Salinized soil potash fertilizer synergistic conditioner as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of soil conditioning, and particularly relates to a salinized soil potash fertilizer synergistic conditioner as well as a preparation method and application thereof. The potassium fertilizer synergistic conditioner for the salinized soil is prepared from the following raw materials in parts by weight: 90 to 110 parts of biochar and 0.9 to 1.1 parts of a microbial agent. Wherein the biochar is herbal biochar prepared by carrying out anaerobic high-temperature thermal cracking on rice hulls. The microbial agent is prepared from bacillus subtilis and bacillus mucilaginosus, and the viable count ratio of the bacillus subtilis to the bacillus mucilaginosus is 1: (2.5-3.5). The biochar and the microbial agent are mixed according to the weight parts, and the potassium fertilizer synergistic conditioner for the salinized soil is obtained. The potassium fertilizer synergistic conditioner for the salinized soil can improve the potassium fertilizer utilization rate of soybeans on the salinized soil, the organic matter content in the soil and the soybean yield are improved, and the salt content of the soil is reduced.

Description

Technical Field

[0001] This invention belongs to the field of soil conditioning technology, specifically relating to a potassium fertilizer enhancement conditioner for salinized soil, its preparation method, and its application. Background Technology

[0002] Saline soils are widespread globally, particularly in arid and semi-arid regions. Salt accumulation in saline soils severely impacts crop growth and yield. Although rich in potassium, saline soils lack organic matter, carbon, nitrogen, and phosphorus. Microbial metabolism in saline soils is more easily limited by carbon and nitrogen; as salinization worsens, the degree of carbon and nitrogen limitation becomes more pronounced, further hindering the efficient absorption and utilization of potassium. Furthermore, saline soils are highly compacted, with poor aeration and permeability, reducing the availability of various nutrients and restricting normal root growth, thus affecting crop growth and yield. Potassium fertilizer is one of the three major fertilizer elements in agricultural production; however, crops in saline soils have low potassium absorption and utilization efficiency, resulting in low potassium fertilizer utilization and waste.

[0003] In existing technologies, conditioners for saline-alkali soils mainly increase crop yields by improving soil permeability or reducing soil salinity. However, these conditioners lack synergy and their effect on improving potassium fertilizer absorption and utilization is not significant. Therefore, developing a potassium fertilizer-enhancing conditioner specifically for saline-alkali soils is of great practical importance. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a potassium fertilizer enhancement and conditioning agent for salinized soils, its preparation method, and its application.

[0005] The first objective of this invention is to provide a potassium fertilizer enhancement conditioner for salinized soil, which is composed of the following raw materials in parts by weight: 90 to 110 parts of biochar and 0.9 to 1.1 parts of microbial inoculant.

[0006] The microbial agent is made from Bacillus subtilis and Bacillus mucilaginosus, with a live bacteria ratio of 1:2.5~3.5. Bacillus subtilis decomposes soil organic matter and promotes the transformation of nutrients such as N, P, and K in the soil. Bacillus mucilaginosus enhances the release of soil mineral nutrients.

[0007] The biochar mentioned above is a herbaceous biochar prepared by anaerobic high-temperature pyrolysis of rice husks. Compared with woody biochar, herbaceous biochar not only has a higher carbon content, which helps improve soil aeration, but also contains nitrogen, phosphorus, and potassium nutrients, which can improve soil fertility.

[0008] The biochar and the microbial agent are mixed in the specified weight proportions to obtain a potassium fertilizer enhancement and conditioning agent for salinized soil.

[0009] Preferably, the biochar contains 45% to 50% carbon.

[0010] Preferably, the total effective viable count of Bacillus subtilis and Bacillus mucilaginosus is ≥5 billion / g.

[0011] Preferably, the Bacillus subtilis is a species of Bacillus in the genus Bacillus, with the Latin name […]. Bacillus subtilis The mentioned Bacillus mucilaginosus is a species of Bacillus in the genus Bacillus, with the Latin name [Latin name missing]. Bacillus mucilaginosus .

[0012] Preferably, the weight ratio of the biochar to the microbial preparation is 100:1.

[0013] The second objective of this invention is to provide an application of a potassium fertilizer enhancement and conditioning agent for salinized soil, the application method comprising the following steps: Potassium fertilizer enhancer and potassium fertilizer are applied to the soil tillage layer in salinized soil.

[0014] Tillage, with a tillage depth of 10cm to 20cm.

[0015] Crops are planted in the tilled soil.

[0016] Field management until crop maturity.

[0017] Preferably, the application rate of the potassium fertilizer enhancement agent for salinized soil is 270~330 kg / mu.

[0018] Preferably, the application rate of the potassium fertilizer enhancement agent for salinized soil is 303 kg / mu.

[0019] The preferred application rate of the potassium fertilizer is 0 kg / mu to 6 kg / mu.

[0020] Preferably, the crop is soybean.

[0021] Preferably, the potassium fertilizer enhancement conditioner for salinized soil is used to improve the utilization rate of potassium fertilizer in the soil.

