Salt-resistant emission-reducing water-soluble fertilizer as well as preparation method and application thereof

Abstract

The invention provides a salt-resistant emission-reducing water-soluble fertilizer as well as a preparation method and application thereof, and belongs to the technical field of fertilizer preparation. The salt-resistant emission-reducing water-soluble fertilizer is prepared from the following raw materials in parts by weight: 1 to 15 parts of beta-cyclodextrin modified 2-chloro-6-trichloromethylpyridine, 0.5 to 2 parts of biochar loaded manganous-manganic oxide particles, 10 to 30 parts of salt-resistant compound microbial agent, 900 to 950 parts of water-soluble fertilizer and 5 to 10 parts of dispersing agent, the salt-resistant compound microbial agent is prepared from bacillus subtilis, bacillus licheniformis and bacillus mucilaginosus according to the mass ratio of (1 to 3): (1 to 2): (1 to 2). The salt-resistant emission-reducing water-soluble fertilizer can reduce the nitrate nitrogen content and the N2O emission amount of soil, the fresh weight, the plant height and the root length of plant seedlings are remarkably increased, the activity of antioxidant enzymes in leaves and the potassium-sodium ratio are remarkably improved, and the salt tolerance of cotton seedlings is remarkably improved. The preparation method is simple in process and suitable for industrial production.

Description

Technical Field

[0001] This invention belongs to the field of fertilizer preparation technology, and particularly relates to a salt-resistant, water-reducing, water-soluble fertilizer, its preparation method, and its application. Background Technology

[0002] While the extensive use of chemical fertilizers has boosted agricultural production, it has also led to problems such as low nitrogen utilization efficiency and severe environmental pollution. The low nitrogen utilization rate of chemical fertilizers means that the remaining nitrogen easily enters the environment through leaching, volatilization, and denitrification, resulting not only in resource waste but also in eutrophication of water bodies and increased greenhouse gas emissions. This nitrogen loss primarily stems from the biological activity of urease, which promotes the hydrolysis of urea into ammonium nitrogen, and ammonia monooxygenase (AMO), which initiates the nitrification process, in the soil. Therefore, existing fertilizers often employ urease and AMO inhibitors to improve nitrogen utilization efficiency.

[0003] 2-Chloro-6-trichloromethylpyridine is a widely used nitrification inhibitor that can suppress the activity of AMO (ammonium nitrate organic matter), thereby delaying the conversion of ammonium nitrogen to nitrate nitrogen and reducing nitrogen loss or N2O emissions. However, 2-Chloro-6-trichloromethylpyridine is significantly hydrophobic and volatile, easily adsorbed, decomposed, or migrated in the soil, resulting in a short field action time and unstable inhibitory effect, limiting its widespread application in fertilizers. Furthermore, 2-Chloro-6-trichloromethylpyridine has poor biocompatibility; its inhibition of nitrifying bacteria is non-selective, and it may simultaneously have toxic effects on other beneficial functional microorganisms, affecting its compatibility with microbial inoculants.

[0004] On the other hand, salinized soil has become a significant limiting factor affecting agricultural production. High-salt environments cause osmotic stress, ion toxicity, and nutrient imbalance in plants, leading to decreased crop yields. Studies have shown that nano-Mn3O4 particles can mimic the activity of antioxidant enzymes, not only scavenging excess reactive oxygen species in plants and increasing the photosynthetic rate of crops under salt stress, but also mitigating oxidative damage and improving crop salt tolerance by maintaining a high potassium-to-sodium ratio. However, its application in agriculture is limited. Furthermore, Mn3O4 nanoparticles have high surface energy, making them prone to aggregation and sedimentation, which hinders their uniform dispersion and stable existence in fertilizer systems, affecting their practical application effectiveness. Summary of the Invention

[0005] Therefore, the purpose of this invention is to provide a salt-resistant, water-reducing, water-soluble fertilizer, its preparation method, and its application. This salt-resistant, water-reducing, water-soluble fertilizer can reduce the nitrate nitrogen content and N2O emissions in the soil, improve nitrogen utilization, enhance the salt tolerance of plant seedlings, and promote the growth of plant seedlings under salt stress.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a salt-resistant, water-reducing, water-soluble fertilizer, which comprises the following raw materials in parts by weight: 1-15 parts of modified 2-chloro-6-trichloromethylpyridine, 0.5-2 parts of nano-enzyme-like particles, 10-30 parts of salt-resistant compound microbial agent, 900-950 parts of water-soluble fertilizer, and 5-10 parts of dispersant; The modified 2-chloro-6-trichloromethylpyridine is 2-chloro-6-trichloromethylpyridine modified with β-cyclodextrin; The nano-enzyme-like particles are manganese tetroxide particles supported on biochar. The salt-resistant compound microbial agent is Bacillus subtilis, Bacillus licheniformis and Bacillus mucilaginosus; the mass ratio of Bacillus subtilis, Bacillus licheniformis and Bacillus mucilaginosus is (1~3):(1~2):(1~2).

[0007] Preferably, the preparation method of the modified 2-chloro-6-trichloromethylpyridine includes the following steps: Weigh 2-chloro-6-trichloromethylpyridine and β-cyclodextrin hydrate by molar ratio, add deionized water to the mixture, stir and grind to obtain modified 2-chloro-6-trichloromethylpyridine.

[0008] Preferably, the molar ratio is 1:1; the mass-to-volume ratio of the mixture to deionized water is 1 mg: 1~1.5 μL; the grinding method is grinding at a frequency of 20~30 Hz for 120~130 min, and the diameter of the grinding ball is 5~15 mm.

[0009] Preferably, the method for preparing the biochar-supported manganese tetroxide particles includes the following steps: (1) Mix MnSO4·4H2O solution and sodium citrate solution, heat and stir to react, generate negatively charged Mn3O4 nanoparticles, cool, centrifuge to collect precipitate 1, use water to re-disperse precipitate 1 to remove impurities, add water to the product after impurity removal to obtain Cit-Mn3O4 dispersion; (2) After grinding and sieving the biochar, the sieved biochar is mixed with dilute hydrochloric acid and stirred. Then it is washed with water until the pH is neutral and dried to obtain dried biochar. (3) The dried biochar was mixed with Cit-Mn3O4 dispersion, stirred and ultrasonically treated, centrifuged, precipitate a was collected, precipitate a was washed with water, dried, ground and sieved to obtain biochar-loaded manganese tetroxide particles, named Cit-Mn3O4@biochar particles.

