Carbon-based biological conditioner for improving phosphorus utilization rate in sandy alkaline soil and application thereof

Abstract

The application discloses a carbon-based biological conditioner for improving phosphorus utilization rate of sandy alkaline vegetable soil and application thereof. The carbon-based biological conditioner is composed of carbon vinegar material and carbon-loaded aspergillus niger agent. The carbon vinegar material is prepared by adsorbing strong acid wood vinegar on strong adsorption biochar. The carbon-loaded aspergillus niger agent is prepared by adsorbing aspergillus niger spore powder on large-pore biochar. The carbon vinegar material is applied by row or hole application before transplanting or sowing of vegetables. The carbon-loaded aspergillus niger agent is applied by root or seed dipping when the vegetables are transplanted or sown. The carbon vinegar material and the carbon-loaded aspergillus niger agent have good phosphorus solubilization effect, and have time and space complementarity in phosphorus solubilization. The carbon vinegar material and the carbon-loaded aspergillus niger agent can effectively and long-acting promote transformation of soil stable state phosphorus into active state phosphorus, meet long-term and sufficient demand of the vegetables for the active state phosphorus, and further improve the utilization rate of soil phosphorus by the vegetables.

Description

Technical Field

[0001] This invention relates to the field of soil conditioners, and in particular to a carbon-based bioconditioner for improving phosphorus utilization in sandy alkaline soils used for crop cultivation and its application. Background Technology

[0002] Although the total phosphorus fertilizer input is relatively high in open-field vegetable cultivation under sandy alkaline soils, the soil has a sufficient total phosphorus content but a low content of reactive phosphorus due to the easy fixation of phosphorus in alkaline soils and the strong leaching of phosphorus in sandy soils. In many open-field vegetable production areas, the available phosphorus content is below 35 mg / kg, which is sufficient for grain crop production, but a limiting factor for high-yield vegetables with high phosphorus requirements, such as open-field garlic, onions, broccoli, peppers, Chinese cabbage, and watermelons. Applying conditioners to reduce the fixation of reactive phosphorus in the soil into stable phosphorus and promote the utilization of soil phosphorus by vegetables is a major need in sandy alkaline soil production areas.

[0003] Chinese patent CN115786168A discloses a highly efficient salt-tolerant phosphate-solubilizing bacterium and its application; Chinese patent CN115322923A discloses a phosphate-solubilizing bacterium and its application in saline-alkali land; Chinese patent CN115873745A discloses a salt-tolerant phosphate-solubilizing bacterium and its application; Chinese patent CN112175880A discloses a salt-tolerant phosphate-solubilizing bacterium and its application; and Chinese patent CN113980822A discloses a salt-tolerant Aspergillus niger strain and its application as a phosphate-solubilizing fungus in promoting corn growth in saline-alkali land. These patents all screen for phosphate-solubilizing bacteria suitable for saline-alkali soil, but they do not involve product development of the bacteria. The application effect of a single bacterium is limited. For example, after a single strain is applied to the soil, the colonization rate is low, and there is a lack of synergistic phosphate-solubilizing materials. The phosphate-solubilizing effect is weak in the early stages after application to the soil, and the phosphate-solubilizing effect disappears in the later stages, requiring additional large amounts of phosphate fertilizer for crop growth. Chinese patent CN112661579A discloses a phosphorus-solubilizing microbial agent that can improve saline-alkali soil and its preparation method. Chinese patent CN112831440A discloses a salt-tolerant phosphorus-solubilizing marine bacterium 3-1a, microbial organic fertilizer, its preparation method, and its application. However, none of these patents address how to improve phosphorus utilization in sandy alkaline vegetable soils. Currently, there are no reports on biological conditioners specifically targeting the low phosphorus utilization in sandy alkaline vegetable soils. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a carbon-based bioconditioner for improving phosphorus utilization in sandy alkaline soils used for crop cultivation. This bioconditioner uses highly absorbent biochar, strong acid wood vinegar, large-pore biochar, and Aspergillus niger A181 spore powder, which has a strong phosphorus-solubilizing effect, as raw materials. It has advantages such as ease of implementation, environmental friendliness, and wide applicability to various crops. It can efficiently increase the available phosphorus content in the root growth zone of sandy alkaline vegetables, and the phosphorus-enhancing effect of the carbon-based bioconditioner is long-lasting, making it applicable to a variety of vegetable crops.

