The Effect Of Drought-modified Water On Soil Microbes And Its Response To Water

In order to reveal the effects of changing dry soil(DS)to paddy field(PF)on soil microorganisms,black soil changing from DS to PF different years was chosen and sampled by five sampling methods.The near dry field was for comparison.The research focused on the changing of diffirent soil microorganisms number and microbial response to moisture after changing DS to PF.The results showed that:(1)pH decreased significantly(P<0.05)after changing DS to PF,with the increasing of acidification.Soil EC(electrical conductivity)increasing at first then decreased significantly.Among them,soil EC was highest after changing from DS to PF for five years which reveal that the effect of changing DS to PF was significantly and ions density increased,especially in the first five years.After that the EC and ions density decreased gradually.(2)The numbers of bacteria increased significantly(P<0.05)and then decreased gradually in the depth of 0-5 cm and5-10 cm.However the number of fungi were opposite The numbers of bacteria decreased significantly(P<0.05)then increased after DS to PF for five years,the fungi were opposite.The number of actinomycetes was least after DS to PF for ten years.This showed that changing DS to PF benefited the accumulation of bacteria and not good for fungi in first five years.But the phenomenon were opposite after longterm changing DS to PF.(3)The number of nitrifying bacteria,nitrosation bacteria,aerobic nitrogen fixed bacteria,ammonifying bacteria increased,but the number of denitrifying bacteria decreased after turning DS to PF.With the increasing of that years,the number of nitrifying bacteria and nitrosation bacteria increased at first then decreased.The number of aerobic nitrogen-fixed bacteria decreased at first then increased.The number of denitrifying bacteria decreased gradually.Among them,the number of nitrifying bacteria and nitrosation bacteria,which were changing DS to PF for ten years,were the more abundant.However,the number of aerobic nitrogen-fixed bacteria were the least,and the number of ammonifying bacteria was the most which were changing DS to PF for five years.(4)With the increasing of changing DS to PF years,the numbers of organic phosphobacteria decreased,inorganic phosphobacteria cellulose utilization microorganisms decreased at first years then increased.Overall,organic phosphobacteria were the least which were changing DS to PF for ten years,inorganic phosphobacteria were the most which were paddy for five years.(5)Under appropriate culture temperature,fungi optimum soil moisture was 10%,bacteria,actinomycetes optimum soil moisture were 20%;among them,nitrifying bacteria,nitrosation bacteria,aerobic nitrogen-fixed bacteria,denitrifying bacteria,ammonifying bacteria,cellulose utilization microorganisms,organic phosphobacteria,inorganic phosphobacteria optimum soil moisture were 20%.(6)Soil pH,electrical conductivity(EC),organic phosphobacteria,inorganic phosphobacteria and cellulose utilization microorganisms have closely relationship,they affectsoil phosphorus transformation and circulationtogether,thereby affecting plants absorption and utilization on phosphorus.Nitrogen conversion microorganisms have closely related,interaction,they plays a vital role in soil and effect on nitrogen cycling transformation nitrogen balance,plant growth.