Medium element fertilizer for saline-alkali soil improvement and preparation method thereof

Abstract

The invention belongs to the technical field of saline-alkali soil restoration, and particularly relates to a medium element fertilizer for saline-alkali soil improvement and a preparation method thereof. According to the invention, calcium superphosphate in the fertilizer can provide a phosphorus source required by crop growth and can release Ca < 2 + > to replace Na < + >, and the complexing agent can chelate Cl <-> and SO4 < 2-> to synergistically reduce soil salinity; wherein the nitrogen source, the potassium source and the magnesium source can provide nitrogen, potassium and magnesium required by plant growth, and manganese, silicon and calcium elements in the pretreated electrolytic manganese residues enhance the salt resistance of crops; through the synergistic effect of all the components, the finally obtained fertilizer can synchronously realize saline-alkali soil desalination, pH value reduction and organic matter and nutrient supply improvement, so that plant growth is promoted.

Description

Technical Field

[0001] The present invention belongs to the technical field of saline-alkali land restoration, and in particular relates to a medium-element fertilizer for improving saline-alkali land soil and a preparation method thereof. Background Art

[0002] Saline-alkali land refers to soil with a higher salt content than normal cultivated land, which affects the normal growth and development of crops. During the formation of saline-alkali land, soluble salts are redistributed and accumulated in the soil, resulting in a higher salt content than normal soil or an alkalinity greater than 20%. Saline-alkali land contains a large amount of Na + The soluble salts, mainly NaHCO3 and Na2CO3, lead to high soil pH value, and also destroy the soil structure, reduce soil fertility, poor physical and chemical properties, and seriously restrict the normal growth of plants.

[0003] Traditional soil modification methods rely primarily on chemical treatment, which works by applying chemically modified materials such as gypsum, fly ash, citric acid, black alum, or phosphogypsum. The application of these materials alters the soil's physical and chemical properties, increasing its acidity. Chemical treatment involves applying acidic salts to improve the properties of saline-alkali soil, lowering its pH, increasing its cation exchange capacity, and reducing its salt content.

[0004] However, the above-mentioned improvement methods have the problems of single function and unstable effect, and the focus is also on reducing the salt content of the soil. There is not much research on whether the subsequent soil improvement can truly promote plant growth and planting, and whether it can be fully developed and utilized. Summary of the Invention

[0005] The purpose of the present invention is to provide a medium-element fertilizer for improving saline-alkali soil and a preparation method thereof.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a medium-element fertilizer for improving saline-alkali soil, comprising the following components in percentage by mass:

[0008] Pre-treatment of electrolytic manganese slag 30-50%, superphosphate 10-20%, magnesium source 2-4%, complexing agent 8-15%, potassium source 5-10%, nitrogen source 3-8% and organic waste 10-25%;

[0009] The raw materials for preparing the pretreated electrolytic manganese slag include electrolytic manganese slag, a pH value regulator and a heavy metal solidifying agent.

[0010] Preferably, the pH regulator includes humic acid; the mass ratio of the electrolytic manganese slag to the pH regulator is 3-4.5:7;

[0011] The heavy metal curing agent includes rice husk powder; the mass ratio of the electrolytic manganese slag to the heavy metal curing agent is 4-5.5:6.

[0012] Preferably, the preparation method of the pretreated electrolytic manganese slag comprises:

[0013] After the electrolytic manganese slag and the pH value regulator are mixed, a heavy metal curing agent is added to perform heavy metal curing to obtain the pretreated electrolytic manganese slag.

[0014] Preferably, the pH value of the pretreated electrolytic manganese slag is 6.0 to 8.0;

[0015] The particle size of the pretreated electrolytic manganese slag is ≤50 mesh.

[0016] Preferably, the complexing agent includes at least one of humic acid and rice husk powder.

[0017] Preferably, the potassium source includes at least one of potassium sulfate and potassium chloride.

[0018] Preferably, the nitrogen source includes at least one of urea and ammonium bicarbonate.

[0019] Preferably, the magnesium source includes at least one of magnesium sulfate and magnesium oxide.

