Organic state potassium phosphite liquid fertilizer and preparation method thereof

Abstract

The invention relates to an organic state potassium phosphite liquid fertilizer and a preparation method thereof. The effective component of the liquid fertilizer is at least one potassium phosphite compound with the structure shown in the formula (I) to the formula (V), and phosphorous acid and specific polyhydric alcohol are subjected to esterification reaction and then neutralized with potassium carbonate or potassium hydroxide to prepare the liquid fertilizer. The liquid fertilizer has nutrition and sterilization functions, and can effectively prevent fungal and bacterial diseases; an esterification reaction product is stable in property and not prone to being oxidized into orthophosphate with oxygen to lose the sterilization effect, meanwhile, precipitation with medium trace elements is reduced, and compatibility with pesticides is good; organic ester leaves have good affinity, the structure is beneficial to direct absorption of plants, bidirectional transportation can be carried out in xylem and phloem, and the utilization efficiency is high; the foliage affinity is strong, leaves are not easy to burn after high-concentration spraying, and the foliage fertilizer is suitable for various modes such as foliage spraying and drip irrigation. The method is mild in reaction, is operated at normal temperature, does not need heating, is simple and convenient in process, and is suitable for large-scale production and popularization.

Description

Technical Field

[0002] This invention belongs to the field of fertilizer technology, specifically relating to an organic potassium phosphite liquid fertilizer and its preparation method. Background Technology

[0004] Plant nutrition and disease control are core to ensuring improved quality and efficiency in agricultural production. Driven by the development of green agriculture, the development of integrated products that combine nutritional and disease-resistant functions has become an important research direction. Among these, phosphorous acid (HPO3) and its salts show unique application value: the phosphate ions (H2PO3⁻) released by it can not only serve as a potential phosphorus source, providing phosphorus nutrition to plants after oxidation or metabolism, but also act as an elicitor, directly activating the plant's systemic resistance and inducing the synthesis of defensive substances such as phytoalexins. This results in significant preventative and control effects against oomycete diseases (such as downy mildew and blight) and some bacterial diseases.

[0005] Currently, the mainstream products on the market are inorganic phosphites, especially dipotassium hydrogen phosphite (K₂HPO₃). As a phosphorus-potassium compound source, inorganic potassium phosphite has significant drawbacks in practical applications: its phosphate ions are chemically unstable in solution, easily oxidized and degraded, causing pipe blockage and nutrient loss; this precipitation risk leads to poor compatibility with micronutrients and pesticides, limiting tank mixing application; furthermore, as an inorganic ion, its absorption is easily constrained by the environment, and its mobility within plants is poor, making it difficult to achieve efficient protection of the entire plant, and high-concentration spraying also carries the risk of leaf burn. To address the stability issue, patent CN119161217A uses the addition of antioxidants and nitrogen-filled packaging to delay oxidation, but this does not fundamentally solve the problem of the material's inherent instability, and the risk of failure remains high if the packaging integrity is damaged during storage and transportation. Another patent, CN110436983A, uses phosphorous acid and potassium carbonate to neutralize and generate potassium phosphite in situ. Although this simplifies the process, its active ingredient is still in an inorganic ionic state, failing to overcome the inherent limitations of the above-mentioned absorption, migration, and ion antagonism at the biological and chemical levels.

[0006] Therefore, there is an urgent need to develop a highly efficient, stable, and unified functional fertilizer that combines the triple functions of "nutrient supply, immune activation, and direct disease prevention" and is compatible with modern agriculture. Summary of the Invention

[0008] To address the aforementioned technical deficiencies, this invention provides an organic potassium phosphite liquid fertilizer and its preparation method. The aim is to obtain a series of structurally stable and functionally excellent organic potassium phosphite compounds by esterifying phosphorous acid with polyols to form potassium salts through molecular structure design. This results in a novel functional liquid fertilizer that combines high nutritional efficiency, stable bactericidal activity, excellent compatibility, and high absorption and transport efficiency.

