GCEAgricultural ScienceCrop Production2023

Which of the following best explains why leguminous crops are commonly included in a crop rotation programme?

AThey produce large quantities of organic matter that suppress weeds
BThey fix atmospheric nitrogen into the soil through root nodule bacteriaCORRECT
CThey have deep taproots that break up hardpan layers in the soil
DThey release natural pesticides that control soil-borne pathogens
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Why the answer is B, and why the others tempt you.
Leguminous crops such as cowpea, groundnut, and soybean form symbiotic relationships with Rhizobium bacteria in root nodules, which fix atmospheric nitrogen (N₂) into ammonium compounds available to plants. This enriches the soil with nitrogen, reducing the need for synthetic nitrogen fertilizers for subsequent crops in the rotation. The other options do not accurately describe the primary agronomic reason for including legumes in rotation.
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