Effects Of Intercropping Different Kinds Of Aromatic Plants On Soil Microbial Biomass And Nutrient Cycling In Apple Orchard

In recent years,orchard intercropping,as a traditional organic management measure,has been more and more used in organic cultivation of fruit trees.However,there are few studies on the dynamic changes of soil microbial community after long-term planting of aromatic plants among fruit trees.Studying the interaction among soil microbiome,mulch crops and nutrient cycle will contribute to more effective and sustainable management of perennial crop systems.In order to study the effects of intercropping different aromatic plants on soil microbial biomass and nutrient cycling in apple orchard,this study set clear tillage,natural grass,intercropping Mentha canadensis Linnaeus Medicago sativa L.,vulpia myuros and geratum conyzoides L.were treated.From April to October 2018 to 2020,the soil nutrient content and enzyme activity of topsoil(0 ? 20 cm)and deep soil(20 ? 40 cm)were measured,and the soil microbial diversity in May and August was sequenced by phospholipid fatty acid biomarker(PLFA biomarker).The results are as follows:(1)Intercropping different aromatic plants improved the physical and chemical properties of orchard soil to a certain extent.It is speculated that the change trend of soil physical and chemical indexes is related to the biomass and root exudates of aboveground and underground parts of plants.The soil water content in the late stage of intercropping was higher than that in the early stage of intercropping.Intercropping mint and alfalfa reduced the soil p H,and intercropping Mint had a good effect on the improvement of soil.(2)Compared with clear tillage,intercropping different aromatic plants can improve the activity of related enzymes in soil,intercropping alfalfa can improve the activity of soil invertase,and intercropping peppermint can improve the activity of soil nitrogenase.(3)Compared with clearing tillage,intercropping different aromatic plants can affect the community structure of bacteria and fungi in soil.Planting aromatic plants decreased the content of soil fungi,and intercropping peppermint significantly increased the content of soil arbuscular mycorrhizal fungi.(4)Correlation analysis showed that soil multifunctional index was negatively correlated with p H,and positively correlated with Gram-positive bacteria and Gram-negative bacteria.In May,soil invertase activity was significantly positively correlated with water content,organic carbon,total nitrogen,available phosphorus,nitrogenase activity and arbuscular mycorrhizal fungi content,and negatively correlated with alkali hydrolyzable nitrogen and total potassium;There was a significant negative correlation between soil p H and nitrite reductase.In August,invertase activity was significantly negatively correlated with Cu content and positively correlated with alkali hydrolyzable nitrogen and total phosphorus content.In conclusion,intercropping peppermint and alfalfa significantly reduced soil p H,increased soil invertase activity and nitrogenase activity,reduced soil fungal biomass,increased soil arbuscular mycorrhizal fungal biomass,and promoted the correlation between soil C,N cycle and physical and chemical properties,microbial and enzyme activities.