[0022] Compared with the prior art, the present invention has the following beneficial effects: 1. The potassium fertilizer enhancement and conditioning agent for salinized soil of the present invention is composed of the following raw materials in parts by weight: 90-110 parts biochar and 0.9-1.1 parts microbial inoculant. The biochar is herbaceous biochar prepared by anaerobic high-temperature pyrolysis of rice husks. Biochar helps improve soil permeability and contains nitrogen, phosphorus, and potassium nutrients, which can improve soil fertility and provide growth conditions for soil microorganisms and soybeans. The microbial inoculant is made from Bacillus subtilis and Bacillus mucilaginosus. Bacillus subtilis is a species of Bacillus and has the function of decomposing soil organic matter and promoting the transformation of nutrients such as N, P, and K in the soil. Bacillus mucilaginosus is a species of Bacillus and has the function of increasing the release of soil mineral nutrients. Bacillus subtilis and Bacillus mucilaginosus can increase the content of available nitrogen, phosphorus, and potassium in the soil, providing sufficient nutrients for soybean growth. The biochar and the microbial inoculant are mixed in the specified parts by weight to obtain the potassium fertilizer enhancement and conditioning agent for salinized soil. The synergistic effect of biochar and microbial agents improves soil permeability and nutrient content, thereby increasing the utilization rate of potassium fertilizer in the soil by soybeans.

[0023] The potassium fertilizer enhancement conditioner for salinized soil of this invention, through the synergistic effect of biochar and microbial agents, can increase the content of organic matter, available potassium, available phosphorus, and inorganic nitrogen in the soil, increase soil field water holding capacity, increase cation exchange capacity, and reduce soil bulk density and soil salinity. The increased content of organic matter, available potassium, available phosphorus, and inorganic nitrogen in the soil provides sufficient nutrients for soybean growth. The reduction in soil bulk density and soil salinity provides a favorable growth environment for soybeans. On this basis, soybeans can fully absorb various elements in the soil for growth, and the absorption and utilization rate of potassium fertilizer in the soil is more complete. This is the result of the combined action of biochar and microbial agents, which promotes soybean growth, and the growing soybeans further accelerate the absorption of potassium fertilizer, forming a good positive feedback loop. In addition, this invention found that other soil bacteria, such as Bacillus megaterium, Trichoderma, and arbuscular mycorrhizal fungi, when combined with biochar, can improve soil fertility, enhance the ability to degrade pollutants, and promote plant growth. However, the lack of effect on promoting potassium fertilizer absorption by plants indicates that the combination of Bacillus subtilis and Bacillus mucilaginosus of the present invention has the specificity to promote potassium fertilizer absorption.

[0024] 2. The application of the potassium fertilizer synergist for salinized soil in this invention involves applying the synergist and potassium fertilizer to the soil surface and then tilling the soil to a depth of 10-20 cm. Tillage mixes the synergist and potassium fertilizer into the soil, improving soil structure and increasing the content of microorganisms and potassium in the soil, thus providing a favorable growing environment and sufficient nutrients for crops. Crops are then planted in the tilled soil. Field management continues until crop maturity. The application of the potassium fertilizer synergist for salinized soil in this invention not only improves the absorption and utilization rate of potassium fertilizer by soybeans and reduces soil salinity, but also increases the content of protein, soluble sugars, and vitamin C in soybean seeds, thereby improving the quality of soybean seeds.

[0025] 3. The potassium fertilizer enhancement conditioner for salinized soil provided by this invention can improve the permeability of salinized soil, increase the organic matter content in the soil, and reduce the salt content in the soil, which is of great significance for the improvement of salinized soil. Attached Figure Description

[0026] Figure 1 This is a diagram showing the potassium uptake of soybeans according to the present invention.

[0027] Figure 2 This is a diagram showing the potassium fertilizer utilization rate of the present invention.

[0028] Figure 3 This is a diagram illustrating the agronomic efficiency of the potassium fertilizer of this invention.

[0029] Figure 4 This is a diagram showing the available potassium content in soil according to the present invention.

[0030] Figure 5 This is a diagram showing the soil salinity under different treatments according to the present invention.

[0031] Figure 6 This is a diagram showing the soil organic matter content according to the present invention.

[0032] Figure 7 This is a graph showing the inorganic nitrogen content in soil under different treatments according to the present invention.

[0033] Figure 8 This is a diagram showing the available phosphorus content in soil according to the present invention.

[0034] Figure 9 This is a diagram showing the soil cation exchange capacity of the present invention.

[0035] Figure 10 This is a diagram showing the soil bulk density of the present invention.

[0036] Figure 11 This is a diagram of soil field water holding capacity according to the present invention. Detailed Implementation

[0037] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the following detailed description, in conjunction with preferred embodiments and accompanying drawings, provides a clear and complete account of the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0038] It should be noted that all technical terms used in this invention are for the purpose of describing specific embodiments only and are not intended to limit the scope of protection of this invention. Unless otherwise specified, all raw materials, reagents, instruments and equipment used in the following embodiments of this invention can be purchased from the market or prepared by existing methods.

[0039] The *Bacillus subtilis* strain used in this invention was purchased from Tianjin Kunhe Biotechnology Group Co., Ltd., with an effective viable count ≥1.2 billion / g; the *Bacillus mucilaginosus* strain was also purchased from Tianjin Kunhe Biotechnology Group Co., Ltd., with an effective viable count ≥3.8 billion / g. The biochar used in this invention is rice husk herbaceous biochar, with a carbon content of 45%~50%, produced by Tianjin Yadel Biomass Technology Co., Ltd.

[0040] Example 1 A potassium fertilizer enhancement and conditioning agent for salinized soil comprises the following raw materials in parts by weight: 100 parts biochar and 1 part microbial inoculant. The biochar has a carbon content of 45%. The microbial inoculant is made from Bacillus subtilis and Bacillus mucilage, with a viable bacteria ratio of 1:3. The total viable bacteria count of the microbial inoculant is ≥5 billion / g. The biochar and the microbial inoculant are mixed in the stated parts by weight to obtain the potassium fertilizer enhancement and conditioning agent for salinized soil.

