Humic acid and graphite vinasse compounded soil conditioner as well as preparation method and application thereof

Abstract

The invention provides a humic acid and graphite vinasse compounded soil conditioner as well as a preparation method and application thereof, and belongs to the technical field of development of biological agricultural auxiliaries. The soil conditioner provided by the invention can obviously improve the ecological conditions of the greenhouse vegetable continuous cropping soil, effectively alleviate continuous cropping obstacles, directly optimize the physical structure of the soil, continuously improve the basic fertility of the soil, synchronously increase the yield of vegetable crops and improve the product quality, and has a wide application prospect. And a key support is provided for sustainability and economy of greenhouse vegetable production.

Description

Technical Field

[0001] This invention relates to the field of bio-agricultural adjuvant development technology, and in particular to a humic acid-based sub-graphite distiller's grains compound soil conditioner, its preparation method, and its application. Background Technology

[0002] Soil, as the foundation of agricultural production, directly impacts crop growth, development, yield, and quality through its physical, chemical, and biological properties. However, long-term intensive farming, improper fertilization and irrigation, and soil degradation under special conditions (such as continuous cropping obstacles and salinization in greenhouse agriculture) lead to numerous problems, including soil structure damage, decreased organic matter content, nutrient imbalance, decline of beneficial microbial communities, and exacerbation of soil-borne diseases. These issues have become bottlenecks restricting sustainable agricultural development. Against this backdrop, soil conditioners, as exogenous substances or materials that can be artificially applied to soil to improve its unfavorable physical, chemical, or biological properties, thereby enhancing soil productivity, promoting plant growth, or repairing degraded soil, have received widespread attention and importance in their research and application.

[0003] Existing soil conditioners are diverse, and based on their main components and improvement objectives, they can be broadly categorized as follows: organic (such as farmyard manure, commercial organic fertilizer, humic acid, biochar, etc., mainly used to increase soil organic matter, improve structure and microbial environment); inorganic minerals (such as bentonite, zeolite, gypsum, lime, etc., mainly used to adjust soil pH, improve saline-alkali land, improve physical structure or increase mineral elements); microbial preparations (such as probiotics, mycorrhizal fungi, etc., mainly used to regulate soil microbial flora, inhibit pathogens, and promote nutrient transformation); and certain synthetic polymer materials. In the field of greenhouse vegetable cultivation, due to the high multiple cropping index, enclosed environment, and large amount of fertilizer application, the problem of continuous cropping obstacles is particularly prominent, becoming a key limiting factor affecting stable vegetable yield and quality improvement.

[0004] To address this issue, single-type soil conditioners (such as those that only supplement organic matter or only adjust pH) are often insufficient to systematically tackle the complex problems arising from the interplay of multiple factors, including deterioration of soil physical structure, imbalance of nutrient elements, imbalance of microbial communities, and accumulation of autotoxic substances. Therefore, seeking comprehensive soil conditioners that can synergistically improve multiple soil obstacle factors, effectively alleviate continuous cropping obstacles, and comprehensively enhance the basic productivity of the soil is one of the research directions that urgently needs in-depth exploration for green and sustainable facility vegetable production. How to develop highly efficient, stable products with multiple improvement effects through the scientific compounding and functional integration of components has become a crucial breakthrough in improving the application effect of soil conditioners. Summary of the Invention

[0005] The purpose of this invention is to provide a humic acid-based sub-graphite distiller's grains compound soil conditioner, its preparation method, and its application, providing a product with better soil improvement effects.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: The present invention provides a compound soil conditioner, which, by weight, comprises 25-35 parts of humic acid, 10-20 parts of graphite, 45-55 parts of distiller's grains, and 3-7 parts of bentonite.

[0007] Preferably, the humic acid is a commercially available product with a humic acid content of ≥65%.

[0008] Preferably, the particle size of the sub-graphite is 100-300 mesh.

[0009] Preferably, the moisture content of the lees is ≤15% and the organic matter content is ≥45%.

[0010] Preferably, the particle size of the compound soil conditioner is 1-4 mm.