[0005] To achieve the above-mentioned objectives, this invention first provides a carbon-based biological conditioner for improving phosphorus utilization in sandy alkaline soils. This carbon-based biological conditioner consists of two components: carbon ester material and carbon-borne Aspergillus niger agent. In application, the preferred mass ratio of carbon ester material to carbon-borne Aspergillus niger agent is 3.33-20:1 (e.g., 10:1, 20:1, 10:3, 20:3, 5:1, etc.).

[0006] The above-mentioned charcoal vinegar material is obtained by the following method: strong adsorption biochar (crushed and passed through a 10-mesh sieve) is mixed with wood vinegar at a weight ratio of 3:1 for adsorption, and then dried in the dark until the moisture content is less than 15% (inclusive) to obtain the primary material; then the primary material is mixed with wood vinegar at a weight ratio of 3:1 for adsorption, and then dried in the dark again until the moisture content is less than 20% (inclusive) to obtain the charcoal vinegar material.

[0007] The aforementioned highly adsorbent biochar refers to biochar with a specific surface area of ​​10 m². 2 Biochar with a specific surface area of ​​10 m² or more is considered conventional biochar. For example, biochar made from mushroom residue, lychee stalks, eucalyptus bark, coconut shells, etc., can achieve a specific surface area of ​​10 m² / g through vacuum pyrolysis at 700℃ for 1 hour. 2 / g or more (Reference: Zou Ganghua, Dai Minjie, Zhao Fengliang, et al. Analysis of biochar characteristics of typical agricultural and forestry waste in Hainan [J]. Journal of Tropical Crops, 2020, 41(07): 1498-1504.); Alternatively, rice straw and corn straw can be pyrolyzed at 450-600℃ for 6 hours under constant temperature, with nitrogen gas introduced during the oxygen-limited period, to achieve a specific surface area of ​​10m². 2 / g or more (Reference: Yang Yuzhen, Gao Baolong, Huang Yi, et al. Study on adsorption characteristics of straw-based biochar for lead and cadmium at medium and high pyrolysis temperatures [J]. Geology in China, 2023, 50(01): 52-60.); or it can be purchased through commercial channels.

[0008] The aforementioned wood vinegar is preferably a commercially available wood vinegar with a titratable acid content (see the literature "Lin Cong, Dai Hongjun, Wang Zhenping. Effects of wood vinegar on the quality and accumulation of sugar, acid and other substances in wine grapes 'Cabernet Sauvignon' [J]. Northern Horticulture, 2014, (04): 17-21.") of 2 mol / L or higher.

[0009] The above-mentioned carbon-supported Aspergillus niger agent components were obtained by the following method: [The text abruptly shifts to a seemingly unrelated topic about fungal content and a specific ingredient.] 10 Aspergillus niger spore powder with a CFU / g or higher is diluted 10 times with sterile water to obtain an Aspergillus niger spore suspension. The Aspergillus niger spore suspension is then mixed with large-pore biochar (crushed and passed through a 20-mesh sieve) at a weight ratio of 1:1 and dried in the shade until the moisture content is less than 15% (including 15%). This is the carbon-supported Aspergillus niger agent.

[0010] The aforementioned large-pore biochar refers to biochar with a pore volume of 0.1 cm³. 3 Commercially available biochar with a volume of / g or higher is considered conventional biochar in this field. For example, biochar prepared from straw or miscellaneous wood waste can achieve a micropore volume of up to 0.1 cm³. 3 / g of biochar (Reference: Zhang Zhengrong. Preliminary study on the improvement of soil physical properties by biochar [D]. Zhejiang University, 2014.); or by using paulownia wood, persimmon wood, peach wood, etc., to dry-steam and decompose at 450℃ to form micron-sized pores with a volume of up to 0.1cm. 3 / g of biochar (Reference: Shen Weibao, Zhang Yun, Wang Ziqing et al. Pore structure analysis of biochar prepared from wood [J]. China Powder Technology, 2015, 21(2):24-27+31.); or it can be purchased through commercial channels.

