A slow-release oxygen-supplying conditioner for cold-waterlogged fields, its preparation method and application

Abstract

This invention provides a slow-release oxygen-supplying conditioner for cold-waterlogged fields, its preparation method, and its application. The slow-release oxygen-supplying conditioner comprises core material particles and a wall material layer coating the outer surface of the core material particles. The core material particles include calcium peroxide, natural silica-calcium-magnesium-based minerals, and starch. The wall material layer comprises natural clay minerals and sodium alginate. The mass ratio of core material to wall material is (1-5):1. The preparation method is as follows: First, the components of the core material particles are mixed, and granulation is performed using a sodium silicate aqueous solution as a binder to obtain the core material particles. Then, the components of the wall material layer are mixed and coated onto the surface of the core material particles using a glycerol-containing aqueous solution as a coating liquid, followed by drying and curing. This invention utilizes the physical barrier and chemical slow-release effect of the composite wall material of natural minerals and sodium alginate to significantly slow down the oxygen release rate of calcium peroxide, while simultaneously supplementing nutrients such as calcium, magnesium, and silicon, improving the reducing environment of the soil, promoting crop growth, and is suitable for industrial production.

Description

Technical Field

[0001] This invention belongs to the field of agricultural soil improvement technology, and in particular relates to a core-shell structure slow-release oxygen-supplying conditioner for cold-waterlogged or gleyed paddy fields, its preparation method and application. Background Technology

[0002] Cold-waterlogged fields are a major type of low-yield field in rice-growing areas of southern my country. They are characterized by high groundwater levels, low soil temperature, low redox potential, and a large accumulation of reducing substances (such as ferrous ions and hydrogen sulfide). These unfavorable factors severely inhibit the growth and development of rice roots, leading to low yields. Calcium peroxide (CaO2), as an environmentally friendly solid oxygen-releasing agent, slowly releases oxygen upon contact with water, effectively increasing soil oxygen content and inhibiting the formation of reducing toxic substances. However, the oxygen release rate of ordinary calcium peroxide powder after contact with water is still relatively fast, and its effect is short-lived, making it difficult to meet the oxygen supply requirements of rice throughout its entire growth cycle. Furthermore, excessively rapid local oxygen release may cause oxidative stress to the roots.

[0003] In existing technologies, researchers have attempted to coat calcium peroxide to delay oxygen release. Currently reported calcium peroxide slow-release technologies mostly use synthetic polymers such as ethyl cellulose as the coating layer. Ethyl cellulose-coated calcium peroxide has been considered the most effective in slow-release treatment in several studies. However, these synthetic polymers are extremely difficult to biodegrade naturally in soil environments, and the environmental and ecological risks of long-term cumulative use lack systematic assessment. Furthermore, existing materials have limited functions, mostly confined to oxygen supply, and lack systematic solutions to the multiple obstacles in cold-waterlogged fields.

[0004] To address the aforementioned problems, this invention provides a slow-release oxygen conditioning agent with controllable oxygen release rate, long effective period, environmental friendliness, and the ability to simultaneously release mineral elements required by plants, as well as its preparation method. Summary of the Invention

[0005] The main objective of this invention is to provide a slow-release oxygen-supplying conditioner for cold-water soaking fields, its preparation method, and its application, in order to solve the technical problems of existing calcium peroxide-based conditioners, such as uncontrollable oxygen supply rate, short shelf life, single function, and environmentally unfriendly coating materials.

[0006] To achieve the above objectives, the present invention provides a slow-release oxygenation conditioner for cold-waterlogged fields, comprising core material particles and a wall material layer coating the outer surface of the core material particles. The core material particles comprise calcium peroxide, natural silicon-calcium-magnesium-based minerals and starch, and the wall material layer comprises natural clay minerals and sodium alginate. The mass ratio of the core material to the wall material is (1-5):1.

[0007] Furthermore, the core material particles comprise the following raw materials in parts by weight: 20-80 parts calcium peroxide, 20-80 parts natural silicon-calcium-magnesium-based minerals, and 5-10 parts starch.

