Acid soil conditioner, application thereof and acid soil improvement method

Abstract

The invention provides an acid soil conditioner and application thereof and an acid soil improvement method, and relates to the technical field of soil improvement, the acid soil conditioner comprises wormcast and a microbial agent; the microbial agent comprises penicillium kirschmannii with the viable bacterium concentration of 106 to 108 CFU / mL; the ratio of the mass of the wormcast to the volume of the microbial agent is (2-6g): (1-3mL). According to the acid soil conditioner provided by the invention, the wormcast and the penicillium kirschinii are applied in a compound manner, and a synergistic driving mechanism is constructed through organic nutrition input of the wormcast and functional microorganism guidance of the penicillium kirschinii, so that the pH, organic matter and nutrient content of soil can be improved, and a micro-ecological structure can be improved; the diversity and biological activity of soil microorganisms can be remarkably improved, the microbial network structure is optimized, the stability and toughness of a soil ecological system are enhanced, and the ecological function of acidified soil is restored, so that comprehensive improvement of crop biomass and nutrient utilization efficiency is promoted.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of soil improvement, in particular to an acid soil improver, application thereof and an acid soil improvement method. BACKGROUND

[0002] Acid soil is a kind of degraded soil resource widely distributed in southern China. Its low pH, poor nutrients and structure deterioration seriously restrict the sustainable development of agriculture and the realization of the multi-functionality of the ecological system. Data shows that the area of acid soil with pH less than 6.5 in China has reached 311.1 million km2, accounting for 32.4% of the land area, among which strong acid soil (pH < 5.5) is particularly common in the southern red-yellow soil region. Influenced by high temperature and heavy rain, strong leaching and improper fertilization, the physicochemical properties of acid soil deteriorate, leading to a decline in soil biodiversity and a disorder in micro-ecological structure, and a serious degradation of soil ecological function, which has become one of the main bottlenecks in the current agricultural green transformation and food security guarantee. Recent studies have shown that soil pH is a decisive factor affecting the diversity of microorganisms, fungi and protozoa. In particular, in a strong acid environment (pH < 5.5), the alpha diversity of soil biological community is significantly reduced, the community assembly mechanism changes from certainty to randomness, and the ecological network structure tends to be unstable.

[0003] Therefore, improving the pH of acid soil, improving its physicochemical structure and nutrient status, is a key link to promote the recovery of its biodiversity and the improvement of crop productivity. At present, conventional improvement measures rely on materials such as lime and biochar, which can short-term improve pH and structure, but have problems such as non-persistent improvement effect, unsustainable resources and significant side effects. SUMMARY

[0004] The present application provides an acid soil improver and an acid soil improvement method, to solve the defects of non-persistent improvement effect, unsustainable resources and significant side effects in the prior art, and to provide a composite ecological improver capable of effectively and persistently improving the pH of acid soil, improving its physicochemical structure and nutrient status.

[0005] The present application provides an acid soil improver, which comprises earthworm manure and a microbial agent. The microbial agent comprises Penicillium chrysogenum with a viable bacterial concentration of 10 6 ~10 8 CFU / mL. The mass of the earthworm manure to the volume of the microbial agent is (2~6 g):(1~3 mL).

