Plastic coating is a common formulation of a slow release fertilizer. Release is dependent on:

Plastic coating is a common formulation of a slow release fertilizer. Release is dependent on:

• A. Soil moisture
• B. Temperature
• C. Light exposure
• D. pH

Answer: (A)

Moisture in the soil is the main driver of release for plastic-coated slow-release fertilizers. The coating acts as a semi-permeable barrier, so water entering the soil permeates the coating and causes it to swell, creating a pathway for nutrients to diffuse out into the surrounding soil. When soil moisture is higher, the coating swells more and release speeds up; when the soil is dry, there isn’t enough water to penetrate the coating, and release is minimal. Temperature can influence how fast diffusion occurs, but it doesn’t override the need for water. Light exposure and pH don’t control the release mechanism in this type of coating.

Moisture in the soil is the main driver of release for plastic-coated slow-release fertilizers. The coating acts as a semi-permeable barrier, so water entering the soil permeates the coating and causes it to swell, creating a pathway for nutrients to diffuse out into the surrounding soil. When soil moisture is higher, the coating swells more and release speeds up; when the soil is dry, there isn’t enough water to penetrate the coating, and release is minimal. Temperature can influence how fast diffusion occurs, but it doesn’t override the need for water. Light exposure and pH don’t control the release mechanism in this type of coating.