稻田氨挥发损失和水稻产量对不同水氮处理的响应

为了实现减少氨挥发带来的环境负效应和增加作物产量的目的,在典型的江汉平原稻作区,设计4种不同的水氮管理模式:1)U+CI(普通尿素+常规灌溉),对照(CK);2)US+SWD(普通尿素减氮20%+薄浅湿晒节水灌溉);3)CRU+CI(树脂包膜控释尿素+常规灌溉);4)CRUS+SWD(树脂包膜控释尿素减氮20%+薄浅湿晒节水灌溉),探究了减氮与节水灌溉搭配的条件下,控释尿素对稻田氨挥发损失和水稻产量的影响。结果表明:不同水氮处理间稻田土壤铵态氮浓度无显著差异,但在水稻不同生育期间差异显著,表现为返青期>分蘖期、孕穗期、抽穗期>成熟期;各水氮处理氨挥发最高峰出现在施肥后的1~3 d,其中CRU+CI的氨挥发速率最快,为N 1.46 kg·hm^-2·d^-1。在整个晚稻生长季,基肥期和分蘖期是氨挥发的主要时期;节水减氮搭配下,常规施肥稻田的氨挥发总量显著小于控释肥处理稻田的氨挥发总量。其中US+SWD分别比CRU+CI和CRUS+SWD氨挥发总量降低了21.3%和15.3%,损失率分别降低了0.9%和14.8%;其中U+CI的氨挥发总量分别比CRU+CI和CRUS+SWD的氨挥发总量降低了15.7%和9.4%,损失率分别降低了15.5%和27.3%。稻田氨挥发损失量与土壤铵态氮浓度显著正相关。相比U+CI(CK),CRU+CI的水稻产量和CRUS+SWD的水稻产量均显著增加,其中CRU+CI增加了17.4%,CRUS+SWD增加了11.0%,而两个处理之间的水稻产量没有显著差异。因此,综合增产效应和节能减排效应,CRUS+SWD是该区域目前最佳的水肥管理方式。

Responses of ammonia volatilization and grain yield under different water and fertilizer practices in a rice paddy

In order to reduce the negative environmental effects caused by ammonia volatilization and increase the grain yield,four different water management and nitrogen schemes were designed for the late rice in a typical rice-growing area of the Jianghan Plain,including:1)U+CI:common urea with conventional irrigation,as the control(CK);2)US+SWD:20%reduction of common urea nitrogen with“thin and shallow alternate wetting drying”water-saving irrigation;3)CRU+CI:polymer-coated urea with conventional irrigation;4)CRUS+SWD:20%reduction of polymer-coated urea nitrogen with“thin and shallow alternate wetting drying”water-saving irrigation.Responses of nitrogen reduction with water-saving irrigation and controlled-release urea on ammonia volatilization loss and grain yield were measured.Results showed that there was no significant difference in the content of ammonium nitrogen in paddy soils with different water and nitrogen treatments,but there were significant differences in different growth periods of rice,ranked as:regreening stage>tillering stage,booting stage,heading stage>maturity stage.The NH3 volatilization peak among different treatments occurred within one to three days after fertilization,and the ammonia volatilization rate of CRU+CI treatment was the fastest(N 1.46 kg·hm^-2·d^-1).During the whole growing season of the late rice,base stage and tillering stage were the main periods of ammonia volatilization.Under nitrogen reduction with water-saving irrigation condition,the ammonia volatilization loss in conventional fertilized paddy field was significantly less than that of controlled release fertilizer treatment.The total ammonia volatilization amount and the loss rates in US+SWD treatment reduced by 21.3%,0.9%and 15.3%,14.8%,respectively,compared with CRU+CI and CRUS+SWD.The total ammonia volatilization amount and the loss rate in U+CI treatment reduced by 15.7%,15.5%and 9.4%,27.3%,respectively,compared with CRU+CI or CRUS+SWD.There was a significant positive correlation between ammonia emission and soil ammonium nitrogen content in paddy fields.Compared with U+CI(CK),the grain yield of CRU+CI and CRUS+SWD increased significantly by 17.4%and 11.0%,respectively.But the rice yield of CRUS+SWD was not significantly different from that of CRU+CI.Thus,CRUS+SWD is the best fertilization method for increasing the grain yield and reducing environmental risks.