Abstract:

【Objective】 The objective of this study was to investigate the difference of nitrogen release from incorporated rice straw and nitrogen utilization of rice under different tillage patterns. 【Method】 Rice straw was incorporated into field under no-tillage and conventional tillage in the late seasons of 2006 and 2007 and nitrogen contents in incorporated straw were measured at different growth stages after incorporation. At the same time, rice straw with 15N feed was incorporated into pot under no-tillage and conventional tillage, nitrogen and 15N uptake by rice plant were measured at maturity. 【Result】 Residual nitrogen amount in incorporated straw decreased and obvious differences were observed at different stages. The nitrogen loss in incorporated straw was about 60% during the 0-40 days and about 10% during the 40-100 days. However, the residual nitrogen content increased in two tillage patterns. Nitrogen in straw was more easily released under no-tillage than conventional tillage if the straw status was not considered. Nitrogen in wet incorporated straw was more easily released under no-tillage while dry straw under conventional tillage. 【Conclusion】 Great nitrogen dry matter production efficiency (NDMPE) and grain yield were observed under conventional tillage. No tillage was beneficial to straw nitrogen release, but nitrogen uptake from incorporated straw by rice plant and nitrogen use efficiency were decreased.

Key words: rice, tillage patterns, no-tillage, nitrogen utilization