This study was conducted to form 9 models of
multiple cropping rotation in Yongding county, a main tobacco producing area,for
9 models of multiple cropping.The result showed that “ spring tobacco rice early autumn corn vegetable”and“spring tobacco rice ratooning ricecrop changing”were optimized models to resolve land use contradiction between grain and tobacco production for grain stablization and profit increase.It is imperative to change early spring tobacco into spring tobacco because of the quality and the yield of early spring tobacco are lower than that of spring tobacco, and the profit of the former is two times less than that of the latter.The result also indicated that organic matter content in soil increased significantly after multiple cropping
rotation and paddy upland rotation; total N、P、K also increased but not significantly; although rapidly-available N、P、K tended to decrease progressively, total soil fertility did not decreased.The
utilization ratios of land, temperature and sunlight resources were high in our experiment and multiple cropping index amounted to 300%-400%, the utilization ratio of active accumulated temperature attained 82 5%-97 7% and the utilization ratio of sunlight reached 80 9%-97 6%.The higher natural resources utilization ratios were, the higher output, output value and net profit were.