施氮水平对河套灌区套作小麦-玉米土壤微生物量碳、氮的影响研究

Effects of Nitrogen Application on Soil Microbial Biomass Carbon and Nitrogen of Intercropping Wheat-Corn in Hetao Irrigation Area

通过田间试验研究了河套灌区套作小麦(Triticum aestivum L.)-玉米(Zea mays L.)在不同施氮水平下(小麦N0 0 kg·hm^(-2)、N1 90 kg·hm^(-2)、N2 180 kg·hm^(-2)、N3 270 kg·hm^(-2);玉米N0 0 kg·hm^(-2)、N1 135 kg·hm^(-2)、N2 270 kg·hm^(-2)、N3 405 kg·hm^(-2))土壤微生物量碳、氮的变化规律,为农业生产中定量施氮提供有益的生物参数和指标。结果表明:小麦全生育期内土壤微生物量氮、碳含量呈现出"升-降-升"趋势,抽穗期土壤微生物量氮达到最大值,灌浆期的下降幅度最大,土壤中的养分被小麦大量吸收消耗,此时微生物矿化出一部分微生物量氮以供作物吸收利用,土壤微生物量含量大幅下降。玉米土壤微生物量氮、碳含量随生育期进程推进而先增加后降低,在抽雄期出现峰值,土壤中的有效养分充足,同时,根系代谢活动旺盛,分泌物增多,使微生物代谢加快,为微生物的生长和繁殖提供了充足的营养环境。套作小麦-玉米土壤微生物量碳、氮含量均随着施氮水平的升高呈现出先增加后降低的趋势,在N2(小麦180 kg·hm^(-2)、玉米270 kg·hm^(-2))水平下,土壤微生物量碳、氮含量最高。N2处理的小麦微生物量碳较N0增加了53.7%,微生物量氮则是N0的3.29倍;N2处理的玉米微生物量碳、氮分别是N0的2.61、5.38倍。回归分析表明,土壤微生物量与施氮量之间表现为显著的二次型回归关系,适宜的氮肥施用量对微生物量碳、氮的负效应较低;根据边际分析及综合土壤微生物量碳、氮,推荐小麦最佳施肥量为165.9~187.5 kg·hm^(-2),玉米最佳施肥量为227.5~287.9 kg·hm^(-2)。

The dissertation studied the changes of intercropping wheat(Triticum aestivum L.)and corn(Zea mays L.)soil microbial biomass nitrogen and carbon under different nitrogen application levels(wheat:N0 0 kg·hm-2,N1 90 kg·hm-2,N2 180 kg·hm-2,N3 270 kg·hm-2;corn:N0 0 kg·hm-2,N1 135 kg·hm-2,N2 270 kg·hm-2,N3 405 kg·hm-2)in Hetao irrigation area through field experiment.It provides beneficial biological parameters and indicators for quantitative nitrogen application in agricultural production.The results indicated that the soil microbial biomass nitrogen and carbon presented a rising-lowering-up trend during the whole growth period of wheat.Soil microbial biomass nitrogen reached the maximum at heading stage,the biggest drop in filling period.The nutrients in the soil were absorbed and consumed by the wheat in large quantities.At this time,the microorganisms might also mineralize a part of the microbial biomass nitrogen to be absorbed and utilized by crops and soil microbial biomass decreased significantly.Corn soil microbial biomass nitrogen,carbon increased first and decreased then with growth period.There was a peak in the tasseling period.The effective nutrients in the soil were sufficient.At the same time,the metabolic activities of the roots were vigorous,and the secretions were increased,which accelerated the metabolism of microorganisms and provided a sufficient nutrient environment for the growth and reproduction of microorganisms.With the increase of nitrogen application rate,the soil microbial biomass carbon and nitrogen contents of intercropping wheat and corn increased first and then decreased.The soil microbial biomass carbon and nitrogen were highest at N2(wheat 180 kg·hm-2,corn 270 kg·hm-2).Compared with N0,the microbial biomass carbon of wheat N2 treated increased by 53.7%.And the microbial biomass nitrogen was 3.29 times higher than that of N0.The microbial biomass carbon and nitrogen of corn N2 treatment was 2.61 and 5.38 times higher than that of N0 respectively.Regression analysis showed that soil microbial biomass and nitrogen application showed the significant quadratic regression relationship.The regression equation showed that the suitable nitrogen existed lower negative effect of microbial biomass nitrogen and carbon.Based on marginal analysis and comprehensive soil microbial biomass carbon and nitrogen,we recommend that the best fertilizer rate for wheat should be 165.9~187.5 kg·hm-2,and for corn should be 227.5~287.9 kg·hm-2.