Special water-soluble compound fertilizer for strawberry and preparation method thereof

Abstract

The application discloses a kind of water-soluble compound fertilizer special for strawberry and a preparation method thereof, and belongs to the technical field of compound fertilizer preparation.The preparation of the compound fertilizer includes the following steps: wet-process phosphoric acid is subjected to defluorination and desulfurization treatment to obtain purified phosphoric acid, ammonia gas is introduced into the purified phosphoric acid to adjust the pH to 4.2-4.6, slurry C is obtained, pressure filtration is performed, residue D and liquid E are obtained;liquid E is taken and ammonia gas is introduced to adjust the pH to 7.8-8.0, cooling filtration is performed, concentration is performed, granulation is performed, drying is performed, crushing is performed, screening is performed, and material F is obtained;residue D is taken and immersed in oxalic acid solution, standing is performed, filtration is performed, deionized water, hydroxyethylidene diphosphonic acid and lysine are added to the filtrate, mixing and stirring are performed, filtration is performed, concentration is performed, spray drying is performed, and material G is obtained;material F and material G are mixed, and the compound fertilizer is obtained, which promotes fruit formation, increases yield, and improves the quality and taste of strawberry fruits.

Description

Technical Field

[0001] This invention belongs to the field of compound fertilizer preparation technology, specifically relating to a water-soluble compound fertilizer for strawberries and its preparation method. Background Technology

[0002] In modern agricultural production, the application of chemical fertilizers is one of the important means to achieve increased crop yields. Water-soluble compound fertilizers, containing a variety of nutrients and with a balanced nutrient composition, are more easily and quickly absorbed by plant roots compared to traditional solid fertilizers, resulting in a high utilization rate of nutrients. Therefore, they are widely used in strawberry cultivation. Phosphorus is one of the essential nutrients for plant growth and development, playing a crucial role in the growth and development of strawberries. Phosphorus fertilizer can improve strawberry flower bud differentiation and the number of flowers, increase the quality of inflorescences, and thus increase the yield of flowers and fruits. Phosphorus fertilizer can also promote fruit enlargement and coloring, improving the quality and taste of strawberries. Furthermore, phosphorus fertilizer can enhance the development and nutrient absorption capacity of strawberry roots, improve the root system's resistance to stress, and mitigate the impact of environmental stress on strawberry yield and quality. Therefore, it is necessary to artificially apply phosphorus fertilizer during the flowering and fruit-setting stages of strawberries to meet the growth and development needs of the strawberry plants.

[0003] However, after applying phosphorus-containing water-soluble compound fertilizer, the phosphorus in the soil is easily adsorbed onto the surface of soil particles or reacts with soil substances to form insoluble phosphates. The strawberry roots cannot effectively absorb the phosphorus in the soil, resulting in low phosphorus utilization efficiency. This will lead to insufficient nutrients during the flowering and fruit setting period of strawberries, resulting in a reduction in the number of flower buds. The flowers wither quickly after opening and eventually fall off, reducing fruit formation and yield. The strawberry fruits are deformed, small and tasteless, or even stunted in development, resulting in poor quality and taste of the strawberry fruit. Summary of the Invention

[0004] The purpose of this invention is to provide a water-soluble compound fertilizer specifically for strawberries and its preparation method, belonging to the field of compound fertilizer preparation technology. The preparation of the compound fertilizer includes the following steps: wet-process phosphoric acid is subjected to defluorination and desulfurization treatment to obtain purified phosphoric acid; ammonia gas is introduced into the purified phosphoric acid to adjust the pH to 4.2-4.6, resulting in slurry C; the slurry C is then filtered to obtain residue D and liquid E; liquid E is purged with ammonia gas to adjust the pH to 7.8-8.0, cooled, filtered, concentrated, granulated, dried, crushed, and sieved to obtain material F; residue D is immersed in oxalic acid solution, allowed to stand, filtered, and deionized water, hydroxyethylidene diphosphonic acid, and lysine are added to the filtrate; the mixture is stirred, filtered, concentrated, and spray-dried to obtain material G; material F and material G are mixed to obtain the compound fertilizer.

[0005] The technical problem this invention aims to solve is to prevent phosphorus applied to the soil from being adsorbed onto the surface of soil particles or reacting with soil substances to form insoluble phosphates, thereby improving the absorption and utilization rate of phosphorus by strawberry roots and improving the quality of strawberry fruit.