[0010] Preferably, in step (1), the molar concentrations of the MnSO4·4H2O solution and the sodium citrate solution are (0.04~0.1):(0.1~0.5); the volume ratio of the MnSO4·4H2O solution to the sodium citrate solution is (1~2):1; the heating and stirring are carried out at 85~100℃ and 500~600rpm for 1.5~3.5h; and the mass-volume percentage of the Cit-Mn3O4 dispersion is 1%~3%. In step (2), the biochar is one or more of coconut shell char, almond shell char, and rice husk char, and the sieve mesh size is 350-450 mesh; the mass-to-volume ratio of the sieved biochar to dilute hydrochloric acid is 1g:(9-11)mL; the concentration of the dilute hydrochloric acid is 0.8-1.2M; and the stirring is carried out at 28-32℃ and 350-450rpm for 1-2.5h. In step (3), the mass-to-volume ratio of the dried biochar to the Cit-Mn3O4 dispersion is 1g:5~20mL; the stirring is performed at 500~600rpm for 1~3h; the ultrasonic treatment is performed at 35~45kHz and 350~450W for 1~2h; the ultrasonic treatment is intermittent, with each ultrasonic treatment lasting 4~6min and an interval of 1~3min; and the grinding and sieving process is performed with a mesh size of 350~450 mesh.

[0011] Preferably, the dispersant is one or more of sodium hexametaphosphate, sodium polyphosphate and sodium humate; the water-soluble fertilizer includes inorganic compound fertilizer; the inorganic compound fertilizer includes one or more of nitrogen fertilizer, phosphorus fertilizer and potassium fertilizer; the mass ratio of N, P2O5 and K2O in the inorganic compound fertilizer is (9~13):(15~25):(15~25).

[0012] Preferably, the nitrogen fertilizer is one or more of urea, ammonium chloride, and ammonium sulfate; The phosphate fertilizer is one or more of monoammonium phosphate, diammonium phosphate, potassium dihydrogen phosphate, ammonium polyphosphate, and potassium polyphosphate. The potassium fertilizer is one or more of potassium nitrate, potassium sulfate, potassium chloride, and potassium dihydrogen phosphate.

[0013] This invention provides a method for preparing the above-mentioned salt-resistant, water-reducing, and water-soluble fertilizer, comprising the following steps: After mixing water-soluble fertilizer and sodium hexametaphosphate, Cit-Mn3O4@biochar granules, modified 2-chloro-6-trichloromethylpyridine, and salt-resistant microbial agents are added and mixed to obtain salt-resistant water-soluble fertilizer.

[0014] This invention provides an application of the above-mentioned salt-resistant, water-reducing, water-soluble fertilizer or the salt-resistant, water-reducing, water-soluble fertilizer obtained by the above-mentioned preparation method in at least one of the following a~e: a. Improve the salt tolerance of plant seedlings; b. Promotes the growth of seedlings under salt stress; c. Reduce soil nitrate nitrogen content and N2O emissions; d. Improve nitrogen utilization efficiency; e. It increases the activity of antioxidant enzymes in plant leaves.

[0015] Preferably, the growth traits include one or more of the following: fresh weight of cotton seedlings, plant height, and root length; the plant is cotton; and the antioxidant enzyme is one or more of the following: superoxide dismutase, peroxidase, and catalase.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a salt-tolerant, water-soluble fertilizer, its preparation method, and its application. By modifying 2-chloro-6-trichloromethylpyridine, using nano-enzyme-like particles, and inoculating with salt-tolerant compound microorganisms, it achieves a comprehensive effect of nitrification inhibition, salt tolerance and emission reduction, and improved fertilizer efficiency. Studies have found that applying this salt-tolerant, water-soluble fertilizer can reduce soil nitrate nitrogen content and N2O emissions, improve nitrogen use efficiency, and significantly increase seedling fresh weight, plant height, and root length. It also significantly increases the activity of antioxidant enzymes in leaves and the potassium-sodium ratio, enhancing the antioxidant capacity and ion balance regulation ability of seedlings, thereby significantly improving the salt tolerance of cotton seedlings.

[0017] The salt-resistant, water-reducing, and water-soluble fertilizer preparation method of the present invention is simple and suitable for industrial production. Attached Figure Description

[0018] Figure 1 The salt-resistant, water-reducing, and water-soluble fertilizers of Examples 1-3 and the inorganic compound fertilizer of Comparative Example 1, and the salt-resistant, water-reducing, and water-soluble fertilizers of Comparative Examples 2-3, and their effects on soil N2O emissions and NO3 emissions. - -N content and NH4 + -N content, a is the comparison result of soil N2O emissions by the salt-resistant and water-reducing soluble fertilizers of Examples 1-3 and the inorganic compound fertilizer of Comparative Example 1, and the salt-resistant and water-reducing soluble fertilizers of Comparative Examples 2-3; b is the NO3 content of the soil by the salt-resistant and water-reducing soluble fertilizers of Examples 1-3 and the inorganic compound fertilizer of Comparative Example 1, and the salt-resistant and water-reducing soluble fertilizers of Comparative Examples 2-3. - The comparison results of -N content, c represents the salt-resistant and water-reducing soluble fertilizers of Examples 1-3 and the inorganic compound fertilizer of Comparative Example 1, and the salt-resistant and water-reducing soluble fertilizers of Comparative Examples 2-3 on the NH4 content of the soil. + Comparison results of -N content. Detailed Implementation

[0019] This invention provides a salt-resistant, water-reducing, water-soluble fertilizer, which comprises the following raw materials in parts by weight: 1-15 parts of modified 2-chloro-6-trichloromethylpyridine, 0.5-2 parts of nano-enzyme-like particles, 10-30 parts of salt-resistant compound microbial agent, 900-950 parts of water-soluble fertilizer, and 5-10 parts of dispersant; The modified 2-chloro-6-trichloromethylpyridine is 2-chloro-6-trichloromethylpyridine modified with β-cyclodextrin; The nano-enzyme-like particles are manganese tetroxide particles supported on biochar. The salt-resistant compound microbial agent is Bacillus subtilis, Bacillus licheniformis and Bacillus mucilaginosus; the mass ratio of Bacillus subtilis, Bacillus licheniformis and Bacillus mucilaginosus is (1~3):(1~2):(1~2).

