Soil Enzyme Activity and Physicochemical Properties of Tea Garden

Tianyu Li

, Lidan Mu

, Zhengjun Yang

, Chunhua Zhang

and Ruifang Wang

Pu’er University, Pu’er, Yunnan, 665000, China

Corresponding author

Keywords: Tea Garden, Soil Enzyme Activity, Fertilizer.

Abstract: Soil enzymes play an important role in material circulation and energy flow in ecosystems. In this study,

three tea plantations, without fertilizer, organic fertilizer and chemical fertilizer were carried out to

determine the activity of soil hydrogen peroxide enzyme and sucrose enzyme, and the physical and

chemical properties of soil (soil weight, soil moisture content, soil pH and soil temperature). The results

showed that the soil enzyme activity of fertilizer applied was the highest, and the soil enzyme activity

without fertilizer was the lowest. Soil enzyme activity is closely related to soil physical and chemical

properties, which is of great significance to improve the yield and quality of tea leaves.

1 INTRODUCTION

Soil microorganisms can have a significant effect on

enzyme activity. For example, cellulase, phosphatase

and urease are closely related to the content of

microorganisms. As the content of microorganisms

increases, their activities also increase. Nasegy used

root inoculation to change the genetic traits of

microorganisms, enhance the activities of

phosphatase and phosphonate esterase in soil, and

weaken the activities of enzymes such as glycosides

(Naseby 1998).

Soil moisture content, temperature (heat) and air

have significant effects on soil enzyme activity.

Enzyme activity is active in the case of relatively

high soil moisture but decreases when the soil is too

wet. The amount of pyrethroase in the mucous grain

with the temperature are negative correlation when

temperature at 25-60 ℃, soil temperature increased

to 70 ℃, enzyme activity increased, but the

temperature is higher than 70 ℃, the pyrethroase will

occur in a short period of time passivation

phenomenon. The enzyme becomes inactivated when

the temperature rises to 150 ℃ and heats up for a

day. Overrein found a correlation between enzyme

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activity and oxygen elements of pyrethroenes, which

are affected by air directness (Min 1978).

Soil pH has a great effect on the rate of enzyme

chemical reaction. Urease is most active in the pH

range of 6.5 to 7.0. Some enzymes, such as

deoxygenase and hydrogen peroxide enzyme, are

completely inactivated when the pH is lowered

below 5.0. Soil pH also affects urease protein

structure and smaller molecules such as amino group,

which changes enzyme activity. The lower the

acidity, the more enzymes the clay can absorb.

Urease can be adsorbed much in weak acid medium

than that in weak base medium.

The organic matter in soil can directly affect the

physical and chemical properties of soil. The

enzymes will be attached to the surface of organic

matter, some in humus complex, still active. Urease,

invertase and acid phosphatase are directly affected

by organic matter, N and P elements (Liu 2003). Fan

Jun found that the activities of urease and protease

increased with the increment of organic matter

content (Fan 2003).

The diameter and stability of soil aggregates were

closely related to enzyme activities. The enzyme

activity was higher in the smaller aggregate diameter.

Urease of umber soil and black soil mostly

accumulates in micro-reunion, which are the same

size as soil clay (Zhou 1980). In the soil solution,

only a small amount of soil enzymes, more soil

enzymes gathered on the clay surface. Protease and

urease are the same, mostly concentrated in soil clay.

734

Li, T., Mu, L., Yang, Z., Zhang, C. and Wang, R.

Soil Enzyme Activity and Physicochemical Properties of Tea Garden.

DOI: 10.5220/0011281000003443

In Proceedings of the 4th International Conference on Biomedical Engineering and Bioinformatics (ICBEB 2022), pages 734-738

ISBN: 978-989-758-595-1

Sprayed pesticides can enter the soil and affect

soil enzyme activity directly. Shen Biao found that

chlorobenzene, a substance in pesticides, can

stimulate urease activity. Dehydrogenase activity

decreased when chlorobenzene concentration was

increased (Shen 1997). Organochlorine pesticides,

the main component of which is HCH, can inhibit

hydrogen peroxide enzyme activity (Pang 2002). He

Wenxiang found that Insecticidal Dan inhibited

urease, oxidase activity and phosphatase (He 2002).