[0020] Preferably, the medium-element fertilizer for improving saline-alkali soil further comprises auxiliary materials; the auxiliary materials comprise at least one of diatomaceous earth and microbial agents;

[0021] The mass percentage of the diatomaceous earth in the medium-element fertilizer for improving saline-alkali soil is 2-5%;

[0022] The mass percentage of the microbial agent in the medium-element fertilizer for improving saline-alkali soil is 1-5%.

[0023] The present invention also provides a method for preparing the medium-element fertilizer for improving saline-alkali soil according to the above technical solution, comprising the following steps:

[0024] first mixing pretreated electrolytic manganese slag, superphosphate, a potassium source, and a magnesium source to obtain a base material;

[0025] The base material, the complexing agent, the organic waste and the nitrogen source are mixed for a second time to obtain the medium-element fertilizer for improving saline-alkali land.

[0026] The invention provides a medium-element fertilizer for improving saline-alkali soil. The fertilizer comprises the following components in percentage by mass: 30-50% of pretreated electrolytic manganese slag, 10-20% of superphosphate, 2-4% of a magnesium source, 8-15% of a complexing agent, 5-10% of a potassium source, 3-8% of a nitrogen source and 10-25% of organic waste. The raw materials for preparing the pretreated electrolytic manganese slag include electrolytic manganese slag, a pH value regulator and a heavy metal solidifying agent.

[0027] In the present invention, superphosphate in fertilizer can provide the phosphorus source required for crop growth and release Ca 2+ Replacement of Na + , the complexing agent can chelate Cl - and SO4 2- The invention synergistically reduces soil salinity by 30-50%. The nitrogen, potassium, and magnesium sources provide the nitrogen, potassium, and magnesium required for plant growth, and pre-treat the manganese, silicon, and calcium in the electrolytic manganese slag to enhance crop salt tolerance. Through the synergistic effect of the various components, the resulting fertilizer simultaneously desalinates saline-alkali soils, lowers pH, and increases organic matter and nutrient supply, thereby promoting plant growth. Furthermore, the invention utilizes electrolytic manganese slag to prepare a medium-element fertilizer, enabling resourceful utilization of the electrolytic manganese slag. DETAILED DESCRIPTION

[0028] The present invention provides a medium-element fertilizer for improving saline-alkali soil, comprising the following components in percentage by mass:

[0029] Pre-treatment of electrolytic manganese slag 30-50%, superphosphate 10-20%, magnesium source 2-4%, complexing agent 8-15%, potassium source 5-10%, nitrogen source 3-8% and organic waste 10-25%;

[0030] The raw materials for preparing the pretreated electrolytic manganese slag include electrolytic manganese slag, a pH value regulator and a heavy metal solidifying agent.

[0031] Measured by mass percentage, the medium-element fertilizer for improving saline-alkali soil provided by the present invention comprises 30-50% pretreated electrolytic manganese slag, specifically 30%, 35%, 40%, 45%, or 50%. In the present invention, the pH regulator preferably comprises humic acid; the heavy metal solidifying agent preferably comprises rice husk powder; the mass ratio of the electrolytic manganese slag to the pH regulator is preferably 3-4.5:7; and the mass ratio of the electrolytic manganese slag to the heavy metal solidifying agent is preferably 4-5.5:6. In the present invention, the manganese, silicon, and calcium elements in the pretreated electrolytic manganese slag can enhance the salt resistance of crops and provide nutrients such as manganese sulfate, selenium, and sulfur required for crop growth.

[0032] In the present invention, the method for preparing the pretreated electrolytic manganese slag preferably comprises: mixing the electrolytic manganese slag and a pH regulator, adding a heavy metal curing agent, and performing heavy metal curing to obtain the pretreated electrolytic manganese slag.

[0033] In the present invention, after the heavy metal solidification, the obtained material is preferably dried and pulverized in sequence. In the present invention, the pH value of the pretreated electrolytic manganese slag is preferably 6.0 to 8.0; the particle size of the pretreated electrolytic manganese slag is preferably ≤50 mesh. In the present invention, pH adjustment can reduce the pH value of the electrolytic manganese slag, and heavy metal solidification can reduce the leaching rate of Mn and Cd in the electrolytic manganese slag, so that the Mn / Cd leaching concentration of the fertilizer is lower than the farmland risk screening value, meeting the requirements of the national standard GB15618-2018.

