摘要:为研究不同草田轮作模式下土壤养分及细菌群落的组成特征，以5年紫花苜蓿-1年小麦（A5W1）、5年紫花苜蓿-1年玉米（A5C1）、5年紫花苜蓿-2年小麦（A5W2）和5年紫花苜蓿-2年玉米（A5C2）草田轮作模式为对象，测定了土壤有机质、全氮、全磷、全钾、碱解氮、速效磷和速效钾含量，在此基础上，基于16S rRNA基因序列扩增子测序研究了4种轮作模式下耕层土壤细菌群落组成特征。结果表明：轮作第2年各土壤养分含量较第1年显著下降。细菌组成研究结果显示，4种轮作模式下占优势的菌门为变形菌门、放线菌门和厚壁菌门。土壤细菌群落优势属以丙酸杆菌属（Propionibacterium）、芽孢杆菌属（Bacillus）、链球菌属（Streptococcus）以及奈瑟氏球菌属（Neisseria）为主。土壤细菌多样性以A5C2轮作处理最高，A5C1最低；聚类分析显示A5W1和A5C1的组成最接近，其次是A5C2，A5W2的组成与前两者相差较大。土壤养分含量与几种优势属之间呈显著相关性（P<0.05 or P<0.01）。研究结果揭示了河西走廊灌溉区种植紫花苜蓿多年后轮作小麦和玉米改善土壤肥力和防治某些土传植物病害微生物的机理。



Abstract:To study the characteristics of the composition of soil nutrients and bacterial communities under different grass-crop rotation modes, this paper measured the content of soil organic matter, total nitrogen(TN), total phosphorus(TP), total potassium(TK), alkali-hydrolyzable nitrogen(AN), rapidly available phosphorus(AP) and rapidly available potassium(AP) with the 5-year alfalfa-1-year wheat(A5W1), 5-year alfalfa-1-year corn(A5C1), 5-year alfalfa-2-year wheat(A5W2) and 5-year alfalfa -2-year corn(A5C2) rotation modes as the subjects of study. On such a basis, this paper further studied the characteristics of the composition of bacterial communities in topsoil under 4 rotation modes in view of 16S rRNA amplicon sequencing. The results indicated that:the content of soil nutrients in the second year of rotation was significantly lower than that in the first year. The study on bacterial composition revealed that the dominant bacterial phyla under the 4 rotation modes were Proteobacteria, Actinobacteria, and Firmicutes. Main advantageous bacterial genera in soil were Propionibacterium, Bacillus, Streptococcus, and Neisseria. In terms of bacterial density in soil, the A5C2 mode was the highest and the A5C1 mode the lowest. According to cluster analysis, the compositions of A5W1 and A5C1 were the closest, followed by A5C2; the composition of A5W2, however, showed a large difference from the former two. The content of soil nutrient was significantly correlated to the advantageous genera(P<0.05 or P<0.01). The results revealed the mechanism behind the improvement of soil fertility and the control of certain soil-borne plant disease microorganisms in the Hexi Corridor Irrigation Area by shifting to wheat and corn after years of planting alfalfa.





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