[0011] Preferably, the process includes the following steps: mixing humic acid with sub-graphite for 10-15 minutes; adding the distiller's grains in three batches, with an interval of 3-7 minutes between each addition, and continuing to mix for 10-20 minutes; adding bentonite and mixing for 15-25 minutes to obtain the mixture, which is the compound soil conditioner.

[0012] Preferably, the mixing speed of the humic acid and the sub-graphite is 40~50 r / min.

[0013] Preferably, the preparation method further includes granulating the mixture and drying it at 50~60℃ until the moisture content is ≤8%.

[0014] This invention also provides the application of the above-mentioned compound soil conditioner in improving soil quality and enhancing crop quality.

[0015] Preferably, the application rate is determined according to the soil type: 2.0~3.0 t / ha for sandy soil, 2.5~3.5 t / ha for clay soil, and 3.5~4.5 t / ha for degraded soil; Apply the amendment 10-20 days before crop sowing; After spreading, till the soil to a depth of 15-25cm to mix it thoroughly. Immediately after application, irrigate to 75%–85% of the soil's field capacity.

[0016] The technical effects and advantages of this invention are as follows: The soil conditioner provided by this invention can significantly improve the ecological conditions of soils used for continuous cropping of greenhouse vegetables, effectively alleviate continuous cropping obstacles, directly optimize the physical structure of the soil, continuously improve the basic fertility of the soil, and simultaneously increase the yield and improve the quality of vegetable crops, providing key support for the sustainability and economy of greenhouse vegetable production. Detailed Implementation

[0017] This invention provides a compound soil conditioner that, through a scientifically proportioned blend of multiple components, aims to improve soil structure, enhance nutrient utilization efficiency, and promote crop growth. Specifically, by weight, the compound soil conditioner comprises 25-35 parts humic acid, 10-20 parts graphite sub-graphite, 45-55 parts distiller's grains, and 3-7 parts bentonite. This formulation fully considers the synergistic effects between the components. For example, humic acid provides organic matter and ion exchange capacity, graphite sub-graphite enhances pore structure, distiller's grains slowly release nutrients, and bentonite acts as a binder and water retainer, thereby optimizing the overall physicochemical properties of the soil, such as reducing bulk density, increasing water holding capacity, and regulating pH. This conditioner is suitable for various types of farmland soils, including sandy soils, clay soils, and degraded soils, and its application can significantly improve crop yield and quality.

[0018] In this invention, humic acid is a widely used organic substance, its concept originating from the natural humification process. It is mainly composed of high-molecular-weight organic compounds formed from the decomposition of plant and animal remains by microorganisms. The properties of humic acid include: a complex aromatic structure rich in functional groups such as carboxyl and phenolic hydroxyl groups, which gives it strong cation exchange capacity (typically 100-300 meq / 100g), adsorption properties, and buffering effect; its color is usually dark brown to black, and its solubility is poor, but it can partially dissolve under alkaline conditions. Humic acid has extremely widespread conventional uses in agriculture, primarily for soil improvement, such as improving soil aggregate structure, increasing soil organic matter content (generally by 5%-15%), promoting microbial activity, chelating heavy metal ions to reduce toxicity, and acting as a plant growth stimulant to enhance root development. In addition, humic acid also has wide applications in environmental remediation and fertilizer additives. Humic acid is commercially available, with common sources including extracts from weathered coal, lignite, or peat. Commercially available products are typically supplied in powder or granule form, and their humic acid content labeling must comply with national standards (such as GB / T 33804-2017). For example, this preferred formulation requires a humic acid content ≥65%, ensuring high activity and effectiveness and preventing impurities from affecting the improvement effect. During routine procurement, users can obtain humic acid from agricultural input suppliers, such as professional manufacturers in Shandong and Henan provinces. The product content must be verified through quality inspection reports.

