Application of biochar and phosphate-solubilizing bacteria in the improvement of acid low available phosphorus soil

Abstract

The application provides application of phosphate-solubilizing bacteria SIP-2 combined with pig manure biochar in improving acid low-effective phosphorus soil, and belongs to the technical field of soil improvement. The application provides application of phosphate-solubilizing bacteria SIP-2 combined with pig manure biochar in improving acid low-effective phosphorus soil, and the preservation number of the phosphate-solubilizing bacteria SIP-2 is CGMCC No.41935. The application further provides a soil improver comprising the phosphate-solubilizing bacteria SIP-2 and pig manure biochar. The phosphate-solubilizing bacteria SIP-2 and pig manure biochar are combined for use in the application to play a synergistic effect, which not only realizes degradation of inorganic phosphorus-containing minerals in soil to improve soil phosphorus availability, but also simultaneously improves soil pH, soil organic matter content and soil available potassium content, and further reduces soil bulk density and inhibits soil-borne pathogenic bacteria, so that the application can effectively alleviate acidification and nutrient deficiency problems of weak acid soil in the south, and the improvement effect is remarkable.

Description

Technical Field

[0001] This invention belongs to the field of soil improvement technology, specifically relating to the application of phosphorus-solubilizing bacteria SIP-2 combined with pig manure biochar in improving acidic soils with low available phosphorus. Background Technology

[0002] In southern my country, weakly acidic soils are subject to multiple obstacles, including soil structure degradation, increased acidification, rapid mineralization and low accumulation of organic matter, severe fixation of available phosphorus, and a high proportion of low- and medium-yield fields. These factors include abundant rainfall with uneven spatial and temporal distribution, steep mountain slopes, long-term monoculture, and excessive application of chemical fertilizers.

[0003] Currently, pig manure is mostly disposed of through open-air dumping or simple composting, which not only releases large amounts of greenhouse gases and harmful substances such as methane, ammonia, and hydrogen sulfide, exacerbating air pollution and the greenhouse effect, but also causes nitrogen and phosphorus nutrient runoff loss and the risk of pathogen spread. Furthermore, pig manure is rich in organic matter, heavy metal residues, and antibiotics; its natural decomposition cycle is long and the humus conversion rate is low. Direct application to the field can easily cause seedling burn, soil-borne diseases, and groundwater pollution, failing to meet the sustainable development needs of farmland ecological cycles and soil fertility. The application of agricultural microbial agents can increase soil biodiversity, improve the soil environment, and promote nutrient activation and utilization; however, existing agents have varying adaptability to different soil types, and without a carrier, they are prone to failure to colonize in the soil. Therefore, developing a microbial agent suitable for the weakly acidic soil environment of southern my country that can promote the colonization of phosphate-solubilizing bacteria is of great significance for overcoming the challenges of degraded soil structure, low organic matter content, severe lack of available phosphorus, and weak acidity in southern weakly acidic soils, and for realizing the resource utilization of straw. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide the application of phosphate-solubilizing bacteria SIP-2 combined with pig manure biochar in improving acidic soils with low available phosphorus. It can significantly increase soil pH, available phosphorus, available potassium, organic matter and alkaline nitrogen content, reduce soil bulk density and inhibit soil-borne pathogens, effectively alleviate the problem of nitrogen, phosphorus and potassium deficiency in weakly acidic soils, provide technical support for green agricultural development, and has broad application prospects.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides the application of phosphate-solubilizing bacteria SIP-2 combined with pig manure biochar in improving acidic soils with low available phosphorus. The preservation number of the phosphate-solubilizing bacteria SIP-2 is CGMCC No.41935.

[0006] The present invention also provides the application of SIP-2 phosphorus-releasing bacteria combined with pig manure biochar in any of the following: (1) increasing soil pH; (2) increasing soil organic matter content; (3) increasing soil available nitrogen content; (4) reducing soil bulk density; (5) increasing soil available potassium content; (6) increasing soil available phosphorus content; (7) inhibiting soil-borne pathogens.

[0007] Preferably, the method for preparing pig manure biochar includes the following steps: using pig manure as raw material, carbonizing it in an inert gas N2 environment; the pyrolysis temperature of the carbonization is 600℃, the heating rate is 15℃ / min, and the temperature is kept constant at 600℃ for 45 min.

[0008] The present invention also provides a soil conditioner, comprising phosphate-solubilizing bacteria SIP-2 or phosphate-solubilizing bacteria SIP-2 inoculum, and pig manure biochar.

