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研究了新疆连作、轮作棉田土壤可培养微生物区系及活性变化。结果表明,棉花多年连作造成土壤中可培养微生物数量减少,连作6～8年、9～12年、大于13年的棉田与连作小于5年的棉田相比,土壤微生物总量分别下降了40.2%,46.7%,52.4%。连作超过5年后,土壤微生物菌群结构逐渐从高肥的“细菌型”向低肥的“真菌型”转化,细菌/真菌(B/F)和放线菌/真菌(A/F)比值均降低,拮抗菌减少,病原菌积累。氮素生理群氨化细菌、硝化细菌、好气性自生固氮菌数量下降,反硝化细菌数量增加。连作还导致土壤呼吸强度、纤维素分解强度下降,微生物活性降低。连作棉田与草木樨、番茄、春麦、玉米倒茬轮作能使土壤微生物数量明显增长,有益于调节菌群平衡,提高微生物活性,固氮菌数量呈现显著增长。不同轮作作物的效应不同,以草木樨、番茄的效应更为突出。
The cultivable microbial flora and its activity in continuous cropping and rotation cotton fields in Xinjiang were studied. The results showed that the amount of soil microorganisms decreased after continuous cropping for several years. The total amount of soil microorganisms decreased by 40.2% in cotton fields of continuous 6 to 8 years, 9 to 12 years and more than 13 years compared with those of continuous cropping less than 5 years. , 46.7%, 52.4%. After more than 5 years of continuous cropping, the structure of soil microbial community was gradually transformed from high-fat “bacteria” to “low-fat” “fungi”. Bacteria / fungi (B / F) and actinomyces / F) ratio decreased, antagonistic bacteria decreased, the accumulation of pathogens. Nitrogen physiological group ammoniated bacteria, nitrifying bacteria, aerobic autotrophic nitrogen decreased, the number of denitrifying bacteria increased. Continuous cropping also resulted in soil respiration, decreased cellulose decomposition strength and decreased microbial activity. Continuous cropping of cotton fields and plants such as grass mulberry, tomato, spring wheat and corn rotation crop rotation could significantly increase the number of soil microorganisms, which is beneficial to regulate the flora balance and increase the microbial activity. The number of nitrogen-fixing bacteria showed a significant increase. The effects of different crop rotation are different, with the effect of vegetation, tomato, tomato is more prominent.