[0019] Preferably, the sub-graphite is a natural mineral material, conceptually an allotrope of amorphous carbon, composed of carbon elements, but with a disordered layered structure, unlike the regular crystals of graphite. The properties of sub-graphite include: high porosity (porosity can reach 30%~50%), good adsorption performance (specific surface area of ​​approximately 50~200 m² / g), chemical inertness, and excellent electrical conductivity and thermal stability; its color is usually grayish-black, its texture is relatively light, and it is easy to crush. The conventional use of sub-graphite in soil improvement is mainly as a physical structure regulator to increase soil aeration and drainage, reduce soil compaction, and its pores can adsorb water and nutrients, achieving a slow-release effect; industrially, it is also used in filter materials, electrodes, or as an additive in composite materials. Sub-graphite is commercially available, commonly sourced from natural mineral deposits or as an industrial byproduct; commercially available products require crushing and screening. This preferred embodiment requires the sub-graphite to have a particle size of 100–300 mesh. This range is based on conventional practice: fine powders of 100 mesh (approximately 150 μm) to 300 mesh (approximately 50 μm) ensure thorough mixing with soil particles, avoiding uneven distribution due to excessive coarseness or dust pollution due to excessive fineness, while optimizing porosity control. Users can procure these from mining or chemical suppliers, and the products must conform to particle size standards (such as ISO 3310-1).

[0020] Preferably, the distillers' grains are a byproduct of the brewing industry, defined as fermented grain residue, primarily composed of incompletely utilized starch, protein, cellulose, and microbial metabolites. The properties of distillers' grains include: high organic matter content (typically ≥45%, making it a high-quality source of organic fertilizer), a certain moisture content (which needs to be controlled during normal storage to prevent mold growth), and rich in nutrients such as nitrogen, phosphorus, and potassium (e.g., total nitrogen content of approximately 1.5%~3.0%); its appearance is moist or dry granular, with a distinctive odor. The conventional uses of distillers' grains in agriculture are mainly for soil improvement and organic fertilizer, improving soil fertility through the slow release of nutrients, promoting microbial diversity, and reducing reliance on chemical fertilizers; it also has applications in the feed and bioenergy sectors. This preferred solution requires that the moisture content of the lees be ≤15% and the organic matter content be ≥45%. This requirement is based on standard quality control: a moisture content of ≤15% prevents spoilage during transportation and storage (too high a moisture content will lead to mold, while too low a moisture content will affect the uniformity of mixing), and an organic matter content of ≥45% ensures sufficient nutrient supply and complies with the standards for the resource utilization of organic waste (such as NY / T 525-2021). The lees are commercially available, commonly sourced from waste from breweries or distilleries. Commercially available products must undergo drying and crushing. Users can purchase them from local brewing companies or agricultural input companies, and the products should be accompanied by quality inspection certificates.

[0021] Preferably, the bentonite is a clay mineral, specifically a natural aluminosilicate with montmorillonite as its main component, possessing a layered structure and cation exchange properties. Bentonite's properties include: high swelling capacity (expanding to 10-20 times its original volume upon contact with water), strong adsorption capacity (cation exchange capacity approximately 60-100 meq / 100g), binding capacity, and water retention; its color is typically grayish-white or light yellow, and its texture is fine. Common uses of bentonite include as a binder and water-retaining agent in soil amendment, improving soil structure, reducing nutrient loss, and adjusting pH; industrially, it is also used in drilling mud, casting, and environmental protection materials. Bentonite is commercially available, commonly sourced from natural deposits, and is supplied in powder form, conforming to industry standards (such as JC / T 205-2011). In this invention, bentonite is used as an auxiliary component (3-7 parts), and its small addition enhances the formability and stability of the mixture, preventing the amendment from dispersing during application.

[0022] Preferably, the particle size of the compound soil conditioner is 1-4 mm. This particle size range is selected based on conventional agronomic practices: a particle size of 1-4 mm facilitates mechanical application (e.g., via a seeder or fertilizer spreader), ensuring uniform distribution; simultaneously, this size promotes slow decomposition in the soil, achieving a slow-release effect of nutrients, avoiding the risk of excessively fine particles (<1 mm) being easily blown away or leached by wind, or excessively coarse particles (>4 mm) affecting the contact area with the soil. Conventional soil conditioners often use similar particle sizes (e.g., 1-5 mm) to balance ease of operation and functional effectiveness.

