A stable and efficient liquid nitration inhibitor, its preparation method and application

Abstract

This invention discloses a stable and efficient liquid nitrification inhibitor, its preparation method, and its application, belonging to the field of agricultural chemicals and fertilizer enhancement technology. The stable and efficient liquid nitrification inhibitor comprises the following components: a nitrification-inhibiting active ingredient, a co-solubilizing agent, a stabilizer system, a regulating buffer, an antifreeze agent, and the balance being deionized water. The nitrification inhibitor of this invention is a homogeneous and transparent liquid, stable during long-term storage, and miscible with various liquid fertilizers and irrigation water in any proportion, making it more convenient to use. Adding it to liquid fertilizer or irrigation systems can effectively inhibit soil nitrification, increase nitrogen fertilizer utilization by 15-20%, significantly reduce nitrate nitrogen leaching and greenhouse gas emissions, and is particularly suitable for modern fertigation agriculture.

Description

Technical Field

[0001] This invention belongs to the field of agricultural chemicals and fertilizer enhancement technology, and in particular relates to a stable and efficient liquid nitrification inhibitor, its preparation method and application. Background Technology

[0002] Nitrification is one of the main pathways of nitrogen loss in farmland. Ammonium nitrogen is converted to nitrate nitrogen by nitrifying bacteria in the soil, easily leading to leaching and denitrification gaseous losses. Nitrification inhibitors are key substances for suppressing this process. Currently, mainstream nitrification inhibitors such as 3,4-dimethylpyrazole phosphate, 2-chloro-6-trichloromethylpyridine, and dicyandiamide are mostly commercially available in solid granule or powder form.

[0003] However, with the popularization of fertigation technology, the proportion of liquid fertilizers and fertilizers applied through irrigation systems is increasing. Solid nitrification inhibitors have significant drawbacks when mixed with liquid fertilizers: poor solubility, uneven mixing, and easy settling and clogging in storage tanks or pipelines; potential compatibility issues with other components in liquid fertilizers (such as phosphate, calcium, and magnesium ions), leading to precipitation; and poor chemical stability of aqueous solutions of some highly effective inhibitors (such as DMPP) during long-term storage, resulting in easy decomposition and inactivation. While existing technologies have attempted to prepare nitrification inhibitors into suspensions or simple aqueous solutions, these generally suffer from poor physical stability (layering, crystallization) or insufficient chemical stability, making it difficult to meet the requirements for commercial storage and use.

[0004] Therefore, developing a liquid nitrification inhibitor composition that is chemically stable, highly compatible with the complete nutrient components of common liquid fertilizers, and can effectively inhibit nitrification has become an urgent need for the development of modern agricultural technology. Summary of the Invention

[0005] The purpose of this invention is to overcome the inconvenience of applying existing solid nitrification inhibitors in liquid fertilization systems and the instability of existing liquid formulations during storage, and to provide a highly stable and efficient liquid nitrification inhibitor with water as the continuous phase.

[0006] To achieve the above-mentioned objectives, the present invention employs the following technical solution: a stable and efficient liquid nitration inhibitor, comprising the following components by mass percentage: 5.0% ~ 25.0% nitration-inhibiting active ingredient, 10.0% ~ 30.0% co-solubilizing solubilizer, 1.0% ~ 8.0% stabilizer system, 0.5% ~ 5.0% pH adjusting buffer, 0 ~ 5.0% antifreeze agent, and the balance being deionized water; the nitration-inhibiting active ingredient is composed of a first active ingredient and a second active ingredient; the stabilizer system is composed of an antioxidant and a metal ion chelating agent, which can prevent the active ingredient from being oxidized or decomposed by interaction with trace metal ions during storage.

[0007] Furthermore, the mass ratio of the first active ingredient to the second active ingredient is 0.2 to 5; this compound system combines rapid and sustained effects, and has a synergistic effect.

[0008] Furthermore, the mass ratio of the antioxidant to the metal ion chelating agent is 0.4 to 1.6.

[0009] Further, the first active ingredient is 3,4-dimethylpyrazole phosphate, 2-chloro-6-trichloromethylpyridine, or chloridine; the second active ingredient is dicyandiamide.

