不同类型作物生长对土壤有效氮构成和氮肥转化利用的影响

采用高、低氮处理研究盆栽种植大豆、棉花、玉米和高粱对土壤有效氮构成和氮肥转化利用的影响,以期为不同类型作物的氮肥合理利用及其利用率的提高提供技术指导。结果表明,与施氮肥不种植作物(对照)相比,种大豆、棉花、玉米、高粱使土壤有效氮含量分别显著降低53.48%、51.54%、33.10%、55.03%,并影响有效氮构成。其中,种大豆、棉花、玉米、高粱使土壤无机氮含量分别显著降低85.41%、83.09%、70.89%、83.35%,水解有机氮含量分别显著增加1.41、1.53、2.11、1.28倍;种大豆、棉花、玉米、高粱使无机氮所占比例分别显著降低68.61%、65.09%、56.47%、63.00%,水解有机氮所占比例分别显著增加4.18、4.21、3.66、4.08倍。与对照相比,种大豆、棉花、玉米、高粱使铵态氮肥转化率分别显著提高93.66%、38.19%、32.58%、38.31%,以种大豆增幅最高;种大豆、棉花、玉米、高粱处理的铵态氮肥硝化率都变为负值,以种大豆降幅最大。种大豆、棉花、玉米、高粱处理的氮肥利用率分别为52.01%、28.31%、24.16%、28.40%,以种大豆处理的氮肥利用率最高。综上,作物生长通过对氮素的吸收利用和对土壤环境的改变,抑制土壤硝化作用,并促进土壤水解有机氮的形成,从而影响土壤有效氮的构成和施入土壤氮的转化利用。豆类作物较非豆类作物抑制土壤硝化作用的能力强,对土壤铵态氮的利用效率高。

Effects of Growing of Different Types of Crops on Constitution of Soil Available Nitrogen and Transformation and Utilization of Nitrogen Fertilizer

The soybean,cotton,maize and sorghum were planted in pot under low nitrogen,high nitrogen treatments,the soil available nitrogen constitution and transformation and utilization of nitrogen fertilizer were determined,so as to provide technical guidance for reasonable use and improving use efficiency of nitrogen fertilizer for different types of crops.Compared with the control with nitrogen but unplanted crop,growing soybean,cotton,maize,sorghum significantly decreased the soil available N contents by 53.48％,51.54％,33.10％,55.03％,and influenced the constitution of soil available N.Thereinto,growing soybean,cotton,maize and sorghum significantly decreased soil inorganic N contents by 85.41％,83.09％,70.89％ and 83.35 ％,but increased soil hydrolysable organic N contents by 1.41,1.53,2.11 and 1.28 times,respectively;growing soybean,cotton,maize and sorghum significantly decreased the rate of soil inorganic N to available N by 68.61％,65.09％,56.47％ and 63.00％,but increased the rate of soil hydrolysable organic N to available N by 4.18,4.21,3.66 and 4.08 times,respectively.Compared with the control,growing soybean,cotton,maize and sorghum significantly increased the transform rate of ammonium nitrogen fertilizer by 93.66％,38.19％,32.58％ and 38.31％ respectively,and growing soybean treatment had the highest increasing range;the nitrification rates of ammonium nitrogen fertilizer of growing soybean,cotton,maize and sorghum treatments were negative values,and growing soybean treatment had the highest decreasing amplitude.The ammonium nitrogen fertilizer use efficiency of growing soybean,cotton,maize and sorghum treatments were 52.01％,28.31％,24.16％ and 28.40％ respectively,and growing soybean treatment had the highest value.In conclusion,growing crops suppressed the soil nitrification and accelerated the development of soil hydrolysable organic nitrogen by the utilization of soil available nitrogen and the alteration of soil environment,and hence impacted the constitution of soil available nitrogen and the transform and use of ammonium nitrogen applied in soil.Leguminous crops had stronger ability of suppressing nitrification,making use of ammonium compared with non-Leguminous crops.