[0020] In this invention, the salt-resistant and water-soluble fertilizer preferably comprises the following raw materials in parts by weight: 10-15 parts of modified 2-chloro-6-trichloromethylpyridine, 1-2 parts of nano-enzyme-like particles, 20-30 parts of salt-resistant compound microbial agent, 930-950 parts of water-soluble fertilizer, and 8-10 parts of dispersant; more preferably, the salt-resistant and water-soluble fertilizer is preferably composed of the following raw materials in parts by weight: 10-15 parts of modified 2-chloro-6-trichloromethylpyridine, 1-2 parts of nano-enzyme-like particles, 20-30 parts of salt-resistant compound microbial agent, and 930-950 parts of water-soluble fertilizer. More preferably, the salt-resistant and water-soluble fertilizer is composed of the following raw materials in parts by weight: 15 parts modified 2-chloro-6-trichloromethylpyridine, 2 parts nano-enzyme-like particles, 30 parts salt-resistant compound microbial agent, 930 parts water-soluble fertilizer, and 10 parts dispersant; or, the salt-resistant and water-soluble fertilizer is preferably composed of the following raw materials in parts by weight: 10 parts modified 2-chloro-6-trichloromethylpyridine, 1.5 parts nano-enzyme-like particles, 20 parts salt-resistant compound microbial agent, 950 parts water-soluble fertilizer, and 8 parts dispersant. The preferred mass ratio of Bacillus subtilis, Bacillus licheniformis, and Bacillus mucilaginosus is (1~3):(1~2):(1~2), more preferably 1:1:1, 3:1:1, or 1:2:2. The Bacillus subtilis, Bacillus licheniformis, and Bacillus mucilaginosus of this invention were all purchased from Shandong Nuojie Biotechnology Co., Ltd., with product numbers Nuojie BS, Nuojie BL, and Nuojie BG, respectively. The dispersant is one or more of sodium hexametaphosphate, sodium polyphosphate, and sodium humate; the water-soluble fertilizer includes inorganic compound fertilizer; the inorganic compound fertilizer includes one or more of nitrogen fertilizer, phosphorus fertilizer, and potassium fertilizer; the mass ratio of N, P2O5, and K2O (i.e., nitrogen fertilizer, phosphorus fertilizer, and potassium fertilizer) in the inorganic compound fertilizer is (9~13):(15~25):(15~25), more preferably (10~12):(17~23):(17~23), and even more preferably 11:20:20; the nitrogen fertilizer is one or more of urea, ammonium chloride, and ammonium sulfate; the phosphorus fertilizer is one or more of monoammonium phosphate, diammonium phosphate, potassium dihydrogen phosphate, ammonium polyphosphate, and potassium polyphosphate; the potassium fertilizer is one or more of potassium nitrate, potassium sulfate, potassium chloride, and potassium dihydrogen phosphate.

[0021] In this invention, the preferred method for preparing the modified 2-chloro-6-trichloromethylpyridine includes the following steps: Weigh 2-chloro-6-trichloromethylpyridine and β-cyclodextrin hydrate by molar ratio, add deionized water to the mixture, stir and grind to obtain modified 2-chloro-6-trichloromethylpyridine.

[0022] In this invention, the molar ratio is 1:1, that is, the molar ratio of 2-chloro-6-trichloromethylpyridine to β-cyclodextrin hydrate is 1:1, and the β-cyclodextrin hydrate is β-CD·8H2O; the mass-to-volume ratio of the mixture to deionized water is preferably 1 mg:1~1.5 μL, more preferably 1 mg:1 μL, 1 mg:1.2 μL or 1 mg:1.5 μL; the grinding method is preferably grinding at a frequency of 20~30 Hz for 120~130 min, more preferably grinding at a frequency of 20 Hz for 120 min, grinding at a frequency of 30 Hz for 120 min or grinding at a frequency of 20 Hz for 120 min; the diameter of the grinding ball is 5~15 mm, such as 5 mm, 10 mm or 15 mm. The modified 2-chloro-6-trichloromethylpyridine is also named β-cyclodextrin-2-chloro-6-trichloromethylpyridine. In this invention, during the grinding process, 2-chloro-6-trichloromethylpyridine molecules gradually enter the hydrophobic cavity of β-cyclodextrin, forming a stable β-cyclodextrin-2-chloro-6-trichloromethylpyridine complex. Simultaneously, the cyclodextrin acts as a molecular cage, effectively reducing the volatilization and loss of 2-chloro-6-trichloromethylpyridine, achieving controlled release of 2-chloro-6-trichloromethylpyridine. The encapsulation of 2-chloro-6-trichloromethylpyridine within the cyclodextrin reduces its toxicity to soil microorganisms and improves its ecological compatibility. Compared to 2-chloro-6-trichloromethylpyridine, β-cyclodextrin-2-chloro-6-trichloromethylpyridine exhibits significantly improved water solubility, stability, and biocompatibility, resulting in a sustained and effective nitrification inhibition effect.

[0023] In this invention, the preferred method for preparing the biochar-supported manganese tetroxide particles includes the following steps: (1) Mix MnSO4·4H2O solution and sodium citrate solution, heat and stir to react, generate negatively charged Mn3O4 nanoparticles, cool, centrifuge to collect precipitate 1, use water to re-disperse precipitate 1 to remove impurities, add water to the product after impurity removal to obtain Cit-Mn3O4 dispersion; (2) After grinding and sieving the biochar, the sieved biochar is mixed with dilute hydrochloric acid and stirred. Then it is washed with water until the pH is neutral and dried to obtain dried biochar. (3) The dried biochar was mixed with Cit-Mn3O4 dispersion, stirred and ultrasonically treated, centrifuged, precipitate a was collected, precipitate a was washed with water, dried, ground and sieved to obtain biochar-loaded manganese tetroxide particles, named Cit-Mn3O4@biochar particles.

