Granular urea-formaldehyde slow-release fertilizer with superabsorbent and moisture preservation

To improve the utilization of fertilizer and water resource at the same time, a new type of slow-release fertilizer with superabsorbent and moisture preservation was developed, with the combination of slow-release technique and superabsorbent polymers. The coatings were formed by the inverse phase polymerization technique. The element analysis results showed that the product contained 22.58% nitrogen element, and the water absorbency of the product was 94 times its own weight if it was allowed to swell in tap water at room temperature for 2 h. The results of the slow-release behavior of N and the water absorbency and retention properties in soil showed that the product not only had good slow-release property but also had excellent water absorbency and water retention capacity, which was a significant advantage over the normal slow-release or controlled-release fertilizers. The effects of the amount of initiator, crosslinker, reaction time, and the degree of neutralization of acrylic acid on water absorbency were investigated and optimized. At the same, a rather new and simple method was used to make homogeneous urea-formaldehyde granules. (c) 2006 Wiley Periodicals, Inc.