Composite modifier for relieving soil hardening and treating saline-alkali soil and preparation method thereof

Abstract

The invention discloses a composite modifier for relieving soil hardening and treating saline-alkali soil and a preparation method thereof. The modifier comprises the following components in percentage by mass: A, 35-55% of porous and ion exchange minerals (two or three of zeolite, medical stone and potassium feldspar), B, 25-45% of pH buffer and flocculation minerals (one or more of calcite and / or gypsum and alumen), C, 10-25% of surface activation and trace minerals (one or more of ruddle, calamine and lapis chloriti), and E, 10-25% of water. And D, 2-10% of a plant extract (one or more of Potentilla striata, Cerbera mangifera, Flos Datura datura and Databaena delavayi). During preparation, A / B / C is subjected to wet grinding until the size is smaller than or equal to 200 meshes for pulping, D is added for homogenizing, and then co-spray drying is performed to obtain coated particle powder. The material has the effects of specific surface and ion exchange, calcium source buffering and rapid flocculation, shell layer slow release and anchoring and the like, the soil conductivity and the exchangeable sodium percentage can be reduced, and gt can be increased; and the proportion of 0.25 mm water-stable aggregate.

Description

Technical Field

[0001] This invention relates to the field of saline-alkali land management technology, and more specifically to a composite soil conditioner and its preparation method for alleviating soil compaction and managing saline-alkali land. Background Technology

[0002] Long-term continuous fertilization, shallow tillage with little turning, and heavy mechanical compaction can easily lead to the enrichment of fine particles in the topsoil and the collapse of pores, resulting in high soil bulk density, poor aeration, and decreased permeability, commonly known as "compaction." In saline-alkali areas, the increased proportion of exchangeable sodium ions (high ESP) and persistently high electrical conductivity (EC) in the soil solution cause the soil double layer to expand, colloids to disperse, and the cycle of aggregate breakage and redispersion to intensify. Compaction and secondary salt damage are intertwined, making it difficult for roots to penetrate the soil and simultaneously impairing crop resistance and yield. Traditional soil improvement methods often rely on single mineral materials (such as zeolite or maifanite) or single chemical conditioners (such as calcium salts and aluminum salts) to address structural or salt damage problems separately. However, single materials often have limitations such as "single effective stage, short window of action, or insufficient duration of effect," making it difficult to simultaneously address "physical structure improvement, chemical salt conditioning, and rhizosphere micro-management" in a single application.

[0003] To alleviate these contradictions, the field of soil science and remediation engineering has gradually emphasized the "multi-mechanism coupling" approach to remediation. This involves providing pore / exchange sites, a stable calcium source, and appropriate flocculation conditions in a single application, supplemented by organic active ingredients that can be slowly released in the rhizosphere to support and maintain aggregate formation, reduce ESP and EC, and improve the microenvironment. However, current common practices often involve stepwise or post-mixing of raw materials, resulting in uncontrollable spatial distribution and release behavior of active components in the field, strong short-term reactions, weak long-term stability, and poor consistency with repeated applications. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a composite soil conditioner and its preparation method for alleviating soil compaction and treating saline-alkali land.

[0005] To achieve the above objectives, the present invention provides the following technical solution, which mainly includes:

[0006] A composite soil conditioner for alleviating soil compaction and treating saline-alkali land, comprising, by weight percentage:

[0007] A. Porous and ion-exchange minerals, 35–55%, selected from two or three of zeolite, maifanite and potassium feldspar;

[0008] B. pH buffering and flocculating minerals 25–45%, including one or more of calcite and / or gypsum and alum;

[0009] C. Surface activation and trace element minerals 10–25%, including one or more of hematite, calamine, and chlorite;

[0010] And D. 2–10% of plant extracts, said plant extracts being selected from one or more of the following: spider lily, sea mango, datura and tea tree;

[0011] The composite modifier is a coated microparticle powder obtained by mixing the mineral slurry formed by A, B, and C with D under wet conditions and then spray drying it, and the particle size of the mineral before spray drying is no greater than 200 mesh.