[0006] The objective of this invention can be achieved through the following technical solutions: A water-soluble compound fertilizer specifically for strawberries and its preparation method, wherein the preparation of the compound fertilizer includes the following steps: (1) The wet-process phosphoric acid is defluorinated and desulfurized to obtain purified phosphoric acid. Ammonia gas is introduced into the purified phosphoric acid to adjust the pH to 4.2-4.6 to obtain slurry C. The slurry C is filtered to obtain slag D and liquid E. (2) Take the liquid E and introduce ammonia gas to adjust the pH to 7.8-8.0, cool and filter, concentrate the filtrate to a relative density of 1.33-1.37 (60℃), granulate, dry, crush and sieve to obtain material F; (3) The residue D was immersed in oxalic acid solution and allowed to stand at 40-55℃ for 3-6 hours. After filtration, deionized water, hydroxyethylidene diphosphonic acid and lysine were added to the filtrate. The mixture was stirred at room temperature for 1-2 hours and then filtered. The filtrate was concentrated to a relative density of 1.21-1.25 (30℃) and spray-dried to obtain material G. (4) Mix the materials F and G to obtain the compound fertilizer; As a preferred technical solution of the present invention, in step (1), the pressure filtration refers to holding the pressure at 40-50MPa for 10-15 minutes.

[0007] As a preferred technical solution of the present invention, in step (2), the drying refers to keeping warm at 90-95℃ for 5-8 hours; the crushing temperature is 30-65℃; and the average particle size of the material F is 3-8mm.

[0008] As a preferred embodiment of the present invention, the moisture content of the material G is less than 1.5%.

[0009] As a preferred technical solution of the present invention, in step (3), the ratio of the residue D, oxalic acid solution, deionized water, hydroxyethylidene diphosphonic acid and lysine is 500g: 8-10mol: 100mL: 10-20g: 5-8g; the concentration of the oxalic acid solution is 5mmol / L.

[0010] As a preferred technical solution of the present invention, in step (4), the mass ratio of material F to material G is 25-45:4-8.

[0011] As a preferred technical solution of the present invention, in step (1), the preparation of purified phosphoric acid includes the following steps: adding defluorinating agent A to wet phosphoric acid, stirring at 50°C for 3-4 hours, filtering, adding desulfurizing agent B to the filtrate, stirring at 50°C for 1-1.5 hours, filtering, passing ammonia gas through the filtrate in a 95-100°C constant temperature water bath to adjust the pH to 3.3-3.5, cooling and filtering, and taking the filtrate to obtain the purified phosphoric acid.

[0012] As a preferred embodiment of the present invention, the ratio of wet-process phosphoric acid, defluorinating agent A, and desulfurizing agent B is 500g: 8-12g: 3-5.6g.

[0013] As a preferred embodiment of the present invention, the defluorinating agent A comprises the following components in parts by weight: 10-12 parts by weight of potassium carbonate 1-2 parts by weight of silicon dioxide; The desulfurizing agent B is barium carbonate.

[0014] A compound fertilizer prepared using the above-described method.

[0015] The beneficial effects of this invention are: (1) The strawberry-specific water-soluble compound fertilizer and its preparation method disclosed in this invention enhance the compressive strength of the compound fertilizer particles, thereby preventing the compound fertilizer from being crushed and clumped during storage and transportation, thus avoiding low solubility when fertilizing strawberries and affecting the absorption of fertilizer by strawberries.

[0016] (2) The strawberry-specific water-soluble compound fertilizer and its preparation method disclosed in this invention remove metal particles from the raw materials by purifying them, thereby avoiding the formation of insoluble phosphorus salts in the compound fertilizer during the preparation process and improving the solubility of the compound fertilizer. At the same time, after dissolving the compound fertilizer, an alkaline water-soluble fertilizer is prepared and applied to the strawberry planting soil, which reduces the conversion rate of soil adsorbing phosphorus fertilizer to form insoluble phosphorus salts, thereby improving the absorption and utilization rate of phosphorus fertilizer by strawberries, and thus improving the yield and quality of strawberries.

[0017] (3) The strawberry-specific water-soluble compound fertilizer and its preparation method disclosed in this invention utilize the synergistic effect of hydroxyethylidene diphosphonic acid and lysine to recycle the removed metal particles into compound fertilizer, thereby increasing the content of trace metal nutrients in the compound fertilizer and improving the quality of strawberries. Detailed Implementation

[0018] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with embodiments, is provided below.

[0019] The wet-process phosphoric acid involved in this invention was purchased from Wenzhou Hongtai Chemical Co., Ltd., and the main raw material composition of the wet-process phosphoric acid is as shown in Table 1 below (not repeated hereafter).

