A mulch is any substance spread on the ground to protect plant roots from heat, cold or drought or to keep fruit clean. Mulching is a long established horticultural practice. Farmers know that shallow cultivation of the soil's surface after a rain slows the rate of water loss from the soil. The shallow layer of dry surface soil acts as a mulch. Mulches can be classified as inorganic or organic.
Plastic is the only inorganic mulch used in vegetable gardens.
Also, mulches prevent raindrops from splashing on the soil surface. See figure 1. Saving soil moisture is an important use of mulch in Texas. A mulch layer on the soil surface allows the soil to soak up more water. Mulch also reduces the rate of water loss from the soil.