[0006] The acid soil improver provided by the application comprises earthworm manure and microbial inoculum, is a biological improver based on organic resources and microbial regulation, and is a more green and feasible improver compared with traditional lime, biochar and other improvers. Specifically, the earthworm manure is rich in organic matter, nutrients such as nitrogen, phosphorus and potassium, and various active microorganisms, has good granular structure and buffering capacity, can improve the soil pH value, improve the microhabitat and enhance the nutrient availability, and the application can significantly improve the richness of key groups such as Pseudomonas and Bacillus in the soil, promote the root development and nutrient absorption of plants. The paecilomyces keratinophilius is a functional microorganism with strong metabolic activity and wide environmental adaptability, has the functions of phosphorus fixation, extracellular polysaccharide production and promotion of aggregate structure formation, and can improve the soil aggregate structure (the proportion of large aggregates is increased by 64.1%) by secreting extracellular polysaccharides, promote the stable accumulation of organic matter and the colonization of microorganisms, and enhance the resilience of the ecological system. In the acid soil, the paecilomyces keratinophilius can recruit specific phosphorus cycle bacterial communities, and through microbial synergy, can enhance the release and retention of nutrients and stabilize the organic-mineral composite structure. The acid soil improver provided by the application is a composite of earthworm manure and paecilomyces keratinophilius, and further controls the viable bacterial concentration of the paecilomyces keratinophilius to be 10 6 ~10 8 CFU / mL, and the mass of the earthworm manure and the volume of the microbial inoculum are (2-6 g):(1-3 mL). Through the organic nutrient input of the earthworm manure and the functional microbial guidance of the paecilomyces keratinophilius, a synergistic driving mechanism is constructed, which can not only improve the soil pH, the content of organic matter and nutrients, and the microecological structure, but also significantly improve the soil microbial diversity and biological activity, optimize the microbial network structure, enhance the stability and resilience of the soil ecological system, restore the ecological function of the acidified soil, and thus promote the comprehensive improvement of the crop biomass and the nutrient use efficiency.

[0007] The acid soil improver provided by the application can construct a positive feedback mechanism of microorganisms-nutrients-soil structure, improve the crop productivity, restore the stability of the soil ecological network, is conducive to the recovery of the biological diversity of the strongly acidic soil and the improvement of the agricultural productivity, provides an efficient, low-carbon and ecologically friendly solution for the sustainable utilization of the acid soil resources in southern China, and has significant agricultural promotion value and ecological benefits.

[0008] As a preferred, the microbial inoculum comprises the paecilomyces keratinophilius with a viable bacterial concentration of 10 7 ~10 8 CFU / mL.

[0009] As preferred, the ratio of the mass of the earthworm manure to the volume of the microbial agent is (3~5 g):(1.5~2 mL), for example, it can be 3 g:1.5 mL, 3 g:1.6 mL, 3 g:1.7 mL, 3 g:1.8 mL, 3 g:1.9 mL, 3 g:2.0 mL, 4 g:1.5 mL, 4 g:1.6 mL, 4 g:1.7 mL, 4 g:1.8 mL, 4 g:1.9 mL, 4 g:2.0 mL, 5 g:1.5 mL, 5 g:1.6 mL, 5 g:1.7 mL, 5 g:1.8 mL, 5 g:1.9 mL, 5 g:2.0 mL, but not limited to the listed values, other values not listed in the value range are also applicable.

[0010] As preferred, the preparation method of the microbial agent comprises: inoculating the PDA culture medium with Paecilomyces fumosaesus after sterilization, culturing at 25~28 ℃, collecting mycelium and spores, and preparing a bacterial suspension with a concentration of 10 6 ~10 8 CFU / mL with sterile water.

[0011] As preferred, the culturing time is 5~9 days, further preferably 6~8 days, for example, it can be 5 days, 6 days, 7 days, 8 days, 9 days, but not limited to the listed values, other values not listed in the value range are also applicable.

[0012] The application provides an application of the acid soil improver in improving acid soil.

[0013] The application provides an acid soil improvement method, which comprises: mixing earthworm manure, a microbial agent and acid soil, and culturing. The microbial agent comprises Paecilomyces fumosaesus with a viable bacterial concentration of 10 6 ~10 8 CFU / mL.