[0012] Preferably, A is 40–50%, B is 30–40%, C is 12–20%, and D is 3–8%.

[0013] Preferably, A contains zeolite and maifanite; B contains calcite and alum; and D contains spider lily extract and datura extract.

[0014] A method for preparing a treatment additive includes the following steps:

[0015] S1) Components A, B and C are wet-ground to 200 mesh according to the proportions described in claim 1, and then mixed with water by metering, stirring and pulping to obtain a mineral slurry;

[0016] S2) The plant raw material of component D is extracted by biotechnology and ground to 200 mesh to obtain a plant extract solution or slurry;

[0017] S3) Under wet conditions, the plant extract is added to the mineral slurry, and stirring and slurrying are continued until homogeneous to obtain a mixed slurry;

[0018] S4) The mixed slurry is fed into a high-tower spray dryer, and the falling particulate powder is collected as the target product;

[0019] S5) When powdered products are required, the powdered microparticles are directly packaged into finished products and stored in the warehouse.

[0020] Preferably, steps S3) and S4) are carried out consecutively, so that component D and mineral slurry are granulated together during spray drying to obtain microparticle powder.

[0021] Preferably, steps S1) and S3) are both carried out in a wet process, and the order of steps is as follows: mineral pulping → adding plant extracts and homogenizing → spray drying.

[0022] Preferably, the particle size of each solid raw material before spray drying is no greater than 200 mesh.

[0023] As can be seen from the above technical solution, compared with the prior art, the beneficial effects of the present invention are as follows: The present invention proposes a formulation system with A (porous and ion-exchange minerals) / B (pH buffer and flocculating minerals) / C (surface activation and trace minerals) / D (plant extracts) as the core, and after homogenization under wet conditions, it is co-spray dried, so that the four functions are coupled at the single particle scale. This route aims to solve the pain points of the prior art, namely "physical structure improvement and chemical conditioning of salt damage are two separate things, the active components have insufficient efficacy and poor field consistency", through the chain effect of "mineral core provides specific surface area and exchange sites - calcium source and aluminum salt synergistic flocculation - organic active shell slow release - particle structure stabilization". Thus, it can simultaneously achieve the relief of compaction and the treatment of salinity in a single application, and maintain a long effective period and good repeatability. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0025] Figure 1 This is a flowchart of the process flow of the present invention.

[0026] Figure 2 This is a schematic diagram of the "core-shell / shell layer" structure of the composite microparticles of the present invention.

[0027] Figure 3 This is a simplified diagram of the process equipment.

[0028] Figure 4 This is a comparison diagram of field experiments of the composite modifier of the present invention.

[0029] Figure 5 This is a diagram showing the soil compaction recovery effect of the composite amendment of this invention. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Example 1

[0032] This embodiment provides a composite soil conditioner for alleviating soil compaction and treating saline-alkali land. By mass percentage of each component in the finished product, A is 46%, B is 34%, C is 15%, and D is 5%. Specifically, A is composed of zeolite and maifanite in a mass ratio of 3:2; B is composed of calcite and alum in a mass ratio of 4:1; C is hematite; and D is composed of Lycoris radiata extract and Datura stramonium extract in a mass ratio of 1:1. The powder obtained by wet homogenization and co-spray drying with the plant extracts is light brown, with nearly spherical or ellipsoidal particles, visible fine grooves on the surface, and a dry, free-flowing texture.