[0010] Furthermore, the co-solubilizer is at least one of propylene glycol, glycerol, N-methylpyrrolidone, ethanol, alkylphenol polyoxyethylene ether, and fatty alcohol polyoxyethylene ether; its function is to fully dissolve the active ingredient and ensure that it does not precipitate at low temperatures.

[0011] Furthermore, the antioxidant is sodium sulfite, ascorbic acid, or propyl gallate; the metal ion chelating agent is disodium EDTA, sodium citrate, or sodium tartrate.

[0012] Furthermore, the pH adjusting buffer is phosphoric acid, citric acid, potassium dihydrogen phosphate-dipoxat phosphate buffer pair, or citrate-sodium citrate buffer pair; used to stabilize the pH of the composition within a weakly acidic range of 4.0-6.5, which is most conducive to the chemical stability of the active ingredient.

[0013] Furthermore, the antifreeze agent is urea, calcium chloride, or glycerol; used to prevent the product from freezing at low temperatures.

[0014] Another object of the present invention is to provide a method for preparing the liquid nitration inhibitor, which is simple, efficient, and suitable for large-scale production; the method for preparing the stable and efficient liquid nitration inhibitor includes the following steps: (1) Add some deionized water and co-solubilizer to the reactor, stir evenly, then add the second active ingredient, metal ion chelating agent and antifreeze agent in the stabilizer system in sequence, heat slowly to 40-50°C, stir until completely dissolved, and obtain solution A; (2) In another reactor, the antioxidant in the first active ingredient and stabilizer system is dissolved in the remaining deionized water to obtain a clear solution B; (3) Add solution B from step (2) slowly to solution A, which has been cooled to room temperature, while stirring. Mix well, adjust the pH of the mixture to 5.0-6.0 with pH adjustment buffer, add deionized water to the specified mass, continue stirring for more than 30 minutes, filter, and obtain a stable and efficient liquid nitrification inhibitor.

[0015] Another object of the present invention is to provide the application of the liquid nitrification inhibitor in stable liquid nitrogen fertilizer, liquid compound fertilizer or as an irrigation additive.

[0016] Furthermore, when used as an irrigation additive, it is added to the irrigation water at a rate of 0.5%-3.0% of the mass of pure nitrogen in the fertilization system.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. High stability and compatibility: Through optimized solvent system, stabilizers, and pH buffering technology, the active ingredients (especially DMPP) are ensured to maintain long-term chemical stability in aqueous environments (decomposition rate <5% after 14 days of heat storage at 54°C). The product is highly compatible with liquid fertilizers containing macro-elements (N, P, K) and micro-elements, exhibiting no precipitation or crystallization and excellent physical stability.

[0018] 2. Extremely convenient to use: The liquid formulation can be seamlessly integrated with any liquid fertilizer system, enabling precise and uniform addition. It solves the problems of dissolution, clogging, and uneven mixing of solid products, making it particularly suitable for modern large-scale agriculture and fertigation.

[0019] 3. Synergistic effect and long-lasting effect: The combination of active ingredients with different mechanisms of action has both fast and long-lasting effects, which can inhibit the activity of soil nitrifying bacteria more broadly and for longer, extending the duration of the nitrification inhibition peak by more than 30%, and more effectively matching the nitrogen requirements of crops.

[0020] 4. Environmentally friendly and highly safe: Water is the main substrate, supplemented with easily biodegradable additives, resulting in a low environmental impact. The weakly acidic pH is friendly to the fertilization system and crop roots. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0022] Example 1

[0023] This invention provides a stable and highly efficient liquid nitration inhibitor with a total active ingredient content of 15%, the components and mass ratio of which are as follows: 3,4-Dimethylpyrazole phosphate (DMPP); Dicyandiamide (DCD) 10.0%; Propylene glycol 15.0%; Fatty alcohol polyoxyethylene ether (AEO-9) 5.0%; Disodium EDTA 0.5%; Ascorbic acid 0.3%; Phosphoric acid (10% aqueous solution); Urea 3.0%; Add deionized water to bring the total to 100%.

