Macroreticular hydrogel effects on dissolution rate of controlled-release fertilizers

The effects of cross-linked sulfonated polystyrene granules (soil conditioner) with three different absorptions of deionized water were investigated on the dissolution of three different K2SO4 fertilizers. One of the fertilizers used was water soluble, whereas the other two were controlled-release fertilizers with differing nutrient release rates. Sail columns regularly rinsed with water for a period of 3 months were used for testing. It was found for water-soluble fertilizer that the quantities of K leached from the columns increased with the absorption capacity of the polymers. In the case of application of the polymer with the highest absorption capacity (100 g of water g(-1) dry polymer), the water-soluble K leached was 188% more than that leached from controlled-release formulations. It was found also that the presence of hydrogels in soil increased dissolution of controlled-release fertilizers. Yet, this increase was relatively small and did not depend significantly on absorption.