[0009] Preferably, when the phosphate-solubilizing bacteria SIP-2 inoculum is a bacterial suspension, the bacterial concentration of the suspension is 1×10⁻⁶. 7 CFU / mL or higher.

[0010] Preferably, the preparation method of the phosphate-solubilizing bacteria SIP-2 agent includes the following steps: inoculating the phosphate-solubilizing bacteria SIP-2 into LB medium, culturing, and collecting the bacterial cells.

[0011] Preferably, the method for preparing pig manure biochar includes the following steps: using pig manure as raw material, carbonizing it in an inert gas N2 environment; the pyrolysis temperature of the carbonization is 600℃, the heating rate is 15℃ / min, and the temperature is kept constant at 600℃ for 45 min.

[0012] The present invention also provides the application of the above-mentioned soil conditioner in any of the following: (1) increasing soil pH; (2) increasing soil organic matter content; (3) increasing soil available nitrogen content; (4) reducing soil bulk density; (5) increasing soil available potassium content; (6) increasing soil available phosphorus content; (7) inhibiting soil-borne pathogens.

[0013] The present invention also provides a method for improving acidic soil with low available phosphorus, including the step of adding the above-mentioned soil conditioner.

[0014] Preferably, after applying the pig manure biochar, the phosphate-solubilizing bacteria SIP-2 are applied in combination; the application rate of the pig manure biochar is 2-20 tons / hectare, and the application rate of the phosphate-solubilizing bacteria SIP-2 is 2×10⁻⁶. 10 The ratio of CFU / kg pig manure biochar and the application of pig manure biochar.

[0015] The beneficial effects of this invention are: This invention combines pig manure biochar with phosphate-solubilizing bacteria SIP-2. Even in acidic soil, the strain can still function efficiently under the condition of pig manure biochar application, solving the problem of low activity and difficulty in colonization of existing bacterial agents in acidic soil, and is highly targeted.

[0016] The combination of the phosphate-solubilizing bacterium SIP-2 and pig manure biochar in this invention has a synergistic effect, which not only degrades inorganic phosphorus-containing minerals in the soil to improve soil phosphorus availability, but also increases soil pH, soil organic matter content and soil available potassium content. It can also reduce soil bulk density and inhibit soil-borne pathogens, effectively alleviate the acidification and nutrient deficiency problems of weakly acidic soil in the south, and has a significant improvement effect. Attached Figure Description

[0017] Figure 1 This is a graph showing the relative abundance differences of the genus *Trichoderma* in potted soil. Different lowercase letters on the columns indicate... p <0.05.

[0018] Figure 2 This graph shows the pH, SOM (solid matter), and available nitrogen content of the potted soil at 60 days. Different lowercase letters on the columns represent... p <0.05.

[0019] Figure 3 This graph shows the bulk density, available potassium, and available phosphorus content of potted soil at 60 days. Different lowercase letters on the columns represent... p <0.05.

[0020] Figure 4 This figure shows the relative abundance differences of Fusarium species in potted soil.

[0021] Figure 5 The image shows the aboveground weight of pak choi at harvest time after 60 days. Different lowercase letters on the columns indicate... p <0.05.

[0022] Figure 6 This is a graph showing the growth of potted bok choy at 60 days.

[0023] Biological Preservation Information The phosphate-solubilizing bacterium SIP-2 mentioned in this invention was deposited on May 13, 2025, at the China General Microbiological Culture Collection Center (CGMCC), Institute of Microbiology, Chinese Academy of Sciences, No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, with accession number CGMCC No. 41935, and taxonomically named *Trichoderma reesei*. Trichoderma reesei . Detailed Implementation

[0024] This invention provides the application of phosphate-solubilizing bacteria SIP-2 combined with pig manure biochar in improving acidic soils with low available phosphorus. The phosphate-solubilizing bacteria SIP-2 is classified as *Trichoderma reesei*. Trichoderma reesei It is deposited at the China General Microbiological Culture Collection Center (CGMCC) with accession number CGMCC No. 41935 and deposit date of May 13, 2025.