[0034] Calculated by mass percentage, the medium-element fertilizer for improving saline-alkali soil provided by the present invention includes 10-20% superphosphate, specifically 10%, 12%, 14%, 15%, 16%, 18%, or 20%. In the present invention, the effects of superphosphate include: (1) phosphate ions combine with sodium ions and calcium ions in saline-alkali soil to form insoluble sodium phosphate and calcium phosphate, effectively fixing free salt in the soil and reducing the salt content; at the same time, it can provide the phosphorus source required for crop growth; (2) superphosphate is an acidic fertilizer containing free acid (such as sulfuric acid), which can react with substances such as sodium carbonate in saline-alkali soil to neutralize alkalinity, reduce soil pH, and alleviate the harm of high alkaline environment to plants; (3) superphosphate destroys the cementation between soil particles, disperses soil aggregates, and enhances permeability and air permeability; at the same time, phosphate ions combine with aluminum ions in the soil to form stable aluminum phosphate salts, reducing particle surface charge adsorption and further optimizing soil structure; (4) after superphosphate reduces saline-alkali stress, it creates a suitable growth environment for beneficial microorganisms. Microorganisms accelerate the soil improvement process by decomposing organic matter and releasing nutrients. Through the four effects of chemical precipitation, acid-base neutralization, structural improvement and biological synergy, the physical and chemical properties of alkaline soil are comprehensively improved, providing favorable conditions for crop growth.

[0035] In terms of mass percentage, the medium element fertilizer for improving saline-alkali soil provided by the present invention includes 2-4% of magnesium source, specifically 2%, 3%, or 4%. In the present invention, the magnesium source preferably includes at least one of magnesium sulfate and magnesium oxide. In the present invention, the magnesium source can adjust the soil pH, improve the soil structure, and reduce the content of heavy metal ions (such as Pb) in saline-alkali soil. 2+ 、Cd 2+ ) leaching, improving environmental safety.

[0036] In terms of mass percentage, the medium-element fertilizer for improving saline-alkali soil provided by the present invention includes 8-15% of a chelating agent, specifically 8%, 9%, 10%, 11%, 12%, 13%, 14%, or 15%. In the present invention, the chelating agent preferably includes at least one of humic acid and rice husk powder. In the present invention, the chelating agent can chelate Cl - and SO4 2- , and promote the formation of aggregate structure.

[0037] The secondary element fertilizer for improving saline-alkali soil provided by the present invention comprises 5-10% by weight of a potassium source, more preferably 5%, 6%, 7%, 8%, 9%, or 10%. In the present invention, the potassium source preferably comprises at least one of potassium sulfate and potassium chloride. In the present invention, the potassium source can replenish potassium ions and inhibit sodium absorption.

[0038] The secondary element fertilizer for improving saline-alkali soil provided by the present invention comprises, by weight percentage, 3-8% of a nitrogen source, specifically 3%, 4%, 5%, 6%, 7%, or 8%. In the present invention, the nitrogen source preferably comprises at least one of urea and ammonium bicarbonate. In the present invention, the nitrogen source can provide the nitrogen required for crop growth.

[0039] The secondary element fertilizer for saline-alkali soil improvement provided by the present invention comprises 10-25% organic waste, specifically 10%, 12%, 15%, 18%, 20%, 22%, or 25%, by weight percentage. In the present invention, the organic waste preferably comprises at least one of straw powder, distiller's grains, and biogas residue. In the present invention, the organic waste can enhance soil organic matter, replenish soil nutrients, and improve soil structure.

[0040] In the present invention, the saline-alkali soil-improving medium-element fertilizer preferably also includes an auxiliary material; the auxiliary material preferably includes at least one of diatomaceous earth and a microbial agent; the microbial agent preferably includes at least one of a phosphate-solubilizing agent and a potassium-solubilizing agent. In the present invention, the mass percentage of the diatomaceous earth in the saline-alkali soil-improving medium-element fertilizer is preferably 2-5%, and the mass percentage of the microbial agent in the saline-alkali soil-improving medium-element fertilizer is preferably 1-5%. In the present invention, the diatomaceous earth can absorb salt; the microbial agent can improve soil structure, activate nutrients, inhibit pathogens, and promote crop growth.