[0009] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0010] An organic potassium phosphite liquid fertilizer, comprising at least one potassium phosphite compound selected from the structures shown in formulas (I) to (V):

[0011]

[0012] Formula (I) is potassium dihydrogen bisphosphite ethylene glycol ester;

[0013] Formula (II) is potassium dihydrogen bisphosphite-1,3-propanediol ester;

[0014] Formula (III) is potassium dihydrogen bisphosphite-1,4-butanediol ester;

[0015] Formula (IV) is potassium dihydrogen bisphosphite diethylene glycol ester;

[0016] Formula (V) is potassium glycerol dihydrogen phosphate.

[0017] Another aspect of the present invention provides a method for preparing organic potassium phosphite liquid fertilizer, comprising the following steps: obtaining phosphite through esterification reaction of phosphorous acid with polyol, and then neutralizing it with potassium source to form a salt to obtain potassium phosphite compound.

[0018] Preferably, the polyol is selected from ethylene glycol, 1,3-propanediol, 1,4-butanediol, diethylene glycol, or glycerol; and the potassium source is selected from potassium carbonate or potassium hydroxide.

[0019] Preferably, the reaction steps are as follows: phosphorous acid and polyol are weighed separately, and under nitrogen protection, phosphorous acid and polyol are subjected to esterification reaction to generate bisphosphite; after the reaction is complete, potassium source is added to the obtained reaction solution for neutralization and salt formation reaction, and cooling water is introduced during the reaction to control the temperature at 20-60℃. After the reaction is completed, potassium phosphite compound solution is generated, thus obtaining the organic bisphosphite potassium liquid fertilizer.

[0020] Preferably, the phosphorous acid can be in powder, molten state, or aqueous solution.

[0021] Preferably, the esterification reaction of phosphorous acid with a polyol under nitrogen protection includes the following steps: weighing phosphorous acid powder, dissolving it in deionized water to prepare an aqueous solution of phosphorous acid, adding the aqueous solution of phosphorous acid and the polyol sequentially into the reaction vessel, starting stirring, controlling the rotation speed at 60-120 r / min, and continuously introducing high-purity nitrogen (purity ≥99.99%) at a flow rate of 0.5-1.5 L / min to replace the air for 10-20 minutes. The simultaneous introduction of nitrogen while stirring is to more thoroughly replace the air in the reaction vessel and prevent the phosphorous acid from being oxidized. Under nitrogen protection and stirring conditions, the esterification reaction starts and continues for 2-3 hours to obtain a bisphosphite ester intermediate solution. Specifically, the concentration of the aqueous solution of phosphorous acid is 70%-85%, and the molar ratio of phosphorous acid to polyol is 1.5-2:1.

[0022] Preferably, the step of adding a potassium source to the obtained reaction solution for neutralization and salt formation includes: slowly adding the potassium source solution dropwise to the intermediate solution over 1 hour using a constant-pressure dropping funnel; turning on the cooling water during the reaction; controlling the reaction temperature at 20-60°C; continuing stirring for 0.5-1 hour after the addition is complete; and then cooling to room temperature. The resulting clear and homogeneous solution is the organic potassium phosphite liquid fertilizer. More preferably, the reaction temperature is always controlled below 50°C.

[0023] Preferably, an aqueous solution of potassium carbonate or potassium hydroxide is added to the neutralization reaction; wherein the molar ratio of potassium carbonate to diphosphite is 1:1; or the molar ratio of potassium hydroxide to diphosphite is 2:1.

[0024] Preferably, the reaction pathway for the specific preparation steps is as follows (the equations for the neutralization reactions of phosphite with potassium carbonate or potassium hydroxide in the reaction pathway are listed separately):

[0025] The reaction pathway of potassium dihydrogen bisphosphite ethylene glycol ester is as follows:

[0026] ,

[0027]

[0028] or ;

[0029] The reaction pathway of potassium monohydrogen bisphosphite-1,3-propanediol ester is as follows:

[0030] ,

[0031]

[0032] or ;

[0033] The reaction pathway of potassium dihydrogen bisphosphite-1,4-butanediol ester is as follows:

[0034] ,

[0035]

[0036] or ;

[0037] The reaction pathway of potassium dihydrogen bisphosphite diethylene glycol ester is as follows:

[0038] ,

[0039]

[0040] or ;

[0041] The synthetic route for potassium dihydrogen bisphosphite is as follows:

[0042] ,

[0043] or .