[0024] In this invention, in step (1), the molar concentration of the MnSO4·4H2O solution and the sodium citrate solution is preferably (0.04~0.1):(0.1~0.5), more preferably (0.05~0.08):(0.2~0.4), and even more preferably 0.05:0.3, 0.08:0.4 or 0.05:0.2; the volume ratio of the MnSO4·4H2O solution and the sodium citrate solution is preferably (1~2):1, more preferably 1:1 or 2:1; the heating and stirring method is preferably to stir the reaction at 85~100℃ and 500~600rpm for 1.5~3.5h, more preferably to stir the reaction at 90~100℃ and 500~600rpm for 2~3h, and even more preferably to stir the reaction at 100℃ and 600rpm for 3h, 100℃ and 600rpm for 2h or 90℃ and 500rpm for 2h. In this invention, the centrifugation can be selected as centrifugation at 10000~13000 rpm for 20~30 min. During redispersion, the amount of deionized water added is not specifically limited; washing the redispersion precipitate with water using conventional methods in the art is sufficient. The number of redispersions can be 3~5 times, such as 3, 4, or 5 times. Water is added to the purified product to obtain a Cit-Mn3O4 dispersion. The mass-volume percentage of the Cit-Mn3O4 dispersion is 1%~3%, more preferably 1.5%~2.5%, and more preferably 2%. The 1%~3% percentage refers to the percentage of 1~3g Cit-Mn3O4 in 100mL of water.

[0025] In step (2), the biochar is one or more of coconut shell biochar, almond shell biochar, and rice husk biochar; the sieve mesh size is 350-450 mesh, more preferably 380-420 mesh, and even more preferably 400 mesh; the mass-to-volume ratio of the sieved biochar to dilute hydrochloric acid is 1g:(9-11)mL, more preferably 1g:(9.5-10.5)mL, and even more preferably 1g:10mL; the concentration of the dilute hydrochloric acid is preferably 0.8-1.2M, more preferably 0.9-1.1M, and even more preferably 1M; the stirring is carried out at 28-32℃ and 350-450rpm for 1-2.5h, more preferably at 29-31℃ and 380-420rpm for 1.5-2h, and even more preferably at 30℃ and 400rpm for 1.5h or at 30℃ and 400rpm for 2h; the pH is neutral, meaning pH 7. The drying process involves vacuum drying at 95-95°C for 10-14 hours, more preferably vacuum drying at 100°C for 12 hours or vacuum drying at 95°C for 12 hours. The dried biochar is dried biochar cooled to room temperature, which is 20-25°C.

[0026] In step (3), the mass-to-volume ratio of the dried biochar to the Cit-Mn3O4 dispersion is 1g:5~20mL, more preferably 1g:8~15mL, and even more preferably 1g:8mL, 1g:12mL, or 1g:15mL; the stirring is performed at 500~600rpm for 1~3h, more preferably at 500~600rpm for 2h, such as at 500rpm for 2h or 600rpm for 2h; the ultrasonic treatment is performed at 35~45kHz and 350~450W for 1~2h, more preferably at 37kHz. Ultrasonic treatment at 42 kHz and 380-420 W for 1-2 hours, more preferably at 40 kHz and 400 W for 1 hour or at 40 kHz and 400 W for 2 hours; the ultrasonic treatment is intermittent, with each ultrasonic treatment lasting 4-6 minutes followed by an interval of 1-3 minutes, more preferably 4.5-5.5 minutes followed by an interval of 1.5-2.5 minutes, more preferably 5 minutes followed by an interval of 2 minutes; the centrifugation is performed at 10000-15000 rpm for 15-25 minutes. The washing method is not particularly limited in this invention; conventional methods in the art can be used, as long as the loosely adsorbed particles are removed. After washing, the particles are vacuum dried at 80℃ for 24 hours, followed by grinding and sieving. The mesh size of the sieve is 350-450 mesh, more preferably 370-420 mesh, and more preferably 400 mesh. The biochar-supported manganese tetroxide particles are also referred to as Cit-Mn3O4@biochar particles.

[0027] In this invention, Mn3O4 nanoparticles prepared using the sodium citrate method possess a negative surface charge. Furthermore, through the adsorption and loading effects of the porous structure of biochar, particle aggregation is significantly reduced, ensuring uniform distribution and long-term stability in the fertilizer system and improving the crop's salt tolerance. Simultaneously, biochar can also improve soil physicochemical properties, synergistically acting with other components to enhance fertilizer utilization while simultaneously strengthening crop salt tolerance.

[0028] This invention provides a method for preparing the above-mentioned salt-resistant, water-reducing, and water-soluble fertilizer, comprising the following steps: After mixing water-soluble fertilizer and sodium hexametaphosphate, Cit-Mn3O4@biochar granules, modified 2-chloro-6-trichloromethylpyridine, and salt-resistant microbial agents are added and mixed to obtain salt-resistant water-soluble fertilizer.

[0029] In the above preparation method, the water-soluble fertilizer and sodium hexametaphosphate are mixed at 10-14 rpm for 9-11 minutes, or at 12 rpm for 10 minutes. When Cit-Mn3O4@biochar granules, modified 2-chloro-6-trichloromethylpyridine, and salt-resistant microbial agent are mixed, the mixing method is 12 rpm for 0.5 hours.

[0030] This invention provides an application of the above-mentioned salt-resistant, water-reducing, water-soluble fertilizer or the salt-resistant, water-reducing, water-soluble fertilizer obtained by the above-mentioned preparation method in at least one of the following a~e: a. Improve the salt tolerance of plant seedlings; b. Promotes the growth of seedlings under salt stress; c. Reduce soil nitrate nitrogen content and N2O emissions; d. Improve nitrogen utilization efficiency; e. It increases the activity of antioxidant enzymes in plant leaves.

[0031] In this invention, the growth traits include one or more of the following: fresh weight of cotton seedlings, plant height, and root length; the plant is cotton; and the antioxidant enzyme is one or more of superoxide dismutase, peroxidase, and catalase. The salt-tolerant, water-reducing, and water-soluble fertilizer or the preparation method of this invention can also be used to improve the antioxidant capacity of cotton seedlings.

[0032] In this invention, unless otherwise specified, all raw material components are commercially available products well known to those skilled in the art.

