MULCH is a layer of material (at least five to seven cm) which is placed on top of the soil to retain soil moisture, protect plant roots from extremes in temperature, reduce weed growth, and protect soil from erosion by wind and water. Materials used for mulching are either organic or synthetic.

Organic materials include peat, sawdust, wood chips, straw, leaves and animal manure. Organic mulch should be placed around plants and trees, taking care not to let it touch the stem as this can cause rot. These are generally applied after the crop is well established. The decomposition of organic materials adds nutrients to the soil for plant uptake.

Plastic is the most common synthetic material used for mulching. If available, biodegradable materials are preferred. Plastic mulches should be applied before the crop is planted and removed at the end of the growing season. The plastic edges must be covered with soil to prevent the plastic from blowing away. Once the plastic has been laid, holes are planted in soil. This could also be done for transplants. An added feature of using plastic mulch is that it could be combined with drip irrigation. If the systems are available, this could also include fertigation.

ADVANTAGES OF MULCHING:
Weed control: mulches generally help to control weeds. When clear plastic is used, some amount of weed growth occurs due to light penetration. The use of black plastic which prevents light penetration is better for controlling weed growth.

Moisture Retention: mulches greatly retard the loss of moisture from the soil. As a result, a more uniform soil moisture regime is maintained and irrigation frequency may be reduced. Irrigation is still needed for mulched crops so that the soil under the mulch does not dry out excessively. A combination of drip irrigation and mulching is therefore recommended.

Reduction of fertilizer leaching: Under mulching, there is a reduction in fertilizer losses due to leaching. As a result, fertilizers are used more efficiently and the potential exists for reducing fertilizer inputs. However, this effect can be negated by over-watering or flooding.
Improving soil structure: The mulch acts as a barrier to the pounding action of rainfall. Thus, soil compaction and crusting are prevented. The soil, therefore, remains loose with good aeration for root growth and development. A less compacted soil also provides a better environment for seedling emergence.

Disease control: Mulches help keep the fruit from coming into contact with the soil where diseases are located. For vine crops, the mulch serves as a protective barrier between the soil and fruit to reduce rot and keep the fruit cleaner. Mulches also reduce rain-splashed deposits of soil and disease organisms for other crops such as tomatoes and boulanger.