| In recent years,the development of intensive agriculture due to soil organic matter content decreased,soil fertility and biodiversity decreased,and ecosystem services weakened.Soil microorganism is an important part of farmland ecosystem,and also an important participant and decomposer of soil nutrient cycle,which plays an important role in regulating soil ecosystem service function.As an important agricultural production and planting management mode,crop rotation has a profound impact on the change of soil physical and chemical properties and the development of sustainable agriculture,but the mechanism of its impact on soil microbial diversity is still unclear.In view of the phenomenon of multiple cropping in one season in hot areas,the long-term rotation of pepper,maize and hard-skinned bean was taken as the breakthrough point to explore the effects of crop rotation on soil nutrients and soil microbial community structure,and to clarify the relationship between soil micro-food network and phosphorus cycle under crop rotation.The results are as follows:(1)Soil nutrient content under different rotation treatments of soil pH,nitrate carbon and nitrogen,available potassium,available P content showed an indigenous increasing trend.Compared with maize monoculture,all rotation treatments significantly increased soil labile P content.However,there was no significant effect on the contents of Ca-P and moderately labile P in soil.In addition,the residual P content in PML treatment was significantly lower than the other three treatments.Soil labile P content is mainly affected by soil total nitrogen and total P.The change of soil physical and chemical properties caused by crop rotation further drives the transformation of phosphorus fraction in soil.(2)Rotation had no significant effect on microbial community richness indices of phoD and AMF.In addition,the Shannon index of phoD in PM and PMG treatments was significantly higher than that in maize monoculture,but there was no significant difference between different rotation treatments.The Shannon index of AMF community in PM rotation was significantly higher than that in maize monoculture,and the difference between different rotation treatments was also different,which showed PM > PMG.(3)Compared with maize monoculture,rotation crops had no significant indigenous effect on soil protozoa diversity index and richness index.Soil protozoa communities were significantly different in different rotations.The relative abundance of dominant species of protozoa in maize monoculture and rotation was the same,which was shown as Filosa-Sarcomonadea > Variosea >Filosa-Imbricatea > Tubulinea.In PML rotation treatment,the relative abundance of dominant species was different from other rotation treatments.Filosa-Imbricatea accounted for 31.89 % of the total protozoa community abundance,which was significantly higher than the other three dominant species.(4)Soil microbial AMF,protozoa and phoD microbial community diversity index were significantly positively correlated with soil microbial biomass phosphorus content and available phosphorus content,and negatively correlated with soil total phosphorus content.The biodiversity index of soil micro-food network was mainly positively correlated with the microbial biomass phosphorus content in soil,and negatively correlated with the soil closed phosphorus content.The results showed that :(1)Crop rotation was beneficial to improve soil acidification caused by single planting,increase the content of soil organic matter and available phosphorus,and improve soil nutrients;(2)Soil microbial phoD community caused by crop rotation is closely related to soil phosphorus cycling. |