[0041] In the present invention, the saline-alkali soil improving medium-element fertilizer preferably further comprises water. When water is present, the saline-alkali soil improving medium-element fertilizer is preferably used in the form of an aqueous solution. The present invention does not specifically limit the water content in the saline-alkali soil improving medium-element fertilizer, and those skilled in the art may adjust the water content as needed.

[0042] In the present invention, the salt adsorption capacity of the medium element fertilizer for saline-alkali soil improvement is preferably ≥50 mg / g (in terms of Na + (calculated); the pH value of the saline-alkali soil improved by the medium-element fertilizer is preferably adjusted from 8.5 to 7.5 (applied in simulated saline-alkali soil for 30 days at a rate of 200 kg per mu); the organic matter content of the medium-element fertilizer for saline-alkali soil improved is ≥15%. In the present invention, the pH value of the medium-element fertilizer for saline-alkali soil improved is preferably 5 to 7.

[0043] The present invention also provides a method for preparing the medium-element fertilizer for improving saline-alkali soil according to the above technical solution, comprising the following steps:

[0044] first mixing pretreated electrolytic manganese slag, superphosphate, a potassium source, and a magnesium source to obtain a base material;

[0045] The base material, the complexing agent, the organic waste and the nitrogen source are mixed for a second time to obtain the medium-element fertilizer for improving saline-alkali land.

[0046] In the present invention, the second mixing method preferably includes dry mixing or wet mixing. The present invention does not specifically limit the process of dry mixing or wet mixing, and the method familiar to those skilled in the art can be used. In the present invention, the dry mixing method is preferably stirring, and the stirring temperature is preferably 50-60°C; the wet mixing method is preferably wet ball milling. In the present invention, the solvent used in the wet mixing process is preferably water; after the wet mixing is completed, it is preferably not dehydrated, and the obtained medium-element fertilizer is used in the form of an aqueous solution.

[0047] In the present invention, when the secondary element fertilizer for improving saline-alkali land includes auxiliary materials, the auxiliary materials are preferably added during the second mixing process.

[0048] Unless otherwise specified, the materials and equipment used in the present invention are all commercially available products in the art.

[0049] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0050] Example 1

[0051] In this embodiment, the medium-element fertilizer for improving saline-alkali soil comprises: 40% pretreated electrolytic manganese slag, 15% superphosphate, 12% humic acid, 2% magnesium sulfate, 8% potassium sulfate, 5% urea, 13% distiller's grains, and 5% diatomaceous earth;

[0052] Preparation of pretreated electrolytic manganese slag: electrolytic manganese slag and humic acid are mixed in a mass ratio of 3:7, and then rice husk powder is added for heavy metal solidification, wherein the mass ratio of electrolytic manganese slag to heavy metal solidifier is 4:6; the resulting material is dried at 80°C and then pulverized to 50 mesh to obtain pretreated electrolytic manganese slag with a pH value of 6.0 to 8.0;

[0053] mixing pretreated electrolytic manganese slag, superphosphate, magnesium sulfate and potassium sulfate to obtain a base material;

[0054] The base material, humic acid, vinasse, urea and diatomaceous earth are stirred and mixed at 60° C. to obtain the medium-element fertilizer, wherein the pH value of the medium-element fertilizer is 5.5-7.

[0055] Example 2

[0056] In this embodiment, the medium-element fertilizer for improving saline-alkali soil comprises: 35% pretreated electrolytic manganese slag, 20% superphosphate, 10% humic acid, 2% magnesium sulfate, 10% potassium sulfate, 6% urea, 16% distiller's grains, and 1% phosphate-solubilizing bacteria agent;

[0057] Using the pretreated electrolytic manganese slag obtained in Example 1;

[0058] mixing pretreated electrolytic manganese slag, superphosphate, magnesium sulfate and potassium sulfate to obtain a base material;

[0059] The base material, humic acid, vinasse, urea and phosphate-solubilizing bacteria are wet-ball-milled to obtain a water-based medium-element fertilizer. The medium-element fertilizer has a pH value of 5.5-7, a solid content of 30%, and a particle size of 400 meshes.

