The Effect Of Continuous Cropping Tobacco And Soil Improvement Synergist On Microbes And Enzymes In Soils With Tobacco

The studies on the effect of continuous cropping tobacco and soil improvement synergist on the microbial quantities, activities and enzyme activities in soil were conducted. The soil improvement synergist experiment was treated with 3kg/667m2 soil improvement synergist,6kg/667m2 soil improvement synergist,9kg/667m2 soil improvement synergist and water. The results were as the followings:1.When the tobacco-continuous-cropping time was within 8 years, the quantities of aerobic bacterium, anaerobic bacterium, actinomycetes and fungus in dry land soils increased with the continuous-cropping years. When the tobacco-continuous-cropping time was more than 8 years, the quantities of the above microbes in dry land soils would decrease. The effect rule of tobacco continuous cropping on microbes in dry land soil was bacterium>fungus> actinomycetes. The effect of tobacco continuous cropping on the activities of urease, cellulase, protease and catalase in the dry land soil was small. The microbial flora and diversity in soil would be changed by tobacco continuous cropping. The plant diseases would often happen in tobacco continuous cropping soil. The long-term tobacco continuous cropping does not benefit the soil ecosystem to develop healthily.2.During tobacco growth period, aerobic bactetia quantity decrease rapidly in the early grwth stage, and slowly increase in the middle and then slightly fluctuate. The quantity of actinomycetes increase in the early stage, followed by a decrease in the following stages. The quantity of fungi increase in the early period, then decrease in the following stages except the treatment by soil improvement synergist (6kg/667m2). Microbial activity sharply increase at strong stage after adding soil improvement synergist. Cellulase actvity increases before growth vigorous stage and decreases after that. Urease activity drops sharply,followed by increases. Protease and catalase activity are not serious in the entire growth period. They both slightly decrease in the early growth stage and tend to moderate in the rest stages. The results show the optimal ways of soil improvement synergist (3～6kg/667m2).