Effects Of Different Cropping Models On Tobacco Productivity Of Yellow Soil In North Guizhou Province

Flue-cured tobacco is an important economic crop which is the major source of farmers' income, local finance and national tax in tobacco-planting area.Meanwhile,the development of tobacco industry has great significance to employ surplus rural labors and promote the harmony of rural areas.However,as the steady decline of arable land,constant emergence of large-scale organizations specialized in tobacco production and intensification of land contradiction between food and tobacco, which lead to unreasonable cropping modals,decrease the yield and quality of flue-cured tobacco, and productivity of tobacco soil.Therefore,studying on effects of different cropping models on productivity of tobacco soil and applying reasonable cropping models in tobacco-planting area are very urgent.This test was implemented in Tobacco Research Center in Zunyi city,Guizhou province,set six different copping models,investigated agronomical characters in several growth period,and analyzed chemical constituents of cured tobacco leaves,compared yield,quality and output value of tobacco leaves and output value of intercropping crops to get the effects of different cropping models on economical benefit of tobacco-planting field;combined with the analysis of soil agro-chemical characters and soil enzymes activity to obtain the effects of different cropping models on productivity of tobacco-planting soil.The results showed that:Agronomical characters,chemical constituents,yield and quality and output value of tobacco had significant differences between treatments of different preceding crops.In the treatments of wheat as preceding crop,agronomical characters were better than those of the treatment of rape as preceding crop in tobacco growth periods.In post-harvest period,yield,quality and output value and chemical indexes of tobacco in the treatments of wheat as preceding crop were significant better than those of the treatment of rape as preceding crop.While,among the treatments of the same preceding crop,there were no such significant differences on above indexes.Available nutrients and enzyme activity of tobacco-planting soil had significant differences between treatments of different preceding crop.From the mature period to post-harvest period of tobacco,the soil available nutrients in treatments of rape as preceding crop showed a significant accumulation,while no such phenomenon showed in treatments of wheat as preceding crop.Soil activity of urease and saccharase in the treatments of rape as preceding crop was weaker than that in the treatments of wheat as preceding crop,while the activity of catalase was higher than that in the treatments of wheat as preceding crop.Organic matters,nitrogen and enzyme activity of intercropping soil had differences among different treatments.The concent of organic matters was higher in sweet potato-planting soil than others,while contents of total and available nitrogen were higher in the soybean-planting soil.In the treatments of wheat as preceding crop,activity of urease and saccharase of intercropping soil was higher than that in the treatments of rape as the preceding crop.In post-harvest period,soil agro-chemical characters and enzyme activity showed that in the same treatment,the intercropping soil was more beneficial to the tobacco growth next year.Content of organic matters,nitrogen in intercropping soil was much higher than that in tobacco-planting soil; content of total nitrogen in soybean-planting soil had significant difference from that in tobacco-planting soil.Activity of urease in intercropping soil was higher than that in tobacco-planting soil,while other enzyme activities were almost in the same lever.From the above, nutrients content in the intercropping soil of treatment wheat→tobacco-sweet potato had relatively narrow variation range,harmonious proportion and higher enzyme activity,which is good to tobacco growth next year.The economical benefit of treatments rape→tobacco-sweet potato,wheat→tobacco-sweet potato and wheat→tobacco,which surpassed 30000yuan/hm~2,were relatively high compared to other treatments.Due to the comparatively low quality and yield of tobacco,the treatment of rape→tobacco-sweet potato was not the best cropping models even though its highest economical benefit.The treatment of wheat→tobacco had no annual alternation of tobacco and intercropping crops which might lead to the unbalanced and unrecoverable changes on physiochemical and biochemical properties of soil.Therefore,comprehensively considered the effects of different cropping models on economical benefit,yield and quality of flue-cured tobacco,agrochemical properties and enzyme activities of soil,the cropping model of wheat→tobacco-sweet potato was relatively suitable for tobacco production in yellow soil of north Guizhou province.