Different fertilization measures also effect

enzyme activity. The enzyme activity was more

active in the organic matter. Enzyme activity can be

enhanced with barnyard manure, but will be reduced

without fertilizer (He 2001). The application of

fertilizer can slightly enhance enzyme activity, and

the root metabolism accelerates, secretes more

substances, increases the growth rate of

microorganisms, enhances enzyme activity finally.

Soil fertility is a measure of the soil's ability to

provide a variety of nutrients needed for crop

growth. It is the comprehensive performance of

basic properties of soil, for agricultural production.

The application of different fertilizers affects the

level of soil enzyme activity, which plays a key role

in soil fertility and can reflect the soil productivity.

Therefore, the study on the soil enzyme activity in

tea garden is a basis for high quality and yield of tea

production, and provides theoretical guidance for tea

planting.

2 MATERIALS AND METHODS

2.1 Soil Samples

In order to take out soil samples randomly, five

sampling points were randomly set in the tea garden,

and about 10g of soil was taken out at a soil depth of

10cm for reserve. The soil was placed in sterile

bottles and marked.

2.2 Hydrogen Peroxide Enzyme

Weigh 5 grams of air-dried soil and put it in a 150

ml triangular flask with 5 ml of 0.3% hydrogen

peroxide solution and 40 ml of distilled water. The

same reagent was taken without soil sample as the

control group. Then the bottle was plugged tightly

with a cork and placed on a shaker. The rotation

speed was adjusted to 120r/min and the oscillation

time was 30min. After 30min, the bottle was taken

out. After opening the cork, 5mL of 1.5mol/L

sulfuric acid was immediately injected and filtered

with dense filter paper.

After filtration, 25mL of filtrate was taken out

and titrated with potassium permanganate solution

with a concentration of 0.002mol/L to reddish color.

The catalase activity was then calculated as

0.002mol/L ml of potassium permanganate solution

per gram of soil weight, which was the difference

between the control group and the soil-taking group.

Its calculation formula is as follows:

Soil hydrogen peroxide enzyme activity (mL

KMnO

/ g air-dried soil) =V / DWT

(V: 0.002mol / L KMnO

solution in mg (mL);

DWT: Air dried soil weight (g)

2.3 Sucrose Enzyme

The activity of sucrose enzyme was determined by

3, 5-dinitrosalicylic acid colorimetry. Using sucrose

as substrate, glucose is produced under the catalysis

of sucrose enzyme. 3, 5-dinitrosalicylic acid reacts

with glucose to form 3-amino-5-nitrosalicylic acid,

which has the maximum absorption value at 508 nm.

Configuration of glucose standard solution: add

an appropriate amount of distilled water to the

beaker, slowly add benzoic acid, and stir with a glass

rod until benzoic acid dissolves and a small amount

of crystals precipitate, to complete the preparation of

saturated benzoic acid solution. Then, 500 mg

glucose was weighed and dissolved in an appropriate

amount of benzoic acid solution, and 100 mL

volumetric flask was filled with benzoic acid

saturated solution for constant volume (5 mg/mL).

Weigh 0.45 g of air-dried soil into a 10 mL

centrifuge tube, add 1 mL phosphoric acid buffer

(pH=5.5) and 0.06 mL toluene, then add 3 mL 8%

sucrose solution, shake well, cover tightly, and place

in an incubator at 37 ℃ for one day. Then take out

the centrifuge tube, shake it well, centrifuge it for 5

min, and set the speed at 4000 r/min. After

centrifugation, remove 0.2 mL of the upper liquid

and add 20 mL to the glass tube. Injected 3,5-

dinitrocylic salicylic acid 0.5 mL in the glass tube,

immediately after the glass tube 5 min heated with

boiling water, after which the surface of the glass

tube with tap water washed 3 min, to achieve

cooling purposes. Then distilled water was used to

dilute the color liquid to 5 mL, and the

spectrophotometer was set at 508 nm for

colorimetry, and the light absorption value was

recorded.