[0008] Furthermore, the wall material layer comprises the following raw materials in the indicated mass fractions: 80-120 parts of natural clay minerals and 15-25 parts of sodium alginate.

[0009] Furthermore, the natural silicon-calcium-magnesium-based mineral is one or more of dolomite, magnesite, limestone, calcium-magnesium feldspar, wollastonite, tremolite, serpentine, and zeolite.

[0010] Furthermore, the natural clay mineral is one or more selected from montmorillonite, kaolinite, illite, vermiculite, sepiolite, attapulgite, and halloysite. Compared with existing synthetic polymer materials such as ethyl cellulose, this invention uses natural clay minerals as encapsulation carriers. As a natural component of soil, these minerals can naturally disintegrate into soil colloids after the controlled release is completed, without producing any synthetic polymer residues, thus possessing unparalleled environmental safety advantages.

[0011] The natural silicon-calcium-magnesium-based minerals in the core material particles of this invention exhibit synergistic effects of ion exchange and structural complementarity with the natural clay minerals in the wall material layer. The natural silicon-calcium-magnesium-based minerals slowly dissolve in the acidic reducing environment of cold-soaked fields, releasing Ca... 2+ and Mg 2+ These divalent cations migrate to the wall material layer, and the Na between the natural clay mineral layer and the wall material layer... + or K + Ion exchange occurs, transforming sodium-based / potassium-based clay minerals into calcium-based / magnesium-based clay minerals. Calcium-based / magnesium-based clay minerals have smaller interlayer spacing (e.g., calcium-based / magnesium-based montmorillonite has an interlayer spacing of 1.2–1.5 nm, while sodium-based montmorillonite has an interlayer spacing of 1.5–2.0 nm), resulting in tighter lamellar stacking and significantly enhanced water molecule barrier properties. Natural silica-calcium-magnesium-based minerals are carbonate or silicate minerals with high hardness (Mohs hardness), serving as a rigid framework in the core material particles. Natural clay minerals are layered silicates with expansibility or plasticity. This "hard-soft" combination ensures structural stability of the core material particles during granulation and storage, while also allowing for moderate expansion after application to fill the gaps between the wall material and the core material. Natural silica-calcium-magnesium-based minerals dissolve in the acidic reducing environment of cold-soaked fields to produce H₂SiO₄. 2- / SiO3 2- or HCO3 - / CO3 2- It can neutralize the acidic intermediate product H2O2 generated by the decomposition of calcium peroxide, maintain the pH of the core material particle microenvironment between 8 and 9, and prevent calcium peroxide from undergoing catalytic decomposition under acidic conditions.

[0012] This invention also provides a method for preparing a slow-release oxygen-supplying conditioner for cold-waterlogged fields, comprising the following steps: S1. Preparation of core material granules: Calcium oxide, natural silicon-calcium-magnesium-based minerals and starch are mixed evenly according to the mass ratio, placed in a granulator, and then sodium silicate aqueous solution is sprayed in while rolling to agglomerate the powder into spherical wet granules. After drying and sieving, core material granules are obtained.

[0013] The starch in the core material granules of this invention functions as both a binder and a pore-forming agent. Firstly, the starch can be uniformly dispersed during the core material granule preparation process. Simultaneously, upon contact with water (water in a sodium silicate aqueous solution), it gelatinizes to form a viscous gel-like substance, assisting the core material granule raw materials in agglomerating into spheres and improving granulation properties. Secondly, when the slow-release oxygen-supplying conditioner is applied to the flooded environment of a cold-waterlogged field, the starch is gradually degraded by soil microorganisms or dissolved by water, forming microporous channels inside and on the surface of the core material granules. This allows the active ingredients (such as calcium peroxide) to be released slowly, effectively avoiding the "explosive release" phenomenon caused by a sudden large influx of water, thus achieving the dual functions of slow release and anti-explosive release.

