Changes characteristics of soil microbial biomass carbon,nitrogen and enzyme activity of Panax notoginseng under optimal management of water and fertilizer
Authors: tuo yunfei , Xiangning Liu , Yang Zheng , Qian Wang , Fei Wang , Zhaoyi Wang , Xiaolan Shi , Mingjing Ding , Fangyuan Shen , Ping Xiang , Qiliang Yang 
Published: October 2022

There is a lack of understanding of the dynamic characteristics of
carbon, nitrogen, and enzyme activity of soil microbial load of Panax
notoginseng in water-fertilizer intercrops. In this study , we reveal
that different water and fertilizer regulations affect microbial biomass
carbon, nitrogen, and enzyme activities. As the study object, we set up
3 irrigations,4 fertilization levels, and 1 control in micro-sprinkler
irrigated Panax notoginseng farmland, Luxi County, Yunnan Province from
2018 to 2020. The findings demonstrated that under the same water and
fertilizer management, the carbon, nitrogen, and enzyme activities of
Panax notoginseng’s soil increased and then decreased with increasing
fertility time, in descending order of flowering, fruiting, seedling,
and rooting periods.. The maximum value is reached during the flowering
period ,while the minimum value is reached during the rooting period.
The soil microbial carbon and nitrogen contents ranged from 0.49 to 1.05
g.kg and from 14.98 to 66.21 mg.kg
, respectively, and soil sucrose enzyme activity was
the largest, ranging from 17.12 to 68.79 mg.kg .d.
. The soil microbial carbon , nitrogen and enzyme
activities of Panax notoginseng increased with the rate of water and
fertilizer application under different water and fertilizer management.
The soil microbial carbon , nitrogen and enzyme activities of Panax
notoginseng at the flowering period were the largest. The soil microbial
carbon and nitrogen activities of Panax notoginseng increased with the
increase of irrigation and fertilizer application, whereas the soil
microbial carbon and nitrogen activities of W3F4 increased by 0.41 g.kg
and 39.52 mg.kg respectively
compared with W1F1. Soil urease, sucrase, acid phosphatase, and catalase
activities were the highest in W3F4, with increases of 44.26%, 61.51%,
42.56, and 32.25% respectively compared to W1F1. There was a
significant positive correlation between soil microbiomass carbon and
nitrogen and enzyme activity under different water and fertilizer
management. Soil microbiomass carbon and nitrogen content determined
soil enzyme activity. The entropy value method combined with the TOPSIS
method was used to analyze the optimal program fit Ci of soil microbial
biomass carbon, nitrogen, and enzyme activity under different water and
fertilizer optimization management and at different fertility periods.
The results showed that the Ci values were F4, F3, F2, and F1 in
descending order under the same irrigation level treatment.The Ci values
decreased and then increased with increasing irrigation water under the
same fertilization level treatment. The carbon, nitrogen, and enzyme
activities of the soil’s microbial biomass were successfully controlled
when Panax notoginseng was treated with W2F4 during the rooting period
and W3F4 during the seedling, flowering, and fruiting periods. This
study is an essential guideline for water and fertilizer regulation of
Panax notoginseng and its yield quality improvement.