Can legumes be used to enrich the soil?  

Expert Answers
bandmanjoe eNotes educator| Certified Educator

Yes, legumes are very good for enriching the soil.  One of the principal nutrients required for plant growth is nitrogen. Nitrogen is 78% of the atmosphere, but it doesn't just absorb into the soil.  This is where legumes come in.  They have nodules on their roots, with a specific type of bacteria that are designed to take the nitrogen out of the atmosphere and fix it directly into the soil.  So crops like peanuts, clover, and alfalfa are very good for crop rotation, to allow the natural fixation of nitrogen back into the soil, so future crops will have the nitrogen they need to grow and fluorish.  Legumes are a good way of getting nitrogen into our diet as well, we can not absorb the nitrogen from the air simply by breathing it in.  We must get nitrogen from plants like legumes that are in the process of incorporating atmospheric nitrogen into their physical structure.

pacorz eNotes educator| Certified Educator

Yes. Legumes, a plant group consisting of the peas, beans, alfalfa and clovers, are a good natural way to improve soil fertility. Nitrogen is plentiful in the earth's atmosphere, but in the gaseous form it is not useful for plants. Legumes have special root structures known as nodules that contain symbiotic bacteria that can do nitrogen fixation, a chemical process that converts nitrogen gas into compounds like ammonia and nitrates. The bacteria usually make more nitrogenous compounds than the plant can absorb, and the excess goes into the soil. Typically after the legume crop is harvested the remaining parts of the plant are tilled back into the soil.