Mineral source nitro-humic acid complex phosphate fertilizer for treating land salinization and preparation method of mineral source nitro-humic acid complex phosphate fertilizer

Abstract

The invention belongs to the technical field of compound fertilizers, and particularly relates to a mineral source nitro-humic acid complex phosphate fertilizer for treating land salinization and a preparation method of the mineral source nitro-humic acid complex phosphate fertilizer. Comprising the following components in parts by weight: 50-80 parts of mineral source nitro humic acid, 5-20 parts of calcium superphosphate, 1-5 parts of a soil conditioner, 1-3 parts of trace elements, 5-15 parts of biochar, 0.5-2 parts of a complex microbial inoculant and 3-8 parts of a coating material.

Description

Technical Field

[0001] The present invention belongs to the technical field of compound fertilizers, and specifically relates to a mineral-source nitrohumic acid complex phosphate fertilizer for treating soil salinization and a preparation method thereof. Background Art

[0002] Saline-alkali land is one of the important challenges faced by global agricultural sustainable development. The high salt content (such as Na + , Cl - etc.) and high pH value (usually exceeding 8.5) in its soil will inhibit the root development of crops, hinder nutrient absorption, and lead to soil compaction and reduced microbial activity, ultimately resulting in crop yield reduction or even crop failure. According to statistics, the global saline-alkali land area exceeds 950 million hectares, and the saline-alkali land area in China also reaches more than 100 million hectares, of which about 30% has the potential for improvement. However, traditional saline-alkali land treatment methods have significant defects: on the one hand, they rely on a large amount of fresh water irrigation to leach salts, exacerbating the problem of water resource shortage; on the other hand, the application of chemical amendments such as lime or gypsum is likely to cause secondary soil salinization, and the long-term use cost is high.

[0003] In recent years, humic acid substances have been widely used in soil improvement due to their characteristics such as improving soil structure, regulating pH, and enhancing nutrient absorption. However, traditional humic acid fertilizers mostly use weathered coal as raw materials, which have problems such as limited resources, high costs, and single functions. Summary of the Invention

[0004] Based on the problems mentioned in the above background art, the present invention provides a mineral-source nitrohumic acid complex phosphate fertilizer for treating soil salinization.

[0005] The technical solution adopted by the present invention is as follows: A mineral-source nitrohumic acid complex phosphate fertilizer for treating soil salinization, comprising the following components by weight: 50 - 80 parts of mineral-source nitrohumic acid, 10 - 20 parts of superphosphate, 1 - 5 parts of soil conditioner, 1 - 3 parts of trace elements, 5 - 15 parts of biochar, 0.5 - 2 parts of compound microbial agent, and 3 - 8 parts of coating material.

[0006] Further, the mineral-source nitrohumic acid is modified by nitric acid, contains nitrate ions, and has a pH of 4 - 6.

[0007] Further, the trace elements are EDTA chelates of iron or zinc.

[0008] Further, the soil conditioner is diatomite shale and bentonite, with a mass ratio of 1:2.

[0009] Further, the compound microbial agent is a mixed microbial population of nitrogen-fixing bacteria and phosphorus-solubilizing bacteria, with a mass ratio of 1:1.

[0010] Further, the coating material is a paraffin - rosin composite film, with a film thickness of 50 - 100 μm.

[0011] The present invention also provides a preparation method of the above-mentioned ore-source nitrohumic acid complex phosphate fertilizer for treating soil salinization, which comprises the following steps: S1. Prepare nitrohumic acid: Mix ore-source humic acid with 65% nitric acid according to a mass ratio of 1:0.3, react at 60°C for 2 hours to generate nitrohumic acid, and adjust the pH to 5.5-6.0 with ammonia water to form an ammonium salt to enhance water solubility; S2. Add nitrohumic acid and superphosphate into the reaction kettle according to a ratio of 2:1, add 5% citric acid as a catalyst, stir at 80°C for 1 hour to form a humic acid-phosphate complex, and perform spray drying on the humic acid-phosphate complex, with an outlet temperature of 120°C, to obtain a complex intermediate with a particle size ≤ 0.5 mm; S3. Mix the complex intermediate with a soil conditioner and biochar, spray into a 3% polyvinyl alcohol solution for granulation, with a granulation particle size of 2-4 mm, and spray the composite microbial agent on the surface of the particles; S4. Coat with a 5% paraffin-rosin composite film, and control the film thickness to be 50-100 μm.

