不同水肥条件下水稻氮素运移与转化规律研究

Nitrogen movement and transformation with different water supply for paddy rice

针对不同的水肥处理,采用15N示踪方法,观测分析了氮素在稻田的时空分布及运移规律、挥发及淋失损失规律、氮素在水稻植株中的分布特征、稻田氮量平衡等。结果表明:不同灌溉方式下,由于稻田水分状况的差异导致土壤养分时空分布不同,从而影响其对作物的有效性;由于节水灌溉稻田水分相对较少,基质浓度较高,挥发损失高于淹灌。虽然节水灌溉下稻田渗漏液NH+3浓度较淹灌高,但由于此时总渗漏量显著减少,氮的总淋失4及NO-较淹灌条件少;节水灌溉下,适当增加追肥次数,有利于减少各种氮素养分的损失,提高氮肥利用率;节水灌溉下水稻对氮素的吸收利用率高于淹灌,且有利于氮素养分向稻谷转移。

With experiment data under different water and nitrogen treatments, this paper studies the changing patterns of nitrogen movement and transformation, losses of ammonia volatilization and nitrogen leaching, nitrogen distribution within rice plant, nitrogen balance in paddy fields.The results shows that ammonia volatilization is high under water saving irrigation (WSI) compared with continuous flooding (CF) because the soil solution concentration is higher. Although concentration of NH^+_4 and NO^-_3in the percolation water is higher under WSI, total nitrogen leaching loss is lower because the total percolation loss is much lower than those of CF. Under WSI conditions, more nitrogen supply splits can decrease nitrogen losses and increase nitrogen efficiency. WSI practice is propitious to nitrogen recovery and its transferred to grain. The WSI regime produces optimal water and fertilizer management for paddy rice when 250-400 kg/hm^2 of urea is applied through three splits.