[0011] The Aspergillus niger spore powder of the above-mentioned carbon-supported Aspergillus niger agent component was obtained by the following method:

[0012] a) Inoculate Aspergillus niger A181 into potato dextrose agar medium and incubate at 28°C for 3 days; then transfer Aspergillus niger A181 into potato dextrose liquid medium with a volume of 80 ml / 250 ml, and then incubate at 28°C on a shaker for 3-4 days at a speed of 160 rpm.

[0013] b) After the culture is completed, inoculate 10% (volume ratio, ml / kg) into sterilized bran and straw solid culture medium (adjust the moisture content to 60%, bran particle size greater than 0.5 mm, add straw to ensure air permeability, the mass ratio of straw to bran is 1:9, the average length of straw is 4 cm, sterilized at 126℃ for 60 min), and culture at 29±1℃ until spore production (about 5-7 days);

[0014] c) Air-dry the sporulating culture naturally or dry it at 30°C, then pass it through a 100-mesh sieve using a shaking method to obtain a black powder, which is the Aspergillus niger spore powder with a bacterial count greater than 10. 10 CFU / g.

[0015] The aforementioned Aspergillus niger strain A181 was deposited on November 12, 2015, at the China General Microbiological Culture Collection Center (CGMCC), with accession number CGMCC No: 11648, taxonomically named Aspergillus niger, and the deposit address is No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, 100101, China.

[0016] Secondly, the present invention also provides the application of the above-mentioned carbon-based biological conditioner in improving the phosphorus utilization rate of sandy alkaline soil. The application method is as follows: the carbon-based biological conditioner's carbon-based material component is applied to the soil in rows or holes before crop transplanting or sowing, and mixed evenly with an appropriate amount of soil (generally the top 20cm of soil) using agricultural tools. The application rate is 100-200 kg / mu. When transplanting or sowing crops, the roots are dipped or seeds are mixed with carbon-borne Aspergillus niger agent, and the application rate is 10-30 kg / mu.

[0017] The preferred crops are vegetables, such as broccoli, peppers, watermelon, garlic, and onions.

[0018] In this application, the term "sandy alkaline soil" refers to soil that simultaneously meets the definitions of "sandy soil" and "alkaline soil". Among them, "sandy soil" refers to soil with a gravel volume content of <25% and a sand content of ≥55% after sieving out gravel (see "Notice of the General Office of the Ministry of Natural Resources on Issuing the Classification Scheme for Surface Substrate" (Natural Resources Office Document

[2020] No. 59)"); "alkaline soil" refers to soil with a pH greater than 7.5 (see "Ma Yijie. Acidity and alkalinity of soil [J]. Soil, 1974, (06): 48-51"). Generally speaking, sandy alkaline soil refers to sandy soil with an alkaline pH.

[0019] Wood vinegar, being highly acidic, can promote the conversion of stable phosphorus in soil into reactive phosphorus. This application analyzed the soil phosphorus-solubilizing effect and properties of wood vinegar at various acid concentrations, clarifying that wood vinegar with a high titratable acid concentration has the best phosphorus-solubilizing effect. However, while wood vinegar can rapidly activate phosphorus in the soil when directly introduced, the effect is short-lived. Furthermore, by adsorbing wood vinegar with high titratable acid content onto biochar with different specific surface areas and then testing its soil phosphorus-solubilizing effect, the results showed that the biochar-based wood vinegar material formed by the adsorption of wood vinegar onto biochar with a high specific surface area allows for the slow release of wood vinegar (adsorbed within the biochar) in the soil, thereby improving the timeliness of phosphorus solubilization.

[0020] This application screened a *Aspergillus niger* strain, A181, with strong phosphorus-solubilizing effects from sandy alkaline vegetable soils. This strain exhibits strong phosphorus-solubilizing properties in sandy alkaline soils. However, direct addition of exogenous microorganisms to the soil results in a high mortality rate. Therefore, *Aspergillus niger* A181 spore powder was prepared and mixed with macroporous biochar for adsorption. This allows *Aspergillus niger* spores to enter the micron-sized pores of the biochar. This biochar-loaded *Aspergillus niger* agent can increase the colonization rate and effective colonization period of *Aspergillus niger* in the soil. This achieves long-term activation of soil basal phosphorus without additional phosphorus application, thereby promoting phosphorus absorption by plants. This not only promotes crop growth but also reduces phosphorus loss and excess phosphorus input.

