Mulching

Mulching is a soil and water conservation practice in which a covering of cut grass, crop residues or other organic materials is spread over the ground, between rows of crops or around the trunks of trees. This practice helps to retain soil moisture, prevents weed growth and enhances soil structure. It is commonly used in areas subject to drought and weed infestation. The choice of the mulch depends on locally available materials. The optimal density of soil cover ranges between 30% and 70%.

In alley-cropping systems, hedgerow biomass is often used as mulch. In orchards, cover crops may also be used as live mulches, especially around young trees that are well-established. Another strategy is to leave crop residues on the ground after harvesting (e.g., pineapple tops, corn stover, rice straw, etc.). This ensures that some nutrients are taken up by the plant and returned to the soil.

Advantages

· Intercepts the direct impact of raindrops on bare soil and reduces runoff and soil loss.
· Suppresses weeds and reduces labor costs of weeding.
· Increases soil organic matter.
· Improves soil chemical and physical properties.
· Increases the moisture-holding capacity of the soil.
· Helps to regulate soil temperature.

Limitations

· Possible habitat for pests and diseases.
· Not applicable in wet conditions.
· Difficult to spread evenly on steep land. Lack of available materials suitable for mulching.
· Some grass species used as mulch can root and become a weed problem.

Factors affecting adoption

Biophysical

· Suited to areas with limited or irregular rainfall.
· Insufficient availability of mulch may be a constraint in upland areas.

Socioeconomic

· Farmers are used to burning crop residues instead of returning them to the soil.

· Labor for collecting mulch and applying it is a problem.

· Mulch is more important in homegardens or valuable horticulture crops than in lessintensive farming systems.