不同氮肥运筹对直播稻田氮素损失与利用的影响

Nitrogen loss and utilization characteristics of different N fertilizer translocations in direct-seeded rice

为探讨不同类型氮肥按不同基蘖肥比例配施对直播稻田径流氮流失、氨挥发及氮肥利用率的影响,本研究开展了田间小区试验,设置了7个施氮处理,即不施氮肥的空白对照(CK)、普通复合肥(基肥)与尿素(分蘖肥)基蘖肥配比4∶6(U_(40))和6∶4(U_(60))、控释掺混肥(基肥)与尿素(分蘖肥)基蘖肥配比7∶3(C_(70))和10∶0(C_(100))、海藻多糖尿素基蘖肥配比4∶6(H40)和6∶4(H60),每个处理设置3个重复。结果表明:径流氮流失量主要集中在基肥施入后,以铵态氮(NH_(4)^(+)-N)为主,与U60处理相比,C_(100)、H_(60)、U_(40)、C_(70)和H_(40)处理总氮流失量分别减少了7.20%、13.36%、24.30%、26.41%和35.92%;不同氮肥之间的氨挥发损失量和损失率呈现出普通复合肥与尿素配施处理>海藻多糖尿素处理>控释掺混肥与尿素配施处理;与U60处理相比,U_(40)、H_(60)、H_(40)、C_(70)和C_(100)处理的氨挥发总损失量分别降低了7.89%、20.81%、27.84%、42.08%和47.00%,C_(70)、C_(100)处理降低效果显著(P<0.05);与U_(60)、C_(100)和H_(60)处理相比,U40、C70和H40处理径流的总氮流失量分别降低了24.30%、20.70%和26.04%。氮肥后移的U40、C_(70)和H_(40)处理的径流氮流失及氨挥发损失均有所降低,且不影响产量;C70处理产量和氮肥农学利用率均为最高,分别为9 116.67 kg·hm^(-2)和29.64 kg·kg^(-1),且氮肥表观利用率为41.99%。研究表明,C_(70)和C_(100)处理均能显著降低稻田径流氮流失,减少氨挥发损失,提高氮肥利用率和直播稻产量。综合考虑产量及环境影响,以控释掺混肥(基肥)与尿素(分蘖肥)按基蘖肥比7∶3配施更值得推广。

To explore the effects of different types of nitrogen fertilizers and different tillering ratios on runoff nitrogen loss,ammonia volatilization,and nitrogen fertilizer use efficiency in direct-seeded rice fields,seven nitrogen application treatments were arranged in field plot experiments with three replicates,including the blank control(CK)without nitrogen fertilizer,common compound fertilizer(base fertilizer),and urea(tiller fertilizer)at ratios of 4∶6(U_(40))and 6∶4(U_(60)),controlled-release blended fertilizer(base fertilizer)and urea(tiller fertilizer)at ratios of 7∶3(C_(70))and 10∶0(C_(100)),and seaweed polysaccharide urea at ratios of 4∶6(H_(40))and 6∶4(H60).The results showed that runoff N loss mainly occurred after basal fertilizer application and was dominated by ammonium nitrogen(NH_(4)^(+)-N).Compared with the U_(60) treatment,Total N loss in the C_(100),H60,U_(40),C_(70),and H_(40) treatments decreased by 7.20%,13.36%,24.30%,26.41%,and 35.92%,respectively.The order of the amount and rate of ammonia volatilization loss between different N fertilizers was as follows:treatment of common compound fertilizer with urea>treatment of seaweed polysaccharide urea>treatment of controlled-release blended fertilizer with urea.Compared with the U_(60) treatment,the total ammonia volatilization loss in the U_(40),H60,H_(40),C_(70),and C_(100) treatments decreased by 7.89%,20.81%,27.84%,42.08%,and 47.00%,respectively,with significant differences between the C_(70) and C_(100) treatments(P<0.05).The total N losses from runoff were reduced by 24.30%,20.70%,and 26.04%for U_(40),C_(70),and H_(40) treatments compared with U_(60),C_(100),and H60 treatments,respectively.N fertilizer setback reduced runoff N loss and ammonia volatilization loss in the U_(40),C_(70),and H_(40) treatments,with no yield loss.The maximum yield of 9116.67 kg·hm^(-2) and the highest N fertilizer agronomic utilization of 29.64 kg·kg-1 occurred in the C_(70) treatment,and the apparent N fertilizer utilization was 41.99%.The study suggested that the C_(70) and C_(100) treatments both significantly reduced runoff N loss and ammonia volatilization loss in direct-seeded rice fields,while improving N fertilizer utilization efficiency and yield.The ratio of 7∶3 between controlled-release blended fertilizer(base fertilizer)and urea(tiller fertilizer)at the base tiller fertilizer ratio is worth pursuing for productivity and environmental protection.