A study on precise nitrogen fertilization in drip irrigation cotton field under film in Xinjiang based on meta-analysis
[Objective]The effect of nitrogen application on cotton yield and its constituent factors is clarified,aiming to provide theoretical reference for the precise application of nitrogen fertilizer and high cotton yield.[Methods]The comprehensive effects and influencing mechanisms of different nitrogen application rates,nitrogen application schemes,and climatic conditions on cotton yield are studied by meta-analysis and path analysis in Xinjiang.[Results]Compared with no nitrogen application,nitrogen application could significantly increase cotton yield with 43.38％.Nitrogen application of 360-480 kg·hm-2 had the greatest effect on cotton yield.Nitrogen application exceeding this range no longer increased cotton yield significantly,and the recommended economic nitrogen application rate in this study was 360-420 kg·hm-2.The nitrogen application scheme of 20％of basic fertilizer,80％of supplementary fertilizer and 6 times of drip application with water at the rate of 6％,8％,22％,25％,12％,and 7％had the greatest effect on cotton yield.The greatest yield increase was achieved by the nitrogen fertilization program.The most obvious effect of nitrogen application was found in cotton fields with annual evaporation＞2 000 mm,annual precipitation＜60 mm,annual sunshine time＜2 864 h,annual effective cumulative temperature＞4 000 ℃,and frost-free period＞200 d,and in fields with sandy soil,initial soil organic carbon content＜5.8 g·kg-1,and initial soil available nitrogen content ≤60 mg kg-1.The results of the pathway analysis showed that nitrogen application contributed most significantly to the enhancement of cotton yield by increasing the soil nitrate nitrogen content,thereby increasing the cotton leaf area index.[Conclusion]It is suggested that nitrogen application rate of 360-420 kg·hm-2 with the above optimization scheme should be used in Xinjiang cotton area to achieve high cotton yield and reduce environmental risk in drip irrigation cotton fields under film.
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