| Recent years, maize straw incorporation has been widely applied in the "wheat-maize"rotation area in the northern part of China, which improved the physicochemical property and the structure of soil. However, large amount of maize straw cannot be decomposed in one season and the cross-district mechanical operations turned to be more and more frequent, which result in that the wheat soil-born disease tend to be more and more severe and the plough layer becomes shallower, water loss and air leak in soil tend to be common, which bring some hidden troubles such as the pest and freeze injury.In order to find a balance way between the efficient use of resources and the more and more severe soil-born disease and farming problems, many specialists and scholars carried out extensive and in-depth research. B1514, a strain of Bacillus Subtilis, has been found to have significant inhibition effect against major pathogens of wheat soil-born disease and also have good decomposition ability to maize straw.The study focused on the optimum of the fermentation medium, fermentation conditions, the composition of carriers, which are very important for the growth and reproduction of the strain. Based on the optimal conditions, we tried2types of application formulation which are tablet and granula. We manufactured the multifunctional soil additive named HAD-2and applied it into the farmland to test the efficacy for the control of soil-born pathogens and the maize straw decomposition.The results showed that the optimum fermentation medium components for B.subtilis strain B1514were glucose1.5%, amylon0.5%, corn flour3%, MnSO40.2%,(NH4)2SO41.5%, MgSO40.02%, KH2PO40.03%and CaCl20.1%, respectively; the optimum fermentation conditions were that putting5%i nitial inoculums into100mL liquid culture in a500mL flask, with the initial pH7.2-7.5and keeping the fermentation temperature at32℃; Under the optimum conditions, the number of live bacterium increased to1.17×1010cfu/mL, and the yield of fermentation increased by115%. Using corn flour, corn stalk powder, and wheat bran (mass ratio1:6:2) as carriers,20oculus screen for wet granulation and1%magnesium stearate as lubricant, can get tablets of B1514up to standard with intact shape and suitable rigidity. Mixing the B1514ferment, which is under the optimum ratio of carriars, with (N4)2SO4, humic acid and calcium powder at the ratio of15:3:1:1, can make the multifunctional soil additive-HAD-2, and the number of bacteria cells is above2×108/g. The wheat in the HAD-2treatment (750kg/hm2) has a higher emergence rate,stronger stem,more tillers and increased the yield by11.5%on average. HAD-2showed significant control effect on wheat soil-born disease. The control efficacy for sharp eyes, root rot and wheat take-all was separately78.7%,78%,75%at elongation stage and69.6%,60.3%,62%at pustulation stage. The HAD-2accelerated the decomposition of maize straw and the rate of decomposition is62.04%, increased38.28%compared to the control treatment at the milk stage of wheat. |
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