提高稻田尿素氮利用率若干方法与机理探讨

SOME METHOLOGICAL AND MECHANICAL EXPLORATION ON INCREASING UREA-N EFFICIENCY IN PADDY FIELD

应用15N示踪技术，研究了稻田使用脲酶抑制剂（BTPT）、硝化抑制剂（EP）及养萍对尿素氮肥效的影响。试验结果表明，稻田使用BTPT和EP均提高了氮素利用率及水稻产量，BTPT、EP和BTPT＋EP处理的15N回收率分别为17.4％、17.8％和18.0％，与不用抑制剂的对照相比，分别提高3.1、3.5和3.7个百分点;水稻产量分别为5300、5150和5450kg／hm2，比对照分别提高了11.8％、8.7％和15.0％。稻田养萍可以抑制氨的挥发，减少尿素氮的损失;养萍及养萍后翻压两种处理的15N回收率分别为28.8％和34.7％，比不养萍的对照分别提高了3.3和9.2个百分点;土壤15N残留率分别为29.3％和40.1％，比不养萍的对照分别提高了5.1和15.9个百分点。养萍对当季水稻产量增加效果不大，而养萍后翻压对当季水稻产量可提高近5％。

Effect of applying urease inhibitor(BTPT), nitration inhibitor (EP)and growing azolla on the efficiency of urea-N has been studied by using 15N-tracing technique. The results showed that, the practice of supplying BTPT or EP increased the N utilization rate and grain yield,15N recovery rate in the treatments of BTPT,EP and BTPT+EP were 17. 4%, 17.8% and 18.0% respectively and were 3. 1%, 3. 5% and 3. 7% higher than that without inhibitor (CK). The grain yield in above three treatments were 5300, 5150 and 5450 kg/hm2, and 11.85%, 8. 7% and15. 0% higher than that CK. Growing azolla in paddy field may inhibit the volatilization of ammonium and thus decrease the urea-N loss. In the treatment of growing azolla and the azolla was incorporated into paddy field, the 15N residual rates in soil were 29. 3% and 40.1%, and were 5.1% and 15.9% higher than that in wlthout azolla,and the recovery rate of 15N were 28. 8% and 34. 7%, and 3. 3% and 9. 2% more than that CK treatment. Growing azolla has less effect on increasing the grain yield in present cropping season, however, azolla incorporated as manure the rice grain yield of present season increased by 5%.