[0021] The carbon-based bioconditioner for improving phosphorus utilization in sandy alkaline vegetable soil provided in this application comprises carbonized ester material and carbon-supported Aspergillus niger agent components. Each component functions independently while also being complementary. The combination of the two effectively enhances the conversion of stable phosphorus to reactive phosphorus in the soil, maintains a high level of available phosphorus in the soil for a long period, thereby improving plant phosphorus utilization and promoting crop growth.

[0022] Compared with existing technologies, it has the following beneficial effects:

[0023] (1) The Aspergillus niger strain screened and preserved for the first time in this application has good phosphorus solubilization effect and can be stably colonized in sandy alkaline soil.

[0024] (2) This invention is the first to utilize a combination of wood vinegar and charcoal-borne Aspergillus niger. Directly adding strong acid wood vinegar to the soil only yields a short-term high concentration of available phosphorus, failing to promote phosphorus absorption by plants. The highly absorbent biochar adsorbs the strong acid wood vinegar to form a charcoal-vinyl alcohol material. This material slowly releases the strong acid wood vinegar into the soil, gradually activating soil phosphorus and meeting the long-term phosphorus requirements of crops. Aspergillus niger, in spore form, is adsorbed by the micron-sized pores of the biochar, increasing its colonization time and quantity in the soil, thereby effectively improving its phosphorus-releasing effect and extending its duration.

[0025] (3) The carbon-based bioconditioner's carbon vinegar material and carbon-borne Aspergillus niger agent are complementary. The carbon vinegar material releases wood vinegar to increase the available phosphorus content in the soil, with its main effect within 30 days after application. The carbon-borne Aspergillus niger agent begins to exert its phosphorus-releasing effect after Aspergillus niger has stably colonized, with its main effect after 20 days after application. The two are complementary in terms of phosphorus-releasing time. The phosphorus-releasing space of the carbon vinegar material is mainly in the application space, i.e., the initial root growth area, while the phosphorus-releasing space of the carbon-borne Aspergillus niger agent spreads into the soil as the root system grows. The two are complementary in terms of phosphorus-releasing space.

[0026] (4) The field application method of this invention is simple and it is an environmentally friendly agricultural carbon-based biological conditioner. Attached Figure Description

[0027] Figure 1 Photographs of colony morphology on plate count plates for routine control and Aspergillus niger A181 treatment;

[0028] Figure 2 The content of different forms of inorganic phosphorus was compared between the conventional control and the carbon-based bioconditioner treatment. Detailed Implementation

[0029] Raw materials involved in the examples:

[0030] Rice husk biochar: purchased from Ji'an Longjing Carbon Technology Co., Ltd., with a micron-sized pore size of 0.12cm. 3 / g; Corn straw biochar: purchased from Nanjing Qinfeng Straw Technology Co., Ltd., specific surface area 1.43m² 2 / g; Fir wood chip biochar: purchased from Henan Housen Environmental Protection Technology Co., Ltd., specific surface area 18.6m² 2 / g.

[0031] Poplar wood vinegar: purchased from Jinan Shengteng Chemical Co., Ltd., with a titratable acid concentration of 0.90 mol / L.

[0032] Fruit shell wood vinegar: purchased from Shijiazhuang Hongsen Activated Carbon Co., Ltd., with a titratable acid concentration of 2.97 mol / L. Culture medium used in the examples:

[0033] Potato glucose agar medium: Peel and cut 200g of potatoes into chunks and cook for 30 minutes. Filter the liquid through four layers of gauze, add 20g of glucose and bring the volume to 1L. Add 20g of agar and sterilize at 121℃ for 30 minutes.

[0034] Potato glucose liquid culture medium: Peel and cut 200g potatoes into pieces and cook for 30 minutes. Filter the liquid through four layers of gauze, add 20g glucose and bring the volume to 1L. Sterilize at 121℃ for 30 minutes.

[0035] Wheat bran and rice straw solid culture medium: Rice straw (average length 4cm) and wheat bran (particle size greater than 0.5mm) are mixed at a mass ratio of 1:9, the moisture content is adjusted to 60%, and sterilized at 126℃ for 60min.