[0044] The present invention has the following beneficial effects:

[0045] 1. The core active ingredient of this product is organic potassium phosphite. Its phosphorus atoms are protected by the steric osmotic effect of the intramolecular ester groups, fundamentally altering its chemical properties. Compared to inorganic phosphites, its stability to oxygen is significantly enhanced, making it less susceptible to oxidation to orthophosphate. This allows it to maintain the unique dual functions of direct bactericidal action and systemic disease resistance induction characteristic of the trivalent state of phosphite, ensuring the reliability of the product's shelf life and field efficacy.

[0046] 2. Because the product exists as a stable organic ester in a molecular form, it effectively avoids the problem of inorganic phosphate ions forming insoluble phosphate precipitates with metal cations such as calcium, magnesium, iron, and zinc. This characteristic makes it highly compatible with various micronutrient fertilizers and commonly used plant protection agents, facilitating tank-mixed fertilization and integrated fertilizer-pesticide application. It is particularly suitable for water and fertilizer management through drip irrigation systems, eliminating the risk of clogging and significantly improving the efficiency and convenience of integrated field management.

[0047] 3. Potassium organic phosphite is a small-molecule organic compound with excellent lipid solubility and surface affinity, easily penetrating the waxy layer of plant leaves and the root surface barrier. It possesses bidirectional transport capabilities within the plant, connecting the xylem and phloem, enabling systematic transport from the application site to new shoots, fruits, and roots, achieving uniform protection and nutrient supply to the entire plant. Its utilization efficiency is far higher than that of inorganic ions with limited mobility.

[0048] 4. This organic esterified form is gentler on plant leaf cell membranes, significantly reducing the risk of leaf burn even under high-concentration foliar spraying conditions, resulting in high safety. This characteristic, combined with its excellent systemic applicability, makes it flexibly applicable to various modern agricultural fertilization methods such as foliar spraying, drip irrigation, and fertigation, meeting the precision management needs of different crops and growth stages.

[0049] 5. The synthesis and preparation process involved in this invention is mild and can usually be carried out at room temperature or under gentle cooling conditions, without the need for external heating, resulting in low energy consumption. The entire process is simple, requires minimal production equipment, and the raw materials are readily available, possessing great potential for large-scale, continuous production, and exhibiting significant advantages in technology transfer and market promotion. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention, and should not be used to limit the scope of protection of the present invention.

[0052] Example 1

[0053] This embodiment provides an organic potassium dihydrogen bisphosphite ethylene glycol ester liquid fertilizer. The main component of the liquid fertilizer has a structural formula selected from formula (I), and it is prepared by the following method:

[0054] Esterification reaction: Phosphorous acid and ethylene glycol were weighed at a molar ratio of 2:1. The phosphorous acid powder was dissolved in deionized water to prepare a 70% aqueous solution of phosphorous acid. The aqueous solution of phosphorous acid and ethylene glycol were added to the reaction vessel sequentially. Stirring was started and the rotation speed was controlled at 100 r / min. High-purity nitrogen gas (purity ≥99.99%) was continuously introduced at a flow rate of 1.0 L / min to replace the air for 20 minutes. Under nitrogen protection and stirring conditions, the esterification reaction was initiated and continued for 2 hours to obtain a solution of ethylene glycol diphosphite intermediate.

[0055] Neutralization and salt formation reaction: A saturated potassium carbonate solution is slowly added dropwise to the intermediate solution over 1 hour using a constant-pressure dropping funnel. The molar ratio of potassium carbonate to ethylene glycol diphosphite is 1:1. Cooling water is turned on during the reaction to maintain the reaction temperature below 50°C. After the addition is complete, the mixture is kept at this temperature and stirred for another 0.5 hours, then cooled to room temperature. The resulting clear and homogeneous solution is the organic ethylene glycol diphosphite liquid fertilizer.

[0056] Example 2

[0057] This embodiment provides an organic potassium dihydrogen bisphosphite-1,3-propanediol ester liquid fertilizer. The main component of the liquid fertilizer has a structural formula selected from formula (II). It is prepared by the following method:

[0058] Esterification reaction: Phosphorous acid and 1,3-propanediol were weighed at a molar ratio of 2:1. The phosphorous acid powder was dissolved in deionized water to prepare a 70% aqueous solution of phosphorous acid. The aqueous solution of phosphorous acid and 1,3-propanediol were added to the reactor sequentially. Stirring was started and the rotation speed was controlled at 100 r / min. High-purity nitrogen gas (purity ≥99.99%) was continuously introduced at a flow rate of 1.0 L / min to replace the air for 20 minutes. Under nitrogen protection and stirring conditions, the esterification reaction was initiated and continued for 2 hours to obtain a solution of bisphosphite-1,3-propanediol ester intermediate.