[0014] As preferred, 10-30 g of the earthworm castings and 5-15 mL of the microbial inoculant are added per kilogram of dry acidic soil, the water content of which is < 2 wt% (w / w); the amount of earthworm castings added per kilogram of dry acidic soil may be, for example, 10 g, 12 g, 15 g, 17 g, 20 g, 22 g, 25 g, 28 g, 30 g, but is not limited to the listed values, and other values not listed within the range are also applicable; the amount of microbial inoculant added per kilogram of dry acidic soil may be, for example, 5 mL, 6 mL, 7 mL, 8 mL, 9 mL, 10 mL, 11 mL, 12 mL, 13 mL, 14 mL, 15 mL, but is not limited to the listed values, and other values not listed within the range are also applicable.

[0015] Further preferably, 15-25 g of the earthworm castings and 8-10 mL of the microbial inoculant are added per kilogram of dry acidic soil, the water content of which is < 2 wt% (w / w).

[0016] The present scheme adds 10-30 g of the earthworm castings and 5-15 mL of the microbial inoculant per kilogram of dry acidic soil, which, on the one hand, can ensure that sufficient earthworm castings exert good granulation structure and buffering capacity in the soil, improve soil pH value, improve microhabitat and enhance nutrient availability, significantly increase the richness of key groups such as Pseudomonadota and Firmicutes in the soil, and promote plant root development and nutrient absorption, and on the other hand, can avoid excessive addition of earthworm castings, which can cause excessive loosening of soil pore structure or local enrichment of organic matter, causing abnormal increase in oxygen content or imbalance in carbon-nitrogen ratio, thereby weakening the low-oxygen adaptability of Paenibacillus and the stability of its extracellular polysaccharide-mediated aggregation, and even destroying its microecological interaction with phosphorus cycle bacteria, ultimately leading to a decrease in phosphorus fixation efficiency and organic-mineral complex structure formation ability; on the one hand, it can ensure that sufficient Paenibacillus forms an effective community in the soil and is not easily inhibited by indigenous microorganisms, achieving phosphorus fixation, extracellular polysaccharide production, and promotion of aggregate structure formation, as well as recruitment of specific phosphorus cycle bacterial communities, thereby enhancing nutrient release and retention through microbial synergy and stabilizing organic-mineral complex structure; on the other hand, it can avoid excessive addition of Paenibacillus, which can cause the soil microbial community to be excessively biased towards a single fungal population, destroying the fungal-bacterial-organic matter multi-element collaborative network established with earthworm castings, causing intensified nutrient competition or accumulation of metabolic products, thereby inhibiting the activity and function of key bacterial groups (such as Pseudomonadota and Firmicutes) in earthworm castings, and weakening the stability of soil aggregates and the sustained release ability of phosphorus.

[0017] As preferred, the temperature of the culture is 25-29℃, for example, it can be 25℃, 26℃, 27℃, 28℃, 29℃, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0018] As preferred, the time of the culture is 40-50 days, preferably 42-48 days, for example, it can be 40 days, 42 days, 44 days, 46 days, 48 days, 50 days, but is not limited to the listed values, and other values not listed in the value range are also applicable. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0020] Figure 1 The result graph of the effect of the improved soil of different treatment groups on the biomass of corn seedlings.

[0021] Figure 2 The result graph of the effect of the improved soil of different treatment groups on the root morphology of corn seedlings.

[0022] Figure 3 The result graph of the effect of the improved soil of different treatment groups on the total root length, root surface area and root volume of corn seedlings.

[0023] Figure 4 The result graph of the effect of different treatment groups on soil enzyme activity.

[0024] Figure 5 The correlation analysis graph of enzyme activity and nutrient absorption.

[0025] Figure 6 The result graph of the effect of different treatment groups on the α diversity of soil bacteria.

[0026] Figure 7 The result graph of the effect of different treatment groups on the α diversity of soil fungi.

[0027] Figure 8 The result graph of the effect of different treatment groups on the α diversity of soil protozoa.