[0014] The starch in the core material particles of this invention can also form a dual slow-release system of "external barrier + internal channel" with the natural clay minerals and sodium alginate in the wall material layer. The natural clay minerals in the wall material layer provide a rigid framework, and sodium alginate forms a dense gel layer upon contact with water, together constituting an external barrier to control the total rate of water entering the core material. The starch is evenly distributed inside the core material particles and is gradually degraded by microorganisms after being applied to the soil, forming a controllable microporous channel network that regulates the permeation path of water inside the core material particles and the outward diffusion rate of oxygen. When the wall material layer develops microcracks due to local defects or long-term immersion, the internal pore network formed by starch can buffer the rapid intrusion of water and prevent the "explosive release" of calcium peroxide. At the same time, the presence of starch pores changes oxygen release from "surface oxygen release" to "bulk oxygen release," resulting in a more stable and sustained oxygen supply curve, significantly improving the integrity of the slow-release system.

[0015] S2. Preparation of wall material layer: Natural clay minerals and sodium alginate are mixed evenly according to the mass ratio and ground into mixed powder; then the core material particles obtained in step S1 are placed in a coating machine, and the mixed powder is spread while the machine is rolling, and coating liquid is sprayed at the same time until a uniform wall material layer is coated on the surface of the core material particles to obtain coated particles.

[0016] S3. Dry and solidify the coated particles to obtain the slow-release oxygen conditioning agent.

[0017] Further, in step S1, the concentration of the sodium silicate aqueous solution is 15-25 wt%, and the modulus is 2.0-4.0; The amount of sodium silicate aqueous solution injected is 10-30% of the total mass of the core material particles.

[0018] This invention utilizes sodium silicate aqueous solution not only as a binder, but also exhibits multiple synergistic effects with calcium peroxide and natural calcium-magnesium silicate minerals in the core material particles. Firstly, there is a chemical stabilization synergy: the alkaline environment of the sodium silicate aqueous solution (pH 11-12) inhibits the surface decomposition of calcium peroxide during granulation and drying. This is because calcium peroxide readily decomposes into H₂O₂ and Ca(OH)₂ in acidic or neutral environments, while in the alkaline sodium silicate solution, a calcium silicate protective film forms on the surface of the calcium peroxide, improving its thermal stability. Secondly, there is an interfacial enhancement synergy: sodium silicate reacts with the Ca in the natural calcium-magnesium silicate minerals... 2+ Mg 2+ The reaction generates calcium magnesium silicate gel, which fills the pores of the core material particles. This gel not only enhances the mechanical strength of the core material particles, but also forms a silicon-rich transition layer on the surface of the core material, providing a "chemical anchor" for subsequent wall coating. Thirdly, there is a slow-release synergistic effect. The silica gel generated by the hydrolysis of sodium silicate forms an inorganic film on the surface of the core material particles, which together with the wall material layer constitutes a double barrier (inner layer: silica gel film; outer layer: montmorillonite + alginate composite film), further delaying water penetration.

[0019] Further, in step S2, the coating solution is an aqueous solution containing glycerol, wherein the glycerol content is 3-60 wt%. The amount of coating liquid sprayed is 10-30% of the total mass of the core material particles.

[0020] In the process of coating the core material particles with a wall material layer, this invention involves spraying an aqueous solution containing glycerol (i.e., a coating solution). This allows the sodium alginate molecular chains in the wall material layer to be more fully hydrated in the presence of glycerol, enhancing the hydrogen bonding between molecular chains and significantly improving the density and continuity of the wall material layer. After drying, a dense, continuous, and crack-free wall material layer is formed, effectively protecting the core material particles. Simultaneously, the glycerol remains in the wall material layer, slowly releasing moisture during the drying process. This prolongs the interaction time between sodium alginate and the functional groups on the surface of the core material particles (such as the hydroxyl groups on the surface of calcium peroxide and the silanol groups formed by sodium silicate), promoting the formation of carboxyl groups (-COO) on sodium alginate. - ) and Ca on the surface of the core material 2+ Ionic cross-linking occurs (from dolomite or calcium peroxide decomposition products), forming a "chemically bonded" interface, which improves the bonding strength between the wall material layer and the core material particle surface and the interfacial bonding strength.

