Method for promoting rapid construction of acid soil aggregate by using green manure

Abstract

The invention discloses a method for promoting rapid construction of acid soil aggregates by using green manure, which comprises the following steps: the green manure is matched with a microbial inoculum to be applied into acid soil, the application amount of the green manure is 2g C kg <-1 > soil, the microbial inoculum is a microbial inoculum of a penicillium ZC1 strain, and the usage amount of the microbial inoculum is more than or equal to 5 * 10 < 9 > cfu of ZC1 bacteria per kilogram of soil. The method provided by the invention can quickly promote the formation of soil aggregates, improve the stability of the soil aggregates and improve the pH value of the soil at the same time. According to the method, a calcium-containing conditioner can be matched, the pH value is better improved, meanwhile, construction of the aggregate is not affected, and the aggregate improving effect is better. According to the method, the green manure can be effectively utilized to promote the improvement of the soil, the organic carbon content of the soil is not influenced while the construction of soil aggregates is rapidly promoted, the acid soil is greatly improved, and the method has a wide application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of soil acidification improvement, and in particular relates to a method for promoting rapid construction of acidic soil aggregates by utilizing green manure. Background Art

[0002] In the past, methods such as returning straw to the field were used to improve soil, which could increase soil organic matter and nutrient content, improve soil physical properties, and be beneficial to the growth and development of crop roots. However, straw decomposes slowly, and mixed grass seeds, insect eggs, and pathogens easily induce diseases and insect pests. Compared with other organic materials such as straw, green manure has the characteristics of low carbon-nitrogen ratio and fast microbial decomposition. After being applied to the soil, it decomposes and releases nutrients through mineralization, increasing soil organic matter, improving soil structure, and promoting nutrient circulation, ensuring stable and high yields of crops.

[0003] Soil aggregates are structural units formed by soil particles being aggregated together through various physical, chemical and biological processes. Soil aggregates are essential to the health and function of soil, and they affect the physical, chemical and biological properties of soil. The stability of aggregates directly affects the behavior of the water-soil interface in the soil surface, especially closely related to rainfall infiltration and soil erosion. Soil aggregates are porous and water-stable, which makes the solid, liquid and gas phases in the soil in a coordinated state. Therefore, aggregates are one of the signs of fertile soil.

[0004] Acidic soil has poor site conditions, shallow soil layers, poor soil aggregates and their stability, and has weaknesses such as acidity, thinness, and stickiness, which further leads to insufficient soil nutrient supply, especially a significant decrease in soil organic carbon, resulting in a serious decline in soil productivity and crop quality. Green manure is rich in nutrients and has a low carbon-nitrogen ratio, but its improvement on acidic soil is limited. Therefore, it is particularly important to promote the improvement of acidic soil by green manure, especially to promote the construction of soil aggregates, which is one of the signs of soil fertility. Summary of the invention

[0005] In view of this, one of the purposes of the present invention is to provide a method for promoting the rapid construction of acidic soil aggregates by using green manure, comprising applying green manure and bacterial agent into acidic soil, wherein the application amount of the green manure is 2 g Ckg -1 soil, the bacterial agent is a bacterial agent of Penicillium ZC1 strain, and the amount of the bacterial agent used is greater than or equal to 5×10 9cfu of ZC1 bacteria. The ZC1 strain has been deposited in the General Microbiology Center of China Microbiological Culture Collection Administration with the deposit number CGMCC No.40237 and the deposit date July 1, 2022. The deposit address is Institute of Microbiology, Chinese Academy of Sciences, No. 3, Yard 1, Beichen West Road, Chaoyang District, Beijing. The Penicillium agent can be prepared by the following method: streak culture of ZC1 bacteria on potato dextrose medium (PDA) at 28°C for 7 days; then pick a single colony and culture it in a PDA liquid medium on a shaker to make a bacterial solution, use a hemocytometer to determine the concentration of the bacterial solution, then centrifuge and discard the original culture medium, resuspend the bacteria in 1 / 10 PDA medium and adjust the concentration of the bacterial solution to be greater than 10 8 cfu / mL. The amount of green manure added was 2g C kg -1 soil, the amount added is equivalent to an average of 30,000 kg hm2 of green manure per year -2 The amount of fresh grass decomposition in the 0-20cm soil layer.

