Which type of fertilizer is more likely to cause nutrient leaching if heavy rains follow its application?

Liquid fertilizers are more likely to cause nutrient leaching following heavy rains due to their high solubility in water. When liquid fertilizers are applied, they dissolve quickly and become available for plant uptake. However, if significant rainfall occurs shortly after application, these soluble nutrients can easily be washed away from the soil surface into water runoff or deeper soil layers, leading to leaching.

In contrast, slow-release fertilizers are designed to release nutrients gradually over time, making them less susceptible to leaching since their nutrients are not immediately available for water movement. Organic fertilizers typically have lower solubility, which helps retain nutrients in the soil during heavy rains. Granular fertilizers, while more easily washed away than slow-release and organic types, still do not dissolve as quickly as liquid fertilizers, thereby reducing the risk of leaching when faced with heavy rainfall. Therefore, liquid fertilizers pose the greatest risk of leaching in such scenarios.