[0036] Example 1: Preparation of carbonized acetic acid material and its phosphorus-solubilizing effect in soil.

[0037] Carbon vinegar material 1 was prepared by taking corn stalk biochar and poplar wood vinegar; carbon vinegar material 2 was prepared by taking corn stalk biochar and fruit shell wood vinegar; carbon vinegar material 3 was prepared by taking fir wood chips biochar and poplar wood vinegar; and carbon vinegar material 4 was prepared by taking fir wood chips biochar and fruit shell wood vinegar.

[0038] Preparation method: Biochar and wood vinegar were adsorbed separately at a weight ratio of 3:1, and then dried in the dark until the moisture content was below 15%. Biochar was then adsorbed again at a weight ratio of 3:1 with wood vinegar, and dried in the dark again until the moisture content was below 20%. These were the biochar-vinegar materials. Four types of biochar-vinegar materials were added to soil samples collected from garlic-growing areas in Xuzhou (available phosphorus content 27.6 mg / kg). The amount of biochar-vinegar material added was 10% of the soil mass. The samples were incubated in a humid environment at 25-30℃ in the laboratory. The available phosphorus content of the soil was measured after 10, 30, and 90 days, according to Bao Shidan's "Soil Agrochemical Analysis". The results are shown in Table 1, where the data are the average of three replicates for each treatment.

[0039] Table 1. Phosphorus solubilization effects of different carbonaceous materials on soil.

[0040]

[0041] Table 1 shows that charcoal vinegar material 4, prepared from fruit shell wood vinegar with high titratable acid concentration and fir sawdust biochar with large specific surface area, can effectively increase the available phosphorus content in the soil compared with other charcoal vinegar materials, and the phosphorus-releasing effect is long-lasting, significantly maintaining for 30 days. Poplar wood vinegar with low titratable acid concentration has a good phosphorus-releasing effect, but it is worse than that of fruit shell wood vinegar, and the phosphorus-releasing effect is not long-lasting. Corn straw biochar with low specific surface area releases wood vinegar at a fast rate, resulting in a short phosphorus-releasing time for the charcoal vinegar material.

[0042] Example 2: Colonization and phosphorus solubilization effect of Aspergillus niger strain A181 in soil

[0043] Aspergillus niger A181 preserved on slant culture medium was inoculated into potato dextrose agar and incubated at 28°C for 3 days to produce black conidia. Soil samples were collected from the broccoli growing area in Xiangshui County, with a total phosphorus content of 0.76 g / kg and an available phosphorus content of 26.9 mg / kg.

[0044] Two treatments were set up: a conventional control (CK) and an Aspergillus niger A181 treatment.

[0045] The standard treatment involves directly filling each pot with 500 grams of soil. The Aspergillus niger A181 treatment involves adding Aspergillus niger A181 black conidia to the soil, resulting in a soil concentration of 10-1 Aspergillus niger conidia. 6 The soil was then placed in pots, 500 grams per pot. Each treatment was replicated in three pots. After 50 days of humidification at 25-30℃, the available phosphorus and Aspergillus niger levels in the soil were measured.

[0046] The determination of Aspergillus niger count was performed according to Shen Ping's "Microbiological Experiments". The results are shown in Table 2, where the data are the average of three replicates for each treatment. Figure 1 Photographs of two soil dilutions after three days of incubation on fungal culture medium after being plated with the diluted solution.

[0047] Table 2. Colonization and phosphorus solubilization effects of Aspergillus niger strain A181 in soil.

[0048]

[0049]

[0050] Table 1 shows that the available phosphorus content of the conventional treatment was 26.7 mg / kg, and the plate count showed that the treatment was effective at 10 mg / kg. -2 No Aspergillus niger colonies were found in the soil dilution agar plates; all colonies were from other microorganisms. However, the Aspergillus niger A181 treatment showed a concentration of 53.9 mg / kg, and agar plate counts indicated that this treatment was effective against 10... -4After the soil dilution was plated, it showed Aspergillus niger colonies, with a count of 5.4 × 10⁻⁶. 4 CFU / g. After adding Aspergillus niger A181 spores to the soil, Aspergillus niger can stably colonize in the soil and has a phosphorus-solubilizing effect on fixed phosphorus in the soil, which can significantly increase the available phosphorus content in the soil.

