Nitrogen mineralization potential of major soil planting tobacco in China

To provide a basis for regulation and control of nitrogen nutrition on flue-cured tobacco，this study investigated the mineralization potential (No) of main soil planting tobacco in China and its distribution. Samples from 18 provinces 317 town were incubated indoor. 117 samples among of them were incubated under aerobic condition for 17 weeks and others were incubated under aerobic condition for 3 weeks including 1 week incubation in advance. The data of the long-term incubation were well fitted by first order model; the mean of the mineralization rate constant (k) is 0.017/d. It was found that No computed by the mean of k did not show significant difference with No fitted. The mean value of No is 130.6 mg/kg, ranging from 5.5–372.0 mg/kg, and the maximum potential supply nitrogen in 30 cm soil surface layer was 470.2 kg/ha with the variability coefficient being 49.5%. There is significant difference on the No between the different tobacco zone. The No is 64.1, 78.8, 99.0，119.9, 127.8, 135.0 and 160.5 mg/kg for north-east tobacco-growing areas, the southern tobacco-growing areas, the Yangtze River middle-upper tobacco-growing areas , the Yangtze River middle-lower tobacco-growing areas, the southwest tobacco-growing areas, respectively. The different No is also observed between differences among various agrotypes. The potential nitrogen supply of agrotypes (containing paddy soil, yellow soil, red soil, purple soil, rendzina) is significantly higher than the agrotypes (brown soil, palm soil) in the north. There is closely positive correlation between No and the content of soil organic matter. The soil nitrogen supply potential should be well known at the macro level. In the region with excessively high No, the tobacco plant zoning should be subjected to adjusting. In the region with high No, agronomic measures could be considered to control and reduce tobacco late reproductive nitrogen supply. The region with the suitable No should be selected first for the development of flue-cured tobacco production.