复播大豆土壤微生物区系对麦–豆轮作体系周年施氮量的响应

为了揭示周年施氮对复播大豆土壤微生物区系的后效及叠加效应，于2017—2019年采用裂区试验设计，在麦–豆周年轮作体系下，设置不同施氮组合(麦季施氮0、104、173、242 kg/hm²，分别标记为N0、N1、N2、N3；复播大豆施氮0、69、138 kg/hm²，分别标记为S0、S1、S2)，探究豆茬土壤细菌、真菌和放线菌数量，土壤菌群结构和氮素生理群数量的变化规律。结果表明：前茬麦季施氮对复播大豆土壤微生物数量具有显著的后效；复播大豆不施氮条件下，麦季N2～N3施氮范围有利于增加豆茬土壤细菌、真菌、放线菌和氮素生理群数量。在冬小麦不施氮条件下，当季豆茬施氮较不施氮处理能显著增加土壤3大类微生物和氮素生理群数量，但豆茬施氮量较高反而显著降低氨化细菌和好气性自生固氮菌数量。麦季各施氮处理与豆茬S1处理组合下土壤3大类微生物数量，细菌与真菌比值(B/F)及放线菌与真菌比值(A/F)，氨化细菌、固氮菌和硝化细菌数量基本均高于与S2处理组合，其中N1S1施氮组合下豆茬土壤放线菌数量、好气性自生固氮菌数量、B/F和A/F值达到最高，N2S1施氮组合...

Response of Soil Microbial Flora of Reseeding Soybean to Annual Nitrogen Application Rate Under Rotation of Wheat and Soybean

In order to reveal the effect of annual nitrogen application on the after-effects and superimposed effects of the soil microbial flora of reseeding soybeans, a split-zone test design was adopted in 2017-2019, and under the wheat-bean annual rotation system, the previous crop and the subsequent crop were explored. Soybean annual different nitrogen application combinations (nitrogen application 0, 104, 173, 242 kg·hm-2 in wheat season, marked as N0, N1, N2, N3, respectively; nitrogen application 0, 69, 138 kg·hm-2 for multiple seeding soybean , Respectively marked as S0, S1, S2) The change law of the number of soil bacteria, fungi and actinomycetes, the structure of soil flora and the number of nitrogen physiological groups in soybean stubble. The results showed that nitrogen application in the previous wheat season had a significant after effect on the number of soil microorganisms in the reseeding soybean; under the condition of no nitrogen application in the reseeding soybean, the range of N2~N3 nitrogen application in the wheat season was beneficial to increase the soil bacteria, fungi, and fungi in the soybean stubble. Actinomycetes and the number of nitrogen physiological groups. Under the condition of no nitrogen application in winter wheat, nitrogen application in the soybean stubble in the current season can significantly increase the number of three types of soil microorganisms and nitrogen physiological groups, but the higher nitrogen application in the soybean stubble can significantly reduce ammoniating bacteria and aerobics. The number of self-generating nitrogen-fixing bacteria. The three types of soil microorganisms, B/F and A/F values, ammonifying bacteria, nitrogen-fixing bacteria and nitrifying bacteria under the combination of each nitrogen treatment in the wheat season and the soybean stubble S1 treatment are basically high. Under the nitrogen combination, the soybean stubble soil actinomycetes, aerobic autogenous nitrogen-fixing bacteria, B/F and A/F values reached the highest, and the number of soil bacteria, fungi and ammonifying bacteria basically reached the peak under the N2S1 nitrogen application combination. Too much annual nitrogen application increases the number of soil denitrifying bacteria, significantly reduces the B/F and A/F values, and inhibits the number of three soil groups of microorganisms and other nitrogen physiological groups to varying degrees. Therefore, proper amount of nitrogen application for the first crop of wheat and subsequent crops of soybeans is an important measure to maintain the dominant soil flora. The optimal application of annual nitrogen fertilizer should fully consider the superimposed effects of the preceding and subsequent crops of nitrogen fertilizer. Under the conditions of this study, the combination of 104~173 kg·hm-2 (N1~N2) nitrogen in wheat season and 69 kg·hm-2 (S1) nitrogen fertilizer in soybean season is beneficial to improve soil microbial survival. The environment and improving soil quality are of great significance to improving soil fertility and maintaining the ecological environment of farmland.