[0059] Neutralization and salt formation reaction: A saturated potassium carbonate solution was slowly added dropwise to the intermediate solution over 1 hour using a constant-pressure dropping funnel. The molar ratio of potassium carbonate to 1,3-propanediol diphosphite was 1:1. Cooling water was turned on during the reaction to maintain the reaction temperature below 50°C. After the addition was complete, the mixture was kept at this temperature and stirred for another 0.5 hours, then cooled to room temperature. The resulting clear and homogeneous solution is the organic potassium diphosphite-1,3-propanediol diester liquid fertilizer.

[0060] Example 3

[0061] This embodiment provides an organic potassium dihydrogen bisphosphite-1,4-butanediol ester liquid fertilizer. The main component of the liquid fertilizer has a structural formula selected from formula (III), and it is prepared by the following method:

[0062] Esterification reaction: Phosphorous acid and 1,4-butanediol were weighed at a molar ratio of 2:1. The phosphorous acid powder was dissolved in deionized water to prepare a 70% aqueous solution of phosphorous acid. The aqueous solution of phosphorous acid and 1,4-butanediol were added to the reactor sequentially. Stirring was started and the rotation speed was controlled at 100 r / min. High-purity nitrogen gas (purity ≥99.99%) was continuously introduced at a flow rate of 1.0 L / min to replace the air for 20 minutes. Under nitrogen protection and stirring conditions, the esterification reaction was initiated and continued for 2 hours to obtain a solution of bisphosphite-1,4-butanediol ester intermediate.

[0063] Neutralization and salt formation reaction: A saturated potassium carbonate solution was slowly added dropwise to the intermediate solution over 1 hour using a constant-pressure dropping funnel. The molar ratio of potassium carbonate to 1,4-butanediol diphosphite was 1:1. Cooling water was turned on during the reaction to maintain the reaction temperature below 50°C. After the addition was complete, the mixture was kept at this temperature and stirred for another 0.5 hours, then cooled to room temperature. The resulting clear and homogeneous solution is the organic potassium 1,4-butanediol diphosphite liquid fertilizer.

[0064] Example 4

[0065] This embodiment provides an organic potassium dihydrogen bisphosphite diethylene glycol ester liquid fertilizer. The main component of the liquid fertilizer has a structural formula selected from formula (IV), and it is prepared by the following method:

[0066] Esterification reaction: Phosphorous acid and diethylene glycol were weighed at a molar ratio of 2:1. The phosphorous acid powder was dissolved in deionized water to prepare a 70% aqueous solution of phosphorous acid. The aqueous solution of phosphorous acid and diethylene glycol were added to the reaction vessel sequentially. Stirring was started and the rotation speed was controlled at 100 r / min. High-purity nitrogen gas (purity ≥99.99%) was continuously introduced at a flow rate of 1.0 L / min to replace the air for 20 minutes. Under nitrogen protection and stirring conditions, the esterification reaction was initiated and continued for 2 hours to obtain a diethylene glycol diphosphite intermediate solution.

[0067] Neutralization and salt formation reaction: A saturated potassium carbonate solution is slowly added dropwise to the intermediate solution over 1 hour using a constant-pressure dropping funnel. The molar ratio of potassium carbonate to diethylene glycol diphosphite is 1:1. Cooling water is turned on during the reaction to maintain the reaction temperature below 50°C. After the addition is complete, the mixture is kept warm and stirred for 0.5 hours, then cooled to room temperature. The resulting clear and homogeneous solution is the organic diethylene glycol diphosphite liquid fertilizer.