[0041] A method for applying a potassium fertilizer synergist for salinized soil includes the following steps: Apply potassium fertilizer enhancer to saline soil at a rate of 303 kg / mu on the soil surface, then plow to a depth of 15 cm. Plant soybeans with a row spacing of 50 cm and a plant spacing of 15 cm, leaving 2 seedlings per hole. Apply nitrogen fertilizer at a rate of 10 kg / mu (N element), with 5 kg / mu applied as base fertilizer during plowing and another 5 kg / mu applied as top dressing during the flowering and pod-setting stage. Apply phosphorus fertilizer at a rate of 8 kg / mu (P2O5) as base fertilizer during plowing.

[0042] Comparative Example 1 A method for applying a potassium fertilizer synergist for salinized soil includes the following steps: Apply 3 kg / mu of microbial inoculant to the soil surface, then till to a depth of 5 cm. During tilling, plant soybeans with a row spacing of 50 cm and a plant spacing of 15 cm, leaving 2 seedlings per hole. Apply 10 kg / mu of nitrogen fertilizer (calculated as N), with 5 kg / mu applied as base fertilizer during tilling and another 5 kg / mu applied as top dressing during the flowering and pod-setting stage. Apply 8 kg / mu of phosphorus fertilizer (calculated as P2O5) as a single base fertilizer application during tilling.

[0043] Comparative Example 2 A method for applying a potassium fertilizer synergist for salinized soil includes the following steps: Apply biochar at a rate of 300 kg / mu to the soil surface, then plow to a depth of 5 cm. Plant soybeans with a row spacing of 50 cm and a plant spacing of 15 cm, leaving 2 seedlings per hole. Apply nitrogen fertilizer at a rate of 10 kg / mu (N element), with 5 kg / mu applied as base fertilizer during plowing and another 5 kg / mu applied as top dressing during the flowering and pod-setting stage of soybeans. Apply phosphorus fertilizer at a rate of 8 kg / mu (P2O5) as a single base fertilizer application during plowing.

[0044] Comparative Example 3 A method for applying a potassium fertilizer synergist for salinized soil includes the following steps: Till the soil to a depth of 5 cm. Plant soybeans with a row spacing of 50 cm and a plant spacing of 15 cm, leaving 2 seedlings per hole in the soil. Apply nitrogen fertilizer at a rate of 10 kg / mu (N element), of which 5 kg / mu is applied as base fertilizer during tilling and another 5 kg / mu is applied as top dressing during the flowering and pod-setting stage of soybeans. Apply phosphorus fertilizer at a rate of 8 kg / mu (P2O5) as base fertilizer during tilling.

[0045] Example 2 A potassium fertilizer enhancement and conditioning agent for salinized soil comprises the following raw materials in parts by weight: 90 parts biochar and 0.9 parts microbial inoculant. The biochar contains 45%–50% carbon. The microbial inoculant is made from Bacillus subtilis and Bacillus mucilage, with a viable count ratio of 1:2.5. The total viable count of the microbial inoculant is 5.5 billion CFU / g. The biochar and the microbial inoculant are mixed in the stated parts by weight to obtain the potassium fertilizer enhancement and conditioning agent for salinized soil.

[0046] A method for applying a potassium fertilizer synergist for salinized soil includes the following steps: Apply 272.7 kg / mu of potassium fertilizer enhancer and 2 kg / mu of potassium fertilizer to the soil surface for salinized soil, then plow to a depth of 10 cm. Plant soybeans with a row spacing of 50 cm and a plant spacing of 15 cm, leaving 2 seedlings per hole. Apply 10 kg / mu of nitrogen fertilizer (calculated as N element), of which 5 kg / mu is applied as base fertilizer during plowing and another 5 kg / mu is applied as top dressing during the flowering and pod-setting stage of soybeans. Apply 8 kg / mu of phosphorus fertilizer (calculated as P2O5) as base fertilizer during plowing.

[0047] Comparative Example 4 A method for applying a potassium fertilizer synergist for salinized soil includes the following steps: Apply 270 kg / mu of microbial inoculant and 2 kg / mu of potassium fertilizer to the soil surface, then till to a depth of 10 cm. Plant soybeans with a row spacing of 50 cm and a plant spacing of 15 cm, leaving 2 seedlings per hole. Apply 10 kg / mu of nitrogen fertilizer (calculated as N), with 5 kg / mu as basal fertilizer and 5 kg / mu as top dressing. Apply 8 kg / mu of phosphorus fertilizer (calculated as P2O5) as basal fertilizer in a single application.

[0048] Comparative Example 5 A method for applying a potassium fertilizer synergist for salinized soil includes the following steps: Apply biochar at 2.7 kg / mu and potassium fertilizer at 2 kg / mu to the soil surface, then till to a depth of 10 cm. Plant soybeans with a row spacing of 50 cm and a plant spacing of 15 cm, leaving 2 seedlings per hole. Apply nitrogen fertilizer (calculated as N) at a rate of 10 kg / mu, with 5 kg / mu as basal fertilizer and 5 kg / mu as top dressing. Apply phosphorus fertilizer (calculated as P2O5) as a single basal application of 8 kg / mu.

