What factor does resin coated materials, such as osmocote, depend on to release nutrients?

Resin coated materials like Osmocote release nutrients primarily based on soil moisture. These coated fertilizers utilize a polymer resin that surrounds the nutrient granules. The release mechanism is designed so that moisture penetrates the resin coating, causing it to swell and gradually release nutrients into the soil solution. This process ensures that the nutrients are made available to plants effectively over time, aligning with their growth needs.

While temperature, pH level, and sunlight exposure can affect plant growth and nutrient uptake, it is the soil moisture that directly influences the nutrient release from resin-coated fertilizers. Adequate moisture is essential for the swelling of the polymer and subsequent nutrient diffusion, making it the key factor in their performance.