The rate of release of highly soluble inorganic fertilizers can be controlled by enclosing the fertilizer granule in a coating membrane. Factors which affect that rate under growing conditions were studied to gain a better understanding of the mechanism involved. The rate of release remains nearly constant until about two thirds of the fertilizer has been released; thereafter the rate drops off. After the first few days or weeks the rate may increase slightly.

The above progress report is based on Research Project No. 1469.