layer of the earth’s surface that is capable of sustaining life. Therefore, soil is very important to farmers/ cultivators, who depend on soil to provide abundant, healthy crops each year. One major problem in our agriculture is soil erosion, which is most serious on hills due to steep slopes. The steepness of soil does not deter any body taking up cultivation on hills. Soil loss from cultivated slopes is quite high particularly during first two or three years of cultivation. The chief reasons of soil loss are cultivation of steep and unprotected slopes, overgrazing and indiscriminate felling of forest trees. Top soil contains most of the soil’s nutrients and organic matter which takes hundreds to thousands of years to build up under natural conditions. Soil erosion causes these substances to move also. So what is left behind is a depleted soil with poorer structure, lower water-holding capacity, different pH values, and low nutrient levels. Crops receive poor nourishment from the depleted soil, and the food provides poor nourishment to people. The important point is losses of soil take place much faster than new soil can be created. It takes thousands of years to form just a few centimeters of soil Soil conservation is maintaining good soil health, by various practices. The aim of soil conservation methods is to prevent soil erosion, prevent soil’s overuse and prevent soil contamination from chemicals. There are various measures that are used to maintain soil health, and prevent the above harms to soil.Agronomic Soil Conservation measure - All the operations carried out in the field from land preparation to harvesting of crop in order to have maximum harvest are called agronomic practices. Certain manipulations are highly desirable in agronomic practices of crops. They all aim at retaining the productivity of land and the practices are referred to as ‘conservation farming’. Some important conservation farming methods are briefly discussed here. Use of Vegetation: The land should not be kept without crop. There is very scope of soil erosion if there are no crops on the land. The plant canopy protects the soil from the adverse effect of rainfall. Crops and vegetables which cover the ground surface well and have extensive root system reduce soil erosion and provides organic matter to the soil. As a result, the fertility of soil increases and the physical condition of soil is improved. Following cropping systems help in controlling soil erosion – Crop rotation: Growing of the same kind of crop for years in the same field is not a desirable practice as it depletes certain nutrients and organic matter from the soil. Addition of a densely grown, deep rooted, erosion resisting crop is necessary in the rotation. An erosion resisting crop must be grown at least once in two years. A good crop rotation is planned sequence of cropping for checking erosion and maintaining productivity of soil. A good rotation should include densely planted small grain crops, spreading legume crop etc. which may check soil erosion. The practice of mixed cropping is also important from the point of view of soil conservation. Strip Cropping: This is a system of cropping in which a soil conserving crop and a soil depleting crop are grown in alternate strips. Strips run perpendicular to the slope of the land or to the direction of prevailing wind. For the crops of both the strips, other agronomic practices are carried out as usual. This is a very practical and effective measure of controlling soil erosion but more feasible in extensive fields located on slopes. Strip cropping employs several good farming practices including crop rotation, contour cultivation, proper tillage, stubbles mulching, cover cropping etc. Strip cropping is of four types- • Contour strip Cropping: Contour strip cropping is the growing of erosion permitting and erosion resisting crops alternately in strips across the slope and on the contour line. In every passing season the types of crop in the strips should be interchanged. This practice is useful because it checks the fast flow of run-off water increases the infiltration of water in the soil and prevents soil erosion. • Field Strip Cropping: The strips, in this cropping method. may not be exactly on contours. This practice is suitable for uniformly slopping field. The strips should be established across the slope. • Wind Strip Cropping: Strips of crop are grown across the direction of wind regardless of contour. • Buffer Strip Cropping: In this, the severally eroded portion of land is permanently kept under grass and contour strip cropping is practiced in the rest of the area. Cultivation of dense plant and grasses: Cultivation of dense plant and grasses cover the surface of the land and their roots bind the soil particles to form soil aggregates, thus preventing soil erosion. Cultivation of proper crops: Cultivation of row crop in sloppy lands permits soil erosion. Mixed and intercropping practice checks soil erosion and avoids the risks of crop failure. Mulching: Mulching is a practice of putting straw, plant residues, leaves and/or grass on the soil surface to reduce evaporation, erosion and fluctuation in soil temperature. Materials used in mulching, act as physical barriers to movement of water in the soil. Immediate objective of mulching is to reduce loss of moisture from the soil surface by the process of evaporation and protect the soil against the strokes of rain and wind. After decomposition, mulching material incorporates organic matter in the soil which enhances erosion resistant power of the soil. Organic manure: Organic matter is a very important component of the soil which keeps the soil particles clumped together, thereby imparting resistance against erosion. Presence of organic matter is a must for micro- organisms to flourish in the soil. Micro-organisms secrete some slimy substance which helps in binding together of soil particles. Organic matter particles are 10 to 100 times more efficient in retaining moisture than the fine clay particles of the soil. The main source of organic matter in cultivated soil is organic manure. Use of farmyard manure, compost and green manures should be made in order to keep an optimum level of organic matter in the soil. Addition of anything of plant and animal origin contributes to organic matter of the soil. Control of grazing: Grazing increases the soil erosion. But grazing cannot be completely stopped in all areas. So restricted and rotational grazing may be helpful in checking soil erosion to some extent. The areas open to grazing for sometimes should be closed for the following year to facilitate regeneration of forests and to maintain thick ground vegetation. Good tillage: Tillage is the mechanical manipulation of soil by different kinds of implements. Tillage makes the soil loose and friable which helps in retention of water. Tillage operations should be carried out as far as possible on the contour very cautiously as they can do both harm and good to a soil. It removes weeds and enhances moisture retaining capacity of the soil. However, in high rainfall areas deep ploughing should be preferred in order to keep down weeds and preserve greater amount of moisture. Agrostological Soil Conservation measure Agrostological methods involve rotating crops with long duration perennial vegetation and establishing permanent vegetation, in highly eroded lands. The practice of lay farming involves cultivation of agricultural crops in rotation with grasses which is very useful. It improves the fertility of the soil and helps in binding soil particles, thus preventing soil erosion. Areas prone to heavy soil erosion should necessarily be put under thick cover of grasses. Periodic grazing can also be allowed in favorable climatic condition. Agrostological measures also include plantation of trees on the new lands (afforestation) and the lands which have been denuded of forest trees (reforestation). Rows of trees can be planted in contour lines dividing the cultivable land in strips. Afforestation is the best means to check the soil erosion.