化肥有机肥配施对盐渍化土壤氨挥发及玉米产量的影响

针对河套灌区无机氮肥过量施用造成的环境问题,通过探究有机氮替代部分无机氮肥对田间土壤氨挥发的影响,确定盐渍化农田适宜的有机无机氮肥配施用量。于2018年进行田间试验,选取轻度(0.45～0.68 dS·m~(-1))和中度(1.04～1.40 dS·m~(-1))盐渍化农田,以纯施氮量240 kg·hm~(-2)为相同施氮总量进行有机无机氮肥配施,分别设置5个施肥处理:单施化肥、3/4氮由化肥提供+1/4氮由有机肥提供、1/2氮由化肥提供+1/2氮由有机肥提供、1/4氮由化肥提供+3/4氮由有机肥提供、单施有机肥,依次记为U_1、U_3O_1、U_1O_1、U_1O_3、O_1。另外设置空白对照处理(CK),探究不同有机无机氮肥配施量对盐渍化玉米农田土壤氨挥发速率、氨挥发损失量及产量的影响。结果表明:土壤盐分随着有机氮肥施用量增加呈先降后升的趋势;各肥料配施处理追肥后氨高挥发期较施入基肥后明显延长,导致同一处理轻、中度盐渍化土壤追肥后氨挥发损失量较施入基肥后分别高出22.15%～64.03%和14.34～40.66%;同一处理在中度盐渍化土壤上的氨挥发总量较轻度盐渍化土壤高出8.35%～16.46%;土壤氨挥发损失量与有机肥施入比例、土壤盐分之间呈显著二元二次非线性回归关系,分析回归方程各系数可知,适当增大有机肥施入比例可以降低土壤氨挥发,而增加土壤盐分则会使土壤氨挥发增大,增施有机肥和土壤盐分之间会产生共同降低氨挥发损失的效应;有机肥替代部分化肥可提高玉米产量,轻、中度盐渍化土壤U_1O_1处理玉米产量分别较U_1处理高出12.63%和17.05%。在轻度和中度盐渍化土壤上,综合氨挥发损失量及玉米产量,处理U_1O_1既能保证高产,又能显著降低氨挥发损失,故推荐该处理为当地适宜肥料配施模式。

Effects of combined application of chemical and organic fertilizers on ammonia volatilization and maize yield in salinized soil

In order to solve the environmental problems caused by excessive application of inorganic nitrogen fertilizer in Hetao Irrigation District, the aim of this study was to find out the appropriate proportion of organic to inorganic fertilizer application for salinized farmland, with investigation of the effect of organic nitrogen substituting for inorganic nitrogen fertilizer on ammonia volatilization. Field experiments were carried out in 2018. Farmlands with mild(0.45~0.68 dS·m^-1)and moderate(1.04~1.40 dS·m^-1)salinization were selected, as was a pure nitrogen application rate of 240 kg·hm^-2. The same amount of nitrogen was applied to the different treatments, with five treatment sets:chemical fertilizer only, 3/4 chemical fertilizer + 1/4 organic fertilizer, 1/2 chemical fertilizer + 1/2 organic fertilizer, 1/4 chemical fertilizer + 3/4 organic fertilizer, and organic fertilizer only, which were designated U₁, U₃O₁, U₁O₁, U₁O₃, and O₁, respectively. In addition, a blank control treatment(CK)was employed to study the effects of different fertilization treatments on the ammonia volatilization rate, ammonia volatilization loss, and corn yield. Soil salt concentration decreased first and then increased with the increase in organic fertilizer application. The high-volatility period of ammonia after top dressing became significantly longer than that after basal dressing, with result of the same treatment of mildly and moderately salinized soil, the ammonia volatilization loss after top dressing was 22.15%~64.03% and 14.34%~40.66% higher than that after basal dressing, respectively. The total ammonia volatilization of the same treatment in moderately salinized soil was higher than that in mildly salinized soil by 8.35%~16.46%. Soil ammonia volatilization showed a significant nonlinear relationship with organic fertilizer rate and soil salt concentration. An increase in appropriate organic fertilizer application reduced ammonia volatilization. Soil salinity increased and ammonia volatilization increased. Increasing organic fertilizer application and soil salt concentration had the effect of jointly reducing the loss of ammonia volatilization. Replacing some chemical fertilizers with organic fertilizer can increase corn yield in mildly and moderately salinized soil, as the yield of corn treated with U₁O₁ treatment was 12.63% and 17.05% higher, respectively, than that of single application urea. Combined with ammonia volatilization loss and corn yield with the mildly and moderately salinized soil, U₁O₁ not only can ensure high yield, but also can significantly reduce ammonia volatilization loss. It should be recommended as the more suitable treatment for experimental district.