Agricultural Science JS 2
SOIL AND WATER CONSERVATION
Definition:
Soil Conservation refers to all measures adopted in order to maintain the soil and its resources
Methods of Soil Conservation
- Application of organic manure and fertilizer
- Adopting farm practices that do not promote leaching and erosion e.g cover-cropping
- Irrigation and drainage systems
Ways by which Plant Nutrients are Lost
- a) Leaching: this is the washing away of plant nutrients from the topsoil down the soil profile beyond the reach of plants by heavy rainfall. Sandy soil is most susceptible to leaching since the particles are loosely held together, allowing for easy and rapid passing of water.
Control of Leaching
Leaching can be controlled by
- Cover-cropping
- Addition of manure
- b) Crop Removal: when crops are harvested, the nutrients are forever lost from the soil. With time, the nutrient loss becomes quite significant, consequently leading to poor growth and yield of crops.
Control:
Nutrient loss through crop removal can be minimized by
- Crop rotation
- Addition of manure and fertilizer
- c) Burning: this involves the clearing of vegetation by burning. The practice is very common in Nigeria and exposes the land to soil erosion and leaching.
Control :
Instead of burning, the vegetation can be cut and allowed to decay and add nutrients to the soil.
- d) Erosion: this is the wearing away of the soil surface by wind and water. Hence there are two major kinds of erosion, namely wind and water erosion. These are further subdivided into three major forms as stated below:
- Sheet erosion: this involves the removal of the whole top fertile layer of the soil by wind or water. This form of erosion occurs where flood water flows uniformly over a gently sloping land.
- Rill erosion: this has to do with the gradual removal of soil particles along narrow tracks or channels known as rill by raindrops.
iii. Gully erosion: this occurs where flooding cuts deep into the soil to form gullies which are often deepened by further rainfall, forming a ditch.
Erosion Prevention / Control
- Maintenance of vegetation cover and mulching
- Contour ploughing- this is the making of ridges across the slope. It helps to break or reduce the speed of water flow.
- Terracing- involves the construction of a series of short steps on the slopes. It also serves the same purpose as contour ploughing
- Creation of wind-breaks and shelter belts- this involves planting of trees to reduce the impacts of wind on the soil
- Organic manuring
- Avoidance of over-grazing
- Avoidance of Bush burning
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