[0023] Preferably, the preparation method of the compound soil conditioner includes the following steps: First, humic acid and sub-graphite are mixed for 10-15 minutes; this initial mixing step aims to achieve preliminary dispersion of the components, utilizing the adhesiveness of humic acid and the lightweight properties of sub-graphite to form a basic matrix. The mixing speed is preferably 40-50 r / min. This range is based on the conventional mechanical mixing principle: too low a speed (<40 r / min) may lead to uneven mixing and dead zones; too high a speed (>50 r / min) is prone to dust flying and component separation. The gentle speed of 40-50 r / min ensures thorough mixing without damaging the component structure. Second, the distiller's grains are added in three batches, with an interval of 3-7 minutes between each addition, and mixing is continued for 10-20 minutes; this step-by-step addition design is derived from the conventional batch mixing strategy, which can prevent the distiller's grains from agglomerating or causing uneven moisture due to adding them all at once. The 3-7 minute interval allows the components to gradually absorb moisture and integrate, ensuring uniform mixing. Finally, add bentonite and mix for 15-25 minutes to obtain the mixture, which is the compound soil conditioner. The later addition of bentonite utilizes its binding properties to fix the mixture, and mixing for 15-25 minutes ensures the homogeneity of the final product (e.g., coefficient of variation ≤5%, meeting conventional quality control standards). The entire mixing process is carried out in conventional equipment such as a twin-shaft paddle mixer, and the operating environment must be controlled for temperature and humidity to avoid component denaturation.

[0024] Preferably, the preparation method further includes granulating the mixture and then drying it at 50-60°C to a moisture content of ≤8%. Granulation is performed using conventional techniques such as disc granulators or extrusion granulators, with a preferred pore size of 4 mm to match the target particle size (1-4 mm). The granulation process enhances the physical stability of the product, facilitating storage and transportation. The drying step is carried out at 50-60°C. This temperature range is based on conventional hot air drying principles: excessively low temperatures (<50°C) result in low drying efficiency and are prone to microbial growth; excessively high temperatures (>60°C) may damage organic components (such as humic acid and heat-sensitive substances in distiller's grains). Drying to a moisture content of ≤8% is a standard requirement, preventing product mold growth and extending shelf life, meeting agricultural input standards (such as GB / T 23349-2020).

[0025] This invention also provides the application of the aforementioned compound soil conditioner in improving soil quality and enhancing crop quality. Specific application methods include: First, determining the application rate based on soil type: 2.0–3.0 t / ha for sandy soil, 2.5–3.5 t / ha for clay soil, and 3.5–4.5 t / ha for degraded soil. This differentiated application rate is based on conventional soil science knowledge. Sandy soil has large pores and rapid nutrient loss, therefore a lower application rate is used to replenish organic matter; clay soil has high compaction and requires a higher application rate to improve structure; degraded soil (such as saline-alkali or infertile soil) requires the maximum application rate to restore function. The application rate calculation refers to conventional field trial data to ensure economy and effectiveness. Second, applying the conditioner 10–20 days before crop sowing; this time window is based on conventional agricultural arrangements, allowing 10–20 days for the conditioner to initially react with the soil (such as microbial activation), avoiding direct contact with seeds at sowing and affecting germination. Application is done using conventional machinery such as a centrifugal spreader to ensure uniform coverage. Then, after application, rotary tillage to a depth of 15-25cm to mix with the soil. A tillage depth of 15-25cm is for the topsoil layer (the conventional depth is around 20cm) to ensure the amendment is integrated into the root zone. Too shallow (<15cm) limits the effect, while too deep (>25cm) increases energy consumption. Finally, immediately after application, irrigate to 75%-85% of the soil's field capacity. The irrigation amount should be based on conventional field capacity measurements (e.g., tensiometer method). A humidity range of 75%-85% optimizes microbial activity and nutrient release, avoiding excessive moisture (>85%) leading to oxygen deficiency or excessive dryness (<75%) affecting dissolution. The entire application process can be integrated with routine agricultural management, such as monitoring soil pH and nutrient changes.