[0024] The method for preparing the stable and efficient liquid nitration inhibitor includes the following steps: (1) Add some deionized water and co-solubilizing solubilizer (propylene glycol and fatty alcohol polyoxyethylene ether (AEO-9)) to the reactor, stir evenly, then add the second active ingredient dicyandiamide, the metal ion chelating agent disodium EDTA in the stabilizer system and urea in sequence, heat slowly to 40-50°C, stir until completely dissolved, and obtain solution A; (2) In another reactor, 3,4-dimethylpyrazole phosphate and ascorbic acid were dissolved in a portion of deionized water to obtain a clear solution B; (3) Slowly add solution B from step (2) to solution A, which has been cooled to room temperature, while stirring. Mix well, adjust the pH to 5.5 with phosphoric acid (10% aqueous solution), add deionized water to the specified mass, continue stirring for more than 30 minutes, filter, and obtain a stable and efficient liquid nitrification inhibitor.

[0025] Example 2

[0026] This invention provides a stable and highly efficient liquid nitration inhibitor with a total active ingredient content of 20%, the components and mass ratios of which are as follows: 2-Chloro-6-trichloromethylpyridine 8.0%; Dicyandiamide (DCD) 12.0%; Glycerol 20.0%; N-methylpyrrolidone 5.0%; Sodium citrate 1.0%; Sodium sulfite 0.5%; Citric acid-sodium citrate buffer solution; Add deionized water to bring the total to 100%.

[0027] The method for preparing the stable and efficient liquid nitration inhibitor includes the following steps: (1) Add some deionized water and co-solubilizing agent (glycerol and N-methylpyrrolidone) to the reactor, stir evenly, then add the second active ingredient dicyandiamide and the metal ion chelating agent N-methylpyrrolidone in the stabilizer system in sequence, heat slowly to 40-50°C, stir until completely dissolved, and obtain solution A; (2) In another reactor, 2-chloro-6-trichloromethylpyridine and sodium sulfite were dissolved in a portion of deionized water to obtain a clear solution B; (3) Add solution B from step (2) slowly to solution A, which has been cooled to room temperature, while stirring. Mix well, adjust the pH to 5.8 with citrate-sodium citrate buffer, add deionized water to the specified mass, continue stirring for more than 30 minutes, filter, and obtain a stable and efficient liquid nitrification inhibitor.

[0028] Example 3

[0029] This invention provides a stable and highly effective liquid nitration inhibitor with a total active ingredient content of 8%, suitable for cost-sensitive applications or applications requiring high dilution. The components and mass ratios are as follows: Chloridine (CMP) 2.0%; Dicyandiamide (DCD) 6.0%; Glycerol 10.0%; Ethanol 5.0%; Alkylphenol polyoxyethylene ether (OP-10) 3.0%; Disodium EDTA 0.3%; 0.1% propyl gallate; Potassium dihydrogen phosphate-dipotassium hydrogen phosphate buffer solution; Calcium chloride (as an antifreeze) 2.0%; Add deionized water to bring the total to 100%.

[0030] The method for preparing the stable and efficient liquid nitration inhibitor includes the following steps: (1) After adding some deionized water, glycerol, ethanol and OP-10 to the reactor and stirring evenly, add the second active ingredient dicyandiamide, disodium EDTA and calcium chloride in sequence, heat to 45°C and stir to dissolve, and cool to room temperature to obtain solution A; (2) Dissolve chloridine and propyl gallate in a portion of deionized water to obtain a clear solution B; (3) Slowly add solution B from step (2) to solution A, which has been cooled to room temperature, while stirring. Mix well, adjust the pH to 5.0 with potassium dihydrogen phosphate-dipotassium hydrogen phosphate buffer, add deionized water to the specified mass, continue stirring for more than 30 minutes, filter, and obtain a stable and efficient liquid nitrification inhibitor.

[0031] Example 4

[0032] This invention provides a stable and highly efficient liquid nitration inhibitor with a total active ingredient content of 25%, the components and mass ratio of which are as follows: 3,4-Dimethylpyrazole phosphate (DMPP) 10.0%; Dicyandiamide (DCD) 15.0%; Propylene glycol 12.0%; N-methylpyrrolidone 10.0%; Fatty alcohol polyoxyethylene ether (AEO-9) 6.0%; Disodium EDTA 1.0%; Sodium citrate 0.5%; Ascorbic acid 0.8%; Adjust the pH to 5.2 with phosphoric acid (10% aqueous solution); Add deionized water to bring the total to 100%.