[0006] Preferably, the soil is purple soil or red soil, and the pH value is 5-5.5.

[0007] Preferably, the green manure is Vetch. Vetch needs preliminary processing, including collecting Vetch plants, first drying the fresh samples in an oven at 105°C for 30 minutes, then cooling to 60-70°C until drying, and crushing the plants to <0.25mm for subsequent experiments.

[0008] Preferably, the proportions of sand, silt and clay in the purple soil are 20.6%, 38.1% and 41.3% respectively, and the proportions of sand, silt and clay in the red soil are 25.8%, 45.4% and 28.8% respectively.

[0009] Preferably, the green manure applied to the soil is also combined with a calcium-containing conditioner.

[0010] Preferably, the calcium-containing conditioner is quicklime, and the amount used is 0.1% of the soil. The amount of quicklime used cannot be too high, otherwise it will affect the effect of ZC1 bacteria.

[0011] Preferably, the aggregates are water-stable aggregates.

[0012] The second purpose of the present invention is to provide the use of Penicillium ZC1 (preservation number: CGMCC No. 40237) in promoting the formation of soil aggregates. According to the present invention, experiments have found that Penicillium ZC1 has the effect of improving soil and promoting the formation of soil aggregates.

[0013] Preferably, the soil is acidic soil.

[0014] The present invention promotes the decomposition of green manure to improve acidic purple soil and red soil by collocation of Penicillium ZC1 bacterial agent. After a large number of experiments, it is verified that a method proposed by the present invention for promoting the rapid construction of acidic soil aggregates by using green manure can significantly improve the quality of soil aggregates, significantly improve stability, and significantly increase the proportion of soil>0.25mm water-stable aggregates; collocation of calcium-containing conditioners and bacterial agents not only promotes the formation of large soil aggregates, but also significantly improves the soil pH value. The method of the present invention effectively utilizes green manure to promote soil improvement. While rapidly promoting the construction of soil aggregates, the soil organic carbon content is not affected, the soil pH is also significantly improved, and the acidic soil is greatly improved, which has a wide range of application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The effects of calcium-containing conditioners and bacterial agents on the content of water-stable aggregates > 0.25 mm in acidic purple soil and red soil to promote green manure;

[0016] Figure 2 Effects of calcium-containing conditioners and bacterial agents on organic carbon content in acidic purple soil and red soil by promoting green manure;

[0017] Figure 3 Effects of calcium-containing conditioners and bacterial agents added to promote green manure on pH of acidic purple soil and red soil. DETAILED DESCRIPTION

[0018] The present invention will be described in detail below in conjunction with examples, which are merely illustrative and are not intended to limit the scope of application of the present invention. The present invention is not limited to the following embodiments or examples, and any modifications and variations that do not violate the spirit of the present invention should be included within the scope of the present invention.

[0019] 1. Material preparation

[0020] 1. Material name: green manure, calcium-containing conditioner, bacterial agent and soil. Among them, the green manure is Vetch, the calcium-containing conditioner is quicklime powder, the bacterial agent is Penicillium ZC1 bacterial agent (the ZC1 strain has been deposited in the General Microbiological Center of the China Microbiological Culture Collection Administration, with the deposit number CGMCC No.40237, the deposit date is July 1, 2022, and the deposit address is the Institute of Microbiology, Chinese Academy of Sciences, No. 3, No. 1 Beichen West Road, Chaoyang District, Beijing), and the soil is acidic purple soil and acidic red soil.

[0021] 2. Material preparation:

[0022] Vetch: Physical and chemical properties: organic carbon content 341.9 g·kg -1 , total nitrogen content 27.7g·kg -1Before the experiment, Vetch plants were collected and fresh samples were first sterilized in an oven at 105°C for 30 min, then cooled to 60-70°C until dried, and the plants were crushed to <0.25 mm for subsequent experiments.

[0023] Penicillium ZC1 inoculum: Penicillium grows well at 25-35℃, but growth is limited when the temperature exceeds 50℃. Penicillium ZC1 is streaked on potato dextrose medium (PDA) at 28℃ for 7 days. Then a single colony is picked and cultured in a PDA liquid medium on a shaking table to make a bacterial solution. The concentration of the bacterial solution is determined by a hemocytometer. After centrifugation, the original medium is discarded, and the bacteria are resuspended in 1 / 10 PDA medium and the concentration of the bacterial solution is adjusted to be greater than 10 8 cfu / mL, and obtained Penicillium ZC1 agent.

