The Effects Of LMWPE On Soil Microbial Activities And The Screening Of LMWPE Degrading Microorganism

With the development of modern agriculture, the application of plasticfilm has become a fruitful and stable technique for agriculture.With the increasment ofcovering area of plastic film, the film residue in the soil will affect the soil structureand soil fertility.If the residual of plastic film cannot be timely recycled, it will affectcrop production.The present research mainly simulateslow molecular weightpolyethylene(LMWPE) as the residual of plastic film in soil to study the changes of themicrobial activity in soil.During theexperiments,the author plants soybean in the potwhich is full of loam with LMWPE molecular weight and accumulation factors for theall combination experiments(3×3).The molecular weight elements was choosedas2000,5000,100000.The accumulation was choosed as1,50,100years.In threedifferent growth period of soybean(seedling,flowering,seed-filling),we separately testthe Soil microbial biomass carbon,the soil microbial biomass nitrogen,the soilrespiration and the numbers of the three major microorganismin soil(fungi, bacteria,actinomycetes).The other important part of this research is to screen the soil microogenism,whichdegrade LMWPE. And to identify the microorganism.1.LMWPE accumulation and molecular weight acted as the main factor inanalyzing the effects on microorganism activity. Results showed as follows:(1) LMWPE had an inhibitional effect on carbon mineralization ability of soilmicroorgannism.The LMWPE molecular weight≤5000,as the accumulationincreasedSMBC decreased. Molecular weight>100000,as the accumulation SMBC increased. (2) LMWPE had an inbibitional effect on nitrogen mineralization ability of soilmicroorgannism. The LMWPE molecular weight≤5000,as the accumulation increasedSMBN decreased. The LMWPE molecular weight was100000,as the accumulationincreased SMBN increased.(3)LMWPE molecular weight≤5000and accumulation≥100000,it had aninhibitional effect on soil respiration.(4) The results that LMWPE affected on bacterium,fungus and actinomycetesshowed as follows:①The bacteria number increased as the LMWPE accumulation increased.TheLMWPE molecular weight≤2000had accelerated the bateria growth,LMWPEmolecular weight≥5000had an inhibitional effect on bateria growth.②The fungi number increased as the LMWPE accumulation increased.TheLMWPE molecular weight≤2000had accelerated the fungi growth,LMWPEmolecular weight≥5000had an inhibitional effect on fungi growth.③LMWPE had an inhibitory action on actinomycetesgrowth,as it added in soil.2.Finally,a degrading microorganism wasscreened out from the garbagesoil,which belongs toMycota,Eumycota,Phycomycetes,Mucorales,Thamnidiaceae,Thamnidium Link exWallr.From the above,LMWPE had a inhibitory action on SMBCand SMBN,LMWPEmolecular weight≤5000and accumulation≥100000, it had an inhibitional effect onsoil respiration.The LMWPE molecular weight≤2000had accelerated the bateria andfungi growth.The LMWPE molecular weight≥5000had an inhibitional effect onbateria and fungi growth.LMWPE had an inhibitory action on actinomycetes growth,asit added in soil.