[0033] The method for preparing the stable and efficient liquid nitration inhibitor includes the following steps: (1) Add some deionized water, propylene glycol, NMP and AEO-9 to the reactor, stir evenly, then add the second active ingredient dicyandiamide, disodium EDTA and sodium citrate in sequence, heat to 50°C and stir to dissolve, cool to room temperature to obtain solution A; (2) Dissolve DMPP and ascorbic acid in a small amount of warm water to obtain a clear solution B; (3) Slowly add solution B from step (2) to solution A, which has been cooled to room temperature, while stirring. Mix well, adjust the pH to 5.2 with phosphoric acid (10% aqueous solution), add deionized water to the specified mass, continue stirring for more than 30 minutes, filter, and obtain a stable and efficient liquid nitrification inhibitor.

[0034] Comparative Example 1 A physical mixture of equal amounts of the active ingredient, solid 3,4-dimethylpyrazole phosphate (DMPP), and dicyandiamide (DCD).

[0035] Comparative Example 2: A simple aqueous solution containing only 3,4-dimethylpyrazole phosphate (DMPP) (pH unadjusted, no stabilizer).

[0036] Comparative Example 3: The formulation, which does not contain antioxidants and metal ion chelators, has the same composition as in Example 1. Specifically, it consists of: DMPP 5.0%, DCD 10.0%, propylene glycol 15.0%, AEO-9 5.0%, pH adjusted to 5.5 with phosphoric acid, and the remainder being water.

[0037] Performance test 1. High-temperature storage stability test: The products of Examples 1-4 and the samples of Comparative Examples 2 and 3 were sealed and placed in a constant temperature chamber at (54±2)°C for accelerated storage for 14 days. The results are shown in Table 1.

[0038] Table 1 shows the stability test results for samples from Examples 1-4 and Comparative Examples 2-3.

[0039] As shown in Table 1, the products of Examples 1-4 of this invention exhibited excellent chemical stability with a DMPP decomposition rate of less than 5% under accelerated high-temperature conditions. In contrast, Comparative Example 2 (without a stabilizing system) showed severe decomposition, and Comparative Example 3 (lacking antioxidants and chelating agents) also showed a significant decrease in stability, demonstrating that a complete stabilizer system and pH control are both indispensable. Example 4 maintained a decomposition rate of 5% even at a high loading of 25%, proving the effective upper limit of this formulation system.

[0040] 2. Low-temperature stability and physical compatibility testing The products from Examples 1-4 were stored at (-5±2)°C for 7 days, and then observed after being restored to room temperature. Neither product showed crystallization or precipitation, and both remained homogeneous and transparent after being restored to room temperature. The product from Example 1 was mixed with high-phosphorus liquid fertilizer (10-30-10) and calcium-containing suspension liquid fertilizer at the recommended ratio, and allowed to stand at room temperature for 30 days. No precipitation, flocculation, or crystallization occurred, demonstrating excellent physical compatibility.

[0041] 3. Soil nitrification inhibition activity test (indoor culture) Soil samples were collected and treated with an equal amount of ammonium sulfate. Treatments were established: ① Control (CK); ② Comparative Example 1 (solid mixture, total effective component accounting for 2% of pure nitrogen); ③ Product of Example 1 (total effective component accounting for 2% of pure nitrogen). The soil was incubated at 25°C, and the ammonium nitrogen (NH4+) content at different time points was measured. + -N) and nitrate nitrogen (NO3) - -N content.

[0042] Results: On day 28 of cultivation, the nitrification rate of the CK treatment reached over 85%; the nitrification rate of the Comparative Example 1 treatment was approximately 45%; while the nitrification rate of the Example 1 treatment was only 28%, and its ammonium nitrogen content was significantly higher than that of other treatments throughout the entire cultivation period. The nitrification inhibition duration of Example 1 was extended by approximately 10 days compared to the solid Comparative Example 1, demonstrating the synergistic long-lasting advantage of liquid formulation and compound ingredients.

[0043] 4. Liquid fertilizer compatibility test The product from Example 1 was added at the recommended dosage to high-phosphorus liquid fertilizer (N-P2O5-K2O = 10-30-10) and calcium-magnesium-containing suspension liquid fertilizer, and left to stand at room temperature for 30 days. The products remained uniform and transparent, without precipitation, flocculation, or crystallization.