[0049] Comparative Example 6 A method for applying a potassium fertilizer synergist for salinized soil includes the following steps: Apply potassium fertilizer at a rate of 2 kg / mu to the soil surface, then till the soil to a depth of 15 cm. Plant soybeans with a row spacing of 50 cm and a plant spacing of 15 cm, leaving 2 seedlings per hole. Apply nitrogen fertilizer at a rate of 10 kg / mu (calculated as N), with 5 kg / mu as basal fertilizer and 5 kg / mu as topdressing. Apply phosphorus fertilizer at a rate of 8 kg / mu (calculated as P2O5) as basal fertilizer in a single application.

[0050] Example 3 A potassium fertilizer enhancement and conditioning agent for salinized soil comprises the following raw materials in parts by weight: 110 parts biochar and 1.1 parts microbial inoculant. The biochar contains 50% carbon. The microbial inoculant is made from Bacillus subtilis and Bacillus mucilage, with a viable count ratio of 1:3.5. The total viable count of the microbial inoculant is 5.6 billion / g. The biochar and the microbial inoculant are mixed in the stated parts by weight to obtain the potassium fertilizer enhancement and conditioning agent for salinized soil.

[0051] A method for applying a potassium fertilizer synergist for salinized soil includes the following steps: Apply potassium fertilizer enhancer and conditioner to the salinized soil at a rate of 333.3 kg / mu and potassium fertilizer at a rate of 4 kg / mu on the soil surface, then till the soil to a depth of 15 cm. Plant soybeans in the same area with a row spacing of 50 cm and a plant spacing of 15 cm, leaving 2 seedlings per hole. Apply nitrogen fertilizer (calculated as N) at a rate of 10 kg / mu, with 5 kg / mu as basal fertilizer and 5 kg / mu as topdressing. Apply phosphorus fertilizer (calculated as P2O5) as a single basal application of 8 kg / mu.

[0052] Comparative Example 7 A method for applying a potassium fertilizer synergist for salinized soil includes the following steps: Apply 330 kg / mu of microbial inoculant and 4 kg / mu of potassium fertilizer to the soil surface, then till to a depth of 15 cm. Plant soybeans with a row spacing of 50 cm and a plant spacing of 15 cm, leaving 2 seedlings per hole. Apply 10 kg / mu of nitrogen fertilizer (calculated as N), with 5 kg / mu as basal fertilizer and 5 kg / mu as topdressing. Apply 8 kg / mu of phosphorus fertilizer (calculated as P2O5) as basal fertilizer in a single application.

[0053] Comparative Example 8 A method for applying a potassium fertilizer synergist for salinized soil includes the following steps: Apply biochar at 3.3 kg / mu and potassium fertilizer at 4 kg / mu to the soil surface, then till to a depth of 15 cm. Plant soybeans with a row spacing of 50 cm and a plant spacing of 15 cm, leaving 2 seedlings per hole. Apply nitrogen fertilizer (calculated as N) at a rate of 10 kg / mu, with 5 kg / mu as basal fertilizer and 5 kg / mu as top dressing. Apply phosphorus fertilizer (calculated as P2O5) as a single basal application of 8 kg / mu.

[0054] Comparative Example 9 A method for applying a potassium fertilizer synergist for salinized soil includes the following steps: Apply potassium fertilizer at a rate of 4 kg / mu to the soil surface, then till the soil to a depth of 15 cm. Plant soybeans with a row spacing of 50 cm and a plant spacing of 15 cm, leaving 2 seedlings per hole. Apply nitrogen fertilizer at a rate of 10 kg / mu (calculated as N), with 5 kg / mu as basal fertilizer and 5 kg / mu as topdressing. Apply phosphorus fertilizer at a rate of 8 kg / mu (calculated as P2O5) as basal fertilizer in a single application.

[0055] Example 4 A potassium fertilizer enhancement conditioner for salinized soil comprises the following raw materials in parts by weight: 100 parts biochar and 1 part microbial inoculant. The biochar has a carbon content of 48%. The microbial inoculant is made from Bacillus subtilis and Bacillus mucilage, with a viable bacteria ratio of 1:3. The total viable bacteria count of the microbial inoculant is 5.4 billion / g. The biochar and the microbial inoculant are mixed in the stated parts by weight to obtain the potassium fertilizer enhancement conditioner for salinized soil.

[0056] A method for applying a potassium fertilizer synergist for salinized soil includes the following steps: Apply 303 kg / mu of potassium fertilizer enhancer and 6 kg / mu of potassium fertilizer to the soil surface for salinized soil, then plow to a depth of 20 cm. Plant soybeans with a row spacing of 50 cm and a plant spacing of 15 cm, leaving 2 seedlings per hole. Apply 10 kg / mu of nitrogen fertilizer (calculated as N), with 5 kg / mu as basal fertilizer and 5 kg / mu as topdressing. Apply 8 kg / mu of phosphorus fertilizer (calculated as P2O5) as basal fertilizer in a single application.

[0057] Comparative Example 10 A method for applying a potassium fertilizer synergist for salinized soil includes the following steps: Apply 3 kg / mu of microbial inoculant and 6 kg / mu of potassium fertilizer to the soil surface, then till to a depth of 20 cm. Plant soybeans with a row spacing of 50 cm and a plant spacing of 15 cm, leaving 2 seedlings per hole. Apply 10 kg / mu of nitrogen fertilizer (calculated as N), with 5 kg / mu as basal fertilizer and 5 kg / mu as top dressing. Apply 8 kg / mu of phosphorus fertilizer (calculated as P2O5) as basal fertilizer in a single application.