[0021] Furthermore, the particle size of the core material particles is 3-5 mm; The wall material layer has a thickness of 0.2–0.6 mm; The particle size of the slow-release oxygen conditioning agent is 4-6 mm.

[0022] Furthermore, in step S3, the drying temperature is 40–60°C.

[0023] Furthermore, in step S1, the granulator is a disc granulator or a rotary drum granulator.

[0024] In step S2, the coating machine is a water chestnut-type coating machine or a fluidized bed coating machine.

[0025] The slow-release oxygen-supplying conditioner for cold-waterlogged paddy fields provided by this invention can be applied to improve cold-waterlogged paddy fields, gleyed soils, or to inhibit the toxicity of reducing substances in paddy fields.

[0026] The beneficial effects of this invention are as follows: 1. This invention utilizes the dual effects of the rigid framework of natural clay minerals and the gel layer formed by sodium alginate upon contact with water to effectively prevent the rapid penetration of water molecules into the core material. Furthermore, the natural clay minerals and sodium alginate, combined with sodium silicate binder, produce a synergistic effect, significantly delaying the decomposition reaction of calcium peroxide, resulting in significant slow-release oxygen supply performance, greatly extending the effective period of improvement, and meeting the oxygen supply requirements of rice throughout its entire growth cycle. At the same time, it can also effectively reduce the content of ferrous iron, hydrogen sulfide, and reducing substances.

[0027] 2. The natural silicon-calcium-magnesium-based minerals in the core material particles of this invention slowly release trace elements such as calcium, magnesium, and silicon during the oxygen supply process, which can neutralize soil acidity and replenish mineral nutrients; the natural clay minerals in the wall material layer have a high cation exchange capacity, which can adsorb nutrients such as ammonium ions and potassium ions, reduce nutrient loss, and simultaneously improve the physical and chemical properties of the soil.

[0028] 3. The raw materials used in this invention are all natural minerals and biodegradable sodium alginate, starch, glycerin, etc., without synthetic polymer materials. They can be gradually decomposed into harmless components in the soil, with no risk of residual pollution, environmentally friendly, and without secondary pollution, which is in line with the development direction of green agriculture.

[0029] 4. This invention uses a conventional disc granulator or drum granulator for core material granulation and a coating machine for wall material coating. The equipment is highly versatile, requires no complex organic solvents, has a simple preparation process, and operates under mild conditions, making it suitable for large-scale industrial production. Attached Figure Description

[0030] 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 some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0031] Figure 1 This is a finished product image of the slow-release oxygen conditioning agent in Example 1 of the present invention; Figure 2 This is a comparison chart of the oxygen release performance of the sustained-release oxygen conditioning agent prepared in Example 1 of the present invention and that of Comparative Example 1. Figure 3 This is a comparison chart of the changes in mineral element concentration between the slow-release oxygen conditioning agent prepared in Example 1 of the present invention and Comparative Example 2. Figure 4 This is a comparison chart of the changes in soil pore water redox index between the slow-release oxygen conditioning agent prepared in Example 1 of the present invention and Comparative Example 3. Figure 5 This is a comparison chart of the changes in the mineral element content of soil pore water between the slow-release oxygen conditioning agent prepared in Example 1 of the present invention and Comparative Example 4. Figure 6 This is a comparison chart of the slow-release oxygen conditioning agent prepared in Example 1 of the present invention and the soil reducing substance index of Comparative Example 5. Detailed Implementation

[0032] 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 a part of the embodiments of the present invention, and not all of them. 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.

[0033] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0034] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention, as well as the prior art known to those skilled in the art and the description of this invention, may be implemented using any prior art methods, devices, and materials similar to or equivalent to those described, used, or made of materials in the embodiments of this invention.

[0035] The following describes the slow-release oxygen-supplying conditioner for cold-waterlogged fields and its preparation method in conjunction with specific embodiments.

