稻田控释氮肥的施用效果与合理施用技术
Effects and rational application of controlled-release nitrogen fertilizer in paddy field of southern China
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摘要: 选用新型控释氮肥(LP)5个类型,采用其不同用量和组合,在南方典型双季稻区第四纪红壤发育的水稻土上进行早稻和晚稻的一次性基肥试验。结果表明,施用不同控释氮肥,稻田表层土和表面水的NH4+-N含量极显著地低于常规氮肥(尿素);控释肥的氮素释放过程与水稻吸氮过程基本一致。控释氮肥用量以N75kg/hm2较适宜,其用量比尿素N150kg/hm2相比仍可维持高产;早稻施用控释氮肥,可成功地实现施肥、播种、抛秧的一次性技术配套与结合,减轻劳动强度,适当提高种植密度有利于高产;晚稻采用条施的方法可显著地提高产量。与尿素N150kg/hm2比较,早稻选用控释氮肥LPS40或LPS60较好;晚稻选用LP70和LPS80并按LP70(50%)+LPS80(50%)的比例搭配,有利于水稻生长发育和维持高产。控释氮肥具有缓释作用,其供应氮素持久;LPS40和LPS60用量N150kg/hm2且高密度栽培时有一定的后效,可分别提高再生稻产量10%和16%。Abstract: 5 types of controlled release fertilizer (LP) were chosen and basal applied with various rates on early rice and late rice in red soil paddy field of Qiyang, Hunan province of Southern China. The effects of controlled-release fertilizer on rice yield and N dynamics in surface soil and water were studied. Results showed that the NH4+-N concentration in surface water of LP plots were much lower than that of urea within first 7-10 days. It was only about one tenth of that of urea. NH4+-N content in soil of cultivated layer of LP plots was also much lower than that of urea within first ten days. It was around one tenth as well. Therefore, it could deduce N losses from runoff and ammonia volatilization from LP plots should be much lower than that of urea.For early rice, application N 75kg/ha of LPS40 or LPS60, the yield was nearly same as that of urea with application rate being N 150kg/ha; but then, increased application rate of LPS40 or LPS60 to 150kg/ha could not increase yield further under conventional transplanting density. This indicated that for early rice, both LPS40 and LPS60 were suitable and the rational application rate was N 75 kg/ha. However, because N release from LPS40 and LPS60 was longer than that of urea, the yield of ratooning rice applied LPS40 and LPS60 with N 150kg/ha rate and 1.5 times higher transplanting density increased by 10% and 16%, respectively. For late rice, band application using LP70 (50%) + LPS80 (50%) could improve rice development. Broadcast and band application N 75kg/ha, rice yield increased by 18% and 25% respectively comparing with urea N 150 (kg/ha.) While yield applied LP N 150kg/ha was not different significantly with that of urea. Thus, the recommend rate of N is (75 kg/ha) rate with band application for late rice production.