[0020] Table 1

[0021] Example 1 The preparation of the compound fertilizer includes the following steps: (1) Add defluorinating agent A to wet phosphoric acid, stir at 50°C for 3 hours, filter, add desulfurizing agent B to the filtrate, stir at 50°C for 1 hour, filter, purify the filtrate with ammonia in a 95°C constant temperature water bath to adjust the pH to 3.3, cool and filter, take the filtrate to obtain purified phosphoric acid, purify the phosphoric acid with ammonia in a 60°C constant temperature water bath to adjust the pH to 4.2, obtain slurry C, filter under pressure to obtain slag D and liquid E; The ratio of wet-process phosphoric acid, defluorinating agent A, and desulfurizing agent B is 500g:8g:3g; The defluorinating agent A comprises the following components in parts by weight: 10 parts by weight of potassium carbonate 1 part by weight of silicon dioxide; The desulfurizing agent B is barium carbonate; The pressure filtration refers to holding the pressure at 40MPa for 10 minutes. (2) Take the liquid E and put it in a constant temperature water bath at 60°C. Ammonia gas is introduced to adjust the pH to 7.8. After cooling and filtration, the filtrate is concentrated to a relative density of 1.33 (60°C). The filtrate is then granulated, dried, crushed, and sieved to obtain material F. The drying process refers to maintaining a temperature of 90℃ for 5 hours. The crushing temperature is 30°C; The average particle size of the material F is 3 mm; (3) The residue D was immersed in oxalic acid solution, stood at 40°C for 3 hours, filtered, and deionized water, hydroxyethylidene diphosphonic acid and lysine were added to the filtrate. The mixture was stirred at room temperature for 1 hour, filtered, and the filtrate was concentrated to a relative density of 1.21 (30°C). The filtrate was spray-dried to obtain material G with a water content of less than 1.5%. The ratio of the residue D, oxalic acid solution, deionized water, hydroxyethylidene diphosphonic acid, and lysine is 500g:8mol:100mL:10g:5g; the concentration of the oxalic acid solution is 5mmol / L. (4) Mix the materials F and G to obtain the compound fertilizer; The mass ratio of material F to material G is 25:4.

[0022] Example 2 The preparation of the compound fertilizer includes the following steps: (1) Add defluorinating agent A to wet phosphoric acid, stir at 50°C for 3.5 h, filter, add desulfurizing agent B to the filtrate, stir at 50°C for 1.2 h, filter, purify the filtrate with ammonia in a 98°C constant temperature water bath to adjust the pH to 3.4, cool and filter, take the filtrate to obtain purified phosphoric acid, purify the phosphoric acid with ammonia in a 65°C constant temperature water bath to adjust the pH to 4.4, obtain slurry C, filter under pressure to obtain slag D and liquid E; The ratio of wet-process phosphoric acid, defluorinating agent A, and desulfurizing agent B is 500g:10g:4.5g; The defluorinating agent A comprises the following components in parts by weight: 11 parts by weight of potassium carbonate 1.5 parts by weight of silicon dioxide; The desulfurizing agent B is barium carbonate; The pressure filtration refers to holding the pressure at 45MPa for 12 minutes. (2) Take the liquid E and put it in a constant temperature water bath at 62°C. Ammonia gas is introduced to adjust the pH to 7.9. Cool and filter, concentrate the filtrate to a relative density of 1.35 (60°C), granulate, dry, crush and screen to obtain material F; The drying process refers to maintaining a temperature of 92℃ for 6 hours. The crushing temperature is 45°C; The average particle size of the material F is 5 mm; (3) The residue D was immersed in oxalic acid solution, stood at 48°C for 4 hours, filtered, and deionized water, hydroxyethylidene diphosphonic acid and lysine were added to the filtrate. The mixture was stirred at room temperature for 1.5 hours, filtered, and the filtrate was concentrated to a relative density of 1.23 (30°C). The filtrate was spray-dried to obtain material G with a water content of less than 1.5%. The ratio of the residue D, oxalic acid solution, deionized water, hydroxyethylidene diphosphonic acid, and lysine is 500g:9mol:100mL:15g:6g; the concentration of the oxalic acid solution is 5mmol / L. (4) Mix the materials F and G to obtain the compound fertilizer; The mass ratio of material F to material G is 35:6.

