Which agricultural change raises the risk of nutrient runoff by increasing fertilizer and manure application?

• A. Agricultural Intensification
• B. Organic Farming
• C. Hydroponics
• D. Ditch Drainage

Answer: (A)

Increasing the amount and frequency of nutrient inputs raises the potential for nutrients to leave fields. Agricultural intensification expands production on the same land and uses more fertilizer and manure per acre, leading to higher nutrient loads in the soil. When rain or irrigation moves over saturated soils, the excess nutrients are washed away with surface runoff or leached down, ending up in nearby streams, rivers, or groundwater. This elevated input makes it easier for nitrogen and phosphorus to exceed what crops can take up, so more ends up in water bodies and contributes to problems like algal blooms and eutrophication.

Organic farming, by contrast, emphasizes soil-building practices and limits synthetic fertilizers, usually resulting in lower nutrient surpluses. Hydroponics provides nutrients in a controlled, often recirculated system, which minimizes field runoff. Ditch drainage changes water movement and can increase the transport of nutrients, but it does not inherently raise how much fertilizer or manure is applied. The option that directly increases fertilizer and manure application is agricultural intensification.