This is the prevention of soil loss from erosion or reduced fertility caused by over-usage.
WHAT FARMING PRACTICES CAN REDUCE WIND AND WATER EROSION?
- Contour farming: contour farming reduces the steepness of the slope and the length of the slope
- by creating even terraces. It also encourages farmers to till perpendicular (across) to the slope.
- This will increase water infiltration
- Direction of tillage: tilling across the slope will help trap water in the field and reduce the volume and velocity of water running down the field
- Reducing tillage: minimizing the amount of tillage on the field
- Check Dams: check dams help trap the sediment suspended in runoff waters, slow down the velocity of runoff water and increase water infiltration in the landscape
Windbreaks help reduce the wind-speed of the air that passes through the field. The best windbreak has 50% porosity and is planted across the direction of the predominant wind (50% porosity means when you look at the windbreaks from the side 50% of the space is covered by stems, leaves and branches and 50% is
The 4-K Manual – A Guide for 4-K Clubs in Kenya open for air flow). Solid windbreaks are not as effective as they deflect wind and it can lead to increased crop damage in the field. Windbreaks help to increase crop yields because it reduces the speed of the wind leading to less damage to the crop during establishment and during growth and maturation. Trees and shrubs used in windbreaks should include many species that can be beneficial in other ways such as increasing fruit production, providing shade for livestock, and preventing soil erosion.
- Soil Cover: Vegetative cover can help reduce soil erosion as it reduces the impact of rainfall hitting the soil, increases water infiltration and slows down the speed at which runoff flows through the field
- Proper soil management: Soils that are excessively tilled have poor structure and tend to be easily
- eroded by surface water. Reducing tillage, keeping good soil structure and retaining soil organic matter helps hold the soil in place
- Crop residues cover: Having a minimum 30% surface crop residue cover is considered beneficial for minimizing soil erosion. Mulching crop residues helps slow down surface runoff velocities, improve water infiltration, increase soil organic matter levels, and improve the water holding capacity. This may be most important for crops with limited residues such as lentils. If residues are being used for fuel, it is best to leave them in the field for as long as possible to prolong their erosion control benefits
- Increasing surface cover through cropping: Increased use of perennial crops, cover crops, green manure will help reduce potential for erosion because the soil is protected with at least a 30% cover for a longer part of the year. Growing only a short season annual crop once each year makes the soil more vulnerable to erosion
- Permanently cover sloping lands: Re- vegetating steeply sloppy areas with perennial grasses, shrubs and trees may be the only practical solution for stopping erosion on steeply sloppy areas. They can be protected by planting grasses for forage utilization or multipurpose agro-forestry species such as Leucaena leucocephala (Lead tree), Moringa oleifera (Moringa)
- Prevent grazing on sloppy lands: Excessive grazing of sloppy lands is a primary reason for the gullied landscape. Keeping livestock in confined areas eliminates the problem. However, this must be balanced with animal welfare and sustainable fodder production and transport
- Crop Selection: Growing crops that have deep root zones will help stabilize the soil
Vegetative barriers: Planting narrow strips of grasses on field contours can be very effective at helping trap crop residues and sediments from moving off fields
- Perennial grasses: These have a high soil cover and a fine and extensive root system which help prevent soil from being displaced by runoff water
- Alfalfa: These are like perennial grasses but with less surface rooting
- Shrubby trees: These trees have limited surface rooting but intercept water well and encourage other species to grow around them
- Annual seeded grasses: These grasses consist of a solid canopy which intercepts rainfall well and a large root system which holds the soil particles (i.e. millet)
- Annual seeded legumes: These legumes intercepts rainfall well but have limited surface rooting (i.e. peas)
Crops planted in rows do not intercept rainfall well due to their poor crop canopy cover. Soil is left bare in the furrows and is more susceptible to soil erosion (i.e. potatoes and corn)