[0058] Comparative Example 11 A method for applying a potassium fertilizer synergist for salinized soil includes the following steps: Apply biochar at 300 kg / mu and potassium fertilizer at 6 kg / mu to the soil surface, then plow to a depth of 20 cm. Plant soybeans with a row spacing of 50 cm and a plant spacing of 15 cm, leaving 2 seedlings per hole. Apply nitrogen fertilizer (calculated as N) at a rate of 10 kg / mu, with 5 kg / mu as basal fertilizer and 5 kg / mu as top dressing. Apply phosphorus fertilizer (calculated as P2O5) as a single basal application of 8 kg / mu.

[0059] Comparative Example 12 A method for applying a potassium fertilizer synergist for salinized soil includes the following steps: Apply potassium fertilizer at a rate of 6 kg / mu to the soil surface, then plow to a depth of 20 cm. Plant soybeans with a row spacing of 50 cm and a plant spacing of 15 cm, leaving 2 seedlings per hole. Apply nitrogen fertilizer at a rate of 10 kg / mu (calculated as N), with 5 kg / mu as basal fertilizer and 5 kg / mu as topdressing. Apply phosphorus fertilizer at a rate of 8 kg / mu (calculated as P2O5) as basal fertilizer in a single application.

[0060] The following experiments were conducted to demonstrate the effect of the potassium fertilizer enhancement and conditioning agent for salinized soil of the present invention.

[0061] I. Materials and Equipment 1. Test materials The main materials used in this invention are potassium fertilizer and biochar.

[0062] The potassium fertilizer, with a K2O content of 52%, was purchased from Zhejiang Zhenong Aipu Trading Co., Ltd. The biochar is rice husk herbaceous biochar, containing 45%–50% carbon, and was produced by Tianjin Yadel Biomass Technology Co., Ltd.

[0063] The Bacillus subtilis strain of this invention was purchased from Tianjin Kunhe Biotechnology Group Co., Ltd., with an effective viable count ≥1.2 billion / g; the Bacillus mucilaginosus strain was purchased from Tianjin Kunhe Biotechnology Group Co., Ltd., with an effective viable count ≥3.8 billion / g.

[0064] II. Test Methods Experimental Area Overview: The experiment was conducted at the Tianjin Xiqing District Research Base in the coastal salinization area of ​​Tianjin. This area has a warm temperate semi-humid continental monsoon climate, with cold and dry winters controlled by temperate continental air masses and warm, rainy summers, resulting in distinct seasons. The soil type is alluvial soil, with a total water-soluble salt content of 4.48 g / kg, a moderate degree of soil salinization, sulfate ions, sandy loam texture, low soil fertility, and a available potassium content of 119 mg / kg. Soybean yield is between 100 kg / mu and 150 kg / mu.

[0065] 1. Soybean planting methods The experiment employed a split-plot design, with the main plot consisting of a no-conditioner group, a biochar + inoculant group, a biochar group, and a microbial inoculant group. Each treatment group's main plot was further divided into four subplots: I, II, III, and IV. Each subplot was 7m long, 2m wide, and had an area of ​​14m². 2 The land was divided into four sub-regions: sub-regions I, II, III, and IV. Potassium application levels were 0 kg / mu, 2 kg / mu, 4 kg / mu, and 6 kg / mu, respectively. Biochar was applied at a rate of 300 kg / mu, and microbial inoculant at a rate of 3 kg / mu. Potassium fertilizer, biochar, and microbial inoculant were all incorporated into the soil at a depth of 10-20 cm through tilling. Each experiment was repeated three times.

[0066] Soybean field management: Sowing and fertilization time: May 16, 2023. Row spacing: 50cm, plant spacing: 15cm, leave 2 seedlings per hill, maintain 11,000 to 13,000 seedlings per mu (667 square meters). Nitrogen fertilizer (calculated as N) is applied at a rate of 10kg / mu, with 5kg / mu applied as base fertilizer during plowing and another 5kg / mu applied as topdressing during the flowering and pod-setting stage. Phosphorus fertilizer (calculated as P2O5) is applied as a single base fertilizer application during plowing at a rate of 8kg / mu.

[0067] 2. Determination of soybean dry matter accumulation and potassium absorption accumulation Whole soybean samples were collected from each treatment plot at maturity to determine the fresh weight, dry weight, and potassium nutrient absorption status of the plants. Fresh samples were hung in mesh bags to air dry. The calculation of dry matter accumulation was based on the mass data after air drying. The potassium content of soybean roots, stems, leaves, pods, and seeds was determined by flame photometry as described in Bao Shidan, Soil Agrochemical Analysis [M]. Beijing: China Agriculture Press, 2000. The potassium absorption of different parts of soybean was calculated according to formula (1).

[0068] Formula (1): Potassium uptake in different parts of soybean = Dry matter accumulation in different parts of soybean × Potassium content in different parts 3. Calculation of Potassium Fertilizer Utilization Rate and Agronomic Efficiency Potassium fertilizer utilization rate and agronomic efficiency were calculated according to formulas (2) and (3), respectively.

[0069] Formula (2): Potassium fertilizer utilization rate = (Potassium absorption in the potassium-applied area – Potassium absorption in the non-potassium-applied area) / Potassium application rate Formula (3): Potassium fertilizer agronomic efficiency = (Grain yield in potassium-applied area – Grain yield in non-potassium-applied area) / Potassium application rate In formula (2), the potassium fertilizer utilization rate is abbreviated as KUE, and the potassium fertilizer agronomic efficiency is abbreviated as KAE.