[0026] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0027] Example 1 This embodiment prepares a compound soil conditioner with humic acid, sub-graphite and distiller's grains as the main components. Through physical mixing in a specific ratio, the conditioner achieves a synergistic effect of humic acid's structural stability, sub-graphite's porosity regulation ability and distiller's grains' slow-release function of organic nutrients, thus significantly improving the physical and chemical properties of the soil.

[0028] Preparation method: First, select humic acid powder (commercially available product, with packaging indicating humic acid content ≥65%), 200-mesh sieved graphite powder, fermented distiller's grains (moisture content ≤15%, organic matter ≥45%), and the auxiliary component bentonite.

[0029] Weigh the following components in the indicated mass ratios: 30 parts humic acid, 15 parts sub-graphite, 50 parts distiller's grains, and 5 parts bentonite.

[0030] Humic acid and sub-graphite were placed in a mixing device and mixed at 45 r / min for 10 minutes. Then, distiller's grains were added in three batches, each 5 minutes apart, and mixing was maintained for 15 minutes to ensure uniform mixing. Finally, bentonite was added, and mixing continued for 20 minutes until the material was homogeneous (mixing uniformity coefficient of variation ≤5%). The mixture was then granulated using a disc granulator (4 mm aperture), dried with hot air at 55℃ until the moisture content was ≤8%, and sieved to obtain granules with a particle size of 1-4 mm.

[0031] The product provided in this embodiment is suitable for sandy, clayey, or degraded farmland soils, etc. Before application, measure the initial bulk density and pH value of the soil and adjust the dosage according to the soil type: 2.5 t / ha for sandy soil, 3.0 t / ha for clayey soil, and 4.0 t / ha for degraded soil. Fifteen days before crop sowing, evenly spread the soil conditioner on the surface, then immediately rotary tillage (to a depth of 20 cm) to ensure the conditioner is thoroughly mixed with the topsoil. Irrigate immediately after application, using 80% of the soil's field capacity as a baseline, and then maintain regular field management thereafter.

[0032] Example 2 Preparation method: First, select humic acid powder (commercially available product, with packaging indicating humic acid content ≥65%), 200-mesh sieved graphite powder, fermented distiller's grains (moisture content ≤15%, organic matter ≥45%), and the auxiliary component bentonite.

[0033] Weigh the following components in the indicated mass ratios: 25 parts humic acid, 20 parts sub-graphite, 48 parts distiller's grains, and 7 parts bentonite.

[0034] Humic acid and sub-graphite were placed in a mixing device and mixed at 50 r / min for 12 minutes. Then, distiller's grains were added in three batches, with 5-minute intervals between each batch, and the mixture was maintained for 15 minutes to ensure uniform mixing. Finally, bentonite was added, and the mixture was continued for 20 minutes until the material was homogeneous (mixing uniformity variation coefficient ≤ 5%). After mixing, the mixture was shaped by a disc granulator (4 mm aperture), dried with hot air at 55℃ until the moisture content was ≤ 8%, and then sieved to obtain granules with a particle size of 1~4 mm.

[0035] The product provided in this embodiment is suitable for sandy, clayey, or degraded farmland soils, etc. Before application, measure the initial bulk density and pH value of the soil and adjust the dosage according to the soil type: 2.5 t / ha for sandy soil, 3.0 t / ha for clayey soil, and 4.0 t / ha for degraded soil. Fifteen days before crop sowing, evenly spread the soil conditioner on the surface, then immediately rotary tillage (to a depth of 20 cm) to ensure the conditioner is thoroughly mixed with the topsoil. Irrigate immediately after application, using 80% of the soil's field capacity as a baseline, and then maintain regular field management thereafter.

[0036] Example 3 This embodiment provides the following preparation method: First, select humic acid powder (commercially available product, with packaging indicating humic acid content ≥65%), 200-mesh sieved graphite powder, fermented distiller's grains (moisture content ≤15%, organic matter ≥45%), and the auxiliary component bentonite.