[0028] Figure 9 The result graph of the effect of different treatment groups on the community structure and co-occurrence network of soil bacteria. DETAILED DESCRIPTION

[0029] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be clearly and completely described below in combination with the drawings in the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0030] The earthworm manure used in the following examples and comparative examples is from Zhongxiang Earthworm Breeding Professional Cooperative in Shenzhou City, Hebei Province. The earthworm manure is mainly made of cow dung and is made by breeding earthworms. The Penicillium crustosum Penicillium kloeckeri ) is preserved in the China General Microbiological Culture Collection Center, and the preservation number is CGMCC No. 41049. The arbuscular mycorrhizal fungus (AM fungus) used is Glomus mosseae Glomus mosseae ), which is provided by the Arbuscular Mycorrhizal Fungal Germplasm Bank (BGC) of Beijing Academy of Agriculture and Forestry Sciences, and the Glomus mosseae used in the specific embodiments of the present application is the same as that used in the specific embodiments of the patent with the patent number CN114175996A.

[0031] The improved acidic soil in the following examples and comparative examples is the same strong acidic red soil, and the improvement method is the same except for the improver.

[0032] Example 1 1. The acidic soil improver provided in this embodiment is earthworm manure and microbial inoculum; The microbial inoculum is Penicillium crustosum with a viable bacterial concentration of 10 8 CFU / mL; The mass / volume ratio of earthworm manure to microbial inoculum is 4 g:1 mL.

[0033] 2. The preparation method of the acidic soil improver in this embodiment comprises the following steps: S21. The earthworm manure is a particle earthworm manure without impurities, which is dried at 60 ℃ and then sieved through a 100-mesh sieve for use, to obtain treated earthworm manure.

[0034] S22. After the PDA culture medium is sterilized, it is inoculated with Penicillium crustosum and cultured at 25~28 ℃ for 7 days. The mycelium and spores are eluted into sterile water to prepare a bacterial suspension with a concentration of 10 8 CFU / mL, to obtain the microbial inoculum.

[0035] 3. The application of the acidic soil improver in this embodiment (treatment group VF) in improving acidic soil comprises the following steps: S31. Select the strong acidic red soil (pH<5.5, water content of 1wt% (w / w)) dried and sieved through a 2-mm sieve as the test substrate; S32. 40 g of the treated earthworm manure, 10 mL of the microbial inoculum, and 2 kg of the air-dried strongly acidic red soil were mixed and uniformly stirred, and then were planted in pots. The pots were incubated at 25-29 °C under illumination for 9-10 h per day for 45 days, and the soil moisture content was maintained at 20 wt% during the incubation.

[0036] Comparative Example 1 The comparative example was a blank control (treatment group CK), i.e., no treated earthworm manure and microbial inoculum were added. The specific incubation method for the acidic soil included the following steps: S31. The air-dried strongly acidic red soil (pH < 5.5, water content of 1 wt% (w / w)) sieved through a 2 mm sieve was selected as the test substrate; S32. The 2 kg of the air-dried strongly acidic red soil was uniformly stirred and then was planted in pots. The pots were incubated at 25-29 °C under illumination for 9-10 h per day for 45 days, and the soil moisture content was maintained at 20 wt% during the incubation.

[0037] Comparative Example 2 1. The acidic soil amendment provided in the comparative example was earthworm manure.

[0038] 2. The treatment method for the acidic soil amendment of the comparative example included the following steps: The earthworm manure was a pure granular earthworm manure, which was dried at 60 °C and sieved through a 100 mesh sieve to obtain the treated earthworm manure.

[0039] 3. The application of the acidic soil amendment of the comparative example in improving acidic soil (treatment group V) included the following steps: S31. The air-dried strongly acidic red soil (pH < 5.5, water content of 1 wt% (w / w)) sieved through a 2 mm sieve was selected as the test substrate; S32. 40 g of the treated earthworm manure and 2 kg of the air-dried strongly acidic red soil were mixed and uniformly stirred, and then were planted in pots. The pots were incubated at 25-29 °C under illumination for 9-10 h per day for 45 days, and the soil moisture content was maintained at 20 wt% during the incubation.

