Soil Erosion

It is the preservation of soil against deterioration or erosion, and the maintenance of the fertilizing elements for crop production

Most organic matter is located in the topsoil with approximately 50 percent of plant-available phosphorus (P) and potassium (K). Losing topsoil to erosion therefore, contributes to a loss of valuable nutrients and will cause yields to decline over time. Applying more fertilizer can replace these lost nutrients, but is more difficult to replace organic matter. To increase crop yields it’s important to keep the soil in place and build up soil organic matter levels.

Water erosion: this can be caused by intense rains that fall on land with poor soil conservation structures creating torrents of water which erode surface soils. This can result in formation of deep gullies.

Wind erosion: This type of erosion is often worse when the soils are dry, infertile not covered with any crop and wind speeds are high.

• Length of slope: the longer the slope, the more chance the water has to build up and disperse soil particles
• Steepness of slope: the steeper the slope, the more energy the water has to wash out soil from the ground surface
• Lack of surface cover: surface residue The 4-K Manual – A Guide for 4-K Clubs in Kenya intercepts rain droplets and slows down water moving across the field (surface residues act on water in a similar way that windbreaks slow down the wind)
• Soil Type: Certain soils are more prone to erosion. For example, silty soils are particularly
• vulnerable to water erosion especially when water pools on the surface
• Soil Infiltration: The rate of water that permeates through the soil can greatly affect the occurrence of water erosion. If water cannot infiltrate into the soil very easily, water will pool on the surface and is more likely to wash away surface soil. Factors that affect infiltration include:
• Soil type
• Organic Matter
• Tilling: Destroys soil structure

Wind Speed: the more velocity the wind has, the more potential it has for displacing and picking up soil particles

Length of field: the larger the field, the more potential for high wind speeds and the less potential for soil to be trapped in

the landscape

Erosive nature of the soil: when fine soils dry out and are excessively tilled they are highly prone to erosion