Which practice reduces the need for synthetic nitrogen in clover production?

Which practice reduces the need for synthetic nitrogen in clover production?

• A. Increasing irrigation frequency.
• B. Using clover as a nitrogen-fixing crop reduces the need for synthetic nitrogen.
• C. Applying extra phosphorus fertilizer.
• D. Planting clover in shaded areas.

Answer: (B)

The key idea here is that certain plants, like clover, can supply nitrogen to themselves and to the surrounding soil through a natural energy-for-nitrogen partnership. Clover forms nodules on its roots that host Rhizobium bacteria. These bacteria take nitrogen from the air (N2) and convert it into usable forms (like ammonia) that the plant can use for growth. In return, the plant provides carbohydrates to the bacteria. Because this biological nitrogen fixation adds usable nitrogen to the soil, farmers can rely less on synthetic nitrogen fertilizers when clover is part of the rotation or grown as a cover crop. This not only saves input costs but also reduces environmental impacts from fertilizer runoff. Other options don’t address this nitrogen-supply mechanism. Increasing irrigation affects water supply, not the plant’s nitrogen source. Phosphorus helps with energy and root development but doesn’t by itself fix atmospheric nitrogen. Planting in shaded areas reduces photosynthesis and growth, which would hinder nodulation and nitrogen fixation rather than enhance it.

The key idea here is that certain plants, like clover, can supply nitrogen to themselves and to the surrounding soil through a natural energy-for-nitrogen partnership. Clover forms nodules on its roots that host Rhizobium bacteria. These bacteria take nitrogen from the air (N2) and convert it into usable forms (like ammonia) that the plant can use for growth. In return, the plant provides carbohydrates to the bacteria. Because this biological nitrogen fixation adds usable nitrogen to the soil, farmers can rely less on synthetic nitrogen fertilizers when clover is part of the rotation or grown as a cover crop. This not only saves input costs but also reduces environmental impacts from fertilizer runoff.

Other options don’t address this nitrogen-supply mechanism. Increasing irrigation affects water supply, not the plant’s nitrogen source. Phosphorus helps with energy and root development but doesn’t by itself fix atmospheric nitrogen. Planting in shaded areas reduces photosynthesis and growth, which would hinder nodulation and nitrogen fixation rather than enhance it.