[0040] Comparative Example 3 1. The acidic soil amendment provided in the comparative example was a microbial inoculum. The microbial inoculum included Penicillium citrinum with a viable bacterial concentration of 10 8 CFU / mL.

[0041] 2. The preparation method for the acidic soil amendment of the comparative example included the following steps: The PDA culture medium was sterilized and inoculated with Penicillium citrinum, and was incubated at 25-28 °C for 7 days. The mycelium and spores were eluted into sterile water to prepare a microbial inoculum with a concentration of 10 8The microbial inoculum is prepared by washing the mycelium and spores of the Glomus mosseae into sterile water to obtain a bacterial suspension with a concentration of 10

[0042] 3. Application of the acid soil improver of the present comparative example (treatment group F) in improving acid soil, comprising the following steps: S31. Selecting air-dried strongly acidic red soil (pH < 5.5, moisture content of 1wt% (w / w)) sieved through a 2 mm sieve as the test substrate; S32. Mixing 10 mL of the microbial inoculum and 2 kg of the air-dried strongly acidic red soil and stirring evenly, then potting, and culturing at 25-29°C under light for 9-10 hours per day for 45 days, and keeping the soil moisture content at 20wt% during the culturing.

[0043] Comparative Example 4 1. The acid soil improver provided by the present comparative example is a microbial inoculum; The microbial inoculum comprises Glomus mosseae with a viable bacterial concentration of 10 8 CFU / mL.

[0044] 2. The preparation method of the acid soil improver of the present comparative example comprises the following steps: After sterilizing the PDA culture medium, inoculate Glomus mosseae, and culture at 25-28°C for 7 days, wash the mycelium and spores into sterile water to obtain a bacterial suspension with a concentration of 10 8 CFU / mL, and prepare the microbial inoculum.

[0045] 3. Application of the acid soil improver of the present comparative example (treatment group A) in improving acid soil, comprising the following steps: S31. Selecting air-dried strongly acidic red soil (pH < 5.5, moisture content of 1wt% (w / w)) sieved through a 2 mm sieve as the test substrate; S32. Mixing 10 mL of the microbial inoculum and 2 kg of the air-dried strongly acidic red soil and stirring evenly, then potting, and culturing at 25-29°C under light for 9-10 hours per day for 45 days, and keeping the soil moisture content at 20wt% during the culturing.

[0046] Comparative Example 5 1. The acid soil improver provided by the present comparative example is a mixture of earthworm manure and a microbial inoculum; The microbial inoculum comprises Glomus mosseae with a viable bacterial concentration of 10 8 CFU / mL; The mass of the earthworm manure to the volume of the microbial inoculum is 4 g:1 mL.

[0047] 2. The preparation method of the acid soil improver of the present comparative example comprises the following steps: S21. The earthworm manure is impurity-free granular earthworm manure, which is dried at 60 °C and then sieved through a 100-mesh sieve for use, to obtain treated earthworm manure.

[0048] S22. After sterilization, the PDA culture medium is inoculated with M. alpina and cultured at 25-28 °C for 7 days. The mycelium and spores are eluted into sterile water to prepare a microbial inoculum with a concentration of 10 8 CFU / mL.

[0049] 3. Application of the acid soil conditioner of the present comparative example in improving acid soil (treatment group VA), comprising the following steps: S31. Select air-dried strong acid red soil (pH < 5.5, water content 1wt% (w / w)) sieved through a 2-mm sieve as the test substrate; S32. Mix 40 g of treated earthworm manure, 10 mL of microbial inoculum, and 2 kg of air-dried strong acid red soil, and then evenly mix and fill pots. Cultivate at 25-29 °C with 9-10 h of light per day for 45 days, and maintain the soil water content at 20wt% during the cultivation period.

[0050] The above treatment groups are repeated 4 times, and the following performance test results are the average test results of 4 repetitions.