[0033] The recommended physicochemical indicators and factory inspection standards for this product are as follows: First, the moisture content of the finished product after spray drying should not exceed 3.0 wt%, determined by the loss on drying method under constant temperature conditions of 105℃; Second, the particle size of the finished product should be determined by a laser particle size analyzer, with a median diameter (D50) of 100–220 μm and a main peak in volume distribution within the range of 80–300 μm, to ensure uniformity of field distribution and soil mixing; Third, the pH should be determined by a 1.0% (mass fraction) aqueous suspension, typically in the range of 7.0–8.5, to characterize the buffering properties of the calcite / alum mixture; Fourth, the cation exchange capacity (CEC) of the product should be characterized by the blue methylene method or the ammonium ion exchange method for process consistency evaluation; Fifth, the particle morphology should be observed by scanning electron microscopy and the continuity of the dense surface shell should be recorded, with batch-to-batch comparisons used as evidence of structural stability; Sixth, the flowability should be evaluated by the angle of repose method, with a typical value not exceeding 40°, to ensure flowability and distribution stability during mechanical application.

[0034] For ease of field application, the product in this embodiment is packaged in 25kg bags, with an inner composite film lining for moisture protection and an outer woven bag for easy handling. The recommended field application method is a single strip or furrow application before sowing, with a preferred application rate of 1.0–1.5 t / ha. For fields with high salinity, the product can be premixed with organic fertilizer at a mass ratio of 1:3 and applied to the top 10–15 cm of soil. A light irrigation should be performed after sowing or before transplanting to facilitate particle swelling and the initiation of ion exchange processes. The above application methods are only preferred and do not constitute a limitation on the use of the product of this invention.

[0035] This soil conditioner utilizes a wet spray-drying process to create coated microparticles from three types of minerals (A, B, and C) and a type of plant extract (D), achieving a synergistic effect of "pore-ion exchange-buffering / flocculation-bioactive sustained release." Zeolite and maifanite, as the main porous minerals, provide a high specific surface area and cation exchange sites, allowing exchangeable sodium ions in the topsoil to be selectively replaced and adsorbed onto the mineral surface, while also providing a carrier for the nucleation of microaggregates. The addition of potassium feldspar improves the structural stability of the mineral framework. The resulting porous framework increases the total porosity and connectivity of the soil, reduces the topsoil bulk density, and improves permeability and aeration, creating fundamental conditions for alleviating soil compaction.

[0036] Calcite / gypsum in Category B minerals provides the soil with both effectively and slowly soluble calcium sources. After entering the soil solution, calcium ions bridge ions with colloidal surfaces, promoting flocculation and aggregate formation. Alum provides aluminum salt flocculation, rapidly compressing the electric double layer and accelerating the settling and bonding of fine particles, thus significantly reducing sensitive indicators such as soil electrical conductivity (EC) and exchangeable sodium percentage (ESP) in a short period. This combination of "rapid flocculation + slow-release calcium source" allows for a seamless transition between short-term and medium-term chemical improvement effects, avoiding the problems of single salt conditioners being fast-acting but short-lived, and single calcium sources being slow-acting.

[0037] Type C surface-activated materials and trace minerals (such as hematite, calamine, and chlorite) are co-granulated with types A and B during spray drying. This provides additional surface hydroxyl groups and complexation sites for adsorbing or immobilizing free anions and cations, and also forms a stable inorganic shell on the particle surface, which helps improve the mechanical strength and water resistance of the particles. This shell, superimposed on the type A microporous structure, helps prevent particle pulverization during subsequent tillage and irrigation, thus contributing to the maintenance of aggregates and the long-term stability of soil structure.

[0038] Type D plant extracts, after wet mixing, are co-spray-dried with mineral slurry to form a "mineral core-organic active shell / layer" coating structure, transforming the active ingredient from "free-rapid release" to "anchored-slow release." On one hand, the shell layer can inhibit light / heat-induced inactivation, prolonging the duration of biological activity in the rhizosphere microdomain; on the other hand, the physicochemical adsorption of organic molecules on the mineral surface sites reduces the initial release peak, mitigating the risk of irritation to roots and beneficial microorganisms. Compared with post-blending or dry mixing, the microparticles formed by co-spraying have more uniform particle size and denser surfaces, resulting in better dispersibility and repeatability in field application, and exhibiting a longer duration of action and more stable field consistency at the same dosage.

