Development of urea coated with neem (Azadirachta indica) to increase fertilizer efficiency and reduce greenhouse gases emission

Abstract

Urea coated with neem fertilizer is one of the solutions to increase the efficiency of nitrogen fertilizer and reduce greenhouse gases emission. Inhibition of the nitrification rate of urea can reduce NO2- and N2O gas, and at the same time urea can be efficiently absorbed by the plants. Neem (Azadirachta indica) can suppress nitrification rate of 20-50%, which is slightly lower than that of dyciandiamide (DCD) (56-80%). Coating of urea granules was done by dipping urea granules in 1% neem oil, exposed it to 2.5% and 5% neem cake and then homogenized by rotation. The results were compared to urea coated with 5% DCD. The efficiency of fertilizer and nitrification inhibition were measured by nitrate and ammonium changes and fluxes of N2O gas. The results showed that application of urea coated with 5% neem on cabbage plants yielded the highest plant height. However, the leaf length and width were not significantly different with other urea treatments. Application of urea coated neem reduced nitrification rate and N2O emissions in the soil. Soil CO2's levels treated either with 2.5% or 5% neem coated urea showed the lowest levels of CO2 soil. This suggests that neem can reduce N2O and CO2 emissions from urea fertilizer as well as the capacity to reduce nitrification rate. © 2014 Penerbit UTM Press. All rights reserved.