Evaluation On Soil Fertility And Study On NPK Fertilizer Efficiency In Dazhou Burley Tobacco-Growing Areas

The physiognomy of burley tobacco-growing areas in Dazhou is complex and the soil nutrients are of the spatial variation. For lack of systematically information of soil nutrient, it is hard to help the tobacoo grower to fertilize properly. Therefore, a knowledge of soil nutrient of the tobacco-growing soil and suitability evaluation are very important for balanced fertilization. Fifteen rouitine nutrient indicators of soil samples were analyzed and the results showed that:the pH values of the soils were appropriate but a little acid. The phosphorus, exchangeable calcium, effective copper, effective iron, effective manganese and chloride contents were suitable. The organic matter, total nitrogen, alkalined nitrogen, effective boron and effective zinc contents were less than normal values. Available potassium and exchangeable magnesium contents were widespread shortages. Slow available potassium content was in rich. The comprehensive suitability evaluation of soil fertility suggested that:the IFI values in most burley tobacoo-growing areas of Dazhou were in upper levels and suitable for the cultivation of burley.Based on the work above, the terraces of medium fertility soil in burley tobacco growing areas were chosen to build mathematical models in order to guide the tobacoo grower to fertilize properly. The models could be used to calculate the best fertilizing amount of nitrogen, potassium and phosphorus. When objective function was the production, appropriate increase of nitrogen and potassium could increase the production. The best fertilizer:nitrogen was 19.48 kg/667m2, phosphorus was 14.78 kg/667m2, and potassium was 36.21 kg/667m2. When objective function was the benefit, the best fertilizer: nitrogen was 14.14 kg/667m2, phosphate was 10.96 kg/667m2, and potassium was 25.8 kg/667m. When objective function was the proportion of middle and high class leaf, appropriate increase of potassium and nitrogen and decrease of phosphorus could improve the proportion of middle and high class leaf. The best fertilizer:nitrogen was 16.25 kg/667m2,phosphate was 10.96 kg/667m2, and potassium was 29.08 kg/667m2. Inputting the fertilizer amounts, the nicotine, total nitrogen, reducing sugar, tobacco potassium could be calculated by mathematical models for those objectives. Comparative analysis of the chemical composition of three best fertilizers suggested the final recommendations: nitrogen was14.14 kg/667m2, phosphate was 10.96 kg/667m2, and potassium was 25.8kg/667m2.