[0037] Weigh the following components in the indicated mass ratios: 30 parts humic acid, 15 parts sub-graphite, 40 parts distiller's grains, and 15 parts bentonite.

[0038] Humic acid and sub-graphite were placed in a mixing device and mixed at 45 r / min for 10 minutes. Then, distiller's grains were added in three batches, each 5 minutes apart, and mixing was maintained for 15 minutes to ensure uniform mixing. Finally, bentonite was added, and mixing continued for 20 minutes until the material was homogeneous (mixing uniformity coefficient of variation ≤5%). The mixture was then granulated using a disc granulator (3 mm aperture), dried with hot air at 65℃ until the moisture content was ≤8%, and sieved to obtain granules with a particle size of 0.8~3 mm.

[0039] The product provided in this embodiment is suitable for sandy, clayey, or degraded farmland soils, etc. Before application, measure the initial bulk density and pH value of the soil and adjust the dosage according to the soil type: 2.5 t / ha for sandy soil, 3.0 t / ha for clayey soil, and 4.0 t / ha for degraded soil. Fifteen days before crop sowing, evenly spread the soil conditioner on the surface, then immediately rotary tillage (to a depth of 20 cm) to ensure the conditioner is thoroughly mixed with the topsoil. Irrigate immediately after application, using 80% of the soil's field capacity as a baseline, and then maintain regular field management thereafter.

[0040] Example 4 This embodiment prepares a compound soil conditioner with humic acid, sub-graphite and distiller's grains as the main components. Through physical mixing in a specific ratio, the conditioner achieves a synergistic effect of humic acid's structural stability, sub-graphite's porosity regulation ability and distiller's grains' slow-release function of organic nutrients, thus significantly improving the physical and chemical properties of the soil.

[0041] Preparation method: First, select humic acid powder (commercially available product, with packaging indicating humic acid content ≥65%), 150-mesh sieved graphite powder, fermented distiller's grains (moisture content ≤15%, organic matter ≥45%), and the auxiliary component bentonite.

[0042] Weigh the following components in the indicated mass ratios: 35 parts humic acid, 10 parts sub-graphite, 50 parts distiller's grains, and 5 parts bentonite.

[0043] Humic acid and sub-graphite were placed in a mixing device and mixed at 45 r / min for 10 minutes. Then, distiller's grains were added in three batches, each 5 minutes apart, and mixing was maintained for 20 minutes to ensure uniform mixing. Finally, bentonite was added, and mixing continued for 25 minutes until the material was homogeneous (mixing uniformity coefficient of variation ≤5%). The mixture was then granulated using a disc granulator (5 mm aperture), dried with hot air at 55℃ until the moisture content was ≤8%, and sieved to obtain granules with a particle size of 2-5 mm.

[0044] The product provided in this embodiment is suitable for sandy, clayey, or degraded farmland soils, etc. Before application, measure the initial soil bulk density and pH value, and adjust the dosage according to soil type: 3.0 t / ha for sandy soil, 3.5 t / ha for clayey soil, and 4.5 t / ha for degraded soil. Fifteen days before crop sowing, evenly spread the soil conditioner on the surface, then immediately rotary tillage (to a depth of 20 cm) to ensure thorough mixing of the conditioner with the topsoil. Irrigate immediately after application, using 80% of the soil's field capacity as a baseline, and then maintain regular field management thereafter.

[0045] Example 5 This embodiment prepares a compound soil conditioner with humic acid, sub-graphite and distiller's grains as the main components. Through physical mixing in a specific ratio, the conditioner achieves a synergistic effect of humic acid's structural stability, sub-graphite's porosity regulation ability and distiller's grains' slow-release function of organic nutrients, thus significantly improving the physical and chemical properties of the soil.

[0046] Preparation method: First, select humic acid powder (commercially available product, with packaging indicating humic acid content ≥65%), 200-mesh sieved graphite powder, fermented distiller's grains (moisture content ≤15%, organic matter ≥45%), and the auxiliary component bentonite.