[0070] 4. Detection of soybean grain quality indicators The protein, soluble sugar, and vitamin C quality indicators of soybean seeds were determined by the Kjeldahl method, the anthrone colorimetric method, and the 2,6-dichlorophenolindophenol titration method, respectively, all according to the methods described in Bao Shidan, Soil Agrochemical Analysis [M]. Beijing: China Agriculture Press, 2000.

[0071] 5. Soil sample collection and determination of physicochemical indicators Soil samples were collected from each treatment plot after soybean harvest using a quincunx pattern, with a collection depth of 0-20 cm. The mixed samples were then used to determine soil physicochemical properties. All methods used were those described in *Soil Agrochemical Analysis* by Bao Shidan (Beijing: China Agriculture Press, 2000). Specifically, available potassium was determined using a flame photometer method; soil salinity was determined using an oven-drying method; soil organic matter was determined using a volumetric method; nitrate nitrogen was determined using a UV spectrophotometer method; ammonium nitrogen was determined using an indophenol blue colorimetric method; available phosphorus was determined using a molybdenum blue colorimetric method; cation exchange capacity was determined using a sodium acetate-flame photometer method; and soil bulk density and field capacity were determined using a ring cutter method. Soil inorganic nitrogen content was calculated by summing soil nitrate nitrogen and soil ammonium nitrogen.

[0072] 6. Data Analysis Experimental data were processed using Excel 2019 software and statistically analyzed using SPSS 22.0 software. The Duncan method and LSD method were used for significance testing.

[0073] III. Test Results 1. Determination of potassium accumulation in soybeans 1.1 Potassium uptake of soybeans Soybean potassium absorption status as follows Figure 1 As shown in the figure, the results indicated that the potassium uptake of soybeans increased with increasing potassium fertilizer application across all treatments. Treatment IV (biochar + microbial agent) showed the highest potassium uptake, 40.2% higher than the untreated group. Treatments III and IV (biochar + microbial agent) were also shown, with uptakes 29.8% and 46.6% higher than the untreated group, respectively. Among all treatments, the biochar + microbial agent group exhibited the highest potassium uptake. This is because the microbial agent promoted the release of soil mineral nutrients, and the biochar improved soil structure, making it easier for soybean roots to absorb potassium, thus promoting potassium uptake. Therefore, the biochar + microbial agent treatment method can improve the absorption of potassium fertilizer by soybeans.

[0074] 1.2 Potassium fertilizer utilization rate Potassium fertilizer utilization rate, such as Figure 2 As shown. By Figure 2It can be seen that the potassium fertilizer utilization rate in both the biochar + microbial agent and biochar treatment groups showed a trend of first increasing and then decreasing with the increase of potassium fertilizer application rate, with the highest utilization rate in treatment III, at 69.42% and 66.15%, respectively. Overall, treatment III in the biochar + microbial agent group had the highest potassium fertilizer utilization rate at 69.42%, followed by the biochar treatment and treatment II. When the potassium fertilizer application rate exceeds a certain amount, the absorption and utilization efficiency of potassium will decrease, because the absorption of potassium fertilizer by soybeans is not unlimited. Therefore, when the potassium fertilizer application rate is 4 kg / mu, the potassium fertilizer enhancement and conditioning agent for salinized soil of this application can promote the maximum utilization of potassium fertilizer by soybeans.

[0075] 1.3 Potassium Fertilizer Agronomic Efficiency Potassium fertilizer agronomic efficiency such as Figure 3 As shown in the figure. The results showed that, within the same treatment group, the agronomic efficiency of potassium fertilizer decreased with increasing application of potassium fertilizer. Treatment II showed the highest agronomic efficiency among all treatments, with the biochar + microbial agent treatment group achieving the highest efficiency at 17.65 kg / kg, followed by the biochar treatment group, which was significantly higher than the other treatment groups. The biochar + microbial agent treatment group also showed higher agronomic efficiency than the other groups. This indicates that the potassium fertilizer synergist for salinized soil of this invention can improve the agronomic efficiency of potassium fertilizer during soybean cultivation. The main reason is that the potassium fertilizer synergist for salinized soil improves the soil's physical and chemical properties, promotes potassium supply in the soil, and thus increases the efficiency of potassium absorption and utilization by soybeans.

[0076] 2. Detection of soybean grain quality indicators Table 1 shows the quality status of soybeans under different treatments. Regarding protein content, treatment IV had the highest protein content among the biochar + inoculant treatments; treatment II had the highest protein content among the biochar treatments; the protein content of the inoculant treatments showed a trend of first increasing and then decreasing with increasing potassium application; the protein content of all treatments without conditioner was lower than that of treatment I to varying degrees. Overall, the protein content of both the biochar + inoculant and biochar treatments was relatively high. As for vitamin C content, treatments II and III had the highest vitamin C content among the biochar + inoculant treatments, significantly higher than treatment I by 26.99%; among the biochar treatments, treatment II had the highest vitamin C content, significantly higher than treatment I by 30.57%, followed by treatment III; among the inoculant treatments, treatments II and III had the highest vitamin C content. Regarding total soluble sugars, the biochar + microbial agent treatment group, the biochar treatment group, and the microbial agent treatment group all had higher total soluble sugar contents in treatment II, increasing by 23.13%, 19.73%, and 124.36% respectively compared to their respective treatment groups in treatment I. Treatment III, with various types of conditioners, was the next highest. Applying potassium fertilizer synergistic conditioners to saline soils can increase the protein and soluble sugar content of soybean seeds, thus improving soybean seed quality.

