控释氮肥全量基施对宁夏引黄灌区水稻氮素利用效率和淋失的影响

利用田间小区试验研究了控释氮肥全量基施对宁夏水稻产量、氮素利用效率和淋洗损失的影响,为控释氮肥全量基施技术在宁夏引黄灌区应用提供技术依据。以宁粳50号水稻品种为研究对象,以不施氮肥(CK)为对照,参考农民常规施肥(FP)施氮量,设置了4个控释氮肥减量施用处理:控释氮肥135 kg/hm~2(C-135)、控释氮肥180 kg/hm~2(C-180)、控释氮肥225 kghm~2(C-225)和控释氮肥270 kg/hm~2(C-270)。对水稻产量、氮素吸收和利用效率、水稻生育期不同深度淋溶水浓度和淋失量进行测定和分析。结果表明:C-180处理和C-225处理在氮肥用量分别降低了25%和40%的条件下,水稻籽粒产量没有降低,原因在于提高了水稻的有效穗数和穗粒数。与FP比较,控释氮肥施氮量控制在270 kg/hm~2以下时,控释氮肥全量施用各处理氮肥利用率显著提高,C-135、C-180、C-225处理氮肥利用率分别比FP处理提高了10.22,11.10,12.75个百分点。控释氮肥各处理水稻生育期内田面水和不同土体深度淋溶水中的TN浓度均低于FP处理,且延迟了田面水中TN浓度峰值出现的时间,减少了因稻田排水和径流导致的氮素损失。FP处理全生育期氮素淋洗损失总量为24.57 kg/hm~2,控释氮肥各处理素淋洗损失总量在11.54～17.35 kg/hm~2,其中C-180,C-225处理总氮淋失量分别比常规施肥降低了46.17%和49.40%。综合考虑水稻产量和氮素损失因素,宁夏水稻控释氮肥全量基施适宜施氮量在180～225 kg/hm~2。

Effects of Application of Controlled-release Nitrogen Fertilizer on Nitrogen Use Efficiency and Leaching of Rice in Ningxia Yellow River Irrigation Area

A field experiment was carried out to study the effects of controlled-release nitrogen fertilizer (CRNF) application on rice yield, nitrogen use efficiency and leaching loss in Ningxia, to provide technical basis for the application of CRNF in the Yellow River irrigation area. Using Ningjing No.50 rice variety as the research object, with no nitrogen fertilizer (CK) as control, according to the local farmers conventional nitrogen application rate (FP), four controlled release nitrogen fertilizer reduction treatments were set up:CRNF 135 kg/hm² (C-135), CRNF 180 kg/hm² (C-180), CRNF 225 kg/hm² (C-225) and CRNF 270 kg/hm² (C -270). The rice yield, nitrogen uptake and use efficiency, and the concentration of leachate at different soil depth and different rice growth stages were measured. Results showed that the rice grain yields under C-180 and C-225 treatments were not reduced under the reduced nitrogen fertilizer application by 25% and 40%, respectively. That was because the effective panicle number and kernel number of rice were increased. Compared with FP treatment, the nitrogen use efficiencies of CRNF were significantly increased when the nitrogen application rates were below 270 kg/hm², which were 10.22%, 11.10%, and 12.75% higher than FP under C-135, C-180 and C-225 treatments, respectively. The concentrations of total nitrogen (TN) in the surface water and the leachate at different soil depth during the growth period of rice under CRNF were lower than those of FP, and delayed the peak time of TN concentration in the surface water, which reduced the nitrogen loss caused by rice field drainage and runoff. The total nitrogen leaching loss during the whole growth period of FP was 24.57 kg/hm², and the corresponding valueswere between 11.54 kg/hm² to 17.35 kg/hm² under CRNF treatments. The total nitrogen leaching loss was reduced by 46.17% and 49.40% under C-180 and C-225 treatments compared with FP. Considering rice yield and nitrogen loss, the reasonable CRNF application rate in Ningxia is between 180 kg/hm² to 225 kg/hm².