生物炭和秸秆还田对咸水滴灌棉田土壤微生物群落特征及功能差异的影响

干旱区淡水资源不足,农业用水主要依赖于含盐的浅层地下水,但长期咸水灌溉会造成土壤盐分积累,土壤环境恶化,不利于作物生长.因此,在长期淡水（0.35 dS·m^-1,FW）和咸水（8.04 dS·m^-1,SW）灌溉的基础上,采用等碳量设计向土壤中添加生物炭（3.7 t·hm^-2,BC）和秸秆（6 t·hm^-2,ST）,旨在明晰生物炭和秸秆还田对盐渍化土壤理化性质及微生物群落结构的影响.结果表明,咸水灌溉显著增加土壤含水量、电导率、速效磷和全碳的含量,但显著降低了pH值和速效钾的含量.生物炭和秸秆还田均显著增加土壤含水量、速效磷、速效钾和全碳的含量,但显著降低了咸水灌溉条件下的电导率值.各处理土壤优势菌门为变形菌门、放线菌门 、酸杆菌门、绿弯菌门和芽单胞菌门.咸水灌溉显著增加芽单胞菌门和变形菌门的相对丰度,但显著降低酸杆菌门和放线菌门的相对丰度.在淡水灌溉条件下,生物炭还田显著降低绿弯菌门的相对丰度；秸秆还田显著增加变形菌门的相对丰度,但显著降低酸杆菌门、放线菌门 、绿弯菌门和芽单胞菌门的相对丰度.在咸水灌溉条件下,生物炭还田显著降低绿弯菌门和芽单胞菌门的相对丰度；秸秆还田显著增加变形菌门的相对丰度,但显著降低酸杆菌门、放线菌门 、绿弯菌门和芽单胞菌门的相对丰度.LEfSe分析表明,咸水灌溉降低了土壤微生物的潜在标志物和功能数量；咸水灌溉条件下,生物炭还田增加了土壤微生物的潜在标志物和功能数量；秸秆还田增加土壤微生物的潜在功能数量；秸秆还田增加土壤微生物的潜在标志物和功能数量.RDA结果显示,土壤微生物群落和功能结构与EC_1:5 、SWC和pH值显著相关.咸水灌溉会恶化土壤环境,不利于农业生产,其中EC_1:5 、SWC和pH值是驱动土壤微生物群落和功能结构变化的重要因子,采用生物炭和秸秆还田可减缓盐分对土壤和作物的危害,为提高农业生产力奠定基础.

Effects of Biochar and Straw Return on Soil Microbial Community Characteristics and Functional Differences in Saline Water Drip Irrigation Cotton Fields

In arid areas, fresh water resources are insufficient, and agricultural water mainly depends on shallow saline groundwater. However, long-term saline irrigation will cause soil salt accumulation and soil environment deterioration, which is not conducive to crop growth. In this study, based on the long-term irrigation of fresh water (0.35 dS·m^-1, FW) and saline water (8.04 dS·m^-1, SW), biochar (3.7 t·hm^-2, BC) and straw (6 t·hm^-2, ST) were added to the soil by an equal-carbon design. The aim was to clarify the effects of biochar and straw returning on the physical and chemical properties and microbial community structure of salinized soil. The results showed that saline irrigation significantly increased soil water content, electrical conductivity, available phosphorus, and total carbon content but significantly decreased pH value and available potassium content. The contents of available phosphorus, available potassium, and total carbon in soil were significantly increased by biochar and straw returning, but the conductivity value of soil irrigated with saline water was significantly decreased. The dominant bacteria in each treatment were Proteobacteria, Actinomycetes, Acidobacteria, Chloromycetes, and Blastomonas. Saline water irrigation significantly increased the relative abundance of Blastomonas and Proteobacteria but significantly decreased the relative abundance of Acidobacteria and Actinobacteria. Under the condition of fresh water irrigation, the relative abundance of Chlorocurvula was significantly reduced by the return of biochar. Straw returning significantly increased the relative abundance of Proteobacteria but significantly decreased the relative abundance of Acidobacteria, Actinomyces, Chloromyces, and Blastomonas. Under saline irrigation, the relative abundance of Chlorocurvula and Blastomonas were significantly reduced by biochar return to field. Straw returning significantly increased the relative abundance of Proteobacteria but significantly decreased the relative abundance of Acidobacteria, Actinomyces, Chloromyces, and Blastomonas. LEfSe analysis showed that saline irrigation decreased the potential markers and functional numbers of soil microorganisms.Under saline irrigation, biochar returning increased the number of potential markers and functions of soil microorganisms. Straw returning to field increases the number of potential markers of soil microorganisms. RDA results showed that soil microbial community and functional structure were significantly correlated with EC_1:5, SWC, and pH. Saline water irrigation will deteriorate the soil environment, which is not conducive to agricultural production, among which EC_1:5, SWC, and pH are important factors driving changes in soil microbial community and functional structure. Using biochar and straw to return to the field can reduce the harm of salt to soil and crops, laying a foundation for improving agricultural productivity.