Effects of Wheat Straw Mulching Amount on the Quantity of Microorganisms in Different Tobacco Planting Soil

Field experiment was conducted to study the effects of different mulching amount of wheat(the mulching amount being 0,250,500,750 kilogram per 667 squarer meter as 4 treatments) on the quantity of microorganisms in different tobacco planting soil.Result showed that the quantity of bacteria,actinomycetes and cellulose-decomposing bacteria in rhizosphere soil of the upland and paddy increased with the amount of mulching.And the quantities of them reached biggest in treatment with mulching amount of 750 kilogram per 667 squarer meter after harvest,and were respectively 53.03%,47.08%,75.72% and 63.79%,30.27%,69.08% higher than contrast.The quantity of bacteria in rhizosphere soil of the upland in treatments with different mulching amount were 1.81~2.13 times higher than that without mulching,actinomycetes and cellulose-decomposing bacteria were respectively1.08~1.89 and 1.49~4.1 times higher.The quantity of azotobacter were most in treatments with mulching amount of 500 kilogram per 667 squarer meter,and were significantly higher than contrast.There were no effects on the quantity of fungi with straw mulching.The quantity of bacteria in rhizosphere soil of the paddy in treatments with different mulching amount were1.87~2.76 times higher than that without mulching,actinomycetes and cellulose-decomposing bacteria were respectively 1.12~1.43 and 1.3~3.39 times higher.The quantity of fungi and azotobacter were most in treatments with mulching amount of 500 kilogram per 667 squarer meter,,and were 2.24 and 1.60 times higher than contrast.