| As a large agricultural country,huge agricultural wastes are produced in China every year.Hence,the treatment of agricultural wastes is an urgent environmental problem which is needed to be solved immediately.Especially for the area with a low average temperature,straws are very hard to degrade,which will affect the production of crops in the next year.Therefore,in order to improve the degradation of straw,the screened low-temperature strains were used to optimize the preparation processes,finally a composite microbial inoculum was synthesized.The effects of microbial inoculum on the degradation of maize straw and and soil properties were explored by the composting experiment and simulated straw incorporation experiment.It provides a theoretical basis for straw utilization mode and straw utilization rate,and reduces the environmental pollution caused by large-scale burning of straw.Results showed that:(1)The enzyme production conditions was based on the single factor variable method,the highest enzyme activity was observed after 3 days incubation under the following condition: peptone and beef extract(2:1)was the nitrogen source,glucose was the carbon source,p H 7.0,15 ℃.Compared with before optimization,carboxymethyl cellulase(CMCA)and filter paper enzyme(FPA)increased 7.8997U/m L and 3.3363U/m L,respectively.The best microbial inoculum carrier was the ratio of corn straw powder to diatomite is 1:4,the largest effective bacterial was obtained with 45%(m/m)bacterial liquid addition and the effective bacteria was 3.03×109 cfu/g after four days incubation.(2)The corn-straw composting experiment showed that the temperature of the compost body reached above 50℃on the second day of psychrophile inoculum treatment(L)and psychrophile + mesophilic inoculum treatment(LM),and above 50℃on the sixth day of mesophilic inoculum treatment(M),while the control treatment(CK)did not reach 50℃during the whole composting process;in comparison with CK,the microbial inoculum addition could improve the compost body seed germination index(GI),total nitrogen(TN),cellulose degradation rate,hemicellulose degradation rate,humic acid(HA)and HA/FA,and decreased the compost body moisture content,electric conductivity(EC),total organic carbon(TOC),C/N and fulvic acid(FA),the effect of different treatments was in this order LM>L>M>CK.The application of microbial inoculum promoted the composting process of straw and the decay rate of straw,which provided a strong basis for the application of microbial inoculum.(3)Simulated straw incorporation experiment(15℃),showed that compared with CK,straw in combined with microbial inoculum was beneficial to the degradation of maize straw,improving soil available nutrients,organic carbon(SOC),enzyme activity,and humus quality.At 60 days,compared with CK,the weight loss rates of straw treated with psychrophile treatment(L),mesophilic bacteria treatment(M)and psychrophile + mesophilic bacteria treatment(LM)were 19.80%,14.43% and 16.65%,respectively;the alkali hydrolyzed nitrogen,available phosphorus(AP)and available potassium(AK)of LM were 130.35mg/kg,19.57mg/kg and 145.82mg/kg,respectively,compared with other treatments,which increased 13.67mg/kg-33.08 mg/kg,0.70 mg/kg-2.53 mg/kg and 44.12 mg/kg-10.8 mg/kg,respectively.The SOC and humus of LM soil were 17.97g/kg and 6.71g/kg,respectively,which were 0.84 g/kg-1.14g/kg and 0.03g/kg-0.81g/kg higher than those of other treatments.Compared with CK,soil cellulase,urease,acid phosphatase,invertase and catalase could be increased by microbial inoculum treatment.Under low temperature conditions,straw in combine with microbial inoculum could promote straw degradation,improve soil physical and chemical properties,especially LM treatment,which provides theoretical basis for straw incorporation in cold areas. |
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