[0060] Performance Testing

[0061] The medium-element fertilizer obtained in Example 1 was applied to a moderately saline-alkali land in Shanwei, Guangdong (initial salt content 0.32%, pH value 7.6), with an application of 150 kg per mu. After 60 days, the soil salt content dropped to 0.22%, the pH value dropped to 6.8, and the rice emergence rate increased by 45%.

[0062] The aqueous medium-element fertilizer obtained in Example 2 was applied to a saline-alkali land in Inner Mongolia (with an initial salt content of 0.6% and a pH value of 9.4), with an application rate of 200 kg per mu. After 45 days, the soil salt content dropped to 0.35%, the pH value dropped to 8.2, the soil organic matter content increased from 0.5% to 1.2%, and the wheat yield increased by 8%.

[0063] Although the above embodiment provides a detailed description of the present invention, it is only a part of the embodiments of the present invention, not all of the embodiments. Other embodiments can be obtained based on this embodiment without creativity, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. A medium element fertilizer for improving saline-alkali soil, characterized in that: Includes the following components in percentage by mass: Pre-treatment of electrolytic manganese slag 30-50%, superphosphate 10-20%, magnesium source 2-4%, complexing agent 8-15%, potassium source 5-10%, nitrogen source 3-8% and organic waste 10-25%; The raw materials for preparing the pretreated electrolytic manganese slag include electrolytic manganese slag, a pH value regulator and a heavy metal solidifying agent.

2. The secondary element fertilizer for improving saline-alkali soil according to claim 1, characterized in that: The pH regulator includes humic acid; the mass ratio of the electrolytic manganese slag to the pH regulator is 3 to 4.5:7; The heavy metal curing agent includes rice husk powder; the mass ratio of the electrolytic manganese slag to the heavy metal curing agent is 4-5.5:

6.

3. The secondary element fertilizer for improving saline-alkali soil according to claim 1 or 2, characterized in that: The preparation method of the pretreated electrolytic manganese slag comprises: After the electrolytic manganese slag and the pH value regulator are mixed, a heavy metal curing agent is added to perform heavy metal curing to obtain the pretreated electrolytic manganese slag.

4. The secondary element fertilizer for improving saline-alkali soil according to claim 3, characterized in that: The pH value of the pretreated electrolytic manganese slag is 6.0 to 8.0; The particle size of the pretreated electrolytic manganese slag is ≤50 mesh.

5. The secondary element fertilizer for improving saline-alkali soil according to claim 1, characterized in that: The complexing agent includes at least one of humic acid and rice husk powder.

6. The secondary element fertilizer for improving saline-alkali soil according to claim 1, characterized in that: The potassium source includes at least one of potassium sulfate and potassium chloride.

7. The secondary element fertilizer for improving saline-alkali soil according to claim 1, characterized in that: The nitrogen source includes at least one of urea and ammonium bicarbonate.

8. The secondary element fertilizer for improving saline-alkali soil according to claim 1, characterized in that: The magnesium source includes at least one of magnesium sulfate and magnesium oxide.

9. The secondary element fertilizer for improving saline-alkali soil according to claim 1, characterized in that: The medium-element fertilizer for improving saline-alkali soil further includes auxiliary materials; the auxiliary materials include at least one of diatomaceous earth and microbial agents; The mass percentage of the diatomaceous earth in the medium-element fertilizer for improving saline-alkali soil is 2-5%; The mass percentage of the microbial agent in the medium-element fertilizer for improving saline-alkali soil is 1-5%.

10. The method for preparing the secondary element fertilizer for improving saline-alkali soil according to any one of claims 1 to 9, characterized in that: The following steps are involved: first mixing pretreated electrolytic manganese slag, superphosphate, a potassium source, and a magnesium source to obtain a base material; The base material, the complexing agent, the organic waste and the nitrogen source are mixed for a second time to obtain the medium-element fertilizer for improving saline-alkali land.