[0077] Table 1. Quality of soybeans under different treatments Note: Different capital letters indicate the significance level of differences between treatments, P<0.05.

[0078] 3. Soil sample collection and determination of physicochemical indicators 3.1 Content of available potassium in soil The content of available potassium in the soil, such as Figure 4 As shown in the figure, the available potassium content in the soil treated with biochar and microbial agents initially increased and then decreased with increasing potassium application rate. Treatments II and III showed the most significant increases, increasing by 94.36% and 96.58% respectively. Treatment IV, treated with biochar, showed a significantly higher available potassium content than the other treatments. The available potassium content in the microbial agent treatments was 44.74%–59.51% higher than that in treatment I. In the untreated soil, treatment IV had the highest available potassium content, significantly higher than that in treatment I (84%). The biochar + microbial agent treatment significantly increased the available potassium content in the soil. This is mainly because the microbial agent promoted the release of mineral potassium, while the biochar improved soil permeability and increased the availability of potassium. Therefore, potassium fertilizer enhancement conditioners for saline soils can increase the available potassium content in the soil, which is beneficial for potassium absorption and utilization.

[0079] 3.2 Soil salinity Soil salinity Figure 5 As shown in the figure, the salinity of the biochar + microbial agent treatment, and the biochar and microbial agent treatments were all relatively low in treatment III, at 0.19 g / kg, 0.21 g / kg, and 0.22 g / kg, respectively. The soil salinity in the treatments without conditioners was generally higher, with treatment II showing the highest salinity, significantly higher than the other treatments. Potassium fertilizer-enhancing conditioners for saline soils can significantly reduce soil salinity and alleviate the degree of soil salinization.

[0080] 3.3 Soil organic matter content Soil organic matter such Figure 6 As shown in the figure, the soil organic matter content was significantly higher in treatments II and IV with biochar, exceeding that of treatment I by 87% and 136%, respectively. In the biochar + microbial inoculant treatment, the soil organic matter content initially increased and then decreased with increasing potassium application, with treatment III showing the highest content. In the treatments without conditioner, treatment III had the highest organic matter content. In the microbial inoculant treatment, treatment III also had the highest organic matter content. The application of biochar can significantly increase the organic matter content in the soil.

[0081] 3.4 Soil Inorganic Nitrogen Content Soil inorganic nitrogen content such as Figure 7As shown in the figure. The results showed that in the biochar + microbial agent treatment, treatments II and IV had higher inorganic nitrogen content; in the biochar treatment, treatment IV showed a significant increase in inorganic nitrogen content, significantly higher than other treatments; in the microbial agent treatment, the inorganic nitrogen content showed a trend of first increasing and then decreasing with the increase of potassium application rate, with the highest change in treatment II. Microbial agents can increase the inorganic nitrogen content in the soil, which is beneficial to soybean growth and grain development. Therefore, the potassium fertilizer synergist conditioner for salinized soil of the present invention improves potassium fertilizer utilization while also increasing the quality of soybean grains.

[0082] 3.5 Soil available phosphorus content Soil available phosphorus content, such as Figure 8 As shown in the figure, the available phosphorus content in treatment IV (biochar treatment) was significantly higher than in other treatments, exceeding that of treatment I by 116.26%. Among the biochar + microbial agent treatments, treatments III and II had the highest available phosphorus content. The available phosphorus content in the microbial agent treatments was lower than that in treatment I to varying degrees. This indicates that biochar can better increase the available phosphorus content in the soil. Available phosphorus in the soil ensures sufficient phosphorus for soybeans, promoting their normal growth.

[0083] 3.6 Cation Exchange Capacity Cation exchange capacity such as Figure 9 As shown in the figure. The results showed that the soil cation exchange capacity was highest in the biochar + microbial agent treatment, exceeding the untreated treatment by 18.20%, followed by the biochar and microbial agent treatments, which increased by 10.91% and 10.55% respectively compared to the untreated treatment. This indicates that the potassium fertilizer enhancement conditioner for salinized soil of the present invention can enhance cation exchange, and potassium ions are one type of cation. Therefore, the potassium fertilizer enhancement conditioner for salinized soil of the present invention can promote potassium fertilizer absorption and improve potassium fertilizer utilization.

[0084] 3.7 Soil bulk density Soil bulk density as Figure 10 As shown in the figure. The results showed that the soil bulk density of each treatment was reduced to varying degrees compared with the original plot. The reduction in soil bulk density was more significant in the biochar and biochar + microbial agent treatments, decreasing by 21.50% and 13.57% respectively compared with the treatment without conditioner. There was no significant difference between the microbial agent treatment and the treatment without conditioner. Therefore, the potassium fertilizer-enhancing conditioner for saline soil of the present invention can reduce soil bulk density, indicating that the soil porosity has increased and the aeration has improved, which is beneficial to soybean growth.

[0085] 3.8 Soil field water holding capacity Soil field water holding capacity Figure 11As shown in the figure, the results indicate that the field water holding capacity of the biochar treatment was significantly higher than that of the treatment without conditioner, increasing by 15.63%. The biochar + microbial agent treatment was the second highest, increasing by 7.28%, while the microbial agent treatment showed no significant change compared to the treatment without conditioner. This demonstrates that biochar is a key factor in improving soil field water holding capacity. Therefore, the potassium fertilizer-enhancing conditioner for salinized soils of this invention can increase soil field water holding capacity, providing sufficient water for soybean growth.