[0051] Example 3: Preparation of carbon-supported Aspergillus niger agent

[0052] Aspergillus niger A181 mycelium preserved on slant culture medium was inoculated into potato dextrose agar and cultured at 28°C for 3 days to produce black conidia. Then, Aspergillus niger mycelial blocks containing conidia were inoculated into potato dextrose liquid medium (80ml / 250ml), with 3 mycelial blocks (8mm diameter) per bottle. The mixture was then incubated at 28°C and 160rpm on a shaker for 3-4 days to obtain mycelial solution. 80ml of the cultured Aspergillus niger mycelial solution was inoculated into 1.5kg of sterilized wheat bran / straw solid culture medium. After thorough mixing under aseptic conditions, the solid culture was spread evenly in shallow dishes (the dishes were soaked in formalin solution overnight and dried) to a thickness of 3-5cm. A filter cloth sterilized by autoclaving was placed under the dish, and two layers of autoclaved gauze were placed on top. The mixture was incubated at 29±2°C for 5 days until conidia were complete. Air-dry the mixture until the moisture content is less than 10%, then pulverize it using a vibratory mill and pass it through a 100-mesh sieve to obtain Aspergillus niger A181 spore powder, which has a bacterial count greater than 1.26 × 10⁻⁶. 10 CFU / g.

[0053] Dilute Aspergillus niger A181 spore powder 10 times with sterile water to obtain an Aspergillus niger spore powder suspension. Then, mix the suspension with rice husk biochar at a weight ratio of 1:1. Spread the mixture in the dark to a thickness of 3 cm and air dry for 4 days until the moisture content drops to 13.8% (in practice, the moisture content should be below 15%). This is the carbon-supported Aspergillus niger agent.

[0054] Example 4: Application of carbon-based bioconditioning agents in open-field garlic

[0055] A field experiment was conducted in a garlic-growing area in Pizhou City, Xuzhou. The total phosphorus content in the soil was 0.94 g / kg, and the available phosphorus content was 28.4 mg / kg. Five treatments were set up: no phosphorus, conventional control, carbonized vinegar material, carbonized Aspergillus niger inoculant, and carbonized bioconditioner treatment.

[0056] Each process involves 3 duplicate cells, each cell size being 10m². 2The plants were randomly arranged. The phosphorus-free treatment received the same nitrogen and potassium inputs as the other treatments, and the fertilization for the other treatments was the same: 50 kg of 15-15-15 compound fertilizer as base fertilizer, 20 kg of urea as the first topdressing, and 20 kg of 15-5-25 compound fertilizer as the second topdressing. The charcoal-vinegar material treatment involved applying charcoal-vinegar material 4 from Example 1 before garlic planting, mixing it evenly with an appropriate amount of soil using a hoe, at a rate of 200 kg / mu. The charcoal-borne Aspergillus niger inoculant treatment involved dipping the bulbs in the charcoal-borne Aspergillus niger inoculant prepared in Example 3 after wetting them with irrigation water at planting time, at a rate of 20 kg / mu. The charcoal-based bioconditioner treatment combined the charcoal-vinegar material treatment and the charcoal-borne Aspergillus niger inoculant treatment. At harvest, garlic yield, total plant phosphorus content, fertilizer phosphorus utilization rate, and soil available phosphorus content were measured. The phosphorus content of the plants was determined according to Bao Shidan's "Soil Agrochemical Analysis". The results are shown in Table 2, where the data are the average of three replicates for each treatment.

[0057] Table 3. Effects of different treatments on garlic yield, phosphorus uptake, and soil phosphorus.

[0058]

[0059] Table 3 shows that carbon-based biological conditioners can significantly increase fresh bulb yield, total plant phosphorus content, fertilizer phosphorus utilization rate, and soil available phosphorus content, while carbon-carried Aspergillus niger agents also have a good improvement effect, and carbon-based vinegar materials have the weakest improvement effect.

