氮肥用量和配施硝化抑制剂对柴达木枸杞产量及氮素吸收利用的影响

研究氮肥用量和硝化抑制剂对枸杞产量和氮素平衡等的影响，以期为柴达木地区枸杞科学施氮提供依据。设置8个处理，N₆₆₇、N₄₀₀、N₂₆₇、N₁₃₃、CK处理分别施用纯氮667（当地农民习惯施氮量）、400、267、133、0 kg/hm²，N₄₀₀I_2.00、N₂₆₇I_1.33、N₁₃₃I_0.67处理分别施用纯氮400、267、133 kg/hm²并配施纯氮量0.5%的2-氯-6-三氯甲基吡啶（硝化抑制剂）2.00、1.33、0.67 kg/hm²，测定枸杞产量、植株吸氮量和土壤无机氮累积量等指标。结果表明：枸杞产量随施氮量的增加呈先增加后降低的趋势，配施硝化抑制剂可有效提高枸杞产量。2019年N₄₀₀I_2.00、N₂₆₇I_1.33处理的枸杞产量较N₄₀₀、N₂₆₇处理分别增加5.8%、5.0%。两年N₄₀₀I_2.00处理的枸杞产量较N₆₆₇处理分别增加9.3%和6.7%。枸杞的氮肥偏生产力随施氮量的增加而降低。N₄₀₀I_2.00~N₁₃₃I_0.67处理的氮肥偏生产力较N₆₆₇处理增加8.9~45.1 kg/kg。与农民习惯施氮处理相比，减施氮肥及配施硝化抑制剂显著提高植株及果实吸氮量。N₄₀₀I_2.00处理的植株吸氮量及果实吸氮量最高，较N₆₆₇处理提高18.5%及12.8%。同等施氮量下硝化抑制剂的施用降低氮素表观损失量。N₄₀₀I_2.00~N₂₆₇I_1.33处理的表观损失量较N₄₀₀~N₂₆₇处理降低30.7~44.4 kg/hm²。在农民习惯施氮量的基础上减少40%~60%施氮量可保证较高的枸杞产量及植株氮素吸收量。相同施氮量配施硝化抑制剂可显著提高枸杞植株吸氮量，降低氮素表观损失量。在本试验条件下，以施氮量267~400 kg/hm² 同时配施1.33~2.00 kg/hm² 的2-氯-6-三氯甲基吡啶为青海省柴达木地区枸杞生产的适宜施氮组合。

Effects of Different Nitrogen Application Rates Combined with Nitrification Inhibitor on Wolfberry Yield,Nitrogen Uptake and Utilization in Qaidam

Effects of nitrification inhibitor and N fertilizer rate on the yield,N use and N balance of wolfberry were explored for providing a theoretical basis for optimizing N management of wolfberry in Qaidam. A 2-year field study was carried out in Qaidam eight treatments,including N₆₆₇,N₄₀₀,N₂₆₇,N₁₃₃,N₄₀₀I_2.00,N₂₆₇I_1.33,N₁₃₃I_0.67 and CK,were set up. In N₆₆₇,N₄₀₀,N₂₆₇,N₁₃₃,CK,the N amount of 667 (N application rate used by farmers),400,267,133 and 0 kg/hm² were applied,respectively,and nitrapyrin(nitrification inhibitor) 2.00,1.33,0.67 kg/hm² were applied in N₄₀₀I_2.00,N₂₆₇I_1.33,N₁₃₃I_0.67,respectively.At the same time, 2.00,1.33,0.67 kg/hm² 0.5% 2-chloro-6-trichloromethylpyridine were applied,respectively in N₄₀₀,N₂₆₇,N₁₃₃ treatments,and then the yield and N uptake of wolfberry and soil N accumulation were measured. The results showed that with increase of N application rate,wolfberry yield increased at first,and then decreased. The wolfberry yield could be improved effectively by the addition of nitrapyrin. The yield of N₄₀₀I_2.00 and N₂₆₇I_1.33 increased by 5.8% and 5.0%,respectively,compared with N₄₀₀ and N₂₆₇. In contrast to N₆₆₇,the yield of wolfberry with N₄₀₀I_2.00 increased by 9.3% and 6.7% in two years. The partial N productivity decreased with increase of N application rate. The partial nitrogen productivity of N₄₀₀I_2.00-N₁₃₃I_0.67 increased by 8.9-45.1 kg/kg,compared with N₆₆₇. In contrast to the N rate applied by farmers,reducing N fertilizer rate and nitrapyrin addition were beneficial for improving N uptake,especially the N uptake of fruit. Compared with N₆₆₇,N₄₀₀I_2.00 maximized the N uptake of fruit,with an increase of 18.5% and 12.8%. With the same N rate,the addition of nitrapyrin significantly reduced the apparent N loss. The apparent loss of N₄₀₀I_2.00-N₂₆₇I_1.33 was 30.7-44.4 kg/hm² lower than that of N₄₀₀-N₂₆₇,respectively. With the conventional treatment as reference,reducing N fertilizer rate by 40%-60% maintained relatively high wolfberry yield and N uptake. The N application combined with nitrapyrin significantly increased N uptake and reduced N loss. In this study,the N fertilizer rate of 267-400 kg/hm² plus 1.33-2.00 kg/hm² nitrapyrin is the optimum combination for optimizing N management of wolfberry in Qaidam of Qinghai province.