[0025] The phosphate-solubilizing bacterium SIP-2 provided by this invention is a phosphate-solubilizing fungus isolated and screened from acidic red soil. It is adaptable to acidic environments and possesses a high efficiency in dissolving inorganic phosphorus, achieving a phosphorus solubilization efficiency of up to 75.6 mg / L / d in the Mongkina inorganic phosphorus medium. The Mongkina inorganic phosphorus medium consists of: glucose 10.0 g / L, (NH4)2SO4 0.5 g / L, NaCl 0.3 g / L, KCl 0.3 g / L, MgSO4·7H2O 0.3 g / L, FeSO4·7H2O 0.03 g / L, MnSO4·4H2O 0.03 g / L, and Ca3(PO4)2 10.0 g / L. This phosphate-solubilizing bacterium not only has a high efficiency in dissolving inorganic phosphorus, but also increases soil organic matter content, increases soil alkaline nitrogen content, and reduces soil bulk density.

[0026] This invention also provides the application of SIP-2 phosphorus-releasing bacteria combined with pig manure biochar in any of the following: (1) increasing soil pH; (2) increasing soil organic matter content; (3) increasing soil available nitrogen content; (4) reducing soil bulk density; (5) increasing soil available potassium content; (6) increasing soil available phosphorus content; (7) inhibiting soil-borne pathogens. In this invention, the soil is preferably acidic soil, more preferably acidic soil in southern my country.

[0027] In this invention, the preferred method for preparing pig manure biochar includes the following steps: using pig manure as raw material, carbonizing it in an inert gas N2 environment; the pyrolysis temperature of the carbonization is 600℃, the heating rate is 15℃ / min, and the temperature is kept constant at 600℃ for 45 min.

[0028] This invention does not specifically limit the source of pig manure. After carbonization, it is preferable to cool to room temperature, then grind and sieve, with a preferred sieve mesh size of 20 mesh. This invention does not specifically limit the grinding method; conventional grinding methods in the field are acceptable. This invention prepares biochar from pig manure through pyrolysis for application in the field. The pig manure biochar prepared by this invention has a rich porous structure and a stable carbon skeleton, capable of adsorbing and fixing heavy metals and antibiotics, reducing environmental risks, while simultaneously increasing soil organic carbon content, improving topsoil permeability and water and fertilizer retention capacity. This is of great significance for realizing the resource utilization of livestock waste, slowing down farmland soil degradation, and ensuring green agricultural development. Furthermore, the phosphate-solubilizing bacteria SIP-2 of this invention has mild cultivation conditions, high feasibility for large-scale production, low application cost, and is easy to promote and use, showing broad application prospects.

[0029] The present invention also provides a soil conditioner, comprising phosphate-solubilizing bacteria SIP-2 or phosphate-solubilizing bacteria SIP-2 inoculum, and pig manure biochar.

[0030] In this invention, when the phosphate-solubilizing bacteria SIP-2 inoculum is a bacterial suspension, the bacterial concentration of the suspension is preferably 1×10⁻⁶. 7 CFU / mL or higher. The solvent for the bacterial suspension is preferably water. In this invention, the preferred method for preparing the phosphate-solubilizing bacteria SIP-2 agent includes the following steps: inoculating the phosphate-solubilizing bacteria SIP-2 into LB medium, culturing, and collecting the bacterial cells. In this invention, the preferred composition of the LB medium is: 10 g / L tryptone, 5 g / L yeast extract, and 10 g / L sodium chloride. In this invention, the preferred culturing temperature is 30°C, the preferred culturing speed is 180 rpm, and the preferred culturing time is to OD (out of 100°C). 600 Approximately 1 is sufficient. In this invention, after cultivation, the bacterial cells are preferably collected by centrifugation. The preferred centrifugation conditions are 25°C and 6000 rcf, where rcf refers to relative centrifugal force, measured in grams. After collecting the bacterial cells, they are preferably resuspended in water to obtain a liquid phosphate-solubilizing bacterial agent.

[0031] In the soil conditioner provided by this invention, pig manure biochar, as a carbon-rich porous material, can improve the soil aggregate structure, increase porosity, and enhance aeration and water permeability. At the same time, it adsorbs and slowly releases phosphorus and potassium nutrients and reduces leaching. The phosphorus-solubilizing bacteria SIP-2 applied in combination can synergistically activate insoluble phosphorus in the soil, increase soil pH and organic matter content, and reduce soil bulk density. This is crucial for alleviating the lack of available phosphorus in weakly acidic soils in the south, improving the quality of arable land, and buffering the degradation of weakly acidic soils.

