水氮供应对夏棉产量、水氮利用及土壤硝态氮累积的影响

Effects of nitrogen and irrigation water application on yield,water and nitrogen utilization and soil nitrate nitrogen accumulation in summer cotton

通过田间试验,研究了黄淮地区水氮供应对夏棉生长、产量及水氮利用效率的影响,探索在保证产量的同时提高水氮利用效率、减少农田水氮排放的管理模式.试验设置5个氮素水平(0、60、120、180、240 kg·hm^(-2),分别记为N_0、N_1、N_2、N_3、N_4)和3个灌水水平(滴灌,灌水定额30、22.5、15 mm,分别记为I_1、I_2、I_3),使用裂区设计,主区为氮用量,裂区为灌水水平,共15个处理,3次重复.结果表明:氮素和水分施用对夏棉生长和产量都有明显促进作用,但氮素影响更显著,是该地区调控夏棉生长和籽棉产量的主要因素.随着施氮量和灌水量的增加,花铃期生殖器官积累量、地上部干物质积累量和籽棉产量在开始阶段都逐步增加,当施氮量超过180 kg·hm^(-2)时,进一步增施氮肥会导致生殖器官积累量、地上部干物质积累量和籽棉产量减小.籽棉产量在N_3I_1处理达到最大,为4016 kg·hm^(-2).增加施氮量能显著提高地上部总吸氮量和茎叶含氮量,但会降低氮肥偏生产力.灌溉水利用效率和田间水分利用效率分别在N_3I_3和N_3I_1处理最大,分别为5.40和1.24 kg·m^(-3).随着施氮量的增加,土壤硝态氮含量明显增加,且硝态氮累积区域有下移趋势.综合考虑对地上部干物质积累、产量、水氮吸收利用及土壤硝态氮累积等的影响,N_3I_1处理可作为试验区夏季棉花生产的最优水氮管理方案.

A field experiment was carried out to study the effects of nitrogen and irrigation water application on growth,yield,and water and nitrogen use efficiency of summer cotton,and to develop the optimal water and nitrogen management model for suitable yield and less nitrogen loss in summer cotton field in the Huang-Huai region.Two experimental factors were arranged in a split plot design.The main plots were used for arranging nitrogen factor which consisted of five nitrogen fertilizer levels（0,60,120,180,240 kg·hm^-2,referred as N0,N1,N2,N3,N4）,and the subplots for irrigation factor which consisted of three irrigation quota levels（30,22.5,15 mm,referred as I1,I2,I3）.There were 15 treatments with three replications.Water was applied with drip irrigation system.Experimental results showed that both irrigation and nitrogen fertilization promoted cotton growth and yield obviously,but nitrogen fertilizer showed more important effects than irrigation and was the main factor of regulating growth and yield of summer cotton in the experimental region.With the increase of nitrogen fertilization rate and irrigation amount,the dry mater accumulation of reproductive organs,the above-ground biomass at the flowering-bolling stage and seed cotton yield increased gradually,reached peak values at nitrogen fertilization rate of 180 kg·hm^-2 and decreased slowly with the nitrogen fertilization rate further increased.The maximum yield of 4016 kg·hm-2 was observed in the treatment of N3I1.Increasing nitrogen fertilizer amount would improve significantly total N absorption of shoots and N content of stem and leaf,but decrease nitrogen partial factor productivity.The maximum irrigation-water use efficiency of 5.40 kg·m^-3 and field water use efficiency of 1.24 kg·m^-3 were found in the treatments of N3I3 and N3I1,respectively.With increasing nitrogen fertilization amount,soil NO3^--N content increased and the main soil NO3^--N accumulation layer moved downward.By comprehensively considering above-ground biomass,seed cotton yield,water and nitrogen uptake and utilization,and soil NO3^--N accumulation in the soil profile,the treatment N3I1 could be recommended as the optimal water and nitrogen application pattern for summer cotton production in the experimental region.