[0012] Further, in S3, the mixing method uses a double-screw mixer with a rotation speed of 30-50 rpm and a mixing time of 20 minutes to ensure the uniform dispersion of trace elements.

[0013] Further, in S3, the composite microbial agent is sprayed and attached to the surface of the particles in the form of an aqueous solution, with the composite microbial agent: water = 1:5, and the temperature is controlled below 40°C.

[0014] Advantages of the present invention:

[0015] 1. Through the synergistic design of the nitrohumic acid complex phosphate fertilizer, the salt-resistant slow-release coating and the biological microbial agent, the soil environment of saline-alkali land is significantly improved during the treatment of saline-alkali land. The acidic functional groups (-COOH, -NO2, -C6H5) of nitrohumic acid neutralize alkalinity, reducing the soil pH from 8.5-9.5 to 7.0-7.5 (a decrease of 1.5-2.0); nitrohumic acid promotes the leaching of sodium ions through ion exchange and the exchangeable sodium percentage (ESP) is reduced by 10%-15%; biochar and diatomite shale adsorb salt ions such as Cl- and SO4 2- and the soil electrical conductivity (EC) decreases by 30%-50%; humic acid promotes the formation of aggregate structures, and the soil bulk density decreases by 0.2-0.3 g / cm 3 , and the air permeability increases by 40%.

[0016] 2. After complexing superphosphate with nitrohumic acid, it avoids forming insoluble phosphates by combining with Ca 2+ , Fe 3+ ; the paraffin-rosin coating controls the phosphorus release rate, and the retention time of available phosphorus is extended to 2-3 times that of ordinary phosphate fertilizers; phosphate-solubilizing bacteria decompose the fixed phosphorus in the soil and release available phosphorus (PO4 3-)。 Detailed implementation mode

[0017] Example 1:

[0018] The implementation raw materials by weight: 65 parts of mineral source humic acid, 15 parts of superphosphate, 5 parts of soil conditioner, 10 parts of biochar, 1.5 parts of compound microbial agent, 2 parts of trace elements, and 5 parts of coating material.

[0019] (1) React 65 parts of mineral source humic acid with 65% nitric acid at a mass ratio of 1:0.3 at 60 °C for 2 hours to form nitrohumic acid, and then adjust the pH to 6.0 with ammonia water.

[0020] (2) Mix nitrohumic acid and superphosphate in a ratio of 2:1, add 5% citric acid, stir at 80 °C for 1 hour, and spray dry to obtain a complex intermediate.

[0021] (3) Mix the complex intermediate with the soil conditioner, biochar and trace elements, spray into a 3% polyvinyl alcohol solution for granulation, with a particle size of 3 mm, and spray the compound microbial agent.

[0022] (4) Use the coating material, that is, melt paraffin - rosin to coat the particles and cool and solidify.

[0023] Example 2:

[0024] The implementation raw materials by weight: 50 parts of mineral source humic acid, 10 parts of superphosphate, 10 parts of soil conditioner, 5 parts of biochar, 0.5 part of compound microbial agent, 1 part of trace elements, and 3 parts of coating material.

[0025] (1) React 50 parts of mineral source humic acid with 65% nitric acid at a mass ratio of 1:0.3 at 60 °C for 2 hours to form nitrohumic acid, and then adjust the pH to 6.0 with ammonia water.

[0026] (2) Mix nitrohumic acid and superphosphate in a ratio of 2:1, add 5% citric acid, stir at 80 °C for 1 hour, and spray dry to obtain a complex intermediate.

[0027] (3) Mix the complex intermediate with the soil conditioner, biochar and trace elements, spray into a 3% polyvinyl alcohol solution for granulation, with a particle size of 3 mm, and spray the compound microbial agent.

[0028] (4) Use the coating material, that is, melt paraffin - rosin to coat the particles and cool and solidify.

[0029] Example 3:

[0030] The implementation raw materials by weight: 80 parts of mineral source humic acid, 20 parts of superphosphate, 5 parts of soil conditioner, 15 parts of biochar, 2 parts of compound microbial agent, 2 parts of trace elements, and 7 parts of coating material.