[0032] This invention also provides the application of the above-mentioned soil conditioner in any of the following: (1) increasing soil pH; (2) increasing soil organic matter content; (3) increasing soil available nitrogen content; (4) reducing soil bulk density; (5) increasing soil available potassium content; (6) increasing soil available phosphorus content; (7) inhibiting soil-borne pathogens. Verification showed that after 60 days of application of the soil conditioner provided by this invention, the pH increased by 1.43 compared to the control group, the available phosphorus content increased by 976.2%, the available potassium content increased by 183.7%, and the organic matter content increased by 129.0%, effectively alleviating the acidification and nutrient deficiency problems of weakly acidic soils in southern regions, with significant improvement effects. In this invention, the preferred soil-borne pathogens include Fusarium.

[0033] This invention also provides a method for improving acidic soils with low available phosphorus, including the step of adding the aforementioned soil conditioner. In the method provided by this invention, it is preferred that the pig manure biochar is applied followed by the application of the phosphate-solubilizing bacteria SIP-2; when applied in the field, the preferred application rate of the pig manure biochar is 2-20 tons / hectare, more preferably 5-15 tons / hectare, and the preferred application rate of the phosphate-solubilizing bacteria SIP-2 is 2 × 10⁻⁶ tons / hectare. 10 The ratio of CFU / kg pig manure biochar and the application of pig manure biochar are important considerations. When applying to potted plants, it is preferable to add 100 g of pig manure biochar (5% by weight) to 2 kg of soil and mix thoroughly. Then, pour 200 mL of SIP-2 phosphate-solubilizing bacteria solution onto the surface. The optimal number of viable bacteria in the 200 mL SIP-2 solution is 2 × 10⁻⁶. 9 CFU or above.

[0034] The soil conditioner and method for improving acidic soil with low available phosphorus provided by this invention can also improve the growth performance of crops, with Chinese cabbage being a preferred crop.

[0035] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0036] Unless otherwise specified, the following embodiments are all conventional methods.

[0037] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0038] The culture medium preparations in the following examples: The modified Martin's medium consisted of: 5.0 g / L tryptone, 1.0 g / L K2HPO4, 0.5 g / L MgSO4·7H2O, 20.0 g / L glucose, and 2.0 g / L yeast extract. The composition of LB medium is: 10 g / L tryptone, 5 g / L yeast extract and 10 g / L sodium chloride; The above two are liquid culture media. When preparing the corresponding solid culture media, simply add 15 g / L of agar.

[0039] Example 1 Preparation of SIP-2 phosphate-solubilizing bacterial culture: Phosphate-solubilizing bacteria SIP-2 with preservation number CGMCC No. 41935 was inoculated into LB medium and cultured at 30℃ and 180 rpm until OD. 600 Approximately 1. After incubation, the bacterial precipitate was collected by centrifugation at 25°C and 6000 rcf, and resuspended in sterile water to obtain the SIP-2 phosphate-solubilizing bacterial suspension.

[0040] Example 2 Preparation of pig manure biochar: Using pig manure as raw material, under an inert gas N2 environment, the pyrolysis temperature was set at 600℃, the heating rate was 15℃ / min, and the temperature was maintained at 600℃ for 45 min. After cooling to room temperature, the obtained biochar was ground and sieved with a sieve mesh size of 20 mesh to obtain pig manure biochar.

[0041] Example 3 A soil conditioner is composed of phosphate-solubilizing bacteria SIP-2 with accession number CGMCC No. 41935 and pig manure biochar obtained in Example 2.

[0042] Example 4 A soil conditioner is composed of the phosphate-solubilizing bacteria SIP-2 solution obtained in Example 1 and the pig manure biochar obtained in Example 2.

[0043] Example 5 Colonization verification of phosphate-solubilizing bacterium SIP-2 with accession number CGMCC No. 41935 The experiment was divided into the following four groups: Group CK: This group does not contain either the SIP-2 phosphate-solubilizing bacterial solution obtained in Example 1, nor the pig manure biochar obtained in Example 2.

[0044] MB group: Uninfected pig manure biochar group, in which soil is mixed evenly with 5% by weight of pig manure biochar (the pig manure biochar was prepared in Example 2).

[0045] MBP group: After mixing the soil with 5% (by weight) of pig manure biochar (obtained from Example 2), 200 mL of the phosphate-solubilizing bacteria SIP-2 solution obtained in Example 1 was poured over the surface (the effective viable count in the 200 mL solution was 2 × 10⁻⁶). 9 CFU).