Sucrose enzyme activity was expressed as mg of

glucose per unit of soil after one day

Glucose (mg) =100 × a

Soil Enzyme Activity and Physicochemical Properties of Tea Garden

735

(100 is the conversion unit; A: the number of mg of

glucose from the standard curve)

2.4 Soil Physical and Chemical

Properties

2.4.1 Soil Bulk Density

After measuring the quality of the ring knife, go to

the tea garden to take soil samples. Level the area

where the soil samples will be taken. After levelling,

vertically insert the ring knife into the soil, with one

end of the blade downward, until the soil column

reaches the upper end of the ring knife. Clean up the

soil around the ring knife with a shovel and then

remove the ring knife, remove the excess soil with a

soil cutting knife, cover the edge of the ring knife

with filter paper, and bring the bottom cover back to

the laboratory for future use. The soil bulk density

calculation formula is as follows:

Soil bulk density (g / cm

) = dry soil / ring knife

volume

Dry soil weight in ring knife (g) =100 wet soil

weight in ring knife /100 soil moisture content

2.4.2 Soil Moisture Content

Prepare aluminium boxes, and collect about 10 g of

soil samples. Open the lid of the box before putting

it into the oven. The oven temperature is set at 105

℃ and the drying time is 8 h. Then the aluminium

box was taken out and weighed, and then the

aluminium box was put into the oven to dry for 3 h

until the difference between the two weighing was

less than 0.05 g.

W % = (g1-g2) / (g2-g) ×100%

W: water content of soil (%), g: weight of

aluminium box (g), g1: weight of humidified soil in

aluminium box (g), g2: weight of aluminium box

plus dry soil (g)

2.4.3 Soil Ph

Weigh 20g of air-dried soil samples processed by

2mm aperture sieve and put them in a 50ml beaker,

add 20ml of distilled water, and stir the soil

suspension continuously for 5 minutes with a glass

rod. After the soil particles are fully dispersed, stand

for 30min for measurement. When measuring, the

pH meter is inserted into the beaker of the solution

to be measured, and the pH value of the soil sample

is recorded when the reading is stable. The pH meter

is removed, and the pH meter is washed with

distilled water to remove Carbon dioxide. Then, the

moisture can be dried with filter paper before the

measurement of the next soil sample.

2.4.4 Soil Temperature

Soil temperature was measured with a soil

thermometer every 2 h from 6:00 to 18:00, randomly

selected three points in the tea garden. Finally,

multiple values were analysed to obtain the soil

temperature of each tea field.

3 RESULTS AND ANALYSIS

3.1 Enzyme Activity

In Figure 1, hydrogen peroxide enzyme activities of

HS, SM and ZB were 1.89± 0.11, 3.27± 0.89 and

5.70± 1.77, respectively. It can be seen that

hydrogen peroxide enzyme activity of three types of

tea gardens have significant differences. The

hydrogen peroxide enzyme activity of the tea garden

with fertilizer was the strongest, while the enzyme

activity of the tea garden without any fertilizer was

the weakest, indicating that both fertilizer and

organic fertilizer could increase hydrogen peroxide

enzyme activity.

Figure 1: Hydrogen peroxide enzyme activity.

Figure 2: Sucrose enzyme activity.

Note: HS: tea fields treated without any fertilizer,

SM: tea fields treated with organic fertilizer, ZB: tea

1,89

3,27

5,7

HS SM ZB

Hydrogen peroxide

enzyme activity

1,16

1,46

1,81

0,5

1,5

2,5

HS SM ZB

Sucrose enzyme

activity

ICBEB 2022 - The International Conference on Biomedical Engineering and Bioinformatics

736

fields treated with chemical fertilizer; Data in the

figure were mean ± SD; N= 3; Different lowercase

letters indicate significant differences in soil enzyme

activity under different fertilizer application

conditions. Same as below for icon annotation).

In Figure 2, sucrose enzyme activity data were

0.49± 0.91, 0.75± 0.16 and 1.17± 0.07, respectively.