[0031] (1) 80 parts of mineral humic acid react with 65% nitric acid at a mass ratio of 1:0.3 at 60 °C for 2 hours to produce nitrohumic acid, and then the pH is adjusted to 6.0 with ammonia water.

[0032] (2) Nitrohumic acid and superphosphate are in a ratio of 2:1, 5% citric acid is added, and stirred at 80 °C for 1 hour, and then spray-dried to obtain a complex intermediate.

[0033] (3) The complex intermediate is mixed with a soil conditioner, biochar, and trace elements, and sprayed with a 3% polyvinyl alcohol solution to granulate, with a particle size of 3 mm, and a composite microbial agent is sprayed.

[0034] (4) Use a coating material, that is, paraffin-rosin is melted and coated on the particles, and cooled and solidified.

[0035] Comparative Example 1:

[0036] Compared with Example 1, in Comparative Example 1, step (2) complexation is not carried out. Nitrohumic acid and superphosphate are in a ratio of 2:1 and mixed with a soil conditioner and biochar, sprayed with a 3% polyvinyl alcohol solution to granulate, with a particle size of 3 mm, and a composite microbial agent is sprayed. The remaining formulations and preparation methods are the same as those in Example 1.

[0037] Comparative Example 2:

[0038] Compared with Example 1, in Comparative Example 2, there is no step (4), and the remaining formulations and preparation methods are the same as those in Example 1.

[0039] Comparative Example 3:

[0040] Compared with Example 1, in Comparative Example 3, there is no composite microbial agent, and the remaining formulations and preparation methods are the same as those in Example 1.

[0041] The compound fertilizers prepared in Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, and Comparative Example 3 are combined with field test data to verify the saline-alkali land improvement effect and phosphate fertilizer synergistic effect of the technology of the present invention. The test site is the moderately and severely saline-alkali land in the Inner Mongolia Hetao Plain (initial pH 8.9, ESP 18%, total salt content 5.2 g / kg).

[0042] Table 1

[0043] Group pH Decrease ESP Decrease Phosphorus Utilization Rate Yield Increase Rate Cost (yuan) Example 1 1.4 11％ 48％ 48％ 2200 Example 2 1.2 9％ 38％ 40％ 1800 Example 3 1.5 12％ 42％ 49％ 2300 Comparative Example 1 0.8 4％ 18％ 14％ 1500 Comparative Example 2 1.2 9％ 30％ 31％ 2000 Comparative Example 3 1.3 10％ 35％ 38％ 2100

[0044] Among them, the decrease in ESP refers to the decrease in the percentage of exchangeable sodium in the soil (Exchangeable Sodium Percentage), which is one of the core indicators for evaluating the saline-alkali land improvement effect.

[0045] ESP = content of exchangeable sodium ions / soil cation exchange capacity * 100%

[0046] ESP Reduction Mechanism of the Present Invention

[0047] (1) -NO2 Group: The nitro (-NO2) introduced through nitrification modification of nitrohumic acid has a strong negative charge and preferentially adsorbs Na + and replaces it with H + or Ca 2+ .

[0048] Reaction Example:

[0049] Humic Acid-NO2 + Na + → Humic Acid-Na + H + Humic Acid-NO2 + Na + → Humic Acid-Na + H +

[0050] Release of H + Neutralize alkalinity and simultaneously reduce the content of exchangeable sodium

[0051] (2) Adsorption of Biochar and Soil Amendments

[0052] Porous Structure: Biochar and soil amendments physically adsorb and lock free Na + , reducing its chance of participating in soil colloid exchange.

[0053] (3) Biological Desalination by Compound Bacterial Agents

[0054] Phosphate-Solubilizing Bacteria: Secrete organic acids to dissolve calcium salts (such as Ca3(PO4)2) in the soil and release Ca 2+ Replace Na + , promoting the leaching of sodium ions.

[0055] From Table 1, it can be seen that the various data of the compound fertilizers obtained in Example 1, Example 2, and Example 3 are all good, and in Example 3, due to the reduction of the number of coating materials, the cost is more economical.

