Final answer:
Clover is an example of a plant used to make green manure, which helps fix nitrogen in the soil and improves soil health. The practice of including leguminous plants like clover in crop rotation is crucial for maintaining soil fertility and supporting sustainable agriculture.
Step-by-step explanation:
An example of a plant used to make green manure is clover. Leguminous plants, such as clovers, vetches, lucernes, and peas, have a unique ability to fix atmospheric nitrogen through a symbiotic relationship with bacteria known as rhizobia. This process enriches the soil by adding nitrogen, an essential nutrient for plant growth. When these plants are plowed back into the soil as green manure, they release nitrogen and other nutrients that support the growth of subsequent crops.
Additionally, green manure contributes to soil health by improving its structure, which can reduce compaction and increase water retention. Farmers understand the importance of crop rotation that incorporates legumes to maintain soil fertility, as evidenced in the 4-field system where clover is one integral crop. The practice of crop rotation with legumes is an effective strategy to sustain soil productivity and support sustainable agriculture.