Mulch - Definition and Overview

In agriculture and gardening, mulch is a protective cover placed over the soil, primarily to modify the effects of the local climate. A wide variety of natural and synthetic materials are used.

Mulch is used for various reasons:

• to adjust soil temperature by helping soil retain more heat in spring and fall
• to control weeds by cutting off the sunlight they need to grow
• to provide nutrients through the gradual breakdown of the mulch material
• to retain moisture by slowing evaporation

A wide variety of materials are used as mulch:

• organic residues - grass clippings, leaves, hay, straw, sawdust, wood chips, shredded newspaper, wool, etc. In general, these in part act as a direct composting system. There are many differing opinions on what to use. Organic mulches are usually piled to an initial height of several inches.
• compost
• plastic sheeting - Crops grow through slits. This method is common in large-scale vegetable growing, with millions of square feet of plastic mulch used worldwide each year. (Disposal of plastic mulch is cited as an environmental problem.)
• organic sheet mulch - Various products developed as a biodegradable alternative to plastic mulch.

Mulching is an important part of any No-dig gardening regime, such as practiced within permaculture systems.