长期配施有机肥对宁夏引黄灌区水稻产量和稻田氮素淋失及平衡特征的影响

在宁夏引黄灌区的青铜峡稻田,通过4年的田间定位试验研究了长期配施有机肥对水稻籽粒产量、氮素吸收利用和氮素淋失特征的影响。试验共设置5个处理:不施用氮肥(T₁)、常规化学氮肥300 kg·hm^-2(T₂)、优化化学氮肥210 kg·hm^-2+有机肥氮肥90 kg·hm^-2(T₃)、优化化学氮肥240 kg·hm^-2(T₄)、优化化学氮肥195 kg·hm^-2+有机肥氮肥45 kg·hm^-2(T₅).用稻田退水采集装置收集20、60 cm和100 cm深度的淋溶水,计算氮素淋失量。试验结果表明:在常规施氮和优化施氮水平下配施有机肥,水稻籽粒产量没有降低,氮肥利用率分别提高了5.2、1.9个百分点;配施有机肥可以显着降低田面水中的总氮浓度和土体中氮素淋失量,20 cm土层中总氮淋失量分别降低了9.99%和6.02%,100 cm土层中总氮淋失量分别降低了17.9%和9.3%;氮平衡特征计算结果表明,同等施氮水平下配施有机肥氮素表观损失量分别降低了12.1%和12.5%.与常规只施用化肥比较,配施有机肥可以显着降低氮素的淋洗损失,优化施氮水平下配施有机肥(T₅处理)为协调水稻产量和环境安全的合理选择。

Rice Yield, Nitrogen Use Efficiency(NUE) and Nitrogen Leaching Losses as Affected by Long-term Combined Applications of Manure and Chemical Fertilizers in Yellow River Irrigated Region of Ningxia, China

To maximize rice yields, excessively high nitrogen fertilization and irrigation are very common management practices in the Yellow River Irrigated Region of Ningxia. However, these practices have greatly increased the risks of nitrogen losses and non-point source pollution. Production systems with more yields and less environmental impacts are urgently needed in this region. A continuous four year field experiment was conducted to evaluate the effects of combined applications of manure and chemical fertilizers on rice yields and nitrogen utilization and nitrogen leaching losses in Qingtongxia in the Yellow River Irrigated Region of Ningxia. Five nitrogen treatments were used:no nitrogen fertilizer(T₁), conventional chemical nitrogen of 300 kg·hm^-2(T₂), chemical plus organic-chemical nitrogen of 210 kg·hm^-2 + manure nitrogen of 90 kg·hm^-2(T₃), reduced chemical nitrogen of 240 kg·hm^-2(T₄), and optimized chemical nitrogen of 195 kg·hm^-2 + manure nitrogen of 45 kg·hm^-2(T₅). The experimental design was a randomized complete block with three replicates. Each plot was 45 m²(5 m×9 m). An in-situ leaching device was used to sample leachate from 20 cm, 60 cm, and 100 cm soil depths. Total nitrogen, NO₃^--N and NH₄⁺-N leaching losses were calculated based on nitrogen concentrations in the leachate and the volume of the leachate. Compared with the conventional chemical nitrogen, rice grain yields in all treatments with lowered chemical nitrogen with and without manure did not decrease, whereas nitrogen use efficiency was 5.2 and 1.9 percentage points higher. The total nitrogen concentration in the surface water and nitrogen leaching losses at different soil depths were all significantly decreased in lowered chemical nitrogen combined with manure as compared to the conventional chemical nitrogen. At 20 cm soil depth, total nitrogen leaching losses were 9.99% and 16% lower than that in the conventional chemical nitrogen, while 17.9% and 9.3% lower at 100 cm soil depth. Under the same nitrogen level, apparent nitrogen losses were respectively reduced by 12.1% and 12.5% in combined manure and chemical fertilizer treatments over the conventional chemical nitrogen and reduced chemical nitrogen alone. In conclusion, applying chemical nitrogen of 195 kg·hm^-2 + manure nitrogen of 45 kg·hm^-2 could maintain paddy rice yields while alleviating environmental pollution in the Yellow River Irrigated Region of Ningxia.