Which approach helps prevent fertilizers from causing eutrophication near a farm?

• A. Plant cover crops
• B. Use natural fertilizers
• C. Increase irrigation
• D. Use chemical fertilizers

Answer: (B)

Controlling nutrient inputs to water bodies is essential to prevent eutrophication. When fertilizers are applied, excess nitrogen and phosphorus can be washed into nearby streams and lakes during rain or irrigation, fueling algae blooms that choke oxygen from the water.

Natural fertilizers help most because they release nutrients more slowly and tend to stay bound to soil organic matter. This slows down how quickly nutrients become available and reduces the amount that can be washed away, so fewer nutrients reach waterways. They also boost soil structure and microbial activity, which improves nutrient retention on the farm.

Chemical fertilizers, by contrast, are often highly soluble and fast-acting, making it easier for nutrients to runoff or leach into water during rainfall or over-irrigation. Plant cover crops can further reduce runoff by protecting soil and absorbing nutrients, but the direct approach described here—using natural fertilizers—addresses the nutrient load entering waterways more gradually and securely.