A liquid fertilizer with synergistic sulfur and chlorine regulation, its preparation method and application

Abstract

This invention belongs to the field of agricultural fertilizer technology, specifically relating to a liquid fertilizer with synergistic sulfur-chlorine regulation, its preparation method, and its application. This liquid fertilizer achieves synergistic effects through precise design of different sulfur-chlorine ratios. The preparation method includes: solid nutrient pretreatment, base liquid preparation, addition of a protective system and carbon source, post-ripening adaptation of microbial agents, and low-temperature stabilization. This invention solves the pain points of traditional fertilizers, such as imbalanced sulfur-chlorine ratios, poor microbial storage stability, and limited applicability. The formula is suitable for short-term immediate application, long-term storage, saline-alkali land, chlorine-sensitive soil, and home gardening, among other core scenarios. After 6 months of storage, the effective viable bacteria count is ≥800 million / mL. After application, crop yield increases by more than 20%, vitamin C content increases by more than 22%, and soil microbial structure is improved. It is suitable for the green cultivation of lettuce and similar leafy vegetables such as romaine lettuce and spinach.

Description

Technical Field

[0001] This invention belongs to the field of agricultural fertilizer technology, specifically relating to a liquid fertilizer with synergistic regulation of sulfur and chlorine, its preparation method, and its application. Background Technology

[0002] Potassium is an essential nutrient for the growth and development of leafy vegetables such as lettuce, romaine lettuce, and spinach, and it has a dual core function: On the one hand, it can activate the photosynthetic enzyme system, promote carbohydrate synthesis and transport, and enhance the crop's resistance to drought, salt and other stresses; on the other hand, it can significantly inhibit nitrate accumulation, improve quality indicators such as vitamin C and soluble sugar, and ensure the safety of agricultural products for consumption.

[0003] In agricultural production, potassium chloride and potassium sulfate are the two most widely used potassium sources, but both have natural limitations: potassium chloride has a high potassium content (K2O≥60%) and low cost, making it the mainstream choice for field crops, but excessive application of its chloride ions can inhibit the activity of crop nitrogen metabolism enzymes, leading to leaf scorch and quality deterioration; potassium sulfate does not cause chloride stress and is suitable for chloride-sensitive crops and high-quality planting scenarios, but its sulfur element easily combines with calcium and magnesium ions in the soil to form insoluble precipitates, reducing nutrient availability, and its cost per application is more than 30% higher than that of potassium chloride.

[0004] With the development of green agriculture, microbial fertilizers have been widely promoted due to their advantages such as promoting growth, improving soil, and reducing pesticide and fertilizer use. The synergistic application of sulfur, chlorine, and potassium sources with microorganisms has become a research hotspot in the industry. However, existing microbial liquid fertilizer technologies still have the following shortcomings, which seriously restrict their large-scale implementation and application effects: 1. The sulfur-chlorine synergistic design is lacking, and the characteristics of chloride ions are not utilized.

[0005] 2. The adaptability of the microbial protection system is poor, and the problem of chloride ion-specific stress has not yet been solved.

[0006] 3. The chloride ion tolerance threshold is not clearly defined, and the formulation design lacks data support.

[0007] 4. The crude preparation process exacerbates the excessive local salt concentration induced by chloride ions.

[0008] 5. Limited scenario coverage and lack of precise formulations adapted to chloride ions.

[0009] 6. Insufficient synergy among soil, crops, and microorganisms, and neglect of the systemic impact of chloride ions.

[0010] How to overcome the aforementioned technical shortcomings and provide technical support for the green and efficient cultivation of leafy vegetables is a topic worthy of study. Summary of the Invention

[0011] The purpose of this invention is to provide a sulfur-chlorine synergistic liquid fertilizer, its preparation method, and its application. Addressing the shortcomings of existing microbial liquid fertilizers, such as the lack of sulfur-chlorine synergistic design, chloride ion-specific stress leading to microbial agent inactivation, unclear chloride ion safety threshold, crude preparation process causing localized excessive salt concentrations, limited application scenarios, and insufficient synergy between soil, crops, and microbial systems, this invention combines the "low-promoting, high-inhibiting" characteristics of chloride ions on microorganisms with the nutritional needs of leafy vegetables to solve industry pain points. It achieves the synergistic goals of high-quality and high-yield crops, long-term stable microorganisms, and improved soil ecology, providing technical support for the green and efficient cultivation of leafy vegetables.

[0012] The specific technical solution of the present invention is as follows: In a first aspect, the present invention provides a method for preparing a liquid fertilizer with synergistic sulfur and chlorine regulation, comprising the following steps: Step (1) Solid nutrient pretreatment: Nitrogen and phosphorus sources are crushed; soil conditioner is dried, cooled and then crushed; potassium source is ground; potassium source is potassium sulfate and / or potassium chloride; Step (2) Preparation of base solution: Add a portion of solvent, then add nitrogen source, phosphorus source, soil conditioner and potassium source in sequence, start stirring, gradually increase temperature, stir, adjust pH, and add more solvent; Step (3) Protection system and carbon source addition: Add composite protective agent and carbon source additive to base solution, stir to form matrix solution without layering and precipitation; Step (4) Post-ripening and adaptation of microbial agent: Inoculate the microbial agent into the substrate solution and culture statically in the dark, stirring intermittently during the process; Step (5) Low temperature stabilization: Place the substrate solution containing the bacterial agent from step (4) above in a low temperature environment and let it stand. Sampling and testing of effective viable bacteria count, pH, and total nutrient deviation are performed. After passing the test, the solution is sealed and stored.