[0047] Weigh the following components in the indicated mass ratios: 40 parts humic acid, 5 parts sub-graphite, 45 parts distiller's grains, and 10 parts bentonite.

[0048] Humic acid and sub-graphite were placed in a mixing device and mixed at 45 r / min for 10 minutes. Then, distiller's grains were added in three batches, each 8 minutes apart, and mixing was maintained for 15 minutes to ensure uniform mixing. Finally, bentonite was added, and mixing continued for 20 minutes until the material was homogeneous (mixing uniformity coefficient of variation ≤5%). The mixture was then granulated using a disc granulator (4 mm aperture), dried with hot air at 55℃ until the moisture content was ≤8%, and sieved to obtain granules with a particle size of 1-4 mm.

[0049] The product provided in this embodiment is suitable for sandy, clayey, or degraded farmland soils, etc. Before application, measure the initial soil bulk density and pH value, and adjust the dosage according to soil type: 2.5 t / ha for sandy soil, 3.0 t / ha for clayey soil, and 4.0 t / ha for degraded soil. Fifteen days before crop sowing, evenly spread the soil conditioner on the surface, then immediately rotary tillage (to a depth of 25 cm) to ensure thorough mixing of the conditioner with the topsoil. Irrigate immediately after application, using 80% of the soil's field capacity as a baseline, and then maintain regular field management thereafter.

[0050] Experimental Example Four groups of experiments were set up: a control group (no soil conditioner applied), a humic acid-only group (based on the preparation method of Example 1, only the raw materials were replaced with 30 parts humic acid and 70 parts bentonite, 3.0 t / ha), a graphite-only group (based on the preparation method of Example 1, only the raw materials were replaced with 15 parts graphite and 85 parts bentonite, 3.0 t / ha), a distiller's grains-only group (based on the preparation method of Example 1, only the raw materials were replaced with 50 parts distiller's grains and 50 parts bentonite, 3.0 t / ha), and the soil conditioner group provided in Example 1 of this invention (3.0 t / ha). Pot experiments were conducted using soil from a continuously cropping obstacle garden (initial organic matter 1.2%, bulk density 1.45 g / cm³, pH 8.1), with each pot containing 10 kg of soil and planted with Chinese cabbage. Soil samples were collected from the 0–20 cm layer 60 days after application. The following indicators were tested using conventional methods: soil bulk density, organic matter content, field water holding capacity, and available potassium content. The results are shown in Table 1 below: detection indicators control group humic acid group Sub-graphite group Sake lees group This invention group Soil bulk density (g / cm³) 1.45 ± 0.03 1.38 ± 0.02 1.41 ± 0.02 1.39 ± 0.03 1.27 ± 0.01 Organic matter (%) 1.20 ± 0.08 1.65 ± 0.11 1.31 ± 0.07 1.82 ± 0.09 2.47 ± 0.12 Field water holding capacity (%) 28.3 ± 0.9 31.6 ± 1.1 33.7 ± 1.0 30.2 ± 0.8 39.5 ± 1.2 Available potassium (mg / kg) 98.7 ± 5.3 132.6 ± 7.1 108.4 ± 6.2 145.3 ± 8.0 187.9 ± 9.4 Fresh weight of crop (g / plant) 35.2 ± 2.1 42.7 ± 2.5 38.6 ± 1.9 46.3 ± 2.7 61.8 ± 3.3 Based on the above experimental groups, a tomato planting experiment was conducted: The tested soil was from a greenhouse vegetable garden where tomatoes had been continuously grown for 5 years. The soil texture was clay loam, and the initial physicochemical properties were: organic matter 1.18%, bulk density 1.47 g / cm³. 3 pH 8.24, available potassium 102.3 mg / kg; The planting method was plastic greenhouse pot cultivation, with a pot diameter of 30 cm and one plant per pot; the seedlings were four-leaf-one-heart plug seedlings; the entire growth period was 120 days (from transplanting on March 15, 2024 to harvesting on July 13, 2024); environmental control: daytime temperature 25-28℃ / nighttime temperature 16-18℃, relative humidity 60%-70%; each treatment was replicated 4 times, for a total of 20 pots; field management: drip irrigation to maintain soil moisture at 70%±5% field capacity, and uniform spraying of 5% abamectin at 2000 times dilution for disease and pest prevention; other parameters not mentioned were conventional planting parameters.