[0033] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0034] The Bacillus subtilis, Bacillus licheniformis, and Bacillus mucilaginosus used in the embodiments of this invention were all purchased from Shandong Nuojie Biotechnology Co., Ltd., with product numbers Nuojie BS, Nuojie BL, and Nuojie BG, respectively.

[0035] Example 1 A salt-resistant, water-soluble fertilizer based on modified 2-chloro-6-trichloromethylpyridine, comprising the following raw materials: 950 kg of inorganic compound fertilizer, 8 kg of dispersant, 10 kg of modified 2-chloro-6-trichloromethylpyridine, 1.5 kg of Cit-Mn3O4@biochar granules, and 20 kg of salt-resistant microbial agent; the inorganic compound fertilizer has a N, P2O5, and K2O mass ratio of 11:20:20, wherein N is urea, P2O5 is monoammonium phosphate, and K2O is potassium sulfate; the dispersant is sodium hexametaphosphate, and the salt-resistant microbial agent is composed of Bacillus subtilis, Bacillus licheniformis, and Bacillus mucilaginosus in a mass ratio of 1:1:1.

[0036] The preparation method of the above-mentioned salt-resistant, water-soluble fertilizer based on modified 2-chloro-6-trichloromethylpyridine includes the following steps: (1) Preparation of modified 2-chloro-6-trichloromethylpyridine: β-cyclodextrin hydrate (β-CD·8H2O) and 2-chloro-6-trichloromethylpyridine were weighed at a molar ratio of 1:1 and mixed to obtain a mixture. The mixture was then added to a zirconia grinding jar, and deionized water was added at η=1.0 (i.e., 1 μL of water per 1 mg of solid). The mixture was stirred until homogeneous and then ground at 20 Hz for 120 min using a 5 mm diameter grinding ball to obtain modified 2-chloro-6-trichloromethylpyridine.

[0037] During the grinding process, 2-chloro-6-trichloromethylpyridine molecules gradually enter the hydrophobic cavity of β-cyclodextrin, forming a stable β-cyclodextrin-2-chloro-6-trichloromethylpyridine complex.

[0038] (2) Preparation of Cit-Mn3O4@biochar particles: Preparation of S1, 2% Cit-Mn3O4 dispersion S1-1. Prepare 0.05M MnSO4·4H2O solution and 0.3M sodium citrate solution respectively using deionized water, according to Mn 2+ Cit 3- A 1:3 molar ratio was used to mix MnSO4·4H2O solution and sodium citrate solution at a 2:1 volume ratio. The mixture was magnetically stirred for 30 min to obtain a solution. The solution was then transferred to a three-necked flask and reacted at 90°C for 2 h under magnetic stirring at 500 rpm. The solution gradually turned dark brown, and negatively charged Mn3O4 nanoparticles were formed.

[0039] S1-2. After cooling to room temperature, centrifuge at 10,000 rpm for 20 min and collect precipitate 1. S1-3. Redisperse precipitate 1 in deionized water, centrifuge at 10000 rpm for 20 min, and collect precipitate 2 again. S1-4. Repeat step S1-3 three times to remove impurities and obtain the purified product. Finally, use deionized water to prepare a dispersion of about 2% (w / v, g / mL) to obtain a 2% Cit-Mn3O4 dispersion.

[0040] S2. Grind the coconut shell charcoal through a 400-mesh sieve (approximately 38 μm) to obtain sieved biochar. Mix the sieved biochar with 1M dilute hydrochloric acid at a ratio of 1g:10mL (w / v), and stir at 30°C and 400rpm for 1.5h to remove acidic soluble ash and metal ion impurities. Then, wash repeatedly with deionized water until the pH of the supernatant is neutral. Dry under vacuum at 100°C for 12h and cool to room temperature to obtain dried biochar.

[0041] S3. The dried biochar was slowly added to a 2% Cit-Mn3O4 dispersion at a solid-liquid ratio of 1 g: 8 mL. The mixture was stirred at 500 rpm for 2 h, followed by intermittent sonication at 40 kHz and 400 W: 5 min sonication followed by 2 min intermittent cooling, and then intermittent sonication for 1 h to promote biochar particle loading. The precipitate was then collected by centrifugation at 10000 rpm for 15 min and washed twice with deionized water to remove unadsorbed particles. The precipitate was vacuum dried at 80°C for 24 h, cooled, lightly ground, and passed through a 400-mesh sieve to obtain free-flowing black Cit-Mn3O4@biochar particles.

[0042] (3) Preparation of salt-resistant and emission-reducing fertilizer Add 8 kg of sodium hexametaphosphate to 950 kg of inorganic compound fertilizer (the mass ratio of N, P2O5, and K2O in the inorganic compound fertilizer is 11:20:20), and mix at 12 rpm for 10 min. Then, add 1.5 kg of Cit-Mn3O4@biochar granules, 10 kg of modified 2-chloro-6-trichloromethylpyridine, and 20 kg of salt-resistant microbial agent sequentially, and continue mixing for 0.5 h until homogeneous. Immediately after mixing, package the mixture in aluminum foil bags or laminated woven bags, seal, and store in a moisture-proof and light-protected environment.

[0043] Example 2 A salt-resistant, water-soluble fertilizer based on modified 2-chloro-6-trichloromethylpyridine, comprising the following raw materials: 950 kg of inorganic compound fertilizer, 8 kg of dispersant, 10 kg of modified 2-chloro-6-trichloromethylpyridine, 1.5 kg of Cit-Mn3O4@biochar granules, and 20 kg of salt-resistant microbial agent; the inorganic compound fertilizer has a N, P2O5, and K2O mass ratio of 11:20:20, wherein N is urea, P2O5 is monoammonium phosphate, and K2O is potassium sulfate; the dispersant is sodium hexametaphosphate, and the salt-resistant microbial agent is composed of Bacillus subtilis, Bacillus licheniformis, and Bacillus mucilaginosus in a mass ratio of 3:1:1.

