Name a legume that is commonly used as a cover crop.

Crimson clover is a legume that is often used as a cover crop due to its ability to fix nitrogen in the soil, improving fertility and reducing the need for chemical fertilizers. Cover crops like crimson clover are particularly valuable in agricultural systems as they enhance soil structure, prevent erosion, and provide ground cover during periods when the soil might otherwise be bare.

In contrast, wheat, barley, and rice are not legumes but rather cereal grains. These crops primarily serve different purposes, such as food production or grain harvesting, and do not provide the same benefits in terms of nitrogen fixation or soil health that legumes do. The unique characteristics of legumes, such as the presence of root nodules that house nitrogen-fixing bacteria, make them essential for sustainable agricultural practices, particularly in maintaining soil fertility and health.