[0036] Example 1 A method for preparing a slow-release oxygen-supplying conditioner for cold-waterlogged fields is as follows: S1. Preparation of core material particles: Weigh 70 parts by weight of calcium peroxide, 30 parts by weight of dolomite powder (passed through a 200-mesh sieve), and 5 parts by weight of starch, and mix them in a three-dimensional mixer for 30 minutes until homogeneous. Place the mixed powder into a disc granulator (disc inclination angle 45°, rotation speed 25 rpm). While the material is rolling, spray a sodium silicate aqueous solution (concentration 30 wt%, modulus 3.26) evenly as a binder to gradually agglomerate the mixed powder into spherical wet particles. Control the granulation time to approximately 20 minutes, and stop spraying when the particle diameter reaches 3–4 mm. Transfer the wet particles to an oven and dry at 50°C for 4 hours. Remove and sieve, taking particles with a diameter of 3–4 mm as core material particles.

[0037] S2. Preparation of the wall material layer: Weigh 100 parts by weight of montmorillonite and 20 parts by weight of sodium alginate, mix them, and grind them in a ball mill to 300 mesh to obtain a mixed powder. Place 1 kg of the above core material particles in a water chestnut-type coating machine, preheat to 40°C, and keep it rotating. While rotating, spread 0.5 kg of the mixed powder and simultaneously spray 200 g of coating liquid (an aqueous solution containing 30 wt% glycerol) with an atomizing spray gun. The coating process lasts for about 30 minutes. Control the speed of powder spreading and liquid spraying to ensure that the mixed powder is evenly adhered to the surface of the core material particles, thus obtaining coated particles containing a wall material layer.

[0038] S3. Post-treatment: After coating, the coated granules are dried in a 45℃ oven for 2 hours to obtain the finished slow-release oxygen conditioning agent, such as... Figure 1 As shown.

[0039] Comparative Example 1 Compared with Example 1, the difference is that Comparative Example 1 only performs the preparation of core material particles in step S1, and does not perform the preparation of wall material layer in step S2, that is, core material particles without wall material layer are obtained.

[0040] The finished slow-release oxygen conditioning agent prepared in Example 1 and the core material particles prepared in Comparative Example 1 were tested.

[0041] The specific steps for simulating hydroponics are as follows: Place 10g of slow-release oxygen conditioning agent in a 300-mesh nylon bag, then place it in a 250ml deionized water culture bottle, and place the culture bottle in a 25℃ constant temperature incubator.

[0042] Test 1: Dissolved oxygen detection. The dissolved oxygen in the culture flask was tested after 1h, 2h, 4h, 6h, 1d, 3d, 6d, 10d, 14d, 21d, 28d, and 42d of culture. After each test, 250ml of deionized water was replaced and the culture was restarted.

[0043] Test 2: Mineral element detection. After 1h, 2h, 4h, 6h, 1d, 3d, 6d, 10d, 14d, 21d, 28d, and 42d of culture, 10ml of culture solution was taken and mineral element detection was performed using ICP-OES. After each sampling, 250ml of deionized water was replaced and the culture was repeated.

[0044] The simulated soil cultivation experiment follows these steps: The test soil was taken from a severely gleying paddy field in Silao Town, Yunfu City, Guangdong Province. The gleying was obvious, the soil was bluish-black, and the soil was cold and mushy. The top 0-5cm soil was removed, and soil samples from 5-20cm depth were collected, placed in large plastic containers, and immediately transported back to the laboratory, where they were covered with water and left to stand for 3 days. A slow-release oxygen conditioning agent was applied at 0.2% of the wet soil weight and mixed thoroughly. Three treatment groups were set up: a control group (blank), a core material particle group without a wall layer (i.e.,...). Figures 4-6 The uncoated wall material and the slow-release oxygen conditioning agent group (i.e.) Figures 4-6 (The slow-release oxygen conditioning agent in the treatment) was used. Three groups were set up for each treatment group, and the average value of the results was taken.

[0045] Test 3: Detection of redox indices in soil pore water. Soil pore water samples were collected after 1, 5, 12, 17, 22, 32, and 42 days of cultivation to detect dissolved oxygen concentration, ferrous iron content, manganese content, and sulfur content.

