Changes characteristics of
soil microbial biomass carbon,nitrogen and enzyme activity of Panax
notoginseng under optimal management of water and fertilizer
Tuo Yunfei1,Liu Xiangning1,Zheng
Yang1,Wang Qian1,Wang
Fei1,Wang Zhaoyi1,Shi
Xiaolan1,Ding Mingjing1,
Shen Fangyuan1,Xiang Ping1,Yang
Qiliang2
College of Ecology and Environment, Southwest Forestry
University, Kunming 650224
2.College of Modern Agricultural Engineering, Kunming University
of Science and Technology, Kunming 650500)
Corresponding author: Tuo Yunfei,College of Ecology and
Environment,Southwest Forestry University,Kunming,650224,China,
086+13888939641.
Abstract: 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-1 and from 14.98 to 66.21
mg.kg-1, respectively, and soil sucrose enzyme
activity was the largest, ranging from 17.12 to 68.79
mg.kg-1.d.-1. 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-1 and 39.52
mg.kg-1 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.
Keywords: Panax notoginseng;Optimal management of water and
fertilizer;Microbial biomass of Carbon and Nitrogen; Soil enzyme
activity.
Soil microbial biomass (SMB), an active component of soil organic
matter, plays a key role in the regulation of soil ecosystem and its
function, serving as one of the most important biological indicators for
the evaluation of the soil comprehensive quality(Raiesi et
al.,2015;Evangelou et al.,2021).Soil MBC and MBN determine soil
fertility and are important source of soil organic carbon and available
nitrogen (Yu et al.,1999;Zhou et al.,2002). Soil enzyme activity is
derived from soil microorganisms and plant root exudates and is
sensitive to different fertilization responses(Yang et al.,2020). It is
very active in soil ecosystems(Luo et al.,2014;Hill et al.,2012) and
plays a vital role in nutrient cycling (nitrogen fixation, phosphorus
adsorption and desorption, and potassium release, etc.) as well as in
soil structure maintenance and crop yield(Burns et al.,2013;Zhao et
al.,2016). It is a comprehensive soil fertility biological index(Zhang
et al.,2015).As a catalyst for soil organic matter decomposition and
nutrient conversion cycling, soil enzyme has a close relationship with
soil nutrient content and microbial biomass carbon and nitrogen(Wang et
al.,2016). Soil comprehensive fertility is determined by soil microbial
biomass carbon and nitrogen and enzyme activity.
Fertilization and irrigation had significant effects on soil microbial
biomass C and N and enzyme activity. The research by Jiang et al. showed
that irrigation improved soil enzyme activity(Wang et al.,2017;Calderon
et al.,2016), and the research on soil microbial characteristics, soil
enzyme activity, and nutrient regulation in water-saving irrigation
winter wheat fields by Ye Deling et al. showed that soil microbial
characteristics and soil enzyme activity were regulated by irrigation
and were closely related to the cyclic transformation of soil C and N
nutrients(Ye et al.,2016). Li et al. found that nitrogen application
significantly increased soil MBC and MBC: MBN(Li et al.,2018). Xu et al.
studied the effects of fertilization on soil organic carbon (SOC)
content, soil microbial biomass carbon (SMC), and soil microbial biomass
nitrogen (SMN) and found that the yields of early and late rice treated
with 30% organic matter +70% inorganic fertilizer, 60% organic matter
+40% inorganic fertilizer and straw+inorganic fertilizer were higher
than those of the early and late rice treated with inorganic fertilizer
or no fertilizer(Xu et al.,2017). HAO et al. studied the effects of
long-term application of inorganic fertilizer and organic fertilizer on
the organic matter and microbial biomass of three subtropical rice soil,
and the results showed that the mixed application of inorganic
fertilizer with manure or straw improved the organic matter and
microbial biomass of the subtropical paddy soil(Hao et al.,2008). Bach
E.M. et al. showed that the microbial activity in the fertilized
grassland was higher than that in the non-fertilized soil, and the
addition of nitrogen in the fertilized grassland enhanced the soil
microbial biomass and enzyme activity(Bach et al.,2015).
