Ecological Stoichometric Characteristics And Microbial Nutrient Limitation In Intensive Tea Plantation

Intensive planting tea is an important part of intensive agriculture.Intensive planting tea can use limited time and land to produce products to meet human needs.While tea planting meets the demand for agricultural products,the rapid development of intensive planting tea has also brought serious environmental problems,such as large amounts of nitrogen fertilizers and pesticides,the continuous decline in the utilization rate of fertilizers,and the pathogens have developed drug resistance.These problems would lead to soil acidification,imbalance between nitrogen and phosphorus elements,decline in ecosystem stability,and losses in soil microbial diversity,causing environmental damage and huge economic losses.However,recent research on intensive tea planting is mostly focused on soil nutrient,tea quality and planting technology,but the stoichiometry and microbial nutrient limitation in tea plantation process are not clear.Which gives the tea garden ecosystem the nutrient cycle and sustainable utilization bring challenges.Therefore,this research used ecological stoichiometry in intensive agriculture to study the characteristics and influencing factors of ecological stoichiometry in soil,plant and microbe.The eco-enzymatic stoichiometry was used to determine soil microbial nutrient limitation in different land use patterns and acidification degrees of tea garden soil.The variations and influencing factors of soil phosphorus components in different land use and acidification degrees in tea garden soil were analyzed.Finally,phosphorus-dissolving microorganisms were determined in three different land use types and related to influencing factors were analyzed to clarify the different regulating mechanisms in different soils.This research would provide a theoretical basis for the improvement of microbial diversity and phosphorus availability in intensive agriculture.The main conclusions were as follows:(1)The ecological stoichiometric characteristics of soil,plant litter,green leaves and soil microorganisms in the tea garden ecosystem show different variation characteristics.Soil C:N maintained relatively stable.Soil p H,latitude,and litter nutrients were the main factors affecting the stoichiometric characteristics of soil carbon,nitrogen,and phosphorus.Soil microbial biomass carbon and nitrogen were much lower than those in other ecosystems.Plant litter nutrient and stoichiometric ratio and p H were the main factors affecting the stoichiometric characteristics of microbial biomass carbon,nitrogen and phosphorus.Longitude,p H and latitude were the main factors affecting the stoichiometric characteristics of litter carbon,nitrogen and phosphorus.Altitude,soil nutrient and stoichiometric ratio were the main factors affecting the stoichiometric characteristics of leaf carbon,nitrogen and phosphorus.Microbial components are in weak steady state.(2)Land use types and soil acidification significantly affect soil extracellular enzyme stoichiometry.Soil microorganisms under the three different land use were all severely limited by phosphorus vs nitrogen.Compared with farmland and natural forest soils,tea garden soil was more severely limited by phosphorus vs nitrogen.Soil acidification in tea garden soil could aggravate microbial P limitation.In the tea garden,soil p H,soil available nutrients,microbial biomass stoichiometric ratio,and P cycling genes mediated soil microbial P limitation,while soil p H is the best factor predicting microbial C limitation.In natural forests,soil p H,soil available nutrients,and P cycling genes regulated soil microbial P limitation,while soil nutrient stoichiometric ratio mediated soil microbial C limitation.(3)Land use types and soil acidification has no significant effect on soil organic and inorganic phosphorus components.O-P,Ca-P and Fe-P are the main inorganic phosphorus components under the three land use types,while the organic phosphorus components are mainly medium active organic phosphorus.Under different land use,soil available phosphorus,total phosphorus,soil C:P,soil N:P,and soil C:N had significant effects on soil inorganic phosphorus components.Soil total carbon,total nitrogen,total phosphorus,and available phosphorus had significant effects on soil organic phosphorus composition.For tea garden soil,soil available phosphorus,total phosphorus,soil C:P and soil N:P had significant effects on soil inorganic phosphorus components,while soil total carbon,total phosphorus and total nitrogen had significant effects on soil organic phosphorus components.(4)Land use types and soil acidification significantly affect pho D harboring microbes abundance and community structure.Phosphorus-dissolving microorganisms in tea garden soil were mainly Alphaproteobacteria,Planctomycetia,Verrucomicrobiae and Betaproteobacteria at class level.In forest soils,Alphaproteobacteria,Betaproteobacteria,and Planctomycetia were main phosphorus-dissolving microorganisms,while mainly α-proteobacteria were main taxa in framlands.Alphaproteobacteria,Betaproteobacteria,Planctomycetia.Alphaproteobacteria and Betaproteobacteria play a major role in the microbial network.With the continuous intensification of soil acidification in tea garden soil,the diversity of soil microorganisms significantly decreased,and the microbial communities drastically changed.The complexity and stability of soil microbial networks decreased significantly with increasing acidification.Soil p H,microbial biomass carbon,ALP,pho D and AP in tea garden soil had significant effects on the pho D harboring microbes,and MBC and AP had significant effects on the pho D harboring microbes in the natural forest soils.Both tea garden and natural forest soil showed that pho D gene and soil p H were the main factors affecting the activity of ALP.