[0051] Performance test results 1. Effect on crop growth The same method is used to plant corn in the soil improved by the above different treatment groups (above examples and comparative examples), i.e., to cultivate at 25-29 °C with 9-10 h of light per day for 45 days, and maintain the soil water content at 20wt% during the cultivation period. After 45 days, the corn seedling biomass, corn seedling root morphology, and corn seedling nutrients are measured.

[0052] 1.1 Corn seedling biomass The effect of the soil improved by the above different treatment groups on corn seedling biomass is shown in Table 1.1. Figure 1 Figure 1 ​The combined treatment of earthworm castings and *Penicillium clarkii* (VF) showed the strongest effect on promoting maize seedling biomass, with leaf and root biomass increasing by 340.38% and 235.67% respectively compared to the control (CK), and aboveground and underground dry weight increasing by 416.06% and 244.75% respectively. Plant height and stem diameter increased by 58.75% and 80.58% respectively, all significantly higher than the single treatments V and F. The VA treatment was the second best, with leaf biomass (aboveground dry weight), root biomass (underground dry weight), plant height, and stem diameter increasing by 280.02%, 229.56%, 48.13%, and 63.91% respectively compared to CK. Two-way ANOVA analysis showed that the main effect of earthworm castings was extremely significant (p<0.001), and the interaction between earthworm castings and *Penicillium clarkii* was also significant. Mechanistically, earthworm castings enhance pH and readily available nutrients, while *Penicillium clarithroptus* strengthens phosphorus activation and aggregate stability. Both synergistically optimize root morphology and improve N, P, and K absorption, thus jointly driving biomass accumulation. Since *Penicillium clarithroptus* (F) treatment alone is less effective than *Glomus mosieri* (A) treatment, but the synergistic effect of VF is significantly better than that of VA treatment, subsequent results will focus solely on the VF treatment.

[0053] 1.2 Root morphology of maize seedlings The effects of the improved soil in the above treatment groups on the root morphology of maize seedlings are as follows: Figures 2-3 As shown. Due to Figures 2-3 It was found that, compared with the control (CK), all treatments (V, F, and VF) significantly improved the root morphology indicators of maize seedlings. Among them, the VF treatment showed the best effect, with total root length, root surface area, and root volume increasing by 185.05%, 93.46%, and 416.06% respectively compared with the CK. The F and V treatments also showed significant improvements. This indicates that the synergistic effect of earthworm castings and Penicillium kirch significantly promotes root expansion, enhances nutrient absorption capacity, and provides strong support for aboveground growth.

[0054] 1.3 Nutrients for Maize Seedlings The effects of the improved soil in the different treatment groups on the nutrients of maize seedlings are shown in Table 1. As shown in Table 1, compared with the control (CK), all treatments (V, F, and VF) significantly increased the uptake of nitrogen, phosphorus, and potassium in both the aboveground and belowground parts of maize. Among them, the VF treatment showed the best effect, increasing the uptake of nitrogen, phosphorus, and potassium in the aboveground parts by 65.4%, 97.1%, and 192.3%, respectively, and in the belowground parts by 116.1%, 287.5%, and 458.0%, respectively. The application of earthworm castings (V) and Penicillium kirch (F) alone also had significant promoting effects, but the synergistic treatment (VF) showed a stronger nutrient synergistic effect, significantly improving the nutrient uptake efficiency of maize seedlings.

[0055] Table 1

[0056] In Table 1, different letter annotations represent the significant differences of each treatment in p< 0.05 level; total nitrogen (g / kg), total phosphorus (mg / kg), total potassium (mg / kg) refer to the mass of total nitrogen, total phosphorus, total potassium contained in per kilogram of corn seedling aboveground and underground.