[0013] As a preferred option, in step (1), based on 1000L of liquid fertilizer product, the amounts of nitrogen source, phosphorus source and soil conditioner added are 60~325kg, 55~300kg and 100~125kg respectively. In the potassium source, the ratio of potassium sulfate to potassium chloride is (0~720kg): (670~0kg), and the ratio of sulfur to chlorine is: The nitrogen source is one or more of urea, ammonium nitrate phosphorus, or ammonium nitrate. The phosphorus source is one or more of ammonium polyphosphate, ammonium dihydrogen phosphate, and diammonium hydrogen phosphate; Soil conditioners are one or more of humic acid, fulvic acid, alginic acid, and polyglutamic acid.

[0014] As a preferred option, in step (2), the stirring rate is 100~150 r / min, the temperature is increased to 30℃ at a rate of 1℃ every 10 min, the stirring is carried out for 30~45 min, and the pH is adjusted to 6.7~7.2.

[0015] As a preferred embodiment, in step (3), the amount of the composite protective agent added is 6.0~9.0 kg, which is composed of glycerol and xanthan gum in a mass ratio of 2~3:1~2; the stirring speed is 100~150 r / min, and the stirring time is 20~25 min; the amount of the carbon source additive added is 0.1~0.2 kg, and the carbon source additive is one or more of mannitol, sorbitol, xylitol, erythritol, and arabinitol.

[0016] As a preferred embodiment, in step (4), the amount of bacterial agent added is 0.3~0.8 kg, inoculated into the substrate solution, and statically cultured at 28~30℃ in the dark for 27~32 h, with stirring for 10~12 min every 7~8 h during the period, and the stirring rate is 100~110 r / min; the bacterial agent is one or more of Bacillus subtilis, Trichoderma harzianum, Bacillus amyloliquefaciens, Bacillus megaterium, Bacillus colloidis, and Paecilomyces lilacinus.

[0017] Secondly, the present invention provides a liquid fertilizer with synergistic regulation of sulfur and chlorine, comprising 60-325 kg of nitrogen source, 55-300 kg of phosphorus source, 0-720 kg of potassium source, 100-125 kg of soil conditioner, 0.3-0.8 kg of microbial agent, 6.0-9.0 kg of compound protective agent, 0.1-0.2 kg of carbon source additive and 520-770 kg of solvent.

[0018] As a preferred option, the potassium source is potassium sulfate and / or potassium chloride, with a potassium sulfate:potassium chloride ratio of (0~720kg):(670~0kg). The following seven groups of composite potassium source formulations have different sulfur-to-chlorine ratios: Group 1, S / Cl ratio 0:100, K2O provided by potassium sulfate and potassium chloride in ratio 0:120; Group 2, S / Cl ratio 9:100, K2O provided by potassium sulfate and potassium chloride in ratio 20:100; Group 3, S / Cl ratio 23:100, K2O provided by potassium sulfate and potassium chloride ratio 40:80; Group 4, S / Cl ratio 45:100, K2O provided by potassium sulfate and potassium chloride in ratio 60:60; Group 5, S / Cl ratio 95:100, K2O provided by potassium sulfate and potassium chloride in ratio 80:40; Group 6, S / Cl ratio 227:100, K2O provided by potassium sulfate and potassium chloride ratio 100:20; Group 7 has an S / Cl ratio of 100:0 and a K2O ratio of 120:0 provided by potassium sulfate and potassium chloride.

[0019] As a preferred embodiment, the nitrogen source is one or more of urea, ammonium nitrate, or ammonium nitrate; The phosphorus source is one or more of ammonium polyphosphate, ammonium dihydrogen phosphate, and diammonium hydrogen phosphate; The soil conditioner is one or more of humic acid, fulvic acid, alginic acid, and polyglutamic acid; The composite protective agent is composed of glycerin and xanthan gum in a mass ratio of 2~3:1~2; The microbial agent is one or more of Bacillus subtilis, Trichoderma harzianum, Bacillus amyloliquefaciens, Bacillus megaterium, Bacillus mucilaginosus, and Paecilomyces lilacinus. The carbon source additive is one or more of mannitol, sorbitol, xylitol, erythritol, and arabinitol.

[0020] As a preferred option, the liquid fertilizer should be sampled and tested for effective viable bacteria count ≥ 1 billion / mL, pH 6.5~7.5, and total nutrient N:P2O5:K2O deviation ≤ ±2%. After passing the test, it should be sealed and stored. The storage conditions are 5~25℃, protected from light and sealed. After 6 months of storage, the effective viable bacteria count should be ≥ 800 million / mL.

[0021] Thirdly, the present invention provides an application of a sulfur-chlorine synergistically regulated liquid fertilizer in leafy vegetable cultivation, wherein the liquid fertilizer is obtained by the above-mentioned preparation