Study On The Mechanism Of Reed-based Exogenous Carbon On Soil Micro-environment

Increased industrialization and human interference have led to a significant decline in soil quality and sustainable use.Soil fertility is a key factor restricting soil health and the evolution of plant communities,plus carbon sources that change the soil microenvironment by increasing soil fertility and influencing microbial community composition.Aiming at the physicochemical properties,microbial communities and organic carbon mineralization mechanisms of exogenous carbon regulation,the nutrient characteristics and microbial community succession characteristics of reeds were studied by exogenous carbon preparation methods such as aerobic composting and biochar firing,and the response process of soil microenvironment physicochemical properties,enzyme activity and microbial community composition under the regulation of reed-based exogenous carbon（straw,compost and biochar）was investigated,and the influence mechanism of exogenous carbon input on the mineralization process of soil organic carbon was elucidated.1.The effects of conditioners on the composting process and decay of reeds were explored.The results show that the addition of sediment and biochar has a significant role in promoting compost decomposition.After a 50-day composting cycle,under the synergistic effect of sediment and biochar,the GI value of the compost product reached 107.2%,and the HA/FA reached 2.5±0.05,which was better than the quality of the treatment group with the addition of sediment or biochar alone.The Alpha diversity index was the highest in the control group at the initial and intermediate stages of composting,the Alpha diversity index was the highest in the experimental group T₃,which had a single addition of sediment at the time of composting decomposition,and the Sobs index of the end-stage microbial community abundance of compost in the two treatment groups with sediment as a conditioning agent was4.85±0.04,and the microbial diversity was the most abundant.The composition of the communities between the groups is basically the same.Weissella（Weissella spp.）,Saccharomonospora（Glucosinospora spp.）,and Thermoactinomyces（Actinomyces spp.）were dominant strains in the early,middle and final stages of the experiment,which played an important role in the degradation process of reeds.2.2.The physicochemical properties,enzyme activities and bacterial community effects of soil regulated by exogenous carbon of different reed bases were significantly different.After the input of exogenous carbon,the degree of cation exchange in the reed composting treatment group was the most obvious,increasing by between 0.53 and 1.66 cmol/kg.When the amount of addition was 10%,the carbon conversion efficiency of the compost product was the fastest in 60 days,and the soil organic carbon content decreased from 21.5 g/kg to 14g/kg;the experimental group of 10%added compost products also degraded the total nitrogen content in soil and exogenous carbon the fastest,degrading by 17.3%.According to Pearson correlation（p<0.01）coefficient analysis,glucosidase showed a significant positive correlation with the bulk weight（0.97）and carbon source content（0.88）in the soil,and total nitrogen（0.76）and total phosphorus（0.73）as nutrients indispensable for microbial growth and reproduction processes also showed strong correlation.The input of exogenous carbon changes the composition of microbial communities in the soil and improves microbial abundance.Soil microbial community indexes were positively correlated with exogenous carbon addition,and functional microorganisms related to soil organic carbon mineralization mainly included actinomycete phylum,proteobacter phylum,pachyderma phylum,and bacteroides phylum.The addition of homogeneous exogenous carbon,changing the amount of exogenous carbon added is not obvious for the composition of soil microorganisms.When the amount of compost exogenous carbon treatment group was 10%,the growth of soil carbon pool was most obvious.3.The input of exogenous carbon from the compost inhibits soil organic carbon mineralization and increases the potential for soil carbon sequestration.Compost products T₂and T₄have a certain degree of inhibition effect on soil organic carbon mineralization,and the inhibition effect of compost product T4 in the four exogenous carbons is best corresponding to the inhibition rate of the three kinds of additions reaching 13.3%,7.3%and 28.4%,respectively.When the amount of T2 and T4 added to the compost product reaches 15%,the organic carbon content will be lower than the 10%treatment group content after 60 days.According to the kinetic analysis results of the first-level linear equation of soil mineralization,the total mineralization amount of 10%compost exogenous carbon T4 was the highest,and the CO₂content released by removing the foreign source carbon in the experiment was reduced,which inhibited the mineralization of the soil itself.It shows that the metabolic activity of microorganisms in the soil decreases,and the utilization rate of carbon sources is weakened.