Soil Conservation & Water Management

Soil Conservation & Water Management

Soil conservation measures – agronomic measures of soil conservation : Soil conservation is using and managing the land based on the capabilities of the land itself involving application of the best management practices leading to profitable crop production without land degradation.

Control of water erosion:

Water erosion occurs simultaneously in two steps: detachment of soil particles by falling raindrops and transportation of detached particles by flowing water. Hence preventing the detachment of soil particles and their transportation can minimize water erosion. Principles of water erosion control are

– Maintenance of soil infiltration capacity

– Soil protection from rainfall

– Control of surface runoff and

– Safe disposal of surface runoff

For a sound soil conservation programme every piece of land must be used in accordance with the land capability classification.

(Soil Conservation & Water Management)

Measures of water erosion control:
1. Agronomic measures
2. Mechanical measures (Engineering measures)
3. Forestry measures
4. Agrostological measures

Agronomic measures of soil conservation:

In soil and water conservation programmes agronomic measures have to be considered in co-ordination with others for their effectiveness. These measures are effective in low rainfall areas particularly in fairly erosion resistant soils having gentle slope (< 2 %). The different agronomic measures include-

1. Land preparation

2. Contour cultivation

3. Choice of crops

4. Strip cropping

5. Crop rotation / cropping systems

6. Cover crops

7. Mulching

8. Application of manures and fertilizers

9. Application of chemicals

(Soil Conservation & Water Management)

1. Land preparation:Land preparation including post harvest tillage influence intake of water, obstruction to surface flow and consequently the rate of erosion. Deep ploughing or chiseling has been found effective in reducing erosion. Rough cloddy surface is also effective in reducing erosion.

2. Contour cultivation (Contour farming): A line joining the points of equal elevation is called contour. All the cultural practices such as ploughing, sowing, intercultivation etc. done across the slope reduce soil and water loss. By ploughing and sowing across the slope, each ridge of plough furrow and each row of the crop act as obstruction to the runoff and provide more time for water to enter into the soil leading to reduced soil and water loss.

3. Choice of crops :Row crops or tall growing crops such as sorghum, maize, pearl millet etc.,are not effective in conserving soil as they expose majority of the soil and hence they are known as erosion permitting crops. Where as close growing crops such as cowpea, groundnut, green gram, black gram etc., which protect soil are known as erosion resisting crops as they are very effective in reducing soil loss by minimizing the impact of rain drop and acting as obstruction to runoff.

(Soil Conservation & Water Management)

4. Strip cropping: It is a system of growing of few rows of erosion resisting crops and erosion permitting crops in alternate strips on contour (across the slope) with the objective of breaking long slopes to prevent soil loss and runoff. Close growing erosion resisting crops reduce the transporting and eroding power of water by obstructing runoff and filtering sediment from runoff to retain in the field. The width of the erosion permitting and erosion resisting crops vary as per the slope of the field. The strip cropping resembles the intercropping. With increase in per cent slope of the soil, the width of erosion permitting and erosion resisting crops decreases. The normal ratio between the erosion resisting crops and erosion permitting crops is 1: 3. Among the different crops the antierosion value of pillipesara is highest, where as cotton crop recorded the lowest value .

The strip cropping is divided into four types as follows-

i) Contour strip cropping: The erosion permitting crops and erosion resisting crops are grown in alternate strips along the contours.

ii) Field strip cropping: Alternate strips of erosion permitting crops and erosion resisting crops are raised across the general slope not necessarily on exact contour

iii) Wind strip cropping: Strip cropping of erosion permitting and erosion resisting crops across the direction of the most prevailing wind irrespective of the contour.

iv) Buffer strip cropping: this type of strip cropping is practiced in areas having steep slopes and badly eroded soils where strips of permanent cover crops or perennial legumes or grasses or shrubs are alternated with field crops.

(Soil Conservation & Water Management)

The strip cropping is simple, cheap and effective soil conservation practice and can be adopted by the farmers.

5. Crop rotation / cropping system: Monocropping of erosion permitting crops accelerates soil and water loss year after year. Intercropping of erosion permitting crops and erosion resisting crops or their rotation has been found effective for reducing soil and water loss. Inclusion of legumes like lucerne in crop rotation reduces soil loss even in soils having 13% slope.

6. Cover crops: Good ground cover by canopy gives the protection to the land like an umbrella and minimize soil erosion. Besides conserving soil and moisture, the cover crops hold those soluble nutrients, which are lost by leaching. The third advantage of the cover crops is the addition of organic matter. The legumes provide better cover and better protection. Among the legumes cowpea has been found to produce maximum canopy followed by horsegram, green gram, black gram and dhaincha.

(Soil Conservation & Water Management)

7. Mulching: Mulching of soil with available plant residues reduce soil loss considerably by protecting the soil from direct impact of raindrop and reducing the sediment carried with runoff .A minimum plant residue cover of 30 per cent is necessary to keep runoff and soil loss within the acceptable limits. Vertical mulching also reduce soil loss particularly in vertisols by increasing infiltration.

8. Application of manures and fertilizers : Organic manures besides supplying nutrients improve soil physical conditions thereby reduce soil loss. Fertilizers improve vegetative canopy, which aid in erosion control.

9. Use of chemicals: Breakdown of aggregates by the falling raindrops is the main cause of detachment of soil particles. Soils with stable aggregates resist breakdown and thus resist erosion. Aggregate stability can be increased by spraying chemicals like poly vinyl alcohol @ 480 kg/ha (rate will depend on the type of soil). Soils treated with bitumen increase water stable aggregates and infiltration capacity of the soil.