This is the VOA Special English Agriculture Report.

Mulch is material spread over soil. It protects against wind and rain damage. It can also limit weed growth.

Finding materials for organic mulch can be easy. Small pieces of tree bark or cut up leaves can be used. Some people use grass cuttings or newspapers. Others use inorganic material such as shredded rubber from tires. 

Mulch is important to home gardens but also to farms. Farmers may keep the remains of maize or other crops on top of the soil. The crop waste creates mulch. This practice is called conservation tillage.

Organic mulch protects but also improves the condition of the soil. It provides nutrients for plants. It also provides a good environment for earthworms and other helpful organisms in the soil.

As the mulch breaks down, it provides material that keeps the soil from getting hard. This improves the growth of roots and increases the movement of water through the soil. The mulch also improves the ability of the soil to hold moisture.

Experts generally suggest laying mulch to a depth of about ten centimeters. If finer materials are used, such as cut grass, the depth should be two and a half to seven and a half centimeters. The same is true if compost is used for mulch.

Too much mulch can restrict oxygen and water flow to the soil and harm roots. Also, do not build up mulch around the base of trees or plants like a volcano. This could lead to disease or insect damage.

Some gardeners use leaf mulch -- fine particles of leaves -- instead of wood mulch around trees, especially young trees. Leaf mulch can also be used in flower beds.

Mulching is one of the best things people can do for their gardens. It helps keep the soil from getting dry, so it reduces the need for watering. It also limits temperature changes in the soil.

Mulch forms a barrier between the soil and the air. As a result, mulched soil will be cooler in the summertime. And in winter, it may not freeze as deeply as areas without mulch. 

Mulch can be added late in autumn to help moderate the effects of winter weather. The best time is after the ground has frozen but before the coldest weather arrives. Spreading mulch before the ground has frozen may attract small animals searching for a warm place to spend the winter.

And that's the VOA Special English Agriculture Report. Archives of our reports -- including last week's explanation of compost -- can be found at voaspecialenglish.com. I'm Steve Ember.