[0068] Example 5

[0069] This embodiment provides an organic potassium dihydrogen phosphate glycerol liquid fertilizer. The main component of the liquid fertilizer has a structural formula selected from formula (V), and it is prepared by the following method:

[0070] Esterification reaction: Phosphorous acid and glycerol were weighed at a molar ratio of 2:1. The phosphorous acid powder was dissolved in deionized water to prepare a 70% aqueous solution of phosphorous acid. The aqueous solution of phosphorous acid and glycerol were added to the reaction vessel sequentially. Stirring was started and controlled at a speed of 100 r / min. High-purity nitrogen gas (purity ≥99.99%) was continuously introduced at a flow rate of 1.0 L / min to replace the air for 20 minutes. Under nitrogen protection and stirring conditions, the esterification reaction was initiated and continued for 2 hours to obtain a bisphosphite glyceride intermediate solution.

[0071] Neutralization and salt formation reaction: A saturated potassium carbonate solution is slowly added dropwise to the intermediate solution over 1 hour using a constant-pressure dropping funnel. The molar ratio of potassium carbonate to bisphosphite glycerol ester is 1:1. Cooling water is turned on during the reaction to maintain the reaction temperature below 50°C. After the addition is complete, the mixture is kept warm and stirred for 0.5 hours, then cooled to room temperature. The resulting clear and homogeneous solution is the organic bisphosphite glycerol ester liquid fertilizer.

[0072] Field Trial 1:

[0073] Experimental crop: Wheat Bainong 307.

[0074] Test location: Funan County, Anhui Province.

[0075] Sowing time: October 18, 2024.

[0076] Basic soil conditions: Convenient transportation, complete infrastructure, flat terrain, clay soil type, and moderate soil fertility. Previous crop was corn, with a yield of 545 kg / mu. Soil nutrient content was: organic matter 16.04 g / kg, total nitrogen 1.24 g / kg, available phosphorus 32.1 mg / kg, and available potassium 154 mg / kg. pH value was 5.8.

[0077] Experimental Design:

[0078] A randomized block design was adopted, with 7 treatment groups, each with 3 replicates, for a total of 21 cells, each cell having an area of ​​30m². 2 Basic fertilization management (uniform across the field): Base fertilizer: 50 kg / mu of controlled-release blended fertilizer (26-15-8) (applied before sowing); Jointing fertilizer: 7.5 kg of urea (applied at the jointing stage). Water and fertilizer management should be consistent to ensure balanced experimental conditions.

[0079] Test protocol:

[0080] The foliar spraying plans for each treatment group are as follows:

[0081] CK (blank control): Foliar spray with an equal amount of water;

[0082] TK (Experimental Control): Spraying commercially available liquid phosphorous acid fertilizer;

[0083] T1~T5 (Experimental Groups): Spray the liquid fertilizer of Examples 1~5 of this invention.

[0084] Application concentration: All fertilizer treatments were applied as foliar sprays at a concentration of 0.1% of the active ingredient.

[0085] Spraying time and number of times: First spraying: April 6, 2025; Second spraying: April 18, 2025.

[0086] Survey indicators and methods: Disease survey: The disease index was investigated 15 days after the second spray (May 3), focusing on recording the occurrence of common diseases such as powdery mildew (the disease index is expressed as 0-100, and the higher the number, the more serious the disease).

[0087] Disease index survey method: Disease grading standards: Grade 0: No disease spots on leaves; Grade 1: Disease spots cover less than 5% of the total leaf area; Grade 3: Disease spots cover 6% to 15% of the total leaf area; Grade 5: Disease spots cover 16% to 33% of the total leaf area; Grade 7: Disease spots cover 34% to 50% of the total leaf area; Grade 9: Disease spots cover more than 50% of the total leaf area.

[0088] Disease Index (DI) = [Σ(Disease level × Number of leaves at that level) / (Total number of leaves surveyed × Highest disease level)] × 100.

[0089] Yield Survey: At maturity (June 12th), the actual yield of each plot was measured, and the yield per mu (kg / mu) was recorded. Yield components such as thousand-grain weight (g) and number of grains per ear were also investigated. The survey results are shown in Table 1.

