缓/控释肥对双季稻产量、氮素吸收和平衡的影响

在江西省双季稻区连续2年设置大田定位试验,设置不施氮(CK)、分次优化施肥(OPT)、一次性基施缓/控释肥(100CRF)和一次性基施80%缓/控释肥(80CRF)4个施肥处理,研究施用缓/控释肥对双季稻产量、氮素吸收与利用、土壤矿质氮累积以及系统氮素平衡的影响。结果表明:与OPT处理相比,100CRF、80CRF处理2年4季水稻产量均无显著差异,但100CRF处理水稻吸氮量显著提高(P0.05),在2013年早晚稻分别提升32.58%(P0.05)和15.41%(P0.05),80CRF处理与OPT处理无显著差异。施用缓/控释肥与分次优化施肥比较,能提高早晚稻氮肥表观利用率、氮肥表观残留率,降低土壤氮素损失率。在双季稻连作体系,土壤中矿质氮含量在同生育期均表现为早稻高于晚稻,100CRF、80CRF处理与OPT处理在分蘖期、抽穗期、成熟期均无显著差异,但土壤NO–3-N在晚稻成熟期100CRF处理显著高于OPT处理(P0.05)。2年平均100CRF和80CRF处理氮损失量比OPT处理分别减少65.34 kg/hm2(33.08%)和90.64 kg/hm2(45.89%)。氮盈余量分别减少51.63 kg/hm2(29.41%)和85.13 kg/hm2(48.49%)。因此缓/控释肥施用可促进双季稻获得高产,增加植株氮素吸收,维持了较高的土壤氮素水平并减少氮素损失,当前生产条件下,缓/控释肥减量20%,双季水稻在维持高产的同时氮肥利用率最高,氮素损失最低,是一种较为合适的施肥方式。

Effects of Sloe/Controlled-Release Fertilizer on Grain Yield, N Uptake and Soil N Balance in Double Cropping Rice

A location-fixed field experiment was carried out for 2 years under double cropping rice in Nanchang, Jiangxi Province of Southern China. Four treatments were designed which included no nitrogen fertilizer (CK), optimization of nitrogen fertilization application split by three times (OPT), slow/controlled release fertilizer all used as basal fertilizer (100CRF), and 80% slow/controlled release fertilizer all used as basal fertilizer (80CRF). Each treatment had three replicates. Rice grain yield, nitrogen absorption and utilization, soil mineral nitrogen accumulation and nitrogen balance in soil-crop system were investigated. The results showed that compared with OPT, 100CRF and 80CRF did not changed the rice yield significantly, but 100CRF increased nitrogen uptake of rice significantly (P<0.05). Nitrogen uptake increased by 32.58% (P<0.05) in early rice and 15.41% (P<0.05) in late rice in 2013, respectively; while no difference existed in nitrogen uptake between 80CRF and OPT. Compared with OPT, CRF improved utilization rate of nitrogen of rice and thus reduced loss of soil nitrogen. Soil mineral nitrogen was higher in early rice than in late rice in the same growth period, no significant difference existed in soil mineral nitrogen between different treatments in tillering, heading and mature stages, but soil nitrate nitrogen in late rice under 100CRF was significantly higher than that of OPT in mature stage. Compared with OPT, the average nitrogen loss ratio of 100CRF and 80CRF reduced by 65.34 kg/hm² (33.08%) in 2013 and 90.64 kg/hm² (45.89%) in 2014, respectively. Therefore controlled release nitrogen fertilization can promote rice yield, increase nitrogen absorption of rice, maintain high soil nitrogen level, reduce soil nitrogen loss and improve utilization rate of nitrogen fertilizer. Reducing 20% of applied controlled release fertilizer is more reasonable under current situation because it can maintain high yield of cropping rice while has the highest utilization rate of nitrogen fertilizer and the lowest nitrogen loss at the same time.