Response of rice yield to controlled release urea

High nitrogen (N) loss is one of the key problems faced by rice farmers. Nitrogen use efficiency in rice is often low due to high N loss through volatilization, leaching and denitrification. One of the approaches to improve N efficiency is by using controlled Release Urea(CRU). The CRU generally out-performed the granular urea fertilizer in reducing N losses, stimulating plant growth, releases nutrients during the entire growing season, increases N concentrations and yield. The performance of different types of CRU was therefore compared with granular urea in a field experiment with rice variety MR220. This study compared the effect of six different types of CRU fertilizers on rice yield with urea(control). Bakau series (Typic Tropaquept) was used in this study. Rice plants were grown in cylindrical culverts measuring 90 cm in diameter X 60 cm in height. The soil was filled up to 40 cm height and 20 cm space from the top of the culvert was to hold water. Flow regulators were attached to the culvert for adjusting required water level. The soil was flooded and pre-incubate for three weeks to stabilize their physio-chemical properties before sowing. The experiment was conducted using a completely randomized design(CRD) and replicated three times. Six different types of CRU evaluated for two planting seasons on the same plot. Fertilizer was applied once throughout the study. For both seasons, CRU treated plants had a significantly higher rice yield, 6t/ha and 6.2t/ha, than urea-treated plants, 3.7t/ha and 2.2t/ha, for the first an second planting harvest, respectively. It can be inferred that CRU performs significantly better than granular urea. This is important, considering the usually high N losses in rice growing area. From this study, Meister-20, Meister-27, CDU Uber-10 and CRU Duration Type-V can be used as single application for 2 seasons in rice planting. There is a prospect of using CRU to increase rice yield and N efficiency and can be used for two plantings with single application of CRU fertilizers.