When applying fertilizers, which method poses a higher risk for phosphorus contamination?

Broadcasting fertilizers on the surface poses a higher risk for phosphorus contamination due to several factors related to how fertilizers interact with the environment. When fertilizers are applied directly to the surface of the soil, there is a greater likelihood that rainfall or irrigation will cause runoff. This runoff can wash away the phosphorus before it has a chance to be absorbed by the soil or utilized by plants, leading to contamination of nearby water bodies.

Surface-applied fertilizers are particularly vulnerable to loss through erosion and runoff, especially if the soil is dry or if there are heavy rains soon after application. This method does not provide as effective a means of integrating phosphorus into the soil compared to incorporation methods, where soil disturbance helps promote absorption and reduces the potential for loss.

Utilizing techniques such as incorporation or applying organic fertilizers in the spring can help mitigate these risks. Incorporation mixes the fertilizer with the soil, reducing the chance of runoff. Similarly, cover crops can help absorb excess nutrients and prevent erosion, making them less risky for phosphorus contamination. Overall, the method of broadcasting is more prone to leading to environmental concerns related to phosphorus runoff.