Spatial Variability Characteristics of Medium and Micro Nutrients in Wenshan Tobacco-growing Soil Based on GIS

PurposeTo analyze the current status and spatial variation of soil medium and micro nutrient in the major regions of tobacco production in Wenshan, so as to provide the guidance for soil nutrient management and fertilization stratagem.

MethodsA total of 2 740 soil samples were collected from the plough layer of core tobacco field in eight tobacco-growing counties in Wenshan. GPS positioning, geostatistics and geographic information systems (GIS) were used to investigate the soil nutrient status and regional variation characteristics.

ResultsThe mean values of exchangeable calcium and magnesium, available boron, and water-soluble chlorine in soil were 2507.72, 278.60, 0.30, and 10.99 mg/kg, respectively; and their coefficients of variation were 76.54%, 79.39%, 60.01% and 105.64%, respectively, which belonged to strong variation. The contents of exchangeable calcium and magnesium were mainly varied at high to higher level, medium to over high, which occupied 91.29% and 89.66% of the total samples, respectively. Soil available boron content was mainly distributed in ≥0.2-0.5 mg/kg and <0.2 mg/kg regions. The distribution of water-soluble chlorine content was mainly in ≥5-10 mg/kg and ≥10-15 mg/kg regions, and the proportion of deficiency available boron and water-soluble chlorine regions was 94.88% and 97.23%, respectively. All the four nutrients showed anisotropic distribution with moderate spatial autocorrelation (nugget to sill ratio was 25%-75%), and their variation was combined effect of natural factors with anthropic activities.

ConclusionThe exchangeable calcium is higher, available boron and water-soluble chloride content belong to moderate to severe lack in tobacco-growing soil. The exchangeable magnesium content of tobacco-growing soil is moderate in Wenshan, Yanshan, Qiubei, Maguan, Guangnan and Malipo, and the deficiency magnesium is about 10% of the soil in Xichou and Funing. For tobacco production of Wenshan Prefecture, the amount of calcium fertilizer should be reduced to regulate Ca/Mg, and taking appropriate pattern of fertilizing boron, chlorine and magnesium to improve tobacco yield and quality.