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结合6个施氮水平下土壤Nmin速测值分析了土壤Nmin与施肥量和棉花产量关系,对应用土壤Nmin进行棉花氮肥推荐进行了研究。分析结果表明:土壤Nmin与棉花产量和施氮量均呈正相关关系,与土壤深度呈负相关关系;其中0~20cm土层土壤与施氮量和棉花产量相关性最强,可以很好的表征土壤初始供氮能力,因而可以利用它作为棉花氮肥推荐的指标。在考虑土壤初始供氮能力下,供试棉花品种达到最高产量时的最佳施肥量为226kghm-2,此时0~20cm土层土壤Nmin临界值为为20mgkg-1,并结合最佳施肥量和0~20cm土层土壤Nmin临界值计算出了棉花苗期、蕾期、花铃期的氮肥追施量。
The relationship between soil Nmin and fertilizer amount and cotton yield was analyzed based on the Nmin fast measurement of soil nitrogen under six nitrogen levels. The nitrogen fertilizer recommendation of soil Nmin was studied. The results showed that there was a positive correlation between Nmin and cotton yield and N application rate and a negative correlation with soil depth. Among them, soil N and 0 ~ 20cm had the strongest correlation with cotton yield and could be well characterized Soil initial nitrogen availability, so you can use it as a recommended indicator of cotton nitrogen fertilizer. Under the condition of initial soil nitrogen supply capacity, the optimal fertilization rate of the tested cotton varieties was 226 kghm-2, and the critical value of Nmin was 20 mg kg-1 in 0-20 cm soil layer, and the optimal fertilization amount And the Nmin threshold of 0-20 cm soil layer, the top-dressing amount of nitrogen fertilizer was calculated at seedling stage, bud stage and flower-boll stage.