pH distribution and relationship to soil nutrient in Hunan tobacco lands

pH distribution in Hunan tobacco lands was analyzed from 1 089 soil samples and its relationship to soil fertility studied. The results indicate that soil pH in the tobacco lands is generally suitable for tobacco cultivation, with a spatial mean of 6.52 and variation coefficient of 16.81%. About 26.91% of the soil samples has pH between 5.5～6.5, most suitable for high quality tobacco cultivation. And 52.71% of the soil samples has pH of 5.0～7.0, also good for the growth of high quality tobacco. The soil pH for different parts of Hunan tobacco lands is in the following order: South Hunan＞North Hunan＞West Hunan＞East Hunan. The soil pH for different soil types is in the following order too: duck-feces mud＞yellow soil＞blue mud field＞yellow ash soil＞yellow mud field＞red yellow mud. The correlation between soil pH and soil nutrient content, including organic matter, total N, available P, available K, available Zn, available Fe, water soluble Cl, exchangeable Ca and exchangeable Mg is all significant at 0.01 confidence level. Significant differences at 0.01 confidence level among different pH groups exist for the soil nutrients. Organic matter, total N, available P, available Zn and watersoluble Cl content of soils with pH 5.5～6.5 meet high quality tobacco production requirement. Soil available Mn, available Fe, exchangeable Ca and exchangeable Mg all meet the requirement of good tobacco growth. Finally, the content of available K and Cu is relatively low, however, no nutrient deficiency symptom is observed.