Effect Of Plougher-Back Green Manure On Dry Land Of Planting Tobacco Soil Fertility And Growth And Development Tobacco

For the west of Hunan Province planting tobacco dry land soil drought and barren characteristics, using field plot, by using the spare time of winter planting oats,peas Chinese trumper creeper and astragalus sinicus as test crops, The field experiment to investigated the effect of ploughed-back green manures on soil quality improvement including the changes and differences of soil on main physical characters,chemical fertility and biological fertility in the growing stage of tobacco;and the effects of different years of burying green manures on tobacco agronomic traits quality and economic traits,and to study character changes and differences of soil fertility after different ploughed-back green manures.The results shows that:(1) The impact on soil physical properties:ploughed-back green manures could reduce soil bulk density,but the difference is not significant.as the compare shows the two consecutive years of planting green manure can reduce soil bulk density in a large extent.however,it can improve soil porosity,compared with fallowing treatments,the increase is1.5-5.6%which is not significant between green manure processing.it can also improve soil water-holding capacity,the increase is3.9-8.2%. To soil organic matter also have certain enhancement, increased3.2%to8.6%, a direct relationship is that a large number of organic matter ploughed-back into soil; ploughed-back green manure also has good ecological effect, each year can fixed carbon1080-1080kg/hm2, leguminous green manure per year can fixed nitrogen up to63kg/hm2.(2) The impact on soil chemical fertility:the two consecutive years of planting green manure can improve soil total N,the soil total N increased from1.54g/kg to1.73g/kg after green manure planting and the difference is significant in leguminous green manure-compared with grass green manure oats.As for the soil available nutrients can be improved on the whole,the promote on soil available N and P are concentrated on tobacco Flourishes and post-harvest stage,and the impact of leguminous green manure is more efficient. Green Manure can periodic reduce soil pH, leguminous green manure on soil pH is relatively large, year after year Green Manure can decrease soil pH by0.23units. There is some improvement made on soil organic matter, the improve range is3.2%-9.5%.(3) The impact on the soil microbial:it can significantly increase the number of soil fungi, bacteria, actinomycetes, the effects on bacteria, soil bacteria and actinomycetes mainly expressed on early stage of tobacco growth.in comparison, the impact on flue-cured tobacco is small, and the leguminous green manure showed a more significant effect than grass green manure oats but there is a fully opposite effect on soil fungi and the second year is superior to the first year. Different green manure crops on soil microbes are not identical, to changes in the magnitude and intensity the grass green manure bring is relatively low.(4) The impacts on agronomic traits of Hue-cured tobacco:can effectively improve the effective number of leaves, the second year showed a more obvious effect, the average increase is1.6leaves per plant.there is no significant improvement except the oat. green manure made some improvement on plant stems of the tobacco, yet turning over oats similar to CK treatment. The performance of first year on tobacco plants pitch in the green manure is not obvious, while the second year showed a reduce in the pitch of the tobacco which legume green manure larger than the grass.Certain role expressed in the promoting of plant leaf area in tobacco. The effect on agronomic traits of flue-cured tobacco turn out that the Green Manure promote the yield and the good structure formation of tobacco.(5) After green manure ploughed back to soil, nitrogen, potassium and nicotine of upper leaves in flue-cured tobacco,reducing sugar and total sugar content were different degree increase, the middle leaves of tobacco nicotine content decreased, the overall balance of tobacco intrinsic chemical composition the indicators tend to coordinate, as a result, green manure also turned down soil to improve the quality of tobacco leaf were also has a positive impact. While a Significant leaf potassium improvement on the upper part of the flue-cured tobacco which increased by14-20%, the impacts on Economic traits of flue-cured tobacco is mainly manifested in the production, the upper leaf ratio, the average price of flue-cured tobacco thus increasing the production.