[0090] Table 1

[0091] Disease Index Yield per mu 1000 grains weight number of grains per ear Increase in production / % CK 58 429.5 39.23 32.2 -- TK 36 488.7 42.91 33.5 -- T1 18 550.9 44.51 36.4 12.7 T2 16 543.0 44.12 36.2 11.1 T3 20 554.2 44.54 36.6 13.4 T4 21 541.4 45.24 35.2 10.8 T5 19 548.1 45.41 35.5 12.2

[0092] The results are as follows:

[0093] Under different treatments, compared with the blank control and commercially available potassium phosphite fertilizer, the experimental groups treated with the organic potassium phosphite liquid fertilizer of this invention showed significant advantages in disease control, yield, and yield components. The blank control group had a disease index as high as 58 and a yield of only 429.5 kg / mu; the experimental control group treated with commercially available potassium phosphite still had a disease index of 36 and a yield of 488.7 kg / mu, with limited disease control and yield increase effects; while the disease index of each experimental group treated with the product of this invention was significantly reduced to 16-21, with outstanding disease control effect. At the same time, the thousand-grain weight increased to 44.12-45.41 g, the number of grains per ear increased to 35.2-36.6, and the yield reached 543.0-554.2 kg / mu, with a yield increase rate of 10.8%-13.4%, which was significantly better than the control. This indicates that the product of this invention, through its stable organic ester structure, effectively overcomes the defects of inorganic potassium phosphate, such as easy oxidation, easy precipitation, and poor absorption. It achieves the unity of nutrition and bactericidal function, has a long-lasting effect in disease control, high nutrient absorption efficiency, full grain development, and significant yield increase. Its overall effect is significantly better than traditional products, and it has good application value and promotion prospects.

[0094] Field Trial 2:

[0095] Experimental crop: Summer Black grape

[0096] Experimental location: Grape planting base in Daxu Town, Hefei City

[0097] Soil basic conditions: Convenient transportation, complete infrastructure, flat terrain, sandy loam soil type, loose soil structure, and good permeability. Soil fertility is at a moderate level. Soil nutrient content: organic matter 15.74 g / kg, total nitrogen 0.94 g / kg, available phosphorus 9.1 mg / kg, available potassium 104 mg / kg, copper 2.03 mg / kg, zinc 1.74 mg / kg, iron 9.11 mg / kg, manganese 34.5 mg / kg, boron 0.08 mg / kg. pH value 6.7.

[0098] Experimental Design:

[0099] A randomized block design was adopted, with 7 treatment groups, each of which was repeated 3 times, for a total of 21 plots. Each plot had an area of ​​30 m² (5 m × 6 m) and contained 10 grapevines.

[0100] Test protocol:

[0101] CK (blank control): Foliar spray with an equal amount of water;

[0102] TC (Control): Spraying commercially available potassium phosphite liquid fertilizer, dosage: 0.1% of active ingredient concentration;

[0103] T1~T5 (Experimental Groups): The liquid fertilizers of Examples 1~5 of this invention were sprayed respectively, with a dosage of 0.1% of the effective ingredient concentration.

[0104] Spraying time and frequency: All foliar treatments were sprayed once on May 10 and once on May 18, 2024, for a total of 2 applications.

[0105] Fertilizer management (uniform for the whole orchard): Base fertilizer: 50 kg / mu of controlled-release blended fertilizer (26-10-15) + 800 kg / mu of farmyard organic fertilizer + 2 kg / mu of boron fertilizer + 2 kg / mu of zinc fertilizer + 3 kg / mu of magnesium fertilizer; during the fruit enlargement period, apply 20 kg / mu of high-potassium fertilizer in two applications, 15 days apart.

[0106] Survey indicators and methods:

[0107] On June 1st, grape growth and disease index (downy mildew incidence index is expressed as 0-100, with higher numbers indicating more severe disease) were observed and investigated. On July 22nd, grape fruit shape index, single fruit weight, and grape yield were investigated. On July 28th, actual yield was calculated.

[0108] Disease index survey method: Disease grading standards: Grade 0: No disease spots on leaves; Grade 1: Disease spots cover less than 5% of the total leaf area; Grade 3: Disease spots cover 6% to 25% of the total leaf area; Grade 5: Disease spots cover 26% to 50% of the total leaf area; Grade 7: Disease spots cover 51% to 75% of the total leaf area; Grade 9: Disease spots cover more than 76% of the total leaf area.

[0109] Disease index:

[0110] Disease Index (DI) = [Σ(Disease level × Number of leaves at that level) / (Total number of leaves surveyed × Highest disease level)] × 100.