[0039] Example 2

[0040] To prepare the additive described in Example 1, a target finished product quantity of 100 kg was selected. The raw material quantities were calculated according to the finished product proportions: A was 46.0 kg (containing 27.6 kg of zeolite and 18.4 kg of maifanite), B was 34.0 kg (containing 27.2 kg of calcite and 6.8 kg of alum), C was 15.0 kg (containing 15.0 kg of hematite), and D (based on extract solids) was 5.0 kg. D was supplied using a water extract with a solid content of 10% ± 2%, requiring approximately 50 ± 10 kg of extract. To meet the process window for spray drying, the target slurry solid content was controlled at 45% ± 2%, and the slurry viscosity was stabilized at 900–1400 mPa·s at 25°C.

[0041] First, minerals of types A, B, and C are added to the prepared water in proportion and slowly stirred with a paddle mixer at 150–250 rpm for 10–20 minutes to fully wet the powder and form a primary slurry, controlling the slurry temperature to not exceed 35℃. Then, the primary slurry is fed into a wet sand mill and circulated through a 0.6–0.8 mm zirconium oxide media for grinding. Online particle size monitoring is performed until all solid particles are no larger than 200 mesh (equivalent D90 ≤ 75 μm). At the end of the grinding process, the viscosity is measured using a rotational viscometer (25℃, rotor LV-4, 60 rpm). If necessary, a small amount of water is added or the mixture is allowed to stand and degas to ensure the solid content and viscosity fall within the preset range, thus obtaining a homogeneous mineral slurry.

[0042] Next, dried raw materials of Lycoris radiata and Datura stramonium were selected and subjected to conventional water extraction at a 1:1 (mass ratio). The extract was centrifuged to remove residue and concentrated under reduced pressure to adjust the solid content to 10% ± 2%. Coarse insoluble matter was removed by passing the extract through a 100 μm sieve. If necessary, the particle size was lightly ground by wet milling to obtain a particle size no larger than 200 mesh, thus obtaining a plant extract feed solution. The above feed solution was slowly added to the mineral slurry at 300–500 rpm and homogenized again for 10–20 min to ensure that component D was fully dispersed in the slurry without visible particle aggregation, forming a mixed slurry.

[0043] Then, the mixed slurry is fed into a high-tower spray dryer for co-spray granulation. Spraying can be performed using a centrifugal atomizer or a pressure nozzle; in this embodiment, a centrifugal atomizer is preferred. The atomization speed is set to 9000–12000 rpm, and the feed temperature is controlled below 35℃. The inlet temperature of the spray dryer is set to 180±5℃, and the outlet temperature is set to 90±5℃. The feed pump is regulated using a variable frequency closed-loop method to stabilize the tower outlet temperature within the set range. Before atomization, the slurry is sequentially filtered through 100μm and 60μm dual-stage sieves to prevent nozzle or atomizing disc clogging. During spraying, a cyclone separator collects the falling particulate powder, and a secondary collection process recovers the fine powder. The recovered fine powder is combined with the main material in the same batch to ensure consistency across batches.

[0044] After spraying, the collected powder is passed through a 1.5mm sieve to remove abnormally large particles. Moisture content is rapidly determined using a drying method to confirm that the finished product moisture content is no greater than 3.0 wt%. Subsequently, particle size distribution is measured using a laser particle size analyzer to ensure that the D50 is within the range of 100–220 μm. The pH value is measured using a 1.0% aqueous suspension and is within the range of 7.0–8.5. Flowability is measured using the angle of repose method to ensure that the angle of repose is no greater than 40°. Samples are randomly selected for scanning electron microscopy to confirm the formation of a continuous shell structure on the particle surface. After all indicators meet the requirements, the product is packaged in 25kg bags, lined with a composite film for moisture protection and sealed, labeled with the batch number, and stored in the warehouse. The overall yield of 100kg of product produced using this process, based on material balance calculations, is typically no less than 95%, and the batch-to-batch moisture and particle size fluctuations are controlled within a set window, meeting the requirements for dispersibility and stability in field application.

