Nutrient release properties of a urea–magnesium–natural rubber composite coated with chitosan

Abstract

Abstract The use of slow release fertilizer to prevent pollution is studied but the development of a new formula as well as studies on nutrient dissolution are subjects that still need to be explored further. This study we investigated the nutrient-release characteristics of urea–magnesium tablets prepared from rice husk ash, urea, magnesium sulfate and natural rubber. The ammonia-dissolution, urea leaching, and the nitrate-formation rate were found to be proportional to the incubation time. The presence of magnesium in tablet and the chitosan coating affected nutrient-dissolution rate in water. The chitosan coating retarded the release of urea, ammonia and nitrate only if the composite contained high proportion of the magnesium sulfate, but the chitosan coating also accelerated magnesium-ion dissolution.