[0051] The results are shown in Table 2 below: detection indicators control group humic acid group Sub-graphite group Sake lees group This invention group Yield per plant (kg / plant) 3.18 ± 0.23 3.67 ± 0.27 3.42 ± 0.19 3.86 ± 0.31 4.77 ± 0.35 Single fruit weight (g) 148.63 ± 8.42 162.37 ± 9.15 155.29 ± 7.83 169.84 ± 10.26 188.56 ± 11.37 Soluble sugars (%) 3.82 ± 0.21 4.15 ± 0.24 3.97 ± 0.18 4.28 ± 0.26 4.93 ± 0.31 Vitamin C (mg / 100g) 21.37 ± 1.48 24.86 ± 1.72 22.95 ± 1.53 26.43 ± 1.81 30.28 ± 2.14 Fruit cracking rate (%) 18.73 ± 2.15 14.26 ± 1.87 16.48 ± 1.92 12.95 ± 1.68 8.37 ± 1.24 As demonstrated by the above embodiments, this invention provides a comprehensive soil conditioner that can significantly improve the physical and chemical properties of soils affected by continuous cropping obstacles and enhance crop yield and quality. In pot experiments with Chinese cabbage, compared with no application or application of humic acid, graphite, or distiller's grains alone, this conditioner more effectively reduced soil bulk density, increased organic matter content, increased field water holding capacity and available potassium content, and significantly promoted Chinese cabbage growth. In tomato planting experiments, this conditioner also showed significant advantages, significantly increasing per-plant yield, per-fruit weight, soluble sugar and vitamin C content in fruits, and effectively reducing fruit cracking rate compared with the control group and other single-application treatments. These results fully demonstrate that the soil conditioner of this invention has significant comprehensive effects in alleviating continuous cropping obstacles in greenhouse vegetables, optimizing soil structure, improving soil fertility, and enhancing vegetable yield and quality.

[0052] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A compound soil conditioner, characterized in that, By weight, the compound soil conditioner contains 25-35 parts humic acid, 10-20 parts sub-graphite, 45-55 parts distiller's grains, and 3-7 parts bentonite.

2. The compound soil conditioner according to claim 1, characterized in that, The humic acid is a commercially available product with a humic acid content of ≥65%.

3. The compound soil conditioner according to claim 1, characterized in that, The particle size of the sub-graphite is 100~300 mesh.

4. The compound soil conditioner according to claim 1, characterized in that, The moisture content of the lees is ≤15% and the organic matter content is ≥45%.

5. The compound soil conditioner according to claim 1, characterized in that, The particle size of the compound soil conditioner is 1-4 mm.

6. The method for preparing the compound soil conditioner according to any one of claims 1 to 5, characterized in that, The process includes the following steps: mixing humic acid with sub-graphite for 10-15 minutes; adding the distiller's grains in three batches, with an interval of 3-7 minutes between each addition, and continuing to mix for 10-20 minutes; adding bentonite and mixing for 15-25 minutes to obtain the mixture, which is the compound soil conditioner.

7. The preparation method according to claim 6, characterized in that, The mixing speed of the humic acid and the sub-graphite is 40~50 r / min.

8. The preparation method according to claim 6, characterized in that, The preparation method further includes granulating the mixture and drying it at 50~60℃ until the moisture content is ≤8%.

9. The application of the compound soil conditioner according to any one of claims 1 to 5 in improving soil quality and enhancing crop quality.

10. The application according to claim 9, characterized in that, The application rate is determined according to soil type: 2.0~3.0 t / ha for sandy soil, 2.5~3.5 t / ha for clay soil, and 3.5~4.5 t / ha for degraded soil. Apply the amendment 10-20 days before crop sowing; After spreading, till the soil to a depth of 15-25cm to mix it thoroughly. Immediately after application, irrigate to 75%–85% of the soil's field capacity.