Characteristics And Health Evaluation Of Tobacco Planting Soil In Sichuan Province

Soil health assessment plays an increasingly important role in the sustainable development of soil,which is a research hotspot of soil scholars.Sichuan is one of the major tobacco producing areas in China.With the improvement of tobacco quality requirements at present,the research on tobacco soil health evaluation is particularly important.In this study,Liangshan,Luzhou and Panzhihua tobacco planting soils in Sichuan Province were selected as the research objects to explore the differences and correlations of soil physical,chemical and biological properties in 0~20 cm and 20~40 cm soil layers,and to clarify the current health status of tobacco planting soils in Sichuan Province Based on principal component analysis and fuzzy mathematics.The main results are as follows:1.Physical characteristics of soil.The soil texture is mainly composed of silty loam,silty clay loam,and loam.The average soil bulk density of 0-20 cm soil layer is 1.04~1.38 g/cm3,the difference is not significant,and it is positively correlated with the depth of tobacco planting soil layer;The content of >2mm water-stable aggregates in 0~20 cm and 20~40 cm soil layers in Xuyong and Gulin counties is the largest,and the aggregates structure of soil in Xuyong and Gulin counties is better.The average penetration resistance of 0~20 cm and 20~40 cm soil are 223.82~1235.13 k Pa and 954.88~2677.81 k Pa,respectively.The soil penetration resistance of Renhe District,Yanbian County,Miyi County and Mianning County are all above the suitable growth range of tobacco.Soil field capacity decreases with the increase of soil layer.2.Chemical characteristics of soil.The soil p H,total nitrogen,total phosphorus,and total potassium are suitable,soil alkalinity nitrogen is low,and soil available phosphorus,available potassium,exchangeable magnesium,and exchangeable calcium are high.The p H range of soil is 5.26~7.21,and the soil of Yanbian county and Dechang County is acid,and the soils in Huili County are relatively alkaline.Soil total nitrogen,alkali-hydrolyzable nitrogen,total potassium and exchangeable calcium are lower in Yanbian County.Soil total nitrogen,alkali-hydrolyzable nitrogen,total phosphorus,total potassium and exchangeable calcium in Huidong County are lower.Soil alkali-hydrolyzable nitrogen,total phosphorus and exchangeable calcium in Renhe district are lower.Soil alkali-hydrolyzable nitrogen,available phosphorus and total potassium in Miyi County are lower.Soil alkali-hydrolyzable nitrogen and available phosphorus in Dechang County are lower.Soil total nitrogen and total potassium in Huili County are lower.Soil alkali-hydrolyzable nitrogen and exchangeable calcium in Yanyuan County are lower.Soil total phosphorus and total potassium in Xuyong County are lower.The soil total phosphorus in Miyi County is higher.Soil available potassium and exchangeable calcium in Xuyong County are higher.3.Biological characteristics of soil.The soil organic matter content is 17.23~37.33 g/kg,which decreases with the increase of soil depth.0~20 cm soil layer,soil soluble carbon is 107.46~200.35 mg/kg,Miyi County(highest)is 5.13 times that of Renhe District(lowest);microbial carbon is 22.11~113.46mg/kg,Miyi County(highest)is 5.13 times that of Gulin County(lowest);soluble nitrogen is 11.69~31.23mg/kg,Gulin County(highest)is 2.67 times of Huidong County(lowest),and microbial nitrogen is5.55~18.49 mg/kg,Dechang County(The highest)is 3.33 times that of Yanbian County(the lowest).20~40 cm soil layer,soil soluble carbon is 59.68~273.16 mg/kg,microbial carbon is 20.92~99.87 mg/kg,soluble nitrogen is 8.78~25.32 mg/kg,microbial nitrogen is 6.01~17.72 mg/kg,and the soluble carbon,nitrogen and microbial carbon and nitrogen of 0~20 cm soil have little difference with the 20~40 cm soil layer.4.Comprehensive Index of Sichuan Tobacco Soil Health.Through field surveys and verification of soil health scores in small areas,the principal component analysis method is more suitable for evaluating the health of tobacco-growing soil in Sichuan.It is divided into four grades: Class I is {Gulin County,Xuyong County},and the comprehensive score range is [1.373 ~ 2.448],and nitrogen fertilizer,calcium and magnesium fertilizers need to be controlled;Class II is {Miyi County,Dechang County },the comprehensive score range is [0.298~1.373),it is necessary to increase potash fertilizer and control phosphate fertilizer;grade Ⅲ {Huili County,Yanyuan County},the comprehensive score range is [-0.777~-0.298),need to increase phosphate fertilizer and control calcium Magnesium fertilizer;Grade IV is {Huidong County,Renhe District,Yanbian County,Mianning County},the comprehensive score range is [-1.852~-0.777),it is necessary to properly deep-seed tillage,increase organic fertilizer,and control calcium fertilizer and phosphate fertilizer.In conclusion,principal component analysis is more reasonable to evaluate the health level of tobacco planting soils in Sichuan,and the limiting soil factors are clarified,which provides theoretical basis for rational fertilization and ecological division of tobacco area.