[0046] Group P: 200 mL of the phosphate-solubilizing bacteria SIP-2 solution obtained in Example 1 was poured onto the surface of the soil (the effective viable count in the 200 mL solution was 2 × 10⁻⁶). 9 CFU).

[0047] After the above four groups of soils were placed for 60 days, soil samples were collected, total DNA was extracted from the soil, and high-throughput sequencing was performed after PCR amplification of the ITS region to compare and analyze the soil fungal community structure.

[0048] The results for the genus Trichoderma are as follows: Figure 1 As shown, in the MBP treatment group (pig manure biochar combined with phosphate-solubilizing bacteria SIP-2 group), Trichoderma ( Trichoderma The significantly increased relative abundance of fungi demonstrates that 5% pig manure biochar, acting as a carrier or regulatory factor, can significantly induce and promote phosphate-solubilizing bacteria. Trichoderma reesei Highly efficient colonization of SIP-2.

[0049] Example 6 Determination of the effects of pig manure biochar (prepared in Example 2) combined with phosphate-solubilizing bacteria (obtained in Example 1) on promoting the growth of Chinese cabbage and improving soil conditions. Pot experiment setup: Southern slightly acidic soil with minimal human impact was selected. Each polyethylene cultivation pot (20cm in diameter, 15cm in height) was precisely filled with 2 ± 0.01 kg of sieved (2 mm) soil to remove impurities. Pig manure biochar mixed with phosphate-solubilizing bacteria inoculant was mechanically mixed with the soil, and deionized water was added to 60% of field capacity. (Chinese bok choy) Brassica chinensis L.) seeds were surface-sterilized with 30% H2O2 solution for 5 min, rinsed 5 times with sterile deionized water, and 12 seeds were sown in each pot. After germination, 4 seedlings of the same growth rate were left in each pot. Soil moisture was dynamically controlled by weighing (60%±2% WHC), and water lost through evaporation was replenished daily.

[0050] The experiment was divided into a control group (CK, no treatment) and a phosphate-solubilizing bacteria group (P, only 200 mL of the phosphate-solubilizing bacteria SIP-2 solution obtained in Example 1 was poured onto the surface (the effective viable bacteria count in the 200 mL solution was 2 × 10⁻⁶). 9 The following groups were identified: CFU (Chemical Fuel Injection), unloaded pig manure biochar group (MB, 100 g of pig manure biochar (5% by weight) was added to 2 kg of soil and mixed evenly), and pig manure biochar combined with phosphate-solubilizing bacteria group (MBP, 100 g of pig manure biochar (5% by weight) was added to 2 kg of soil and mixed evenly, and 200 mL of phosphate-solubilizing bacteria SIP-2 bacterial solution obtained in Example 1 was poured on the surface (the effective viable bacteria count in 200 mL of bacterial solution was 2 × 10⁻⁶). 9 CFU), with 4 parallels set up for each experimental group.

[0051] Soil samples were collected on day 60 of cultivation. After being air-dried, the soil samples were ground and passed through a 0.25 mm sieve to remove impurities. The weight of the aboveground parts of the Chinese cabbage and the physicochemical properties of the soil were then measured.

[0052] Methods for determining the physical and chemical properties of soil: Weigh 1 g of soil sample (accurate to 0.01 g) into a 10 mL centrifuge tube, add 2.5 mL of ultrapure water, place in a shaker and shake for 30 min to fully disperse the soil particles, let stand for 30 min and then measure the soil pH.

[0053] The content of available phosphorus (soluble phosphorus and adsorbed phosphorus) in acidic soils was determined using the dual-acid method. 0.15 g of soil sample was weighed, and 0.5 mL of available phosphorus determination extract was added. The mixture was shaken and extracted for 1 h. After centrifugation at 10000 g and 25 ℃ for 10 min, the supernatant was collected, and the absorbance at 660 nm was measured using a UV spectrophotometer to calculate the available phosphorus content in the acidic soil.

[0054] The available potassium content in soil was determined using the sodium tetraphenylborate precipitation method. 0.2 g of soil sample was weighed, 1 mL of available potassium determination extract was added, and the mixture was shaken and extracted for 1 h. After centrifugation at 10000 rcf and 25 ℃ for 10 min, the supernatant was collected, and the absorbance at 420 nm was measured using a UV spectrophotometer to calculate the available potassium content in the soil.

