化肥减量替代对华北平原小麦-玉米轮作产量及氮流失影响

为降低氮素流失风险,提高肥料利用效率,在华北平原采用田间定位试验研究了不同施肥措施对小麦-玉米产量、周年氮素淋溶和径流损失的影响。结果表明,相比当地常规施肥处理(CON),减施氮肥150 kg·hm~(-2)的条件下,单施化肥(RF)和10%比例沼液替代(RFM)不会降低小麦和玉米产量。相较于CON处理的氮素年均盈余量218.1 kg·hm~(-2),RF和RFM处理氮盈余量分别显著降低了66.7%和55.9%。CON处理总氮平均淋失浓度和年均淋失量分别为33.70 mg·L~(-1)和22.01 kg·hm~(-2),与之相比,RF处理总氮平均淋失浓度和年均淋失量分别降低了31.45%和30.58%,而RFM处理分别降低了40.65%和43.39%。试验期间径流产流只发生2次,氮素淋溶发生次数和氮损失量远高于径流损失,因此淋溶是氮素流失的主要途径。CON处理总氮平均径流浓度和年均径流流失量分别为23.0 mg·L~(-1)和0.095 kg·hm~(-2),与之相比,RF处理总氮平均径流浓度和年均径流流失量分别降低了32.9%和30.5%,而RFM处理分别降低了45.5%和50.5%。由于施肥量较高,CON处理氮淋溶表观流失率为4.19%,而RF和RFM处理氮淋溶表观流失率分别降低了2.86%和20.76%。NO_3~--N是氮素流失的主要形态,分别占淋溶和径流总氮流失量的66.3%和73.3%,其与总氮流失变化趋势一致。综上,化肥减量配施沼液在保证作物产量的情况下,是降低氮素流失的有效措施。

Effects of chemical fertilizer reduction combined with biogas fertilizer on crop yield of wheat-maize rotation and soil nitrogen loss in North China Plain

To reduce the risk of nitrogen loss and improve the efficiency of fertilizer use, field experiments were conducted in the North China Plain to study the effects of different fertilizer treatments on the crop yield of wheat and maize, annual nitrogen leaching, and runoff loss. The results showed that the yield of wheat and maize was not reduced by applying chemical fertilizer alone or 10% biogas fertilizer substitution with nitrogen fertilizer reduction of 150 kg·hm^-2. Compared with the annual average nitrogen surplus of 218.1 kg·hm^-2 under the CON treatment, the nitrogen surplus of the RF and RFM treatments decreased by 66.7% and 55.9%, respectively. The average leaching concentration and annual leaching amount of nitrogen in the CON treatment were 33.70 mg·L^-1 and 22.01 kg·hm^-2, respectively. Compared with conventional fertilization, the average nitrogen leaching concentration and annual leaching loss in the RF treatment decreased by 31.45% and 30.58%, respectively, whereas that in the RFM treatment decreased by 40.65% and 43.39%, respectively. Runoff occurred only twice during the study. The occurrence of nitrogen leaching and the amount of nitrogen loss in the study area were much higher than that of runoff loss. Leaching was the main pathway of nitrogen loss. The average nitrogen runoff concentration and annual runoff loss in the CON treatment were 23.0 mg·L^-1 and 0.095 kg·hm^-2, respectively. Compared with conventional fertilization, the average nitrogen runoff concentration and annual runoff loss in the RF treatment decreased by 32.9% and 30.5%, whereas that in the RFM treatment decreased by 45.5% and 50.5%, respectively. Due to the higher fertilization rate, the apparent nitrogen leaching rate of the conventional fertilization treatment was 4.19%, whereas that in the RF and RFM treatments decreased by 2.86% and 20.76%, respectively. NO₃^--N was the main form of nitrogen loss, accounting for 66.3% and 73.3% of the total nitrogen loss in leaching and runoff, respectively, which was consistent with the trend in total nitrogen loss. In conclusion, chemical fertilizer reduction combined with biogas fertilizer was an effective measure for reducing nitrogen loss concentration and amount while ensuring crop yield.