[0023] Example 3 The preparation of the compound fertilizer includes the following steps: (1) Add defluorinating agent A to wet phosphoric acid, stir at 50°C for 4 hours, filter, add desulfurizing agent B to the filtrate, stir at 50°C for 1.5 hours, filter, purify the filtrate with ammonia in a 100°C constant temperature water bath to adjust the pH to 3.5, cool and filter, take the filtrate to obtain purified phosphoric acid, purify the phosphoric acid with ammonia in a 70°C constant temperature water bath to adjust the pH to 4.6, obtain slurry C, filter under pressure to obtain slag D and liquid E; The ratio of wet-process phosphoric acid, defluorinating agent A, and desulfurizing agent B is 500g:12g:5.6g; The defluorinating agent A comprises the following components in parts by weight: 12 parts by weight of potassium carbonate 2 parts by weight of silicon dioxide; The desulfurizing agent B is barium carbonate; The pressure filtration refers to holding the pressure at 50MPa for 15 minutes. (2) Take the liquid E and put it in a constant temperature water bath at 65°C. Ammonia gas is introduced to adjust the pH to 8.0. After cooling and filtration, the filtrate is concentrated to a relative density of 1.37 (60°C). The filtrate is then granulated, dried, crushed, and sieved to obtain material F. The drying process refers to maintaining a temperature of 95°C for 8 hours. The crushing temperature is 65°C; The average particle size of the material F is 8 mm; (3) The residue D was immersed in oxalic acid solution, stood at 55°C for 6 hours, filtered, and deionized water, hydroxyethylidene diphosphonic acid and lysine were added to the filtrate. The mixture was stirred at room temperature for 2 hours, filtered, and the filtrate was concentrated to a relative density of 1.25 (30°C). The filtrate was spray-dried to obtain material G with a water content of less than 1.5%. The ratio of the residue D, oxalic acid solution, deionized water, hydroxyethylidene diphosphonic acid, and lysine is 500g:10mol:100mL:20g:8g; the concentration of the oxalic acid solution is 5mmol / L. (4) Mix the materials F and G to obtain the compound fertilizer; The mass ratio of material F to material G is 45:8.

[0024] Comparative Example 1 The difference from Example 1 is that the crushing temperature in step (2) is 25°C, and material F0 is obtained.

[0025] Comparative Example 2 The difference from Example 1 is that the crushing temperature in step (2) is 70°C, and material F00 is obtained.

[0026] The average compressive strength of material F from Example 1, material F0 from Comparative Example 1, and material F00 from Comparative Example 2 was determined according to standard GB / T 10212-1988. The test results are shown in Table 2 below.

[0027] Table 2

[0028] Comparative Example 3 The difference from Example 1 is that in step (1), the wet-process phosphoric acid is not subjected to defluorination and desulfurization purification treatment.

[0029] Comparative Examples 4-6 The difference from Example 3 is that the pH of the liquid E after being adjusted by ammonia gas in a constant temperature water bath at 65°C in step (2) is different, as shown in Table 3. Table 3

[0030] Comparative Examples 7-8 The difference from Example 1 is the ratio of hydroxyethylidene diphosphonic acid and lysine in step (3), as shown in Table 4. Table 4

[0031] Performance testing Experimental Design: 1) Test location and time: The test will be conducted from July 2022 to May 2023. The test location is located in Liuzhuang Village, Quanyang Town, Jieshou City, Anhui Province, with an average annual temperature of 12℃-21℃, an average annual precipitation of about 978 mm, and an annual sunshine duration of 2075 hours.

[0032] 2) Test crop: Miaoxiang No. 7 strawberry seedlings (purchased from Taian Haizhiqing Agricultural Technology Co., Ltd.).

[0033] 3) Test fertilizers: In this experiment, the experimental group was given the compound fertilizers prepared in Examples 1-3 and Comparative Examples 1-8, while the control group was given strawberry fertilizer-specific high-phosphorus water-soluble fertilizer (purchased from Shandong Linyi Dafengshou Agricultural Materials Mall).

[0034] 4) Experimental design: 20 mu of land was randomly selected (each mu is 33.33m wide). 20m), dig out 360 raised ridges (each ridge is 20m in length), 0.6m), with a spacing of 0.4m between each row, 100 Miaoxiang No. 7 strawberry seedlings were planted evenly on each row, and 30 rows were divided into 12 groups. One group was treated with strawberry fertilizer-specific high-phosphorus water-soluble fertilizer as a control group, and the other 11 groups were treated with compound fertilizers prepared in Examples 1-3 and Comparative Examples 1-8 as experimental groups.

