实地氮肥管理提高水稻氮肥利用效率

以籼型杂交稻汕优63和粳稻武育粳3号为材料进行田间小区试验，对实时氮肥管理（RTNM）和实地氮肥管理（SSNM）的农艺表现和氮肥利用效率进行了评价。结果表明，氮空白区的水稻产量为5.5~7.4 t/hm²，说明试验田背景氮颇高。与农民习惯施肥法（FFP）相比，RTNM和SSNM分别增产-4.4％~7.0%和0.2％~9.3%，氮素产谷率分别提高195.7％~297.0%和169.6％~276.4%。2003—2004年在江苏省无锡市两村共计20户稻田中进行水稻SSNM试验示范。2年FFP的氮素产谷率、吸氮利用率和生理氮转化率分别仅有2.8～6.7 kg稻谷/kg N、33.7％～34.7％和8.4～18.6 kg稻谷/kg N；SSNM的施氮量较FFP降低38.7％～41.3％，产量提高2.5％～3.5％，氮素产谷率、吸氮利用率和生理氮转化率分别提高88.3％～117.7％、34.0％～39.5％和46.1％～61.6％。在江苏省大面积推广也取得了类似结果。证明采用SSNM在不降低水稻产量的前提下，提高水稻氮肥利用率是可能的。试验也发现，农户稻田SSNM的氮素产谷率和生理氮转化率的数值依然很低。对水稻氮肥利用率低的原因及提高途径进行了讨论。

Site-specific Nitrogen Management Increases Fertilizer-nitrogen Use Efficiency in Rice

Low fertilizer-nitrogen(N) use efficiency(FNUE) is a serious problem in rice production in China.The objective of this study was to explore the possibility to improve FNUE by adopting real-time N management(RTNM) and site-specific N management(SSNM).With an indica hybrid rice Shanyou 63 and a japonica cultivar Wuyujing 3 as materials,a plot experiment in field conditions was carried out during 20012003 to evaluate agronomic performance and FNUE under RTNM and SSNM.The results showed that grain yield in the plot without N application ranged from 5.5 to 7.4 t/ha(Table 4),indicating rather high indigenous N content in soil.Compared with farmers' fertilizer practice(FFP),RTNM and SSNM increased grain yield by-4.4% to 7.0% and 0.2%9.3%,agronomic efficiency(AE) of fertilizer-N by 195.7)7.0% and 169.6'6.4%,respectively(Table 5).SSNM was demonstrated in 20 farmers' fields in two villages of Wuxi,Jiangsu Province in 2003 and 2004.AE,recovery efficiency(RE) and physiological efficiency(PE) of fertilizer-N in FFP in two years were only 2.86.7 kg grain/kg N,33.74.7% and 8.418.6 kg grain/kg N,respectively.SSNM reduced N rate by 38.7A.3%,increased grain yield by 2.5%3.5%,and enhanced AE,RE and PE by 88.37.7%,34.09.5% and 46.1a.6%,respectively(Table 6 and Table 7),when compared with FFP.Similar results were obtained on large-scale extension of SSNM in Jiangsu Province(Table 8).These results suggested that SSNM has great potential for improving FNUE without any sacrifice in the yield.AE and PE in SSNM in farmers' fields were still very low in this study.Reasons for low FNUE and approaches to improving it were discussed.