[0056] In Comparative Example 1, due to the lack of complexation, its improvement effect is significantly inferior to that of Example 1;

[0057] In Comparative Example 2, due to the lack of coating, the phosphorus release period is shortened, indicating the role of the coating component in extending the fertilizer efficiency;

[0058] In Comparative Example 3, due to the non-use of compound bacterial agents, the phosphorus utilization rate decreases, indicating that compound bacterial agents are indispensable for activating soil nutrients.

[0059] In summary, it shows that the formula of this application is reasonable and the preparation method is reasonable. Through the collaborative design of nitrohumic acid complexed phosphate fertilizer, salt-resistant slow-release coating, and biological bacterial agents, the saline-alkali soil environment is significantly improved in saline-alkali land treatment.

[0060] The above has introduced the present invention in detail. The description of the specific embodiments is only used to help understand the method and its core idea of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A mineral-source nitro-humic acid complex phosphate fertilizer for treating soil salinization, characterized in that, It comprises the following components by weight parts: 50 - 80 parts of mineral source nitrohumic acid, 10 - 20 parts of superphosphate, 1 - 5 parts of soil conditioner, 1 - 3 parts of trace elements, 5 - 15 parts of biochar, 0.5 - 2 parts of compound microbial agent, and 3 - 8 parts of coating material.

2. The complex phosphate fertilizer of ore-derived nitrohumic acid for controlling soil salinization according to claim 1, wherein: The mineral source nitrohumic acid is modified by nitric acid, contains nitrate ions, and has a pH of 4 - 6.

3. The complex phosphate fertilizer of ore-derived nitro humic acid for controlling soil salinization according to claim 1, characterized in that: The trace elements are EDTA chelates of iron or zinc.

4. The mineral-source nitro-humic acid complex phosphate fertilizer for treating soil salinization according to claim 1, wherein: The soil conditioner is diatomite shale and bentonite, with a mass ratio of 1:

2.

5. A mineral source nitro-humic acid complex phosphate fertilizer for treating soil salinization according to claim 1, characterized in that: The compound microbial agent is a mixed microbial community of nitrogen-fixing bacteria and phosphorus-solubilizing bacteria, with a mass ratio of 1:

1.

6. The complex phosphate fertilizer of ore-source nitro humic acid for controlling soil salinization according to claim 1, characterized in that, The coating material is a paraffin - rosin composite film with a film thickness of 50 - 100 μm.

7. The preparation method of the mineral source nitrohumic acid complex phosphate fertilizer for treating soil salinization according to any one of claims 1 - 6, comprising the following steps: S1. Prepare nitrohumic acid: Mix mineral source humic acid and 65% nitric acid at a mass ratio of 1:0.3, react at 60 °C for 2 hours to generate nitrohumic acid, and adjust the pH to 5.5 - 6.0 with ammonia water to form ammonium salts to enhance water solubility; S2. Add nitrohumic acid and superphosphate to the reaction kettle at a ratio of 2:1, add 5% citric acid as a catalyst, stir at 80 °C for 1 hour to form a humic acid - phosphate complex, and perform spray drying on the humic acid - phosphate complex, with an outlet temperature of 120 °C, to obtain a complex intermediate with a particle size ≤ 0.5 mm; S3. Mix the complex intermediate with the soil conditioner, biochar, and trace elements, spray into a 3% polyvinyl alcohol solution for granulation, and form into pellets through a disk granulator with a granulation particle size of 2 - 4 mm, and spray the compound microbial agent on the surface of the pellets; S4. Coat with a 5% paraffin - rosin composite film, controlling the film thickness to be 50 - 100 μm.

8. The preparation method of a mineral-source nitro humic acid complex phosphate fertilizer for treating soil salinization according to claim 7, characterized in that, In S3, the mixing method uses a double - helix mixer with a rotation speed of 30 - 50 rpm and a mixing time of 20 minutes to ensure uniform dispersion of trace elements.

9. The preparation method of a mineral source nitro humic acid complex phosphate fertilizer for treating soil salinization according to claim 7, characterized in that, In S3, the compound microbial agent is in the form of an aqueous solution, with the compound microbial agent: water = 1:5, and is sprayed and adhered to the surface of the pellets, with the temperature controlled below 40 °C.