Effects of rotation and intercropping systems on yield, quality of flue-cured tobacco and soil nutrients

A continuous 6-year field experiment was carried out to study the yield, chemical components, Bacterial Wilt Disease, output value of flue-cured tobacco and soil nutrients in representative yellow soil in south of Guizhou province. Three cropping systems were adopted: single tobacco cropping, tobacco and sweet potato intercropping and tobacco and peanut intercropping. Regarding to the intercropping systems, a new cultivation was established, which was intercropping in one year and changing the cropping area (rotation) next year. The results show that tobacco yield and output are significant increased by about 11.3% and 20.4% under the two intercropping systems from 2004 to 2009, respectively, and as well as the low disease rate of bacterial wilt disease that have decreased by about 11.0% compared to the single tobacco cropping system and the coordinated tobacco chemical constitutions in the two intercropping systems. As to soil nutrients, after 6 years cultivation, there are no significant differences in soil pH, organic matter and total nutrients (N, P and K) under the cropping systems. However, interesting to note is that the proportions of soil available nutrients under single tobacco cropping system are higher than those in the intercropping systems, which reflects unbalanced absorptions of soil nutrients. Yet, it is obvious that the intercropping systems could make good use of soil nutrients and keep a reasonable proportion of soil available nutrients that could meet the vast need of available N of tobacco at the earlier stage, but also prevent from assimilation of redundant nutrients later. Therefore, the intercropping systems with sweet potato（or peanut）could do great effort to decrease the harm of continuous cropping obstacles and will be popularized in south of Guizhou province.