[0057] 2. Effects of the regulation on soil physicochemical properties and microecology 2.1 Effects on soil pH and nutrient content The regulation results of different treatment groups on soil pH are shown in Table 2. As can be seen from Table 2, compared with CK, the earthworm manure treatment (V) can increase the soil pH by 9.2%, and the paecilomyces keratinophilus treatment (F) has no significant effect, but the combined treatment (VF) can still maintain the pH in a reasonable range. This is because the earthworm manure directly neutralizes the pH through chemical neutralization, while the paecilomyces keratinophilus indirectly supports the long-term effectiveness of the earthworm manure by improving soil structure. The two form a "physical wrapping-chemical buffering" system, which stabilizes the pH of the combined treatment in the range suitable for crop growth (5.35) and avoids strong acid stress.

[0058] Table 2

[0059] In Table 2, different letter annotations represent the significant differences of each treatment in p< 0.05 level.

[0060] The regulation results of different treatment groups on soil nutrient content are shown in Table 3. As can be seen from Table 3, compared with CK, the single earthworm manure treatment (V) can increase the soil organic matter, total nitrogen, available phosphorus and available potassium by 43.4%, 71.9%, 23.3% and 30.5% respectively; the paecilomyces keratinophilus treatment (F) has no significant effect on organic matter and total nitrogen, but the available phosphorus decreases by 11.5% and the available potassium increases by 73.5%; the combined treatment (VF) is the best in improving organic matter (57.6%) and total nitrogen (91.2%), and the available phosphorus is the same as V treatment, and the available potassium is lower than F treatment but still significantly higher than CK, indicating that the combination of earthworm manure and paecilomyces keratinophilus can synergistically improve soil fertility and avoid excessive available potassium.

[0061] Table 3

[0062] In Table 3, different letter annotations represent the significant differences of each treatment in p< 0.05 level; organic matter (g / kg), total nitrogen (g / kg), available phosphorus (mg / kg), available potassium (mg / kg) refer to the mass of organic matter, total nitrogen, available phosphorus, available potassium contained in per kilogram of improved soil.

[0063] 2.2 Effects on enzyme activity The effects of the different treatment groups on soil enzyme activity are as follows: Figures 4-5 As shown. Due to Figures 4-5 It was found that earthworm castings treatment (V) significantly increased soil urease activity (+50%), while *Penicillium clarithroptus* treatment (F) increased acid phosphatase activity, with the combined V-F treatment showing the highest increase (+52.44%). Correlation analysis showed a significant positive correlation between urease activity and maize nitrogen uptake (R²=0.574), and a significant positive correlation between acid phosphatase activity and phosphorus uptake (R²=0.485). This indicates that the earthworm castings in the acidic soil conditioner provided by this invention promote nitrogen mineralization by enhancing urease activity, while *Penicillium clarithroptus* accelerates organic phosphorus conversion by increasing phosphatase activity; the two work synergistically to enhance the absorption and utilization of nitrogen and phosphorus by maize.

[0064] 3. Impact on microbial diversity The effects of the different treatment groups on soil microbial diversity are as follows: Figures 6-9 As shown. Due to Figures 6-8 It was found that earthworm castings (V) and *Penicillium kurineumoniae* (F) treatments significantly increased bacterial α-diversity in strongly acidic soils, with Shannon and Chao1 indices both higher than the control (CK) (p<0.05). The VF (combined treatment) showed the largest increase, indicating that the synergistic effect of both treatments significantly enhanced bacterial community richness and evenness, which is beneficial for ecological function restoration. However, there were no significant differences in α-diversity of fungi and protozoa among the treatments, suggesting that earthworm castings and *Penicillium kurineumoniae* primarily regulate bacterial diversity. Furthermore, from... Figure 9 As shown, key functional groups such as Pseudomonas (e.g., ASV311) and Bacillus (e.g., ASV946) were significantly enriched in both vermicompost (V) and the combined treatment (VF), with their relative abundance significantly higher than that in the control (CK) and Penicillium clarkii (F) treatments. This indicates that the addition of vermicompost effectively promoted the colonization and proliferation of beneficial bacterial groups. These key groups, acting as module hubs in the co-occurrence network, showed a significant positive correlation with maize seedling biomass (e.g., ASV311, R²=0.24674, p<0.05), indicating that they play a core role in enhancing soil phosphorus activity, promoting microbial collaboration, and maintaining aggregate structure. This further supports the synergistic optimization effect of the combined use of vermicompost and Penicillium clarkii on the functional structure of bacterial communities.

