Optimization of water and fertilizer management of Panax pseudoginseng based on changes in soil microbial biomass carbon and nitrogen and enzyme activities.

At present, there is a lack of understanding of the dynamic characteristics of the carbon, nitrogen, and enzyme activities of the soil microbial biomass of Panax pseudoginseng under irrigation and fertilization. We set up a field experiment with 3 irrigation and 4 fertilization levels for a total of 12 treatments plus a control in the micro-sprinkler Panax pseudoginseng farmland in Luxi County, Yunnan Province, from 2018 to 2020. The results showed that the soil microbial biomass carbon, nitrogen, and enzyme activities increased from the rooting period to the flowering period, and then decreased in the fruiting period. The soil microbial biomass carbon, nitrogen, and enzyme activities of Panax pseudoginseng reached the maximum values in the flowering period, while the minimum values were reached in the rooting period. There were significant positive correlations between the soil microbial biomass carbon and nitrogen and enzyme activities during different growth periods under different water and fertilizer optimization management. This study revealed the tendency of the carbon, nitrogen, and enzyme activities of the soil microbial biomass of Panax pseudoginseng with the growth periods. It also analyzed the optimal management of different water and fertilizer regimes and the Ci values of soil microbial biomass carbon, nitrogen, and enzyme activities in different growth periods to determine the best water and fertilizer treatment methods in each growth period through the entropy value method combined with the TOPSIS method. The study found that the C i values in the rooting, seedling period, and fruiting periods increased with the increase in the fertilization level under the same irrigation level, and the Ci value in the seedling period and fruiting period increased with the increase of irrigation amount under the same fertilization level. The best water and fertilizer management regime at seedling, flowering, and fruiting periods was W3F4, and the rooting stage was W2F4. [ABSTRACT FROM AUTHOR]