What is the main benefit of green manure?

Correct answer: Increasing organic matter and nutrients in soil

The direct answer is option A: green manure increases organic matter and contributes nutrients to the soil. Green manure is a crop or green plant material grown and then mixed or ploughed into the soil instead of being harvested. Step by step, the plant material decomposes; decomposition adds organic matter, improves soil structure and water-holding ability, and may return nutrients, especially when suitable leguminous plants are used. Better soil fertility can support later crops. Option A is correct because it states the agricultural purpose. Option B is wrong because green manure is not used to cook food. Option C is wrong because it does not remove a crop from the market; it is mainly a soil-management practice. Option D is wrong because it does not poison water, although careless farming practices of any kind should avoid pollution. Remember: green manure is “green plant material for the soil,” not manure used directly as food.