[0044] The preparation method of the salt-resistant, water-soluble fertilizer based on modified 2-chloro-6-trichloromethylpyridine includes the following steps: (1) Preparation of modified 2-chloro-6-trichloromethylpyridine: β-Cyclodextrin hydrate (β-CD·8H2O) and 2-chloro-6-trichloromethylpyridine were weighed at a molar ratio of 1:1 and mixed to obtain a mixture. This mixture was then added to a zirconia grinding jar, and deionized water was added at a ratio of η=1.2 (i.e., 1.2 μL of water per 1 mg of solid). The mixture was stirred until homogeneous and then ground at 30 Hz for 130 min using a 5 mm diameter grinding ball. Modified 2-chloro-6-trichloromethylpyridine was obtained.

[0045] During the grinding process, 2-chloro-6-trichloromethylpyridine molecules gradually enter the hydrophobic cavity of β-cyclodextrin, forming a stable β-cyclodextrin-2-chloro-6-trichloromethylpyridine complex.

[0046] (2) Preparation of Cit-Mn3O4@biochar particles: Preparation of S1, 2% Cit-Mn3O4 dispersion S1-1. Prepare 0.08M MnSO4·4H2O solution and 0.4M sodium citrate solution respectively using deionized water, according to Mn 2+ Cit 3- A 1:5 molar ratio was used to mix MnSO4·4H2O solution and sodium citrate solution at a 1:1 volume ratio. The mixture was magnetically stirred for 30 min to obtain a solution. The solution was then transferred to a three-necked flask and reacted at 100°C for 2 h under magnetic stirring at 600 rpm. The solution gradually turned dark brown, and negatively charged Mn3O4 nanoparticles were formed.

[0047] S1-2. After cooling to room temperature, centrifuge at 13000 rpm for 30 min and collect precipitate 1. S1-3. Redisperse precipitate 1 in deionized water, centrifuge at 13000 rpm for 30 min, and collect precipitate 2 again. S1-4. Repeat step S1-3 three times to remove impurities and obtain the purified product. Finally, use deionized water to prepare a dispersion of about 2% (w / v, g / mL) to obtain a 2% Cit-Mn3O4 dispersion.

[0048] S2. Grind the almond shell charcoal through a 400-mesh sieve (approximately 38 μm) to obtain sieved biochar. Mix the sieved biochar with 1M dilute hydrochloric acid at a ratio of 1g:10mL (w / v), and stir at 400rpm for 2 hours at 30℃ to remove ash and impurities. Then, wash repeatedly with deionized water until the pH of the supernatant is neutral, dry under vacuum at 95℃ for 12 hours, and cool to room temperature to obtain dried biochar.

[0049] S3. The dried biochar was slowly added to a 2% Cit-Mn3O4 dispersion at a solid-liquid ratio of 1g:15mL. The mixture was stirred at 600rpm for 2 hours, followed by intermittent sonication at 40kHz and 500W for 5 minutes each time, followed by intermittent cooling for 2 minutes, for a total of 2 hours to promote biochar particle loading. The precipitate was then collected by centrifugation at 10000rpm for 20 minutes and washed twice with deionized water to remove unadsorbed particles. The precipitate was then vacuum-dried at 80°C for 24 hours, cooled, lightly ground, and passed through a 400-mesh sieve to obtain free-flowing black Cit-Mn3O4@biochar particles.

[0050] (3) Preparation of salt-resistant and emission-reducing fertilizer Add 8 kg of sodium hexametaphosphate to 950 kg of inorganic compound fertilizer and mix at 12 rpm for 10 min. Then add 1.5 kg of Cit-Mn3O4@biochar granules, 10 kg of modified 2-chloro-6-trichloromethylpyridine, and 20 kg of salt-resistant microbial agent in sequence, and continue mixing for 0.5 h until homogeneous. After mixing, immediately package into aluminum foil bags or film-coated woven bags, seal, and store in a moisture-proof and light-proof environment.

[0051] Example 3 A salt-resistant, water-soluble fertilizer based on modified 2-chloro-6-trichloromethylpyridine, comprising the following raw materials: 930 kg of inorganic compound fertilizer, 10 kg of dispersant, 15 kg of modified 2-chloro-6-trichloromethylpyridine, 2 kg of Cit-Mn3O4@biochar granules, and 30 kg of salt-resistant microbial agent; the inorganic compound fertilizer has a N, P2O5, and K2O mass ratio of 11:20:20, wherein N is urea, P2O5 is monoammonium phosphate, and K2O is potassium sulfate; the dispersant is sodium hexametaphosphate, and the salt-resistant microbial agent is composed of Bacillus subtilis, Bacillus licheniformis, and Bacillus mucilaginosus in a mass ratio of 1:2:2.

[0052] The preparation method of the above-mentioned salt-resistant, water-soluble fertilizer based on modified 2-chloro-6-trichloromethylpyridine includes the following steps: (1) Preparation of modified 2-chloro-6-trichloromethylpyridine: β-cyclodextrin hydrate (β-CD·8H2O) and 2-chloro-6-trichloromethylpyridine were weighed at a molar ratio of 1:1 and mixed to obtain a mixture. This mixture was then added to a zirconia grinding jar, and deionized water was added at a ratio of η=1.5 (i.e., 1.5 μL of water per 1 mg of solid). The mixture was stirred until homogeneous and then ground at 30 Hz for 120 min using a 5 mm diameter grinding ball. Modified 2-chloro-6-trichloromethylpyridine was obtained.

[0053] (2) Preparation of Cit-Mn3O4@biochar particles: Preparation of S1, 2% Cit-Mn3O4 dispersion S1-1. Prepare 0.05M MnSO4·4H2O solution and 0.2M sodium citrate solution respectively using deionized water, according to Mn 2+ Cit 3- The MnSO4·4H2O solution and sodium citrate solution were mixed in a 1:4 molar ratio, i.e., a 1:1 volume ratio, and magnetically stirred for 30 min. The mixture was then transferred to a three-necked flask and reacted at 100°C for 3 h under magnetic stirring at 600 rpm. The solution gradually turned dark brown, and negatively charged Mn3O4 nanoparticles were formed.

[0054] S1-2. After cooling to room temperature, centrifuge at 12000 rpm for 30 min and collect precipitate 1. S1-3. Redisperse precipitate 1 in deionized water, centrifuge at 12000 rpm for 30 min, and collect precipitate 2. S1-4. Repeat step S1-3 four times to remove impurities and obtain the purified product. Finally, use deionized water to prepare a dispersion of about 2% (w / v, g / mL) to obtain a 2% Cit-Mn3O4 dispersion.