[0055] Soil organic matter (SOM) content was determined using the potassium dichromate-sulfuric acid oxidation method. 0.1 g of soil sample was weighed, and mercuric sulfate solution and potassium dichromate solution were added. After gentle shaking, concentrated sulfuric acid was added, and the mixture was thoroughly mixed. The sample was then placed in a 135℃ electric thermostatic drying oven for 1 h. After cooling, 1 mL of the reaction solution was transferred to a centrifuge tube and centrifuged at 8000 rcf for 5 min at room temperature. The supernatant was collected, and the absorbance at 585 nm was measured using a UV spectrophotometer to calculate the soil organic matter content.

[0056] Soil alkaline nitrogen content was determined using the alkaline diffusion method. 2.0 g of soil sample was weighed and placed in the outer ring of a diffusion dish. Boric acid solution and an indicator were added to the inner chamber of the dish. The dish was covered with a frosted glass cover, leaving a narrow slit in the outer chamber. 10.0 mL of 1.8 mol / L sodium hydroxide (NaOH) solution was quickly added, and the frosted glass was immediately sealed tightly. Alkaline diffusion was performed at 40℃ for 24 h. The diffusion dish was then removed, and the frosted glass was carefully unscrewed. The amount of ammonia absorbed in the boric acid in the inner chamber was titrated with 0.01 mol / L sulfuric acid standard solution using a semi-micro burette. The endpoint was reached when the color changed from blue to purplish-red.

[0057] Soil bulk density determination: The ring sampler method was used. A 100 cm³ sample was collected. -3The cutting ring is pressed into the soil layer. After the cutting ring is dug out, the excess soil is removed. The soil sample is dried to constant weight and weighed. The soil bulk density is obtained by dividing the dry soil mass by the volume of the cutting ring.

[0058] The relative abundance of Fusarium in potted soil in different groups was determined, as well as the aboveground weight of the bok choy harvested after 60 days of cultivation and the growth of the potted bok choy after 60 days.

[0059] The results are as follows Figures 2-6 As shown.

[0060] Depend on Figure 6 Observation of potted plants revealed that after 60 days of cultivation, the bok choy in the group treated with pig manure biochar combined with phosphate-solubilizing bacteria showed better growth, with significant differences compared to the control group and other treatment groups. Meanwhile, from Figure 5 It can be seen that the aboveground weight of pakchoi in the group treated with pig manure biochar combined with phosphate-solubilizing bacteria was significantly higher than that in the control group and other treatment groups. The aboveground weight of pakchoi in the group treated with phosphate-solubilizing bacteria alone was not significantly different from that in the control group. Although the group treated with pig manure biochar promoted the growth of pakchoi, the effect was weaker than that in the group treated with pig manure biochar combined with phosphate-solubilizing bacteria.

[0061] Depend on Figure 2 and Figure 3 It can be seen that after 60 days of treatment with pig manure biochar combined with phosphate-solubilizing bacteria, the soil pH increased by 1.43 compared to the control group, the available phosphorus content increased by 976.2%, the available potassium content increased by 183.7%, and the organic matter content increased by 129.0%. Compared to the control group, although the application of pig manure biochar alone also significantly increased the content of available phosphorus and alkaline nitrogen, the effect was not as good as that of the pig manure biochar combined with phosphate-solubilizing bacteria group. Meanwhile, from Figure 4 It can be seen that applying pig manure biochar alone and applying pig manure biochar in combination with phosphate-solubilizing bacteria also reduced the relative abundance of Fusarium spp. among plant pathogens in the soil.

[0062] The above results indicate that the method of applying phosphate-solubilizing bacteria in combination with pig manure biochar can effectively alleviate acidification, nutrient deficiency, and reduce soil plant pathogens in weakly acidic soils in the south, with significant improvement effects.

[0063] Synergistic effect analysis: To verify the synergistic effect of pig manure biochar and phosphate-solubilizing bacteria SIP-2, the synergistic effect data of available phosphorus, available potassium and organic matter in pot experiments over 60 days were analyzed, the theoretical superposition effect value was calculated and compared with the actual combined effect.

[0064] Analysis criteria: Taking the CK group value as the baseline, the increment of a certain indicator in the P group (single application of bacteria) is ΔP, and the increment in the MB group (single application of biochar) is ΔMB. If the actual increment in the MBP group > ΔP + ΔMB, then synergistic effect is determined.

