Effects Of Soil Transfer And Fertilization On Soil Microbial Communities In Corn Farmland

Fertilization and climate change can simultaneously impact carbon stability and nutrient cycling in agricultural soil,imposing subsequent consequences on sustainable use of agricultural soil.Microorganisms are crucial drivers of biogeochemical cycles.Unfortunately,effects of fertilization on microbe-mediated degradation of soil organic carbon are difficult to predict.Furthermore,interactive effects of fertilization and climate change on soil microorganisms are not yet know,thus a mechanistic understanding of soil carbon fate is missing.Soil type is an important factor affecting microbial communities,however,it remains elusive how soil type affects microbial responses to environmental changes.The possibility of abrupt climate change events is increasing under human forcing.To address these questions,we conducted factorial experiments including soil transfer simulating abrupt climate change and amendment of nitrogen,phosphorus and potassium fertilizers.Using Geo Chip and high-throughput sequencing,we explored effects of fertilization,abrupt climate change and their interaction on microbial functional genes,bacterial and fungal communities in Mollisol(from Heilongjiang Province),Cambisol(from Henan Province),and Acrisol(from Jiangxi Province).Fertilization had consistent effects on microbial communities in Mollisol,Cambisol,and Acrisol:(i)fertilization increased OTUs of genus Sphingomonas but decreased OTUs of Acidobacteria GP4 group;(ii)fertilization increased relative abundances of functional genes associated with degrading chemically-recalcitrant organic carbon,enhancing soil organic matter(SOM)sequestration;(iii)fertilization increased relative abundances of genes associated with nitrification and denitrification,implying enhancement of nitrogen cycling turnover.Soil transfer and fertilization interactively affected microbial communities and functional genes.Moreover,soil transfer overrode fertilization effects.After soil was southward transferred,magnitude of decrease in recalcitrant carbon-degrading genes by fertilization was diminished.Consequently,SOM was not increased by fertilization despite increases in plant biomass by 27%-108%.This phenomenon was most obvious when Mollisol was southward transferred from Heilongjiang to Jiangxi Province,where fertilization increased the recalcitrant carbon-degrading fungal Basidiomycota taxa by 195% and recalcitrant carbon-degrading genes by 23%-40%,implying a possible priming effect.These results indicated that climate warming could alter microbial responses to fertilization,threatening soil carbon stability.Soil type influenced interaction effect of northward soil transfer and fertilization on carbon degradation genes.When Acrisol was northward transferred from Jiangxi to Heilongjiang Province,magnitude of decrease in recalcitrant carbon-degrading genes by fertilization was increased compared with in-situ effect,resulting in more SOM sequestrated.However,when Cambisol was northward transferred from Henan to Heilongjiang Province,magnitude of decrease in recalcitrant carbon-degrading genes by fertilization was diminished,resulting in less SOM sequestrated.This discrepancy might result from differences in soil p H and nutrient content.Together,changes in SOM are correlated with microbial communities.And this work demonstrates a significantly negative correlation between SOM and abundances of recalcitrant carbon-degrading genes,thus provides insights into the possibility of utilizing carbon-degrading genes to predict soil carbon stability.This study comprehensively investigates the effects of simulated climate change and fertilization on microbial communities,and the microbe-mediated mechanisms underlying soil carbon storage,providing fundamental information for improvement of soil carbon pool estimation model.