连作对大豆根际可培养微生物及土壤理化性状的影响

Effects of soybean continuous cropping on rhisphere culturable microorganisms and physicochemical properties of soil

【目的】探讨大豆重迎茬对根际可培养微生物及土壤理化性状的影响.【方法】以正茬和重迎茬大豆根际土壤为研究对象,在不同生育时期取根际土进行土壤微生物区系、微生物生理类群和土壤理化性状等指标的测定.【结果和结论】大豆重迎茬对土壤可培养微生物及微生物生理类群有较大影响.重迎茬使大豆全生育期细菌、放线菌、氨化细菌、硝化细菌、好气性自生固氮菌和纤维素分解菌总量减少,真菌数量显著增加.各处理土壤平均碱解氮和速效钾含量顺序为:正茬>迎茬>重茬1年>重茬2年>重茬3年;而土壤速效磷含量为正茬>迎茬>重茬1年>重茬3年>重茬2年.轮作正茬大豆土壤团聚体的平均质量直径(MMD)和几何平均直径(GMD)均高于迎茬和重茬各处理,其中以GMD差异更显著.

[Objective]Effects of soybean continuous cropping on soil microorganisms and physicochemical properties were studied .[Method]With the rhisphere soils of cropping and rotation soybean as test materi-als, the following indexes including soil microorganisms , bacterial physiological groups , physicochemical properties were investigated during the different growth stages of soybean .[Result and conclusion]The re-sults showed that there were significant influences of continuous and alternate cropping on soil microor -ganisms .The number of bacteria , actinomycetes decreased , especially the reduction of ammonifying bac-teria, nitrifying bacteria , aerobic nitrogen-fixing bacteria , cellulose-decomposing bacteria , but fungi a-mount increased .The content order of soil available nitrogen and potassium was rotation cropping 〉alter-nate cropping〉1-year continuous cropping 〉2-year continuous cropping 〉3-year continuous cropping . The content order of soil available phosphorus was rotation cropping 〉alternate cropping 〉1-year continu-ous cropping 〉3-year continuous cropping 〉2-year continuous cropping .The mean mass diameter and geometric mean diameter of rotation soil were significantly higher than alternate and continuous cropping .