[0111] The survey results are shown in Table 2:

[0112] Table 2

[0113] Fruit type index Single fruit weight / g Disease Index Yield per mu / kg Increase in production / % CK 1.08±0.06 6.954 85 1043 -- TK 1.09±0.03 7.544 65 1251 -- T1 1.11±0.02 8.622 25 1449 15.8 T2 1.10±0.03 8.641 28 1420 13.5 T3 1.10±0.02 8.710 22 1458 16.5 T4 1.11±0.04 8.588 26 1440 15.1 T5 1.10±0.02 8.547 25 1433 14.5

[0114] The results are as follows:

[0115] Under different treatments, compared with the blank control and commercially available potassium phosphite fertilizer, the experimental groups treated with the organic potassium phosphite liquid fertilizer of this invention showed significant advantages in disease control, fruit quality, and yield. The blank control group had a disease index as high as 85, poor fruit development, and a yield of only 1043 kg / mu. The experimental control group treated with commercially available potassium phosphite still had a disease index of 65 and a yield of 1251 kg / mu, with limited disease control and yield increase effects. However, the disease index of each experimental group treated with the product of this invention was significantly reduced to 22-28, with outstanding disease control effects. At the same time, the fruit shape index increased to 1.10-1.11, the weight of a single fruit increased to 8.547-8.710 grams, and the yield reached 1420-1458 kg / mu, with a yield increase rate of 13.5%-16.5%, which was significantly better than the control. This indicates that the product of this invention, through its stable organic ester structure, effectively overcomes the defects of inorganic potassium phosphate, such as easy oxidation, easy precipitation, and poor absorption. It achieves the unity of nutrition and bactericidal function, has a long-lasting effect on disease control, high nutrient absorption efficiency, full fruit development, and a significant increase in yield. Its overall effect is significantly better than traditional products, and it has good application value and promotion prospects.

Claims

1. An organic potassium phosphite liquid fertilizer, characterized in that, The liquid fertilizer mainly comprises at least one potassium phosphite compound selected from formula (I), formula (II), formula (III), formula (IV) or formula (V). Formula (I) is potassium dihydrogen bisphosphite ethylene glycol ester; Formula (II) is potassium dihydrogen bisphosphite-1,3-propanediol ester; Formula (III) is potassium dihydrogen bisphosphite-1,4-butanediol ester; Formula (IV) is potassium dihydrogen bisphosphite diethylene glycol ester; Formula (V) is potassium glycerol dihydrogen phosphate.

2. The method for preparing organic potassium phosphite liquid fertilizer according to claim 1, characterized in that, Phosphite is obtained by esterification of phosphorous acid with polyol, and then neutralized with potassium source to form a salt to obtain potassium phosphite compound.

3. The method for preparing organic potassium phosphite liquid fertilizer according to claim 2, characterized in that, The polyol is selected from ethylene glycol, 1,3-propanediol, 1,4-butanediol, diethylene glycol, or glycerol; the potassium source is selected from potassium carbonate or potassium hydroxide.

4. The method for preparing organic potassium phosphite liquid fertilizer according to claim 2 or 3, characterized in that, The process includes the following steps: Phosphorous acid and polyol are weighed separately, and under nitrogen protection, the phosphorous acid and polyol are subjected to an esterification reaction to generate bisphosphite; after the reaction is complete, a potassium source is added to the resulting reaction solution for neutralization and salt formation; cooling water is circulated during the reaction to keep the temperature between 20-60℃; after the reaction is complete, a potassium phosphite compound solution is generated, thus obtaining the organic bisphosphite potassium liquid fertilizer; the molar ratio of phosphorous acid to polyol is 1.5~2:

1.

5. The method for preparing organic potassium phosphite liquid fertilizer according to claim 4, characterized in that, The reaction pathway for the preparation steps is as follows: The reaction pathway of potassium dihydrogen bisphosphite ethylene glycol ester is as follows: ， or ; The reaction pathway of potassium monohydrogen bisphosphite-1,3-propanediol ester is as follows: ， or ; The reaction pathway of potassium dihydrogen bisphosphite-1,4-butanediol ester is as follows: ， or ; The reaction pathway of potassium dihydrogen bisphosphite diethylene glycol ester is as follows: ， or ; The synthetic route for potassium dihydrogen bisphosphite is as follows: ， or .

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