[0024] The test soils were acidic purple soil and acidic red soil: purple soil was collected from Jiangjin District, Chongqing (29°28′N, 105°49′E), and red soil was collected from Chuxiong Prefecture, Yunnan Province (24°30′N, 100°35′E). The soil in the 0-40 cm soil layer was collected, and the visible animal and plant remains were removed and naturally air-dried at room temperature. After being sieved through a 2 mm sieve, it was mixed and a portion was taken for the determination of basic physical and chemical properties of the soil, and the rest was used for the test. The basic physical and chemical properties of the test soils are shown in Table 1. The proportions of sand, silt and clay in the acidic purple soil were 20.6%, 38.1% and 41.3%, respectively, and the proportions of sand, silt and clay in the acidic red soil were 25.8%, 45.4% and 28.8%, respectively.

[0025] Table 1 Physical and chemical properties of the tested soil

[0026]

[0027]

[0028] 2. Experimental Methods

[0029] Application: Apply green manure, calcium-containing conditioner, and bacterial agent to the test soil. The application rate of green manure is 2 g Ckg -1 Soil, calcium conditioner added at 0.1% of the soil, bacterial agent added at 5×10 per kg of soil 9 cfu; the control group was CK without adding green manure, calcium-containing conditioner and bacterial agent. Five treatment groups were set up:

[0030] (1) CK: no material is applied;

[0031] (2) G: application of green manure;

[0032] (3) GL: Apply green manure with quicklime;

[0033] (4) GP: Apply green manure combined with Penicillium ZC1 fungicide;

[0034] (5) GLP: Apply green manure with quicklime and Penicillium ZC1.

[0035] Each treatment was repeated 3 times. The amount of green manure added was 2 g C kg -1 The soil was added and the added materials were mixed evenly in the soil to avoid the breakage of aggregates. In order to maintain a uniform condition, the soil of the control group was also subjected to the same operation. The soil-material mixture was gently placed in a culture bottle (250 mL) and the bulk density was controlled to be 1.2 g cm -3 , and then moisten the soil to 60% of the field water holding capacity. All culture bottles were kept in a 4°C incubator for 3 days to allow water balance under the condition of minimum soil microbial activity, and then transferred to a 25±2°C incubator for 56 days. During the entire incubation experiment, the culture bottles were weighed regularly and deionized water was added with a rubber-tipped dropper to control the soil moisture content. On days 0, 7, 14, 28 and 56, destructive sampling was performed to determine the dynamic changes in soil aggregates. The determination method is shown in the third part "Detection Method" below.

[0036] 3. Detection Method

[0037] 1. Determination and calculation of soil aggregates

[0038] The collected soil samples were placed on the top layer of the sieve group of the high-frequency vibrating sieve machine (2mm, 0.25mm and 0.053mm from top to bottom) for dry sieving for 5 minutes to separate air-dried aggregates of different particle sizes (>2mm, 0.25-2mm, 0.053-0.25mm, <0.053mm), which were weighed and recorded for later use. Aggregates of each level obtained by dry sieving were mixed into 50g aggregate mixed soil samples according to their mass percentage for wet sieving analysis. The wet sieving method was used to determine the water-stable aggregates. The well-proportioned soil sample (50g) was placed on the top layer of the sieve group (2mm, 0.25mm and 0.053mm from top to bottom), and four soil aggregates of particle sizes of >2mm, 0.25-2mm, 0.053-0.25mm and <0.053mm were separated. Wash each level of agglomerates on the sieve into a weighed aluminum box, then dry each component in an oven at 40°C to constant weight, cool to room temperature, weigh and store in a ziplock bag, and finally obtain four parts: sticky powder particles (<0.053mm), microaggregates (0.25-0.053mm), fine agglomerates (2-0.25mm), and coarse agglomerates (>2mm).