[0044] 5. Field application trials Field trials were conducted on corn, with the following treatments: ① conventional urea (CK); ② urea + product of Example 1 (total effective ingredient accounts for 1% of pure nitrogen); ③ urea + product of Example 4 (total effective ingredient accounts for 1% of pure nitrogen, the actual added volume is smaller due to the higher concentration).

[0045] Results: Compared with the control (CK), the nitrogen fertilizer utilization rate of the treatment in Example 1 increased by 18.2%, and the nitrous oxide (N2O) emission decreased by 41%; the nitrogen fertilizer utilization rate of the treatment in Example 4 increased by 19.5%, and the N2O emission decreased by 44%. The effects of both were comparable and extremely significant, demonstrating that the high-concentration formulation of Example 4 can reduce packaging, storage, transportation and usage costs while ensuring the effectiveness, thus having a greater commercial advantage.

Claims

1. A stable and efficient liquid nitration inhibitor, characterized in that, It is composed of the following components by mass percentage: 5.0%~25.0% nitration-inhibiting active ingredient, 10.0%~30.0% co-solubilizing solubilizer, 1.0%~8.0% stabilizer system, 0.5%~5.0% pH adjusting buffer, 0~5.0% antifreeze agent, and the balance being deionized water; the nitration-inhibiting active ingredient is composed of a first active ingredient and a second active ingredient; the stabilizer system is composed of an antioxidant and a metal ion chelating agent.

2. The stable and efficient liquid nitration inhibitor according to claim 1, characterized in that, The mass ratio of the first active ingredient to the second active ingredient is 0.2 to 5; the mass ratio of the antioxidant to the metal ion chelating agent is 0.4 to 1.

6.

3. The stable and efficient liquid nitration inhibitor according to claim 2, characterized in that, The first active ingredient is 3,4-dimethylpyrazole phosphate, 2-chloro-6-trichloromethylpyridine, or chloridine; the second active ingredient is dicyandiamide.

4. The stable and efficient liquid nitration inhibitor according to claim 1, characterized in that, The co-solubilizer is at least one of propylene glycol, glycerol, N-methylpyrrolidone, ethanol, alkylphenol polyoxyethylene ether, and fatty alcohol polyoxyethylene ether.

5. The stable and efficient liquid nitration inhibitor according to claim 1, characterized in that, The antioxidant is sodium sulfite, ascorbic acid, or propyl gallate; the metal ion chelating agent is disodium EDTA, sodium citrate, or sodium tartrate.

6. The stable and efficient liquid nitration inhibitor according to claim 1, characterized in that, The pH-adjusting buffer is phosphoric acid, citric acid, potassium dihydrogen phosphate-dipoxat phosphate buffer pair, or citric acid-sodium citrate buffer pair.

7. The stable and efficient liquid nitration inhibitor according to claim 1, characterized in that, The antifreeze agent is urea, calcium chloride, or glycerol.

8. The stable and efficient liquid nitration inhibitor according to any one of claims 1-7, characterized in that, The method for preparing the stable and efficient liquid nitration inhibitor includes the following steps: (1) Add some deionized water and co-solubilizer to the reactor, stir evenly, then add the second active ingredient, metal ion chelating agent and antifreeze agent in the stabilizer system in sequence, heat slowly to 40-50°C, stir until completely dissolved, and obtain solution A; (2) In another reactor, the antioxidant in the first active ingredient and stabilizer system is dissolved with a portion of deionized water to obtain a clear solution B; (3) Add solution B from step (2) slowly to solution A, which has been cooled to room temperature, while stirring. Mix well, adjust the pH of the mixture to 5.0-6.0 with pH adjustment buffer, add deionized water to the specified mass, continue stirring for more than 30 minutes, filter, and obtain a stable and efficient liquid nitrification inhibitor.

9. The stable and efficient liquid nitrification inhibitor prepared by the method of any one of claims 1-7 or claim 8, and its application in stable liquid nitrogen fertilizer, liquid compound fertilizer, or as an irrigation additive.

10. The application according to claim 9, characterized in that, When used as an irrigation additive, it is added to the irrigation water at a rate of 0.5%-3.0% of the mass of pure nitrogen in the fertilization system.

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