[0060] Example 5: Application of carbon-based bioconditioner on open-field broccoli

[0061] A small-plot field experiment was conducted in a broccoli planting area in Xiangshui County, Yancheng City. The total phosphorus content in the soil was 0.76 g / kg, and the available phosphorus content was 26.9 mg / kg.

[0062] The experiment consisted of four treatments: a standard control, carbonized material, carbonized Aspergillus niger inoculum, and a carbon-based bioconditioner. Each treatment had three replicate plots, each plot measuring 20 m². 2 The plants were randomly arranged. Fertilization was consistent across treatments: 80 kg of 15-15-15 compound fertilizer as base fertilizer, 20 kg of urea as the first topdressing, 15 kg of 15-15-15 compound fertilizer as the second topdressing, and 20 kg of 15-15-15 compound fertilizer as the third topdressing. The charcoal-vinegar treatment involved applying charcoal-vinegar material 4 from Example 1 to the planting holes before transplanting broccoli seedlings, mixing it evenly with an appropriate amount of soil using a hoe, at a rate of 150 kg / mu. The charcoal-borne Aspergillus niger treatment involved dipping the broccoli seedlings in the charcoal-borne Aspergillus niger agent prepared in Example 3 after irrigation watering at transplanting, at a rate of 30 kg / mu. The charcoal-based bioconditioner treatment combined the charcoal-vinegar treatment and the charcoal-borne Aspergillus niger agent treatment. Soil available phosphorus content was measured on day 20 after transplanting, and broccoli yield, total plant phosphorus content, and soil available phosphorus content were measured at harvest. The results are shown in Table 4, where the data are the average of three replicates for each treatment.

[0063] Table 4. Effects of different treatments on broccoli yield, total plant phosphorus content, and soil phosphorus.

[0064]

[0065]

[0066] Table 4 shows that at 20 days after transplanting, the results for both the charcoal-based material and the charcoal-based bioconditioner were significantly higher than the conventional control, while the charcoal-borne Aspergillus niger agent was also higher than the conventional control to some extent. Therefore, at 20 days after transplanting, the charcoal-based material played a major role in phosphorus solubilization, while the charcoal-borne Aspergillus niger agent also had a certain phosphorus solubilization effect. At harvest, the charcoal-based bioconditioner significantly increased broccoli yield, total plant phosphorus content, and available phosphorus content in the soil, while the charcoal-borne Aspergillus niger agent also showed a good improvement effect, and the charcoal-based material had the weakest improvement effect. Therefore, after a longer transplanting period, the charcoal-borne Aspergillus niger agent played a major role in phosphorus solubilization.

[0067] Example 6: Application of carbon-based bioconditioning agent on open-field horn peppers

[0068] A field experiment was conducted in the horn pepper planting area of ​​Yandong Town, Tinghu District, Yancheng City. The total phosphorus content of the soil was 1.03 g / kg, and the available phosphorus content was 33.7 mg / kg.

[0069] The experiment consisted of two treatments: a standard control and a carbon-based bioconditioner treatment. Each treatment had three replicate plots, each with a plot area of ​​30 m². 2 The plants were randomly arranged. All treatments received the same fertilization: 40 kg of 15-15-15 compound fertilizer and 500 kg of farmyard manure as base fertilizer; 5 kg of 22-12-16 water-soluble fertilizer as the first topdressing; 10 kg of 19-6-25 water-soluble fertilizer as the second topdressing; and 10 kg of 19-6-25 water-soluble fertilizer as the third topdressing. For the carbon-based bioconditioner treatment, carbon-based material 4 from Example 1 was applied before transplanting the chili seedlings, mixed evenly with an appropriate amount of soil using a hoe, at a rate of 200 kg / mu. After wetting the roots with irrigation water at transplanting, the seedlings were dipped in the carbon-borne Aspergillus niger agent prepared in Example 3, at a rate of 25 kg / mu. Chili yield and plant phosphorus content were measured, and the soil was analyzed for different forms of phosphorus content. The measurement method referred to "Changes in Soil Phosphorus Availability and Influencing Factors Caused by Crop Rotation Under Different Fertilization Patterns". The results are shown in Table 5, where the data are the average of three replicates for each treatment.

[0070] Table 5. Effects of different treatments on pepper yield and phosphorus content in plants.

