施氮对膜下滴灌棉花生长发育及土壤硝态氮的影响

【目的】 研究施氮量对膜下滴灌棉花生长发育及土壤硝态氮的影响,为膜下滴灌棉花的氮肥管理提供理论参考。【方法】 以新陆早52号为材料,设N0(不施氮)、N150(150 kg/hm²)、N250(250 kg/hm²)、N350(350 kg/hm²)、N450(450 kg/hm²)共5个处理,研究膜下滴灌棉花的氮肥运行规律及最佳氮肥施用量。【结果】 不同氮肥处理地上部生物累积量进符合Logistic 曲线模型Y=a/(1+b×exp(-k×t)),最大积累速率出现时间在71~77 d,进入快速积累期在56~60 d。2试验年各处理LAI表现为N450>N350>N250>N150 >N0,最大可达4.51~4.81。0~60 cm土层,硝态氮含量变化表现为随土层深入先增加后降低的趋势,在20~40 cm土层硝态氮含量最高,现蕾阶和铃期消耗土壤硝态氮较多。产量、肥利用率、氮肥贡献率2试验年N350最大,分别在为7 477.5和7 731.7 kg/hm²,40.32%、43.24%,56.09%、57.02%。【结论】 N350(350 kg/hm²)处理效果最佳,施氮量在327.70~340.67 kg/hm²的阈值范围内,有利于棉花形成高产和提高肥料利用率。

Simulating Effects of Nitrogen Application on Growth and Development and Soil Nitrate Nitrogen of Cotton under Mulched Drip Irrigation

【Objective】 To clarify the effect of nitrogen application rate on cotton growth and soil nitrate nitrogen under mulched drip irrigation. 【Methods】 Xinluzao 52 was used as the testing material, and a total of five treatments were set: N0 (no nitrogen application), N150 (150 kg/hm²), N250 (250 kg/hm²), N350 (350 kg/hm²) and N450 (450 kg/hm²) were set in the hope of finding out the operation rule of nitrogen fertilizer and the optimum application amount under mulched drip irrigation and providing the theoretical basis for the relevant management. 【Results】 The results showed that the above-ground bioaccumulation of different nitrogen fertilizers was consistent with the logistic curve model Y=a/(1+b×exp (-k×t)), the maximum accumulation rate appeared from 71to 77 d, and entered the rapid accumulation period from 56 d to 60 d. In the two testing years, the LAI of each treatment showed: N450 > N350 > N250 > N150 > N0, and the maximum was between 4.51-4.81. In the 0-60 cm soil layer, the change of nitrate nitrogen content showed a trend of increasing at first and then decreasing with the depth of soil layer. In the 20-40 cm soil layer, the nitrate nitrogen content was the highest, and the soil nitrate nitrogen was more consumed in the bud stage and the boll stage. In the two year experiments, the yield, fertilizer utilization rate, and nitrogen fertilizer contribution rate were the highest under N350 treatment, which were 7,477.5, 7,731.7 kg/hm²; 40.32%, 43.24%; 56.09% and 57.02%, respectively. 【Conclusion】 Considering all the factors, the N350 (350 kg/hm²) treatment’s effect was the best among the five treatments in our study and the simulation showed that the nitrogen application rate was within the threshold range of 327.70-340.67 kg/hm², which was conducive to high cotton yield and improvement of fertilizer utilization rate.