There have been many studies on the effects of various farmland
management methods on soil microbial biomass C-N and enzyme activities,
but none have been quantitative.Particularly, Notoginseng, a medicinal
plant, has not received much study. The interaction of water and
fertilizer has little effect on the rhizosphere secretion of Panax
notoginseng and soil microbial biomass C-N and enzyme activities,
thereby affecting the farmland soil microbiological properties of Panax
notoginseng. At the moment, research on the interaction of water and
fertilizer is primarily focused on regulating the improvement of soil
saline-alkali land in dryland farmland in the north, as well as crop
yield and quality(Li et al.,2016;Zheng et al.,2020). Panax notoginseng
research is primarily focused on single factors such as cultivation
mode,continuous cropping obstacle of Panax notoginseng, accumulation and
adsorption of heavy metals in soil,and fertilizer element ratio(Tang et
al.,2020). Few studies have been conducted to investigate the effects of
optimal water and fertilizer management on soil microbial biomass C and
N and enzyme activities of Panax notoginseng, as well as the regulation
of the combination of irrigation and fertilization on plant growth,
yield, and quality of Panax notoginseng. Soil microbial biomass C-N and
enzyme activities characterized soil fertility. It was determined that
optimal water and fertilizer management was conducive to the growth,
yield, and quality improvement of Notoginseng by investigating the soil
microbial biomass C-N and enzyme activities under optimal water and
fertilizer management. In this study, a randomized zonal experimental
design with different water and fertilizer interactions was used to
optimize the management of Panax notoginseng through three years of
growth from 2018 to 2020. In this experiment, the effect of different
water and fertilizer management on soil microbial carbon, nitrogen and
enzyme activities of Panax notoginseng was analyzed, and the mechanism
of this management on soil microbial carbon, nitrogen and enzyme
activity response was investigated. The results can provide technical
support for the efficient use and management of water and fertilizer in
Panax pseudoginseng farmland, as well as important practical
significance for guiding the high yield and quality cultivation of Panax
notoginseng.
1 Materials and methods
Test design and sample collection
The experiment was conducted in the typical planting area of Panax
notoginseng in Dali Shu Village, luxi county City, Honghe Prefecture,
Yunnan Province from 2018 to 2020. The growth period of Panax
notoginseng was divided into the rooting period (November~January of
the following year), the seedling period (February~April), the
flowering period (May~July), and the fruiting period (August~October).
Panax notoginseng was covered with a double-layer sun-shading net. To
avoid the influence of natural rainfall on irrigation amount, plastic
film was used to cover and discharge the rainfall, and the excess
rainfall was timely discharged from the test area. Micro-sprinkler
irrigation fertilization was adopted. Irrigation and fertilization were
conducted simultaneously once a month. The fertilizer was soluble
organic fertilizer. The micro-sprinkler flow was controlled according to
the experimental design to meet the design criteria for fertilization
and irrigation in different plots.According to the high-yield and
high-efficiency fertigation system for planting Panax notoginseng in the
local area, two factors (F) and (W) were applied in the experiment. The
former includes four levels, namely, F1(3.20kg/667m2),
F2(4.80kg/667m2), F3(6.20kg/667m2),
and F4 (8.00 kg/667 m2); The latter three levels were
W1(40% field water holding capacity),W2(60% field water holding
capacity) and W3(80% field water holding capacity), one control. A
total of 13 treatments were set, which were W1F1, W1F2, W1F3, W1F4,
W2F1, W2F2, W2F3, W2F4, W3F1, W3F2, W3F3, W3F4 and CK, respectively. CK
was the no-fertilization and no-irrigation control. Each processing
three repeat, each community 16.70m long,1.50m wide, ditching ridging
before planting, the groove depth of 30cm, the groove width of 40cm, to
ensure that the water is not leaking, not diffuse groove, such as
regular weed field management measures.
The sampling was conducted on the third day after irrigation and
fertilization in December of each year, March, June, and September of
the following year from 2018 to 2020. During the experiment, a 1m×1m
sampling point was set in each residential area to remove soil surface
litter and gravel around the sampling point at the sampling depths of
0~20~40cm and 20~40 cm, respectively. The soil samples
were put into a self-sealing bag for labeling, sealed and stored, and
then taken back to the laboratory. The fresh soil sample was divided
into two parts. One part was used to measure soil water content and
microbial carbon and nitrogen content. The other part was spread on
kraft paper and air-dried naturally to remove roots, leaves, and gravel.
Soil enzyme activity was tested after grinding and sieving. The
German-American water-soluble organic fertilizers with N≥21%,
P2O5≥21%、K2O≥21%,
humic acid ≥6%, B≥0.1%, and Mo≥0.007% were selected. The basic
physical and chemical properties of the soil before the test are shown
in Tab.1.