K and Mg Nutrition of Soil and Fertilization Effect on Tobacco Production in Hunan

The K and Mg contents of 3520 soil samples from main tobacco production areas in Hunan were determined. The results showed that the contents of total K, available K and exchangeable Mg averaged to 13.7g kg~(-1), 127.3mg kg~(-1) and 1.16 cmol kg~(-1), respectively. The contents had remarkably difference in different tobacco production areas and most soils were variously low of K and Mg. Results of field experiment showed that the combination application of potassium and magnesium fertilizer(K_2O 360kg hm~(-2), MgSO_4.7H_2O 300kg hm~(-2)) enhanced the growth of tobacco, increased leaves yield,quality and output value of tobacco, increased the amount of K and Mg uptaken by the tobacco.