[0046] Test 4: Mineral element content detection. After 1 day, 5 days, 12 days, 17 days, 22 days, 32 days and 42 days of cultivation, the concentrations of magnesium, silicon and potassium in soil pore water were measured.

[0047] Test 5: Detection of reducing substances. Soil samples were taken after 1, 5, 12, 17, 22, 32 and 42 days of cultivation to detect the total amount of reducing substances, the total amount of active reducing substances, the removal rate of active reducing substances and the oxidation rate of active reducing substances in the soil.

[0048] Dissolved oxygen test results in hydroponic solution: (e.g.) Figure 2The figures show a comparison of the oxygen release performance of the finished slow-release oxygen conditioner prepared in Example 1 and the core material particles prepared in Comparative Example 1. (a) shows the comparison of oxygen release amount, (b) shows the comparison of the 6-hour oxygen burst rate ("6h" refers to the time period from the start of cultivation to 6 hours), and (c) shows the comparison of oxygen release rate. The oxygen concentration in the hydroponic solution of the slow-release oxygen conditioner (Example 1) showed a trend of first increasing and then slowly decreasing. The oxygen concentration peaked on day 10, indicating that the oxygen release of the slow-release oxygen conditioner reached its peak on day 10 and then slowly decreased. The 6-hour oxygen burst rate and oxygen release rate show that the oxygen release rate of the slow-release oxygen conditioner was gradual and not a rapid release after contact with water. The oxygen concentration in the hydroponic solution of the core material particles (Comparative Example 1) showed a trend of first increasing and then slowly decreasing. The oxygen concentration reached its peak on the first day, which means that the oxygen release of the core material particles reached its peak on the first day, which was much lower than that of the slow-release oxygen supply conditioner (Example 1). The oxygen burst release rate and oxygen release rate at 6 hours showed that the oxygen release rate of the core material particles was much greater than that of the slow-release oxygen supply conditioner, indicating that the slow-release oxygen supply conditioner in Experimental Example 1 has a good slow-release oxygen function.

[0049] Results of mineral element analysis in hydroponic solutions: Figure 3 The figures show a comparison of mineral element concentrations between the finished slow-release oxygen conditioning agent prepared in Example 1 and the core material particles prepared in Comparative Example 1. (a) shows the comparison of Ca concentration, (b) shows the comparison of Mg concentration, (c) shows the comparison of K concentration, and (d) shows the comparison of Si concentration. In the hydroponic solution of the slow-release oxygen conditioning agent (Example 1), the Ca ion concentration slowly increased over time, while the Mg, K, and Si ion concentrations slowly decreased over time. In the hydroponic solution of the core material particles (Comparative Example 1), the Ca ion concentration gradually increased over time, the Mg ion concentration showed no significant change over time, and the K and Si ion concentrations gradually decreased over time. The rate of change of mineral elements in the core material particles was much greater than that in the slow-release oxygen conditioning agent, indicating that the slow-release oxygen conditioning agent in Example 1 has a good slow-release function for mineral elements.

[0050] Results of soil pore water redox index detection in soil cultivation experiment: such as Figure 4The figure shows a comparison of the changes in soil pore water redox indices between the finished slow-release oxygen conditioning agent prepared in Example 1 and the core material particles prepared in Comparative Example 1. (a) shows the comparison results of dissolved oxygen concentration, (b) shows the comparison results of ferrous iron concentration, (c) shows the comparison results of manganese iron concentration, and (d) shows the comparison results of sulfur concentration. The dissolved oxygen concentration in the soil pore water of the slow-release oxygen conditioning agent (Example 1) after soil cultivation increased slowly over time, while the concentrations of ferrous iron, manganese iron, and sulfur gradually decreased over time. Compared to the control group (CK), in the experimental group with the added slow-release oxygen conditioning agent, after 42 days, the ferrous concentration decreased by 57.71% (i.e., the ferrous concentration in the control group was 24.71 mg / L, and the ferrous concentration in the slow-release oxygen conditioning agent group was 10.45 mg / L), the manganese concentration decreased by 65.33% (i.e., the manganese concentration in the control group was 3.98 mg / L, and the manganese concentration in the slow-release oxygen conditioning agent group was 1.38 mg / L), and the sulfur concentration decreased by 89.03% (i.e., the sulfur concentration in the control group was 5.56 mg / L, and the ferrous concentration in the slow-release oxygen conditioning agent group was 0.61 mg / L). The dissolved oxygen concentration in the pore water of the soil after soil cultivation of the core material particles (Comparative Example 1) showed a trend of first increasing and then decreasing over time. The concentrations of ferrous iron, manganese iron, and sulfur gradually decreased over time. The sulfur concentration was higher than that of the experimental group with the addition of slow-release oxygen supply conditioner, indicating that the slow-release oxygen supply conditioner can significantly reduce reducing toxic substances such as sulfur in pore water.

