Spatial heterogeneity of soil nutrients and pH in tobacco area based on geostatistics:A case study in a karst area of Youyang county,Chongqing

LIU Yue-jiao; ZHANG Yang; NI Jiu-pai; ZHOU Chuan

Abstract：Evaluation of spatial heterogeneity of soil nutrients and pH forms a basis for management of soil nutrients and fertilization in tobacco-growingareas.In this paper,the spatial heterogeneity of soil nutrients and pH in the tobacco-growing area of Youyang county was evaluated using classical statistics and geostatis-tics.The results indicated rich organic matter and pooravailability of phosphorus in the study area;the varia-tion coefficients for eight soil nutrient indicators ranged from 13.1 1% to 71.46%.The variable coefficient of available phosphorus was the largest among the indicators,while organic matter,total nitrogen and available nitrogen were stable.A significant positive correlation between organic matter and total nitrogen,total phos-phorus,available nitrogen and available phosphorus was noticed,while a clear negative correlation between pH and both available phosphorus and potassium was identified.The semivariograms for soil organic matter, total nitrogen,total phosphorus and available potassium were all well fitted using the exponential curve mod-el,while the correlation between pH and available nitrogen fitted well using the spherical model;total nitro-gen,total phosphorus,available nitrogen and potassium had moderate spatial correlation,and other soil nu-trient indicators showed weak spatial correlation.The spatial distribution of soil nutrients and pH in the east-west direction and the north-south direction area is significantly different,and the variation of spatial distri-bution in the east-west direction was larger than in the north-south direction.The spatial correlation of soil nutrients in tobacco-growing area of Youyang county is not significant,therefore,it can be concluded that the spatial heterogeneity of soil nutrients is mainly affected by the topography,fertilization,tillage and other potential factors.