It can be seen both organic fertilizer and chemical

fertilizer can promote sucrose enzyme.

3.2 Soil Physicochemical Property

Table 1: Soi physicochemical properties of tea garden.

parameter HS SM ZB

Soil moisture (%) 17.3±3.05 31.3±1.53 26.67±3.22

Volume weight of soil (g/cm

) 4.66±0.20 3.86±0.16 4.23±0.11

Soil temperature℃ (0-10cm) 16.64±1.90 16.56±3.35 16.62±2.68

Soil temperature℃ (10-20cm) 17.23±2.02 17.07±2.73 16.68±2.38

Soil pH 5.41±0.15 5.74±0.09 5.06±0.18

It can be found that the highest soil water content

with organic fertilizer is 31.3 ± 1.53, and the lowest

soil water content with no fertilizer is 17.3 ± 3.05. In

terms of soil bulk density, the soil bulk density of

organic fertilizer treatment was significantly lower

than that of the other two treatments, which was 3.86

± 0.16. In terms of soil temperature, there was no

significant difference in soil temperature at the two

depths of the three plots, which were 16.64 ±

1.90℃, 16.56 ± 3.35℃ and 16.62 ± 2.68℃

respectively. From the point of view of soil pH

value, the weakest acidity of tea field without any

fertilizer was 5.74 ± 0.09, and the strongest acidity

was 5.06 ± 0.18 when fertilizer was applied.

4 DISCUSSION AND

CONCLUSIONS

Long-term application of organic fertilizer can

maintain and improve soil voidality, reduce soil bulk

density and increase soil surface water content. On

the contrary, long-term no fertilizer or only fertilizer

will cause poor soil voidality, soil bulk density

increases, resulting in soil compaction, reduce soil

water storage capacity. Long-term use of fertilizers

also acidifies the soil, reducing its pH. The results of

this experiment are similar to those of the above

studies. The soil bulk density of tea garden with

long-term application of organic fertilizer is

significantly lower than that of tea garden with long-

term application of chemical fertilizer and without

fertilizer, while the soil pH and soil water content

are significantly higher than those of the latter two

treatments.

It can be seen from the experimental data that the

activities of catalase and sucrase in the tea garden

with low soil bulk density are higher than those in

the back mountain without fertilizer. The activities

of catalase and sucrase were the strongest in the tea

field with chemical fertilizer, because the application

of chemical fertilizer had a significant effect on the

enzyme activity in the short term, but the long-term

application of chemical fertilizer had a negative

effect on the soil quality and enzyme activity. In the

experimental data, the enzyme activity was the

lowest in the plot with the highest temperature, and

increased in the plot with the lower temperature.

There were obvious differences in enzyme

activities in tea tree soil with different fertilizers, and

soil enzymes were closely related to soil fertility.

Chemical fertilizer can obtain more nutrients in the

short term and increase soil enzyme activity, so the

effect of chemical fertilizer treatment is the most

significant. However, long-term use of chemical

fertilizers is not conducive to the sustainable use of

soil.

Through the experimental data, it is concluded

that under the conditions of larger soil humidity,

moderate temperature, low soil bulk density and low

soil pH, it is conducive to the life and reproduction

of microorganisms, the increase of microbial

number, the increase of soil enzyme activity and the

growth of tea trees. The experiment was carried out

in the dry season and the plants were in a certain

water shortage condition. According to the

experimental data, the application of chemical

fertilizer or organic fertilizer can promote the

physiological activities of microorganisms and

increase the soil water content. So, in the dry season,

tea plants will not grow poorly because of the lack

of water or nutrients in the soil. Sufficient water

Soil Enzyme Activity and Physicochemical Properties of Tea Garden

737

retention capacity and active microorganism have

certain advantages for tea plant growth in dry

season, thus improving the yield and quality of tea in

spring next year.

ACKNOWLEDGEMENTS

This work was supported by the High-Level Talent

Introduction Project (k2015034) and Outstanding

Young Teacher Program (2020GGJS006) of Pu’ er

University.

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