[0039] The stability of soil aggregates is described by two indicators: the mean weight diameter (MWD) of aggregates and the proportion of water-stable aggregates > 0.25 mm (WSA). The calculation method is as follows:

[0040] In the formula is the average diameter of the i-th particle size agglomerates (mm), and wi is the mass fraction of the i-th particle size agglomerates (%).

[0041] WSA=(Mr>0.25) / MT=1-(Mr<0.25) / MT, where Mr<0.25 is the weight of agglomerates with a particle size less than 0.25 mm (g), Mr>0.25 is the weight of agglomerates with a particle size greater than 0.25 mm (g), and MT is the total weight of agglomerates (g).

[0042] 2. Determination of soil organic carbon and pH

[0043] Determination of soil organic carbon content: Grind the naturally air-dried soil and pass it through a 100-mesh sieve. Use the potassium dichromate external heating method to determine the soil organic carbon content. Use the potentiometric method to determine the soil pH value.

[0044] IV. Experimental Results

[0045] 1. Soil water-stable aggregates

[0046] The average mass diameter of soil aggregates and the content of water-stable aggregates >0.25 mm are important parameters for characterizing the size distribution of soil aggregates. The larger the value, the higher the soil aggregation degree, and the stronger the structural stability and corrosion resistance.

[0047] The differences in aggregate size distribution of purple soil and red soil between different treatments are shown in Tables 2 and 3. Compared with CK, all treatments increased the mass fraction of soil aggregates of >2 mm and 0.25-2 mm. In purple soil, the content of macroaggregates (>0.25 mm) in G, GL, GP and GLP treatments increased in the first two weeks and stabilized in the following period. Among them, the content of macroaggregates (>0.25 mm) in GP and GLP treatments increased faster. The content of macroaggregates (>0.25 mm) of each treatment group at 7, 14, 28 and 56 days was added and averaged to obtain the average content of macroaggregates (>0.25 mm) of each treatment group. Compared with CK, the average content of macroaggregates (>0.25 mm) in G, GL, GP and GLP increased significantly by 74.3%, 92.0%, 98.4% and 109.9%, respectively ( Figure 1 Left). In red soil, the content of macroaggregates (>0.25 mm) in G, GL, GP, and GLP treatments increased in the first two weeks and stabilized in the following period. Similarly, the content of macroaggregates (>0.25 mm) in GP and GLP treatments increased faster. Compared with CK, the average content of macroaggregates (>0.25 mm) increased significantly by 27.6%, 33.1%, 49.0%, and 56.2%, respectively ( Figure 1Right). In both soils, the content of macroaggregates in all treatments containing green manure increased significantly. Among them, in the treatments GP and GLP with the addition of bacterial agents, the content of macroaggregates (>0.25 mm) increased faster and more, and the effect of GLP was better.

[0048] Table 2 Effects of different treatments on aggregate content of each particle size in purple soil

[0049]

[0050]

[0051] Note: At the four different particle size levels, different letters in a column indicate that there are significant differences in the percentage of aggregate content among different treatments, P<0.05.

[0052] Table 3 Effects of different treatments on the content of aggregates in different particle sizes of red soil

[0053]

[0054] Note: At the four different particle size levels, different letters in a column indicate that there are significant differences in the percentage of aggregate content among different treatments, P<0.05.

[0055] Table 4 shows the differences in the average weight diameter of aggregates in purple soil and red soil between different treatments. In purple soil and red soil, all treatments increased the average weight diameter of aggregates to varying degrees compared with CK. The average weight diameter peaked on the seventh day and remained relatively stable during the remaining culture time. Different treatments with green manure addition significantly increased the average weight diameter, showing a change of GLP>GP>GL>G>CK. In purple soil, the overall average weight diameter of aggregates in G, GL, GP and GLP treatments (average of the average weight diameters on days 7, 14, 28 and 56) increased significantly by 48.3%, 61.4%, 66.9% and 77.2% compared with CK. In red soil, the overall average weight diameter of aggregates in G, GL, GP and GLP treatments increased significantly by 21.0%, 24.2%, 39.3% and 43.8% compared with CK.

[0056] In summary, soil agglomeration can occur quickly within a short time after adding organic materials, and the addition of microbial agents has a significant promoting effect on the formation of soil aggregates. Moreover, when calcium-containing conditioners are added on the basis of microbial agents, the aggregate formation effect is more obvious.

