缓释尿素对滴灌棉田土壤无机氮及其产量的影响

通过田间试验,研究了基施缓释尿素占总氮量20%,50%和100%对棉田土壤无机氮分布、积累以及棉花产量、氮素吸收利用及农田氮素平衡的影响,明确缓释尿素能否在滴灌棉花上施用,并探讨其施用的适宜基施比例。结果表明,施用缓释尿素可显著提高土壤硝态氮和铵态氮含量,其中各缓释尿素处理的土壤硝态氮含量较不施氮处理分别提高189.27%、195.58%和112.70%。施肥处理土壤无机氮积累量均表现为富集现象,不施氮处理则表现为负积累效应。土壤无机氮含量随基施比例的增加而降低,而土壤氮素表观损失量和氮素盈余量随基施比例的增大均为先降后增的趋势。棉花产量、氮肥利用率和农学效率均随缓释尿素基施比例的增大表现出先增加后降低的趋势,缓释尿素是通过增加棉花单株结铃数或单铃重来实现增产的。综上,本试验条件下,缓释尿素占总氮量50%作基肥的滴灌棉花产量及氮肥利用率较高,土壤氮素表观损失量较低。

Effects of slow-release urea on soil inorganic N and yield in drip-irrigated cotton field

The objective of this experiment was to study the effect of slow-release urea fertilizer on soil inorganic N distribution,N accumulation,residual N concentration,yield,N use efficiency,and the N balance.Findings from this study can be used to determine if slow-release urea can be applied to drip-irrigated cotton and to decide the optimum application rate at planting.The results showed that the concentration of NO3--N and NH4 +-N significantly increased by using slow-release urea,and the content of nitrate nitrogen in the soil treated with slow-release urea increased by 189.27％,195.58％ and 112.70％ respectively.The accumulation amount of inorganic nitrogen in the soil in fertilization treatment showed the enrichment phenomenon,and the negative accumulation effect was shown in the treatment of nitrogen fertilizer.The content of inorganic nitrogen in soil decreased with the increase of the proportion of base fertilizer,while the apparent N loss and the increase of the percentage of nitrogen surplus decreased first and then increased.Cotton yield,nitrogen use efficiency and agronomic efficiency increased first and then decreased with the increase in the proportion of base fertilizer of slow-release urea,and the yield was attributed to the increase in the boll number and boll weight of cotton.In conclusion,under the experimental conditions,with slow-release urea being 50％ of the total nitrogen,the yield of drip-irrigated cotton and nitrogen use efficiency were higher,and apparent N loss was lower.