[0065] Synergistic effect of available phosphorus: The increase in available phosphorus in the single-application group (P) was not significant; the available phosphorus in the single-application group (MB) was 867.8% higher than that in the control group; while the available phosphorus content in the group with pig manure biochar and phosphate-solubilizing bacteria (MBP) was 976.2% higher than that in the control group. The actual increase of MBP was much higher than the simple sum of the increases of P and MB, which confirms that pig manure biochar, by providing a porous carrier to protect the strains and slow-release nutrients, produced a strong synergistic effect with the activated phosphate-solubilizing function of phosphate-solubilizing bacteria.

[0066] Synergistic effect of organic matter: Similarly, the increase in organic matter in the MBP group was significantly greater than the arithmetic sum of the increases in P and MB, indicating that the colonization rate of the strain was improved under the protection of the biochar carrier, and its metabolic activity accelerated the conversion and stabilization of some organic carbon in pig manure biochar.

[0067] Validation of bacterial colonization and functional synergy: Figure 1 The relative abundance of Trichoderma in the MBP group was significantly higher than that in the P group, directly demonstrating that pig manure biochar significantly promoted the colonization of the strain. Figure 4 The results showed that both MBP and MB treatments reduced the relative abundance of Fusarium pathogens, and the growth of pakchoi in the MBP group was better ( Figure 6 ) and above-ground weight ( Figure 5 All of these results are optimal. This confirms that biochar provides a shelter and colonization substrate for the strains, and the successfully colonized strains not only efficiently activate nutrients, but may also inhibit soil-borne pathogens through competitive action, achieving a dual synergy of nutrient enhancement and biological control.

[0068] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. The application of phosphate-solubilizing bacteria SIP-2 combined with pig manure biochar in improving acidic soils with low available phosphorus, characterized in that, The preservation number of the phosphate-solubilizing bacterium SIP-2 is CGMCC No. 41935.

2. The application of phosphate-solubilizing bacteria SIP-2 combined with pig manure biochar in any of the following, characterized in that: (1) Increase soil pH; (2) Increase soil organic matter content; (3) Increase soil available nitrogen content; (4) Reduce soil bulk density; (5) Increase soil available potassium content; (6) Increase soil available phosphorus content; (7) Inhibit soil-borne pathogens.

3. The application according to claim 1 or 2, characterized in that, The preparation method of the pig manure biochar includes the following steps: using pig manure as raw material, carbonizing it in an inert gas N2 environment; the pyrolysis temperature of the carbonization is 600℃, the heating rate is 15℃ / min, and the temperature is kept constant at 600℃ for 45 min.

4. A soil conditioner, characterized in that, This includes SIP-2 phosphate-solubilizing bacteria or SIP-2 inoculum, as well as pig manure biochar.

5. The soil conditioner according to claim 4, characterized in that, When the SIP-2 phosphate-solubilizing bacteria inoculum is a bacterial suspension, the bacterial concentration of the suspension is 1×10⁻⁶. 7 CFU / mL or higher.

6. The soil conditioner according to claim 5, characterized in that, The preparation method of the SIP-2 phosphate-solubilizing bacteria agent includes the following steps: inoculating the SIP-2 phosphate-solubilizing bacteria into LB medium, culturing, and collecting the bacterial cells.

7. The soil conditioner according to claim 4, characterized in that, The preparation method of the pig manure biochar includes the following steps: using pig manure as raw material, carbonizing it in an inert gas N2 environment; the pyrolysis temperature of the carbonization is 600℃, the heating rate is 15℃ / min, and the temperature is kept constant at 600℃ for 45 min.

8. The application of the soil conditioner according to any one of claims 4 to 7 in any one of the following, characterized in that: (1) Increase soil pH; (2) Increase soil organic matter content; (3) Increase soil available nitrogen content; (4) Reduce soil bulk density; (5) Increase soil available potassium content; (6) Increase soil available phosphorus content; (7) Inhibit soil-borne pathogens.

9. A method for improving acidic soil with low available phosphorus, characterized in that, The step includes adding the soil conditioner as described in any one of claims 4 to 7.

10. The method according to claim 9, characterized in that, After applying the pig manure biochar, the phosphate-solubilizing bacteria SIP-2 should be applied in combination; the application rate of the pig manure biochar is 2-20 tons / hectare, and the application rate of the phosphate-solubilizing bacteria SIP-2 is 2×10⁻⁶. 10 The ratio of CFU / kg pig manure biochar and the application of pig manure biochar.

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