[0057] Table 4 Effects of different treatments on the average weight diameter (mm) of purple soil and red soil

[0058]

[0059] Note: At the four different particle size levels, different letters in a column indicate that there are significant differences in the average weight diameters of aggregates among different treatments, P<0.05.

[0060] 2. Soil organic carbon content

[0061] Figure 2 Organic carbon content of purple soil and red soil between different treatments. After 7-56 days of cultivation, all treatments increased soil organic carbon content to varying degrees compared with CK, but there was no significant difference among treatment groups, indicating that calcium-containing conditioners and bacterial agents had no obvious effect on the organic carbon content of soil with green manure. Even in red soil, the organic carbon content of GL and GLP was slightly lower than that of other treatments, indicating that the promotion of soil aggregates was not promoted by organic matter.

[0062] 3. Soil pH

[0063] Figure 3 The pH values ​​of purple soil and red soil under different treatments are shown in Table 1. Soil pH can directly characterize the intensity of soil active acid. When green manure was not applied, the pH of purple soil was 5.04 (the data is the average value of 7-56 days, the same below), and the pH of red soil was 5.31. Green manure significantly increased the pH of soil. In purple soil, the pH of GLP and GL treatments was the highest, which was significantly increased by 21.6% and 18.7% compared with CK, followed by GP and G treatments, which increased by 8.9% and 6.0%, respectively. In red soil, the pH of GL and GLP treatments was the highest, which was significantly increased by 13.7% and 13.0% compared with CK, followed by GP and G treatments, which increased by 6.2% and 5.1%, respectively. This shows that green manure can increase the pH value of acidic purple soil and red soil, and can better reduce soil acidity when combined with calcium-containing conditioners and bacterial agents, especially when combined with calcium-containing conditioners, which effectively neutralizes soil acidity and significantly increases soil pH.

[0064] In summary, it shows that green manure Vetch can promote the formation of soil aggregates, promote the increase of soil organic carbon content, and promote the increase of soil pH. Penicillium ZC1 inoculant can make the soil aggregates of the soil added with green manure Vetch better and faster, but because it has no obvious effect on the content of organic carbon, it shows that Penicillium ZC1 specifically promotes the formation of soil aggregates and thus improves the soil structure. In addition, the addition of calcium conditioner, calcium conditioner and Penicillium ZC1 have a better effect of promoting the formation of soil aggregates and improving the soil pH.

[0065] The conventional techniques and schemes not described in detail in the above embodiments are well known in the art, so they will not be described in detail here. The above experimental examples describe the preferred embodiments of the present invention in detail, but the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, the technical scheme of the present invention can be subjected to a variety of simple modifications, and these simple modifications all belong to the protection scope of the present invention.

Claims

1. A method for promoting the rapid construction of acidic soil aggregates using green manure, characterized in that: The method comprises applying green manure and bacterial agent to acidic soil, wherein the amount of green manure applied is 2 g C kg -1 soil, the bacterial agent is a bacterial agent of Penicillium ZC1 strain, and the amount of the bacterial agent used is greater than or equal to 5×10 9 cfu of ZC1 bacteria; the preservation number of the Penicillium ZC1 strain is CGMCC No.40237.

2. The method according to claim 1, characterized in that The soil is purple soil or red soil, and the pH value is 5-5.

5.

3. The method according to claim 1, characterized in that The green manure is Vetch.

4. The method according to claim 2, characterized in that The proportions of sand, silt and clay in the purple soil are 20.6%, 38.1% and 41.3% respectively, and the proportions of sand, silt and clay in the red soil are 25.8%, 45.4% and 28.8% respectively.

5. The method according to claim 1, characterized in that Green manure applied to the soil is also combined with calcium-containing conditioners.

6. The method according to claim 5, characterized in that The calcium-containing conditioner is quicklime, and the usage amount is 0.1% of the soil.

7. The method according to any one of claims 1 to 6, characterized in that: The aggregates are water-stable aggregates.

8. Use of Penicillium ZC1 in promoting soil aggregate formation, characterized in that: The deposit number of the Penicillium ZC1 strain is CGMCC No.40237.

9. The use according to claim 8, characterized in that The soil is acidic soil.

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