[0051] Results of mineral element content detection in soil culture experiment: such as Figure 5 The table shows the comparison results of soil pore water mineral element content between the finished slow-release oxygen conditioning agent prepared in Example 1 and the core material particles prepared in Comparative Example 1. Among them, (a) is the comparison result of pore water Mg concentration, (b) is the comparison result of pore water Si concentration, and (c) is the comparison result of pore water K concentration. Compared to the control group (CK), in the experimental group with the added slow-release oxygenation conditioner, after 42 days, the magnesium concentration increased by 15.61% (i.e., the Mg concentration in the pore water of the control group was 5.06 mg / L, while the Mg concentration in the pore water of the slow-release oxygenation conditioner group was 5.85 mg / L), the silicon concentration increased by 33.33% (i.e., the Si concentration in the pore water of the control group was 3.39 mg / L, while the Si concentration in the pore water of the slow-release oxygenation conditioner group was 4.52 mg / L), and the potassium concentration increased by 11.06% (i.e., the K concentration in the pore water of the control group was 2.08 mg / L, while the K concentration in the pore water of the slow-release oxygenation conditioner group was 2.31 mg / L). The changes in magnesium, silicon, and potassium concentrations in the soil pore water of the core material particles (Comparative Example 1) after soil cultivation were much lower than those in the experimental group with the added slow-release oxygenation conditioner, indicating that the slow-release oxygenation conditioner can effectively release beneficial mineral elements for plant growth.

[0052] Results of soil reducing substance index testing in soil culture experiment: such as Figure 6As shown, the results of comparing the reducing substance index of the finished slow-release oxygen conditioning agent prepared in Example 1 and the core material particles prepared in Comparative Example 1 are shown. Among them, (a) is the comparison result of the total amount of reducing substances, (b) is the comparison result of the total amount of active reducing substances, (c) is the comparison result of the removal rate of active reducing substances, and (d) is the comparison result of the oxidation rate of active reducing substances. Compared to the control group (CK), in the experimental group with the added slow-release oxygen supply conditioner, after 12 days, the total amount of reducing substances in the soil decreased by 68.38% (i.e., the total amount of reducing substances in the control group was 77.48 cmol / kg, and the total amount of reducing substances in the slow-release oxygen supply conditioner group was 24.50 cmol / kg), the total amount of active reducing substances decreased by 6.50% (i.e., the total amount of active reducing substances in the control group was 17.99 cmol / kg, and the total amount of active reducing substances in the slow-release oxygen supply conditioner group was 16.82 cmol / kg), the removal rate of active reducing substances increased by 647.75% (i.e., the removal rate of active reducing substances in the control group was -1.11%, and the removal rate of active reducing substances in the slow-release oxygen supply conditioner group was 6.08%), and the oxidation rate of active reducing substances increased by 635.29% (i.e., the oxidation rate of active reducing substances in the control group was -0.017 cmol / kg·d, and the total amount of reducing substances in the slow-release oxygen supply conditioner group was 0.091 cmol / kg·d). The removal rate and oxidation rate of active reducing substances in the soil of the core material particles (Comparative Example 1) after soil cultivation were much lower than those of the experimental group with added slow-release oxygen supply conditioner, indicating that the slow-release oxygen supply conditioner can effectively increase the removal rate and oxidation rate of active reducing substances, which helps to reduce the amount of reducing toxic substances in the soil.

