菌剂对高寒地区土壤微生物群落结构及固氮菌群的影响

Effects of Microbial Agents on Soil Microbial Community Structure and Nitrogen-Fixing Bacteria in Alpine Farming Area

为了探究微生物菌剂替代无机化肥对土壤微生物群落结构与固氮菌群的影响。本试验以甘南高寒地区青稞(Hordeum vulgare var.celeste Linnaeus)种植地土壤为研究对象。试验设置不同施肥处理,即不施肥(CK)、单施化肥(T1)、菌剂+75%化肥(T2)、菌剂+50%化肥(T3)、菌剂+25%化肥(T4)和全施菌剂(T5)。通过测定土壤微生物磷脂脂肪酸(Phospholipid fatty acid,PLFA)、自生固氮菌数量等指标。结果表明:随菌剂替代化肥的比例增加,土壤中微生物总PLFA增加,土壤微生物压力指数逐渐减小。土壤脲酶、微生物量氮、硝态氮和铵态氮呈先增加后减少的趋势,在T4处理下达到最大值,分别为0.42 mg·(g·d)^(-1),9.32 mg·kg^(-1),9.66 mg·kg^(-1)和6.84 mg·kg^(-1)。本研究说明菌剂可以部分替代无机化肥,当替代量为75%时,不但不会造成土壤中氮素含量下降,还能改变土壤微生物群落结构。这一发现为青藏高原耕作区无机化肥的减施提供了科学依据。

The aim of this study was to explore the effect of microbial agents replacing inorganic fertilizers on soil microorganisms community structure and soil nitrogen-fixing bacteriaThe soil of Hordeum vulgare var.celeste Linnaeus planting area in the alpine region of Gannan was taken as the research object.Different fertilization treatments were set in the experiment,namely,no fertilization(CK),a single application of chemical fertilizer(T1),fungicide+75%chemical fertilizer(T2),fungicide+50%chemical fertilizer(T3),fungicide+25%chemical fertilizer(T4)and total application of fungicide(T5).The soil microbial phospholipid fatty acid(PLFA)and the number of azotobacter were determined.The results showed that the total microbial PLFA increased and the soil microbial pressure index decreased with the increase of the proportion of microbial agents replacing chemical fertilizers.Soil urease,microbial biomass nitrogen,nitrate nitrogen,and ammonium nitrogen increased first and then decreased,reaching the maximum values under T4 treatment,which were 0.42 mg·(g·d)^(-1),9.32 mg·kg^(-1),9.66 mg·kg^(-1) and 6.84 mg·kg^(-1),respectively.This study showed that microbial agents could partially replace inorganic fertilizers.When the substitution amount was 75%,it would not reduce the nitrogen content in the soil,but change the soil microbial community structure.This finding provides a scientific basis for the reduction of inorganic fertilizers in farming areas of the Qinghai-Tibet Plateau.