What contribution do legumes make to soil fertility?

• A. They enhance soil acidity
• B. They fix atmospheric nitrogen
• C. They reduce soil salinity
• D. They compete with weeds for resources

Answer: (B)

Legumes play a vital role in enhancing soil fertility primarily through their ability to fix atmospheric nitrogen. This process occurs through a symbiotic relationship with specific bacteria known as rhizobia, which inhabit the root nodules of legumes. These bacteria have the ability to convert nitrogen gas from the atmosphere into a form that is usable by plants, such as ammonia. This enrichment of nitrogen in the soil not only benefits the legumes themselves but also enhances the nutrient content of the soil when they decompose, promoting the growth of subsequent crops.

The fixation of nitrogen is particularly important because nitrogen is a crucial nutrient that plants need for growth and development, and it is often one of the limiting factors in plant production. By increasing the nitrogen levels in the soil, legumes reduce the need for chemical fertilizers, leading to more sustainable agricultural practices. This natural fertilization process ultimately improves soil health and productivity, benefiting both the current and future crops grown in that soil.