Abstract:

The paper aims to study the targeted fertilizing method of tobacco in Yuxi. A field experiment with tobacco ‘K326’ was conducted in Yuxi to investigate the relationship of the amount of fertilizer applied at current season, soil nutrients data obtained in soil testing, and the tobacco yield and net output. It was found that the tobacco yield, average price, net output and tobacco leaf qualities were all the highest in N2P2K2 treatment plots (local recommended fertilizer amount) in each experiment site. Under the fertilizer-lacking experiments carried out on different sites, the correlations of soil nutrients (alkaline hydrolyze nitrogen, available phosphorus and available potassium) with tobacco yield were significantly positive. The regression equation between soil nutrient contents and soil nutrient correlation coefficient could be expressed as follows: y_N=0.3246-0.04lnx_N, y_P=0.7061-0.116lnx_P, y_K=0.6244-0.089lnx_K (y_N, y_P and y_K was the effective coefficient of soil nitrogen, phosphorus and potassium respectively; x_N, x_P and x_K was the content of soil alkali-hydrolyzed nitrogen, available phosphorus and available potassium respectively). The nutrient critical value for the optimum yield of high quality ‘K326’ was calculated according to the economic optimum application rate and the levels of available nutrients in soil. To achieve the yield of more than 2700 kg/hm ², the nutrient critical values of high quality ‘K326’ planted in the paddy soil at the elevation of 1500-1800 m could be calculated as follows: N was (161.955±18.345) kg/hm ²; P₂O₅ was (77.610±12.12) kg/hm ²; K₂O was (349.95±45.675) kg/hm ². To achieve the yield of more than 2250 kg/hm ², the nutrient critical values of high quality ‘K326’ planted in the red soil at the elevation of 1500-2000 m could be calculated as follows: N was (138.945±30.705) kg/hm ²; P₂O₅ was (65.295±17.34) kg/hm ²; K₂O was (306.48±49.905) kg/hm ².

Key words: ‘K326’, NPK, soil nutrient correlation coefficient, nutrient critical value for optimum yield