[0055] S2. Grind the coconut shell charcoal through a 400-mesh sieve (approximately 38 μm) to obtain sieved biochar. Mix the sieved biochar with 1M dilute hydrochloric acid at a ratio of 1g:10mL (w / v), and stir at 30℃ and 400rpm for 2 hours to remove ash and impurities. Then wash repeatedly with deionized water until the pH of the supernatant is neutral. Dry under vacuum at 95℃ for 12 hours and cool to room temperature to obtain dried biochar.

[0056] S3. The dried biochar was slowly added to a 2% Cit-Mn3O4 dispersion at a solid-liquid ratio of 1 g:12 mL. The mixture was stirred at 600 rpm for 2 h, followed by intermittent sonication at 40 kHz and 500 W for 5 min each time, then intermittently cooled for 2 min, for a total of 1.5 h to promote nanoparticle loading. The precipitate was then collected by centrifugation at 15000 rpm for 20 min and washed twice with deionized water to remove unadsorbed particles. The precipitate was vacuum dried at 80°C for 24 h, cooled, lightly ground, and passed through a 400-mesh sieve to obtain free-flowing black Cit-Mn3O4@biochar particles.

[0057] 3. Preparation of salt-resistant and emission-reducing fertilizer Add 10 kg of sodium hexametaphosphate to 930 kg of inorganic compound fertilizer and mix at 12 rpm for 10 min. Then add 2 kg of Cit-Mn3O4@biochar granules, 15 kg of modified 2-chloro-6-trichloromethylpyridine, and 30 kg of salt-resistant microbial agent in sequence, and continue mixing for 0.5 h until homogeneous. Immediately after mixing, package in aluminum foil bags or film-coated woven bags, seal, and store in a moisture-proof and light-proof environment.

[0058] Comparative Example 1 The inorganic compound fertilizer with the same nutrients as in Example 1 has a mass ratio of N, P2O5 and K2O of 11:20:20; wherein N is urea, P2O5 is monoammonium phosphate and K2O is potassium sulfate.

[0059] Comparative Example 2 A salt-resistant, water-reducing, and water-soluble fertilizer based on 2-chloro-6-trichloromethylpyridine differs from Example 1 in that the inhibitor is unmodified 2-chloro-6-trichloromethylpyridine, while the composition of other raw materials is the same as in Example 1.

[0060] In the preparation method of this comparative example, except that it does not involve the preparation of modified 2-chloro-6-trichloromethylpyridine and the unmodified 2-chloro-6-trichloromethylpyridine is used instead of the modified 2-chloro-6-trichloromethylpyridine, the other steps are the same as in Example 1.

[0061] Comparative Example 3 A salt-resistant, water-reducing, and water-soluble fertilizer based on modified 2-chloro-6-trichloromethylpyridine differs from Example 1 in that it does not contain Cit-Mn3O4@biochar particles, while the composition of other raw materials is the same as in Example 1.

[0062] In the preparation method of this comparative example, except that the preparation and addition of Cit-Mn3O4@biochar particles are not involved, the other steps are the same as in Example 1.

[0063] Experimental Example 1 (1) A cultivation experiment was conducted in soil using the salt-resistant and water-reducing soluble fertilizers of Examples 1-3, the inorganic compound fertilizer of Comparative Example 1, and the salt-resistant and water-reducing soluble fertilizers of Comparative Examples 2-3 to determine their nitrification inhibition and soil emission reduction effects. 200g of soil was weighed for each treatment and placed in a brown wide-mouth bottle. Fertilizers from Examples 1-3 and Comparative Examples 1-3 were added at a concentration of 0.5g N / kg dry soil. The bottles were sealed and cultured under a field water holding capacity of 60%. Soil and gas samples were collected on days 1, 3, 5, 7, 10, 14, 16, and 21. Nitrate nitrogen, ammonium nitrogen, and nitrous oxide were determined using a flow analyzer and a gas chromatograph, respectively.

[0064] Depend on Figure 1It can be seen that, compared with Comparative Examples 1-2, the ammonium nitrogen content in the fertilized soil of Examples 1-3 was higher than that of other treatments, while the nitrate nitrogen content and N2O emissions were lower than those of other treatments. This indicates that Examples 1-3 have a good inhibitory effect on the process of converting ammonium nitrogen to nitrate nitrogen in the soil and reduce greenhouse gas emissions.

[0065] (2) Pot experiment.

[0066] Using the cotton variety Huamian 3097, the salt-tolerant and water-reducing soluble fertilizers of Examples 1-3, the inorganic compound fertilizer of Comparative Example 1, and the salt-tolerant and water-reducing soluble fertilizers of Comparative Examples 2-3 were applied to potted plants under simulated salt stress. Each treatment was repeated in triplicate to determine its effect on improving the salt tolerance of cotton. Natural soil was collected, dried, sieved, and then placed in pots for the potted experiment. Five days after germinating cotton seeds were planted in the pots, cotton seedlings of uniform height were selected for the experiment. Salt stress was simulated using a 150 mmol / L NaCl solution, with 100 mL of NaCl solution applied twice consecutively, with an interval of 2-3 days. After the stress treatment, the fertilizers described in Examples 1-3 and Comparative Examples 1-3 were added to the water at a rate of 0.2 g N / kg dry soil. The growth of the cotton seedlings was measured after 14 days. The contents of superoxide dismutase, peroxidase, catalase, potassium ion and sodium ion in leaves were determined by riboflavin-nitroblue tetrazolium photoreduction method, guaiacol method, hydrogen peroxide consumption method and acid digestion method, respectively.

[0067] Table 1. Effects of different treatments on cotton seedling growth and salt tolerance.

[0068] As shown in Table 1, compared with Comparative Examples 1 and 3, the fresh weight, plant height, and root length of cotton seedlings in Examples 1-3 were significantly increased. At the same time, the activities of antioxidant enzymes (superoxide dismutase, peroxidase, and catalase) in the leaves were significantly increased, and the potassium-sodium ratio was significantly increased. This indicates that Examples 1-3 can effectively enhance the antioxidant capacity and ion balance regulation capacity of cotton seedlings, thereby significantly improving the salt tolerance of cotton seedlings.

