Effects Of Pig Manure And Straw Continuous Returning On Soil Microbial Community Structure And Activity

At present,livestock and poultry breeding,crop straw and other seed and breeding wastes are rich in resources but low in utilization efficiency,which is closely related to multiple sources,low nutrient release ratio and unbalanced supply in the process of organic decomposition,and soil microorganisms play a key role in the process of organic matter decomposition and nutrient cycling and other soil processes.Therefore,it is of great significance to explore the influence of returning the waste of breeding and breeding industry to soil microbial activity and diversity,and to the soil nutrient circulation and the healthy development of soil ecosystem under the condition of returning livestock and poultry manure and straw.The paddy and wheat rotation area of chengdu plain was selected and the field positioning experiment was adopted to carry out the continuous field return experiment of straw,continuous field return experiment of pig manure and continuous field return experiment of straw and pig manure.Studied under the condition of straw returning with the pig,the growth period of rice and wheat crops each 0-20,20-40 cm soil culturable bacteria,fungi,actinomycetes number,microbial biomass carbon and nitrogen,soil respiration,and bacteria community diversity and structure changes,so from the perspective of microbial activity and biodiversity,to explore the regional farming waste reasonable use,farmland for ensuring healthy development of the chengdu plain are planting and sustainable resources and environment have important significance.The main research results are as follows:(1)Continuous straw mulching treatment promoted the increase of bacteria,fungi and actinomyces in rice and wheat at all growth stages and in all soil layers.The effect of fertilizer plus half of straw mulching treatment was better than that of fertilizer plus total of straw mulching.Microbial biomass,nitrogen content and soil respiration of rice and wheat were consistent with microbial biomass,and conventional fertilizer plus half amount of straw returned to the field had the best effect.(2)Continuous treatment of pig manure promoted the increase of microorganism quantity of rice and wheat,and the number of microorganism increased first and then decreased with the growth period,and the heading period was the peak period.Among the treatments,the combined application of 50% fertilizer was better than 25%,and 100% manure was better.Soil microbial biomass carbon and nitrogen and soil respiration intensity were basically consistent with the change rule of microbial population.(3)The results showed that different treatments could promote the growth of soil microbial population and reach the peak at heading stage.Among them,50% of pig manure nitrogen plus 50% of fertilizer nitrogen plus straw could increase the number of bacteria,fungi and actinomyces more than other treatments.The change trend of microbial biomass carbon and nitrogen content in rice season was consistent with that in wheat season.It was best to use 50% of pig manure nitrogen plus 50% of fertilizer nitrogen plus straw in the field,followed by 100 manure plus straw in the field.In rice and wheat 0-20 cm,from heading stage to maturity stage,soil respiration was inhibited by fertilizer treatment.The results of different pig manure dosage test under the condition of full straw returning showed that different treatments could promote the growth of soil microorganism.Among them,50% pig manure nitrogen plus 50% fertilizer nitrogen plus total straw returning treatment could increase the number of bacteria,fungi and actinomycetes more effectively than other treatments,and reached the peak value at heading stage.The microbial carbon and nitrogen content in 0-20 cm soil layer at heading stage of wheat season increased by 7.43% and 15.76% respectively,and soil respiration content increased by 21.84% compared with 100% pig manure nitrogen plus straw total treatment.The variation regularity of rice season was basically consistent with that of wheat season.(4)The results showed that there was no significant difference in the richness index and Shannon diversity index between different treatments of rice and wheat.Illumina Miseq platform sequencing results showed that the dominant bacteria were Proteobacteria,Acidobacteria,Chlorofiexi and Actinobacteria.In wheat season,the abundance of Proteobacteria was the highest under fertilizer treatment,followed by 50% pig manure nitrogen plus 50% fertilizer nitrogen treatment.Compared with chemical fertilizer treatment,the relative abundance of Acidobacteria,Chlorofiexi,Actinobacteria,Nitrospirae,Planctomycetes and Firmicutes were increased in 50% pig manure nitrogen plus 50% fertilizer nitrogen,chemical fertilizer nitrogen plus straw returning and 50% pig manure nitrogen plus 50% chemical fertilizer nitrogen plus straw returning treatments.In rice season,compared with control and chemical fertilizer treatment,50% pig manure nitrogen plus 50% chemical fertilizer nitrogen,conventional fertilizer plus total straw returning and 50% pig manure nitrogen plus 50% chemical fertilizer nitrogen plus total straw returning increased the relative abundance of Acidobacteria and Gemmatimonadetes,but decreased the abundance of Nitrospirae.Compared with chemical fertilizer treatment,50% pig manure nitrogen plus 50% chemical fertilizer nitrogen treatment increased the relative abundance of Actinobacteria and Planctomycetes.50% pig manure nitrogen plus 50% chemical fertilizer nitrogen plus straw returning treatment also increased the relative abundance of Planctomycetes and Bacteroidetes.Conventional fertilizer plus total straw returning treatment only increased the relative abundance of Firmicutes.Comprehensive the above results,from the aspects of microorganism quantity,activity,bacterial community diversity into account,the fertilizer plus half of straw mulching treatment,50% pig manure nitrogen plus 50% chemical fertilizer nitrogen and 50% pig manure nitrogen plus 50% chemical fertilizer nitrogen plus straw returning treatment on soil microflora influence is bigger,more conducive to the construction of a healthy and stable soil microflora,and promoting the sustainable development of resources and environment.