[0071]

[0072] The results in Table 5 show that the carbon-based bioconditioner can significantly increase the yield and phosphorus content of chili peppers, and to some extent increase the phosphorus content of the fruit.

[0073] Figure 2 The figures represent the contents of different forms of inorganic phosphorus in the two treatments of this embodiment. Resin-P and NaHCO3-P represent inorganic phosphorus extracted from resin and NaHCO3, respectively, both of which are active phosphorus. NaOH-P and dHCl-P represent inorganic phosphorus extracted from sodium hydroxide and hydrochloric acid, respectively, both of which are moderately active phosphorus. cHCl-P and Residual-P represent inorganic phosphorus extracted from concentrated hydrochloric acid and residual phosphorus, respectively, both of which are stable phosphorus. The carbon-based bioconditioner significantly increased the content of active phosphorus and reduced the content of stable phosphorus.

Claims

1. A carbon-based bioconditioner for improving phosphorus utilization in sandy alkaline soils, characterized in that, The conditioning agent is obtained by mixing charcoal-based vinegar material and charcoal-borne Aspergillus niger agent at a mass ratio of 3.33-20:1; The charcoal-vinyl acetate material is obtained by the following method: Strongly adsorbing biochar is mixed with wood vinegar and dried until the moisture content is below 15% to obtain a primary material; then, the primary material is mixed with wood vinegar and dried again until the moisture content is below 20% to obtain the charcoal-vinyl acetate material; the strongly adsorbing biochar has a specific surface area > 10 m². 2 / g of biochar; the wood vinegar has a titratable acid content >2mol / L; The carbon-borne Aspergillus niger agent is obtained by the following method: [The following is a process involving a bacterial content of 10...] 10 Aspergillus niger spore powder with a CFU / g or higher was diluted 10 times with sterile water to obtain an Aspergillus niger spore suspension. This suspension was then mixed with macroporous biochar at a 1:1 mass ratio and dried until the moisture content was below 15%. This mixture is the carbon-supported Aspergillus niger agent. The macroporous biochar refers to biochar with a pore volume > 0.1 cm³. 3 / g of biochar; the Aspergillus niger spore powder refers to the spore powder produced by Aspergillus niger with accession number CGMCC NO:11648.

2. The carbon-based bioconditioner for improving phosphorus utilization in sandy alkaline soil according to claim 1, characterized in that, The mixing of highly adsorbent biochar and wood vinegar refers to mixing the highly adsorbent biochar and wood vinegar at a mass ratio of 3:1; the further mixing of the primary material and wood vinegar refers to mixing the primary material and wood vinegar at a mass ratio of 3:

1.

3. The carbon-based bioconditioner for improving phosphorus utilization in sandy alkaline soil according to claim 1, characterized in that, The Aspergillus niger spore powder was prepared by the following method: a) Inoculate Aspergillus niger into potato dextrose agar medium and incubate at 28°C for 3 days; then transfer to potato dextrose liquid medium and incubate in a shaker at 28°C for 3-4 days to obtain the primary culture; b) The primary culture was inoculated into a bran and straw solid culture medium and cultured at 29±1℃ until sporulation occurred to obtain a sporulated culture; The preparation method of wheat bran and rice straw solid culture medium is as follows: Mix rice straw and wheat bran at a mass ratio of 1:9, adjust the moisture content to 60%, and sterilize at 126℃ for 60 min; c) Air dry the spore-producing culture naturally or dry it at 30°C, and pass it through a 100-mesh sieve to obtain a black powder, which is the Aspergillus niger spore powder.

4. The application of the carbon-based bioconditioner as described in any one of claims 1-3 in improving the phosphorus utilization rate of sandy alkaline soil; the carbon-based material is applied to the soil in rows or holes before transplanting or sowing vegetables, and the roots are dipped or seeds are mixed with carbon-borne Aspergillus niger agent when transplanting or sowing vegetables.

5. The application according to claim 4, characterized in that, The application rate of the carbonized vinegar material is 100-200 kg / mu, and the application rate of the carbon-borne Aspergillus niger agent is 10-30 kg / mu.

6. The application according to claim 5, characterized in that, The vegetables include any one of broccoli, chili peppers, watermelon, garlic, and onions.

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