2.4 Effect evaluation of different water and fertilizer optimal management on soil microbial biomass C and N and enzyme activity of Panax notoginseng farmland
To comprehensively and systematically reflect the effects of different wat and fertilizer optimal management on soil microbial biomass carbon and nitrogen and enzyme activity of Panax notoginseng farmland, and avoid the difficulty in evaluating the quality of what and fertilizer management due to a large number of test indexes. The entropy value method combined with TOPSIS method was used to analyze the indicators of soil microbial biomass carbon, nitrogen and enzyme activity at different fertility periods under different water and fertilizer optimization management of Panax notoginseng. This method can determine the fit degree Ci and its ranking for the optimal solution of soil microbial biomass carbon, nitrogen and enzyme activity at different fertility periods under different water and fertilizer optimization management to find the optimal water and fertilizer management solution at different fertility periods.As shown in Tab.3,The greater the value of the optimal solution fit Ci, the better the microbial biomass carbon, nitrogen and enzyme activity of Panax notoginseng soil for that treatment.Under the same irrigation treatment, the Ci values were F4, F3, F2 and F1 in descending order, and the advantages and disadvantages of microbial biomass carbon, nitrogen and enzyme activity of Panax notoginseng soil were F4, F3, F2 and F1 in descending order. Under the same fertilization treatment, the Ci values decreased and then increased with the increase of irrigation, and the advantages and disadvantages of microbial biomass carbon, nitrogen and enzyme activity of Panax notoginseng soil were W2, W1 and W3 in descending order.The maximum Ci value of 0.836 for the W2F4 treatment and the next highest Ci value of 0.794 for the W3F4 treatment at the rooting period, and the worst Ci values of 0.214 and 0.133 for the W1F2 and W1F1 treatments, respectively, for soil microbiomass carbon , nitrogen and enzyme activity. The maximum Ci value of 0.806 for the W3F4 treatment and the next highest Ci value of 0.801 for the W2F4 treatment at the seedling period. The worst soil microbial biomass carbon, nitrogen and enzyme activity treatments were W1F2 and W1F1 with Ci values of 0.263 and 0.111, respectively.The maximum Ci value for the W3F4 treatment was 0.733, followed by 0.568 for the W2F3 treatment, and the worst Ci values for soil microbiomass carbon , nitrogen and enzyme activity were 0.216 and 0.189 for the W2F1 and W1F1 treatments, respectively. The maximum Ci value for the W3F4 treatment was 0.835, followed by 0.766 for the W3F3 treatment, and the worst Ci values for soil The worst soil microbial carbon, nitrogen and enzyme activity treatments were W2F1 and W1F1, with Ci values of 0.273 and 0.068, respectively.According to the optimal scheme fit Ci analysis of soil microbiomass carbon, nitrogen and enzyme activities at different fertility periods under different water and fertilizer optimal management, W2F4 treatment at rooting period, W3F4 treatment at seedling, flowering and fruiting periods were favorable to regulate soil microbiomass carbon, nitrogen and enzyme activities of Panax notoginseng soil and promote root growth.