[0045] To further improve continuity and stability, the "plant extract addition and homogenization" (S3) and "spray drying" (S4) can be operated in series. The mineral slurry and plant extract feed liquid are homogenized in an online static mixer at a mass flow ratio of 9:1 to 11:1 and then directly fed into the spray tower. A constant liquid level control (±2cm) is set in the top hopper of the tower to stabilize the feed cycle, and the feed flow rate is finely adjusted with the outlet temperature as the main control variable. This continuous implementation method helps to reduce the fluctuations in viscosity, solids content, and atomization shear caused by manual batch feeding, and ensures the repeatability of the formation of the coating layer and particle size distribution.

[0046] In terms of process, controlling the particle size of each solid raw material to no more than 200 mesh significantly improves the homogeneity of wet pulping and the nucleation efficiency of spray agglomeration, enabling uniform distribution of A / B / C / D at the single particle scale. This results in two direct effects: First, ion exchange and buffering / flocculation reactions no longer depend on macroscopic mixing uniformity, but occur at the near-neighbor interface of the same particle, improving the reaction efficiency per unit dose; second, the coating shell is more complete, and the sustained-release curve is more controllable, thus allowing the decrease in EC and ESP, the increase in the proportion of >0.25mm agglomerates, and the improvement in permeability to maintain an observable and stable trend over a longer time scale.

[0047] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0048] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A composite soil conditioner for alleviating soil compaction and treating saline-alkali land, characterized in that, By weight percentage, including: A. Porous and ion-exchange minerals, 35–55%, selected from two or three of zeolite, maifanite and potassium feldspar; B. pH buffering and flocculating minerals 25–45%, including one or more of calcite and / or gypsum and alum; C. Surface activation and trace element minerals 10–25%, including one or more of hematite, calamine, and chlorite; And D. 2–10% of plant extracts, said plant extracts being selected from one or more of the following: spider lily, sea mango, datura and tea tree; The composite modifier is a coated microparticle powder obtained by mixing the mineral slurry formed by A, B, and C with D under wet conditions and then spray drying it, and the particle size of the mineral before spray drying is no greater than 200 mesh.

2. The composite modifier according to claim 1, characterized in that: A is 40–50%, B is 30–40%, C is 12–20%, and D is 3–8%.

3. The composite modifier according to any one of claims 1–3, characterized in that: A contains zeolite and maifanite; B contains calcite and alum; and D contains extracts of spider lily and datura.

4. A method for preparing the composite modifier as described in claim 1, characterized in that, Includes the following steps: S1) Components A, B and C are wet-ground to 200 mesh according to the proportions described in claim 1, and then mixed with water by metering, stirring and pulping to obtain a mineral slurry; S2) The plant raw material of component D is extracted by biotechnology and ground to 200 mesh to obtain a plant extract solution or slurry; S3) Under wet conditions, the plant extract is added to the mineral slurry, and stirring and slurrying are continued until homogeneous to obtain a mixed slurry; S4) The mixed slurry is fed into a high-tower spray dryer, and the falling particulate powder is collected as the target product; S5) When powdered products are required, the powdered microparticles are directly packaged into finished products and stored in the warehouse.

5. The production method according to claim 4, characterized in that, Steps S3) and S4) are carried out consecutively, so that component D and mineral slurry are granulated together during spray drying to obtain microparticle powder.

6. The preparation method according to claim 4, characterized in that, Steps S1) and S3) are both carried out in a wet process, and the order of the steps is as follows: mineral pulping → adding plant extracts and homogenizing the pulp → spray drying.

7. The preparation method according to claim 4, characterized in that, Before spray drying, the particle size of each solid raw material should not exceed 200 mesh.

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