Effect of release controlled urea on rice yield and N use efficiency in Sichuan basin


15 Feb 2010

2009 Annual Interpretive Summary

Effect of Controlled-Release Urea on Rice Yield and Nitrogen Use Efficiency in the Sichuan Basin, 2009

The objective of this study was to evaluate the effects of controlled-release urea (CRU) applied at rice transplanting and regular urea (RU) split between transplanting and the tillering stage. The study will assess treatment impact on crop yield, N uptake, residual soil N, and economic benefit. The experiment was conducted on a medium-to-high fertility soil with four N rates (0, 75, 112.5, and 150 kg N/ha). Each rate of N was tested with both CRU and RU. In addition, a RU treatment using a 40:60 split between a basal application at transplanting and a top-dressing at tillering was compared against a 40:60 split of RU:CRU applied as a single basal application at transplanting. All treatments received equal rates of P and K applied at transplanting.

When N was applied as a single basal application, CRU significantly increased yield compared to RU by properly controlling tillering and facilitating the formation of bigger ears. The optimal N rate of CRU appeared to be 112 kg N /ha. When RU was used in a 40:60 split between transplanting and tillering, yield improved by only 3% compared to the single basal application at transplanting. Mixing RU and CRU at a ratio of 40:60 and using a single basal application could reduce the time spent applying fertilizer, increase yield, and lower the costs associated with CRU. CRU was superior to RU in enhancing N recovery (up to 70%) and agronomic efficiency. Both N recovery and agronomic efficiency were increased as N rate decreased. The net income from CRU, at each N rate, was 2% to 8% higher than RU.

The results suggest that CRU is a promising candidate to replace RU as a single basal N application in single rice. A mixture of 40% RU and 60% CRU can be another option to reduce the cost associated with CRU while maintaining high rice yields. Sichuan-BFDP-09