Glossary of gardening terms - M:

Machinery
A machine is any mechanical or organic device that transmits or modifies energy to perform or assist in the performance of tasks. It normally requires an input as a trigger, and transmits the modified energy to an output, which performs the desired task.

Mulch
A layer of material spread on top of the soil around plants. Organic material such as shredded bark, compost or leaf mold retain moisture and insulate roots. Inorganic material such as black plastic suppress weeds and retain moisture in the soil.