[0086] IV. Discussion of Results The experimental results show that the potassium fertilizer utilization rate was highest in treatment II of the biochar + microbial agent group, followed by treatments III and II of the biochar group. Treatment II of the biochar group exhibited higher agronomic efficiency and productivity. Regarding soil physicochemical properties, both the biochar + microbial agent treatment group and the biochar treatment group were effective in increasing soil organic matter. In terms of inorganic nitrogen, treatment IV of the biochar group and treatment II of the microbial agent group were more effective in increasing soil inorganic nitrogen content, followed by treatment II of the biochar + microbial agent group. Regarding available phosphorus, treatment IV of the biochar group was most effective in increasing available phosphorus, followed by treatment I of the microbial agent group and treatment III of the biochar + microbial agent group. Regarding available potassium, treatment IV of the biochar group was most effective in increasing available potassium, followed by treatments III and II of the biochar + microbial agent group. The biochar + microbial agent treatment group was more effective in reducing soil salinity, with treatment III showing the most significant effect. In terms of improving soil cation exchange capacity and enhancing soil fertility, the biochar + microbial agent treatment group showed the best effect, followed by the biochar and microbial agent treatment groups. The biochar treatment group was most effective in improving soil field water holding capacity and reducing soil bulk density, followed by the biochar + microbial agent treatment group. Regarding dry matter accumulation, the biochar treatment group was most effective in increasing soybean dry matter accumulation, with treatment II showing the most significant effect, followed by biochar treatment III. In terms of potassium uptake, treatments with biochar + microbial agent and biochar treatment IV had higher potassium levels, followed by biochar + microbial agent treatment III and microbial agent treatment IV. Regarding improving vitamin C content, treatment II of the biochar + microbial agent group was the best, followed by biochar + microbial agent treatment III; microbial agent treatment II was most effective in increasing total sugar content, followed by biochar treatment II and biochar + microbial agent treatment II; biochar treatment II was most effective in increasing soybean protein content, followed by biochar + microbial agent treatments I and IV. Potassium fertilizer utilization rate and agronomic efficiency are key factors affecting soybean quality, followed by soil physicochemical properties.

[0087] In conclusion, applying potassium fertilizer enhancer to saline soils can increase the protein and vitamin C content in soybean seeds, thereby improving soybean quality. Furthermore, this enhancer can also improve soil physicochemical properties, such as increasing organic matter content and improving soil water holding capacity.

[0088] Soil conditioners can improve the structure of saline-alkali soils, regulate soil pH, and improve the microbial environment, playing a vital role in enhancing soil nutrient availability and increasing the productivity of saline-alkali soils. This invention systematically analyzes the application of different types of conditioners, both individually and in combination, along with varying amounts of potassium fertilizer. It integrates improving crop nutrient absorption efficiency with the improvement of the physicochemical properties of saline-alkali soils, considering both the crop production efficiency resulting from soil conditioner application and the improvement of the soil salinization environment, thereby achieving the goal of green, efficient, and healthy improvement and management of saline-alkali soils.

[0089] It should be noted that when numerical ranges are involved in this invention, it should be understood that both endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as in the embodiments, preferred embodiments are described in this invention to avoid redundancy. Although preferred embodiments of this invention have been described, those skilled in the art, once they understand the inventive concept of this invention, can make other changes and modifications to these embodiments, and all such changes and modifications fall within the scope of this invention.

[0090] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. If such modifications and variations fall within the scope of equivalents of this invention, then this invention is also intended to include these modifications and variations.

Claims

1. A potassium fertilizer synergist for salinized soil, characterized in that, It is composed of the following raw materials in parts by weight: 90 to 110 parts biochar and 0.9 to 1.1 parts microbial inoculant; The microbial agent is made from Bacillus subtilis and Bacillus mucilaginosus, and the ratio of live bacteria of Bacillus subtilis and Bacillus mucilaginosus is 1:2.5~3.

5. The biochar and the microbial agent are mixed in the specified weight proportions to obtain a potassium fertilizer enhancement and conditioning agent for salinized soil.

2. The potassium fertilizer synergist for salinized soil according to claim 1, characterized in that, The biochar has a carbon content of 45% to 50%.

3. The potassium fertilizer synergist and conditioner for salinized soil according to claim 1, characterized in that, The total viable count of the microbial agent is ≥5 billion / g.

4. The potassium fertilizer synergist and conditioner for salinized soil according to claim 1, characterized in that, The weight ratio of biochar to microbial preparation is 100:

1.

5. The application of the potassium fertilizer synergist for salinized soil according to claim 1, characterized in that, The application method includes the following steps: Apply potassium fertilizer enhancer and potassium fertilizer to the soil surface in saline soil. Tillage, with a tillage depth of 10cm~20cm; Plant crops in tilled soil; Field management until crop maturity.

6. The application of the potassium fertilizer synergist and conditioner for salinized soil according to claim 5, characterized in that, The application rate of the potassium fertilizer enhancement agent for salinized soil is 270 kg / mu to 330 kg / mu.

7. The application of the potassium fertilizer synergist for salinized soil according to claim 5, characterized in that, The application rate of the potassium fertilizer enhancement agent for salinized soil is 303 kg / mu.

8. The application of the potassium fertilizer synergist for salinized soil according to claim 5, characterized in that, The application rate of the potassium fertilizer is 0 kg / mu to 6 kg / mu.

9. The application of the potassium fertilizer synergist for salinized soil according to claim 5, characterized in that, The crop in question is soybean.

10. The potassium fertilizer synergist and conditioner for salinized soil according to claim 1, characterized in that, It is used to improve the utilization rate of potassium fertilizer in the soil.

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