[0069] Furthermore, although Comparative Example 2 showed some improvement over Comparative Examples 1 and 3 in terms of cotton seedling growth, antioxidant enzyme activity, and ion balance, all indicators were lower than those in Examples 1-3. These results indicate a significant synergistic effect between modified 2-chloro-6-trichloromethylpyridine, Cit-Mn3O4@biochar particles, and salt-tolerant microbial agents; the combined application of these three agents can effectively improve the salt tolerance and nitrogen use efficiency of plants.

[0070] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A salt-tolerant reduced discharge water-soluble fertilizer, characterized by, The anti-salt reduction water-soluble fertilizer comprises the following raw materials in parts by weight: The modified 2-chloro-6-trichloromethylpyridine is 2-chloro-6-trichloromethylpyridine modified by β-cyclodextrin; The nano mimetic enzyme particle is a biochar-loaded trimanganese tetroxide particle; The anti-salt composite microbial agent is Bacillus subtilis, Bacillus licheniformis and Bacillus mycoides; the mass ratio of the Bacillus subtilis, Bacillus licheniformis and Bacillus mycoides is (1-3):(1-2):(1-2). The preparation method of the modified 2-chloro-6-trichloromethylpyridine comprises the following steps:

2. The salt-reducing water-soluble fertilizer according to claim 1, characterized in that, The modified 2-chloro-6-trichloromethylpyridine is obtained by stirring and grinding a mixture of 2-chloro-6-trichloromethylpyridine and β-cyclodextrin hydrate in a molar ratio and adding deionized water to the mixture. The molar ratio is 1:1; the mass-volume ratio of the mixture to deionized water is 1 mg:1-1.5 μL; the grinding mode is 20-30 Hz frequency grinding for 120-130 min, and the diameter of the grinding ball is 5-15 mm.

3. The salt-reducing water-soluble fertilizer according to claim 2, characterized in that, The preparation method of the biochar-loaded trimanganese tetroxide particle comprises the following steps:

4. The salt-reducing water-soluble fertilizer of claim 1, wherein, (1) MnSO4·4H2O solution and sodium citrate solution are mixed, heated and stirred to react to generate negatively charged Mn3O4 nanoparticles, which are cooled, centrifuged to collect the precipitate 1, and then dispersed in water to remove impurities to obtain a product after impurity removal, and water is added to obtain a Cit-Mn3O4 dispersion; (2) The sieved biochar is mixed with dilute hydrochloric acid, stirred, washed with water until the pH is neutral, and then dried to obtain dried biochar; (3) The dried biochar is mixed with the Cit-Mn3O4 dispersion, stirred and ultrasonically treated, centrifuged to collect the precipitate a, washed with water, dried, ground and sieved to obtain a biochar-loaded trimanganese tetroxide particle, which is named as Cit-Mn3O4@biochar particle. In step (1), the molar concentrations of the MnSO4·4H2O solution and the sodium citrate solution are (0.04-0.1):(0.1-0.5); the volume ratio of the MnSO4·4H2O solution to the sodium citrate solution is (1-2):1; the heating and stirring mode is stirring at 85-100℃ and 500-600 rpm for 1.5-3.5 h; and the mass-volume percentage of the Cit-Mn3O4 dispersion is 1%-3%; 5. The salt-reducing water-soluble fertilizer according to claim 4, characterized in that, In step (2), the biochar is one or more of coconut shell charcoal, almond shell charcoal and rice husk charcoal, and the mesh size of the sieving is 350-450 meshes; the mass-volume ratio of the sieved biochar to dilute hydrochloric acid is 1 g:(9-11) mL; the concentration of the dilute hydrochloric acid is 0.8-1.2 M; and the stirring is carried out at 28-32℃ and 350-450 rpm for 1-2.5 h; ​ In step (3), the mass-volume ratio of the dried biochar to the Cit-Mn3O4 dispersion liquid is 1 g:5-20 mL; the stirring is 500-600 rpm for 1-3 h; the ultrasonic treatment is 35-45 kHz, 350-450 W for 1-2 h; the ultrasonic treatment is intermittent ultrasonic treatment, the intermittent ultrasonic treatment is 4-6 min each time, and the intermittent time is 1-3 min; the mesh number of the ground and sieved is 350-450 mesh.

6. The salt-reducing water-soluble fertilizer of claim 1, wherein, The dispersant is one or more of sodium hexametaphosphate, sodium polyphosphate, and sodium humate; the water-soluble fertilizer includes inorganic compound fertilizer; the inorganic compound fertilizer includes one or more of nitrogen fertilizer, phosphorus fertilizer, and potassium fertilizer; the mass ratio of N, P2O5, and K2O of the inorganic compound fertilizer is (9-13):(15-25):(15-25).

7. The salt-reducing water-soluble fertilizer according to claim 6, characterized in that, The nitrogen fertilizer is one or more of urea, ammonium chloride, and ammonium sulfate; The phosphorus fertilizer is one or more of monoammonium phosphate, diammonium phosphate, potassium dihydrogen phosphate, ammonium polyphosphate, and potassium polyphosphate; The potassium fertilizer is one or more of potassium nitrate, potassium sulfate, potassium chloride, and potassium dihydrogen phosphate.

8. The method for preparing the salt-reducing water-soluble fertilizer according to any one of claims 1 to 7, characterized in that, The method comprises the following steps: After mixing the water-soluble fertilizer and sodium hexametaphosphate, Cit-Mn3O4@biochar particles, modified 2-chloro-6-trichloromethyl pyridine, and salt-tolerant microbial inoculants are added and mixed to obtain a salt-tolerant and water-soluble fertilizer for reducing emissions.

9. The salt-tolerant and water-soluble fertilizer for reducing emissions of any one of claims 1-7 or prepared by the method of claim 8 is applied in at least one of a-e, a. improving the salt tolerance of plant seedlings; b. promoting the growth of salt-stressed plant seedlings; c. reducing the soil content of nitrate nitrogen and N2O emissions; d. improving nitrogen use efficiency; e. improving the antioxidant enzyme activity in plant leaves.

10. Use according to claim 9, characterized in that, The growth traits include one or more of fresh weight, plant height, and root length of cotton seedlings; the plants are cotton; the antioxidant enzymes are one or more of superoxide dismutase, peroxidase, and catalase.

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