[0065] The acid soil improver provided by the application realizes significant synergistic promotion of strong acid soil nutrient structure, biological network and crop growth by adding earthworm manure and paecilomyces keratinophilus, and has good replicability and popularization value. Specifically, earthworm manure is used as an organic improvement filler, which has the functions of carbon source supply, physicochemical property adjustment and beneficial microorganism carrier, so as to realize synergistic optimization of strong acid soil pH and nutrient structure; paecilomyces keratinophilus is introduced as functional microorganisms, which promotes soil aggregate formation and microecological stability through exopolysaccharide secretion, rebuilds soil microbial network structure and improves biological diversity; through the combined application mechanism of earthworm manure and paecilomyces keratinophilus, carbon source input and microbial colonization are synergistically driven, which significantly improves soil organic matter, total nitrogen, available phosphorus and crop root nutrient absorption capacity, at the same time, a complete regulation path of "pH -> microbial diversity -> plant nutrient absorption -> biomass improvement" is constructed, forming a strong acid soil ecological restoration system with clear theory and clear mechanism, and the materials used in the acid soil improver of the application have wide sources, are ecological and safe, and low cost, which has good environmental adaptability and popularization, and meets the requirements of green agricultural sustainable development.

[0066] Finally, it should be pointed out that: the above examples are only used to illustrate the technical solutions of the application, but not to limit them; although the application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the application.

Claims

1. An acid soil improver, characterized in that, The acid soil improver comprises earthworm manure and microbial inoculum; The microbial inoculant includes Penicillium chrysogenum at a viable cell concentration of 10 6 ~10 8 CFU / mL. The ratio of the mass of the earthworm manure to the volume of the microbial inoculum is (2-6 g):(1-3 mL).

2. The acid soil amendment of claim 1, wherein, The microbial inoculant includes a viable cell concentration of 10 7 ~10 8 CFU / mL of Penicillium camembertii.

3. The acidic soil improver according to claim 1 or 2, characterized in that, The ratio of the mass of the earthworm manure to the volume of the microbial inoculum is (3-5 g):(1.5-2 mL).

4. The acidic soil improver according to claim 1 or 3, characterized in that, The preparation method of the microbial agent comprises the following steps: inoculating P. krameri in PDA culture medium after sterilization, culturing at 25-28 DEG C, collecting mycelium and spores, and preparing a bacterial suspension with a concentration of 10 6 ~10 8 CFU / mL by using sterile water.

5. The acidic soil amendment of claim 4, wherein, The culture time is 5-9 days, preferably 6-8 days.

6. Use of the acid soil improver according to any one of claims 1-5 for improving acid soil.

7. A method of ameliorating an acid soil, characterised by, The improvement method comprises: mixing the earthworm manure, the microbial inoculum and the acid soil, and then culturing; The microbial inoculant includes Penicillium camembertii at a viable cell concentration of 10 6 ~10 8 CFU / mL.

8. The method for improving an acid soil according to claim 7, wherein 10-30 g of the earthworm manure and 5-15 mL of the microbial inoculum are added per kilogram of dry acid soil, and the water content of the dry acid soil is <2wt% (w / w). Preferably, 15-25 g of the earthworm manure and 8-10 mL of the microbial inoculum are added per kilogram of dry acid soil, and the water content of the dry acid soil is <2wt% (w / w).

9. The method for improving an acid soil according to claim 7 or 8, characterized by, The culture temperature is 25-29℃.

10. The method for improving an acid soil according to any one of claims 7 to 9, wherein The culture time is 40-50 days, preferably 42-48 days.

Images