[0053] The above technical solutions of the present invention are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made under the technical concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A slow-release oxygen-supplying conditioner for cold-waterlogged fields, characterized in that, It includes core material particles and a wall material layer covering the outer surface of the core material particles. The core material particles include calcium peroxide, natural silicon-calcium-magnesium-based minerals and starch. The wall material layer includes natural clay minerals and sodium alginate. The mass ratio of the core material to the wall material is (1-5):

1.

2. The slow-release oxygen-supplying conditioner for cold-waterlogged fields according to claim 1, characterized in that, The core material particles comprise the following raw materials in parts by weight: 20-80 parts calcium peroxide, 20-80 parts natural silicon-calcium-magnesium-based minerals, and 5-10 parts starch.

3. The slow-release oxygen-supplying conditioner for cold-waterlogged fields according to claim 1, characterized in that, The wall material layer comprises the following raw materials by mass fraction: 80-120 parts of natural clay minerals and 15-25 parts of sodium alginate.

4. The slow-release oxygen-supplying conditioner for cold-waterlogged fields according to claim 2, characterized in that, The natural silicon-calcium-magnesium-based minerals are one or more of the following: dolomite, magnesite, limestone, calcium magnesium feldspar, wollastonite, tremolite, serpentine, and zeolite.

5. The slow-release oxygen-supplying conditioner for cold-waterlogged fields according to claim 3, characterized in that, The natural clay mineral is one or more of the following: montmorillonite, kaolinite, illite, vermiculite, sepiolite, attapulgite, and halloysite.

6. The method for preparing the slow-release oxygen-supplying conditioner for cold-waterlogged fields according to any one of claims 1-5, characterized in that, Includes the following steps: S1. Preparation of core material granules: Calcium oxide, natural silicon-calcium-magnesium-based minerals and starch are mixed evenly according to the mass ratio, placed in a granulator, and then sodium silicate aqueous solution is sprayed in a rolling state as a binder to make the powder agglomerate into spherical wet granules. After drying and sieving, core material granules are obtained. S2. Preparation of wall material layer: Natural clay minerals and sodium alginate are mixed evenly according to the mass fraction and ground into mixed powder; then the core material particles obtained in step S1 are placed in a coating machine, and the mixed powder is spread while the machine is rolling, and coating liquid is sprayed at the same time until a uniform wall material layer is coated on the surface of the core material particles to obtain coated particles. S3. Dry and solidify the coated particles to obtain the slow-release oxygen conditioning agent.

7. The method for preparing the slow-release oxygen-supplying conditioner for cold-waterlogged fields according to claim 6, characterized in that, In step S1, the concentration of the sodium silicate aqueous solution is 15-25 wt%, and the modulus is 2.0-4.0; The amount of sodium silicate aqueous solution injected is 10-30% of the total mass of the core material particles.

8. The method for preparing the slow-release oxygen-supplying conditioner for cold-waterlogged fields according to claim 6, characterized in that, In step S2, the coating solution is an aqueous solution containing glycerol, wherein the glycerol content is 3-60 wt%. The amount of coating liquid sprayed is 10-30% of the total mass of the core material particles.

9. The method for preparing the slow-release oxygen-supplying conditioner for cold-waterlogged fields according to claim 6, characterized in that, The particle size of the core material particles is 3-5 mm; The wall material layer has a thickness of 0.2–0.6 mm; The particle size of the slow-release oxygen conditioning agent is 4-6 mm.

10. The application of the slow-release oxygen-supplying conditioner for cold-waterlogged paddy fields as described in any one of claims 1-5, or the slow-release oxygen-supplying conditioner for cold-waterlogged paddy fields prepared by the preparation method described in any one of claims 6-9, in improving cold-waterlogged paddy fields, gleyed soils, or inhibiting the toxicity of reducing substances in paddy fields.

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