[0035] 5) Experimental treatment: Apply the above-mentioned test fertilizers at the flowering and fruit setting stages of Miaoxiang No. 7 strawberry seedlings, with an application rate of 20-30 kg per mu; when using, the above-mentioned test fertilizers are prepared into liquid water-soluble fertilizers at a water-fertilizer ratio of 800:1 and sprayed onto the soil around the roots of Miaoxiang No. 7 strawberry seedlings.

[0036] The test results are shown in Table 5 below.

[0037] Table 5

[0038] Results Analysis Because the average compressive strength of the compound fertilizers in Comparative Examples 1-2 decreased due to the change in crushing temperature during the preparation process, the compound fertilizers were severely agglomerated and did not dissolve completely during fertilization, resulting in reduced fertilizer efficiency. Because the compound fertilizer in Comparative Example 3 contained a lot of F and S in its raw materials during the preparation process, it entered the soil and affected the growth and development of strawberry plants. Because the pH of compound fertilizer with a ratio of 4-5 is low after dissolving in water, the soil adsorbs the phosphate fertilizer to form insoluble phosphate salts, which are difficult for strawberry plants to absorb. Because the pH of the compound fertilizer in Comparative Ratio 6 was too high after being dissolved in water, the soil became too alkaline, which affected the growth and development of strawberry plants. Because the ratio of hydroxyethylidene diphosphonic acid and lysine in compound fertilizers with a ratio of 7-8 is different, the amount of trace metal nutrients is reduced, which affects the growth and development of strawberry plants.

[0039] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing a water-soluble compound fertilizer specifically for strawberries, characterized in that, The preparation of the compound fertilizer includes the following steps: (1) The wet-process phosphoric acid is defluorinated and desulfurized to obtain purified phosphoric acid. Ammonia gas is introduced into the purified phosphoric acid to adjust the pH to 4.2-4.6 to obtain slurry C. The slurry C is filtered to obtain slag D and liquid E. (2) Take the liquid material E, pass ammonia gas through it to adjust the pH to 7.8-8.0, cool and filter, concentrate, granulate, keep warm at 90-95℃ for 5-8h to dry, crush at 30-65℃, and sieve to obtain material F with an average particle size of 3-8mm; (3) The residue D was immersed in oxalic acid solution, allowed to stand, filtered, and deionized water, hydroxyethylidene diphosphonic acid and lysine were added to the filtrate. The mixture was stirred, filtered, concentrated and spray-dried to obtain material G. (4) Mix the materials F and G to obtain the compound fertilizer.

2. The method for preparing a water-soluble compound fertilizer specifically for strawberries according to claim 1, characterized in that, In step (1), the pressure filtration refers to maintaining pressure at 40-50 MPa for 10-15 minutes.

3. The method for preparing a water-soluble compound fertilizer specifically for strawberries according to claim 1, characterized in that, The moisture content of the material G is less than 1.5%.

4. The method for preparing a water-soluble compound fertilizer specifically for strawberries according to claim 1, characterized in that, In step (3), the ratio of the residue D, oxalic acid solution, deionized water, hydroxyethylidene diphosphonic acid, and lysine is 500g: 8-10mol: 100mL: 10-20g: 5-8g; the concentration of the oxalic acid solution is 5mmol / L.

5. The method for preparing a water-soluble compound fertilizer specifically for strawberries according to claim 1, characterized in that, In step (4), the mass ratio of material F to material G is 25-45:4-8.

6. The method for preparing a water-soluble compound fertilizer specifically for strawberries according to claim 1, characterized in that, In step (1), the preparation of purified phosphoric acid includes the following steps: adding defluorinating agent A to wet-process phosphoric acid, stirring at 50°C for 3-4 hours, filtering, adding desulfurizing agent B to the filtrate, stirring at 50°C for 1-1.5 hours, filtering, and then introducing ammonia into the filtrate in a 95-100°C constant-temperature water bath to adjust the pH to 3.3-3.5, cooling and filtering, and taking the filtrate to obtain the purified phosphoric acid.

7. The method for preparing a water-soluble compound fertilizer specifically for strawberries according to claim 6, characterized in that, The ratio of wet-process phosphoric acid, defluorinating agent A, and desulfurizing agent B is 500g: 8-12g: 3-5.6g.

8. The method for preparing a water-soluble compound fertilizer specifically for strawberries according to claim 6, characterized in that, The defluorinating agent A comprises the following components in parts by weight: 10-12 parts by weight of potassium carbonate 1-2 parts by weight of silicon dioxide; The desulfurizing agent B is barium carbonate.

9. A compound fertilizer prepared by the preparation method according to any one of claims 1-8.

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