| Returning straw to the field is an effective way of resourceful utilization of straw,but the slow decomposition of straw after returning to the field in the natural state can lead to increased soil pests and diseases,and even affect crop growth.Inoculated with microbial agents is an efficient measure to accelerate straw decomposition.However,the current microbial agents fail to achieve sustained efficiency in promoting decay.In this study,rumen fluids with efficient cellulose degradation capacity were used as decomposing agents,and red loamy rice soils were used as research objects in a nylon bag straw return pot experiment.The effects of different conditions on the rotting of straw by rumen microorganisms were investigated by setting up a straw decomposition cycle of 10-90 days,30%,70% and 100% soil moisture content,and 5,10,20 and 30 cm depths of return to the field.The changes in soil nutrients,enzyme activities and microbial community succession were analyzed after the rumen fluids were used to promote the decay of straw.The main results are as follows:(1)Returning straw to the field with rumen fluids can continue to accelerate straw decomposition within 90 days of return.When the decomposition proceeded to 30 days,the straw degradation rate of the samples from straw with 40 m L rumen fluids reached a maximum of 39.52%,which was 41.37% higher than that of the control group.The change in decomposition rate showed a trend of fast before and then slow,at 90 days,the straw degradation rate was 59.10% and 51.33% in the treatment and control groups,respectively,which increased by 15.14% in the treatment group.Furthermore,it was found that the activities of cellulase,sucrase and urease were increased by 5.70%,18.55% and 13.80%,respectively,and the soil nutrient content was improved compared with the control.The addition of rumen microorganisms allowed more cellulose-degrading microorganisms to participate in the process of straw decay,and the phylum Actinobacteria became the dominant phylum in the soil bacterial community structure.(2)Soil moisture content significantly affected the activity of rumen microorganisms after returning to the field.When the soil moisture content was 70%,the rumen fluids had the best performance in promoting the decay of straw,and the straw degradation rate reached 49.96% in 30 days.Moreover,it accelerates the destruction of a large number of organic functional groups in the lignocellulose of straw,making the relative crystallinity of cellulose as low as 31.96%,which is easier to decompose.And the highest sucrase activity in the soil,which accelerated the accumulation of soil organic matter and effective phosphorus content.When the soil moisture content was 100%,the application of rumen fluids increased the activities of urease,cellulase and catalase,and promoted the accumulation of available potassium and available nitrogen content.In addition,the change in soil moisture content will lead to the variation of microbial community structure for degrading straw,and the application of rumen fluids can enhance the microbial community structure for degrading straw under different soil moisture content conditions.(3)The proper depth at 20 cm of straw returning to the field was favorable for rumen microorganisms to accelerate straw decomposition.When the straw was returned to a depth of 10 cm,it was the most suitable for soil microorganisms to degrade the straw,and the straw degradation rate was 37.85%.When the depth was 20 cm,the rumen microorganisms obtained a more favorable growth and reproduction environment in the soil,and the straw degradation rate reached 46.43%,which was 44.78% higher compared with the control.In addition,the increased microbial activity also produced more extracellular enzymes,and the soil urease,cellulase and sucrase activities increased by 24.43%,79.18% and 50.90%,respectively.The rumen fluids contained bacteria and fungi with high cellulolytic capacity,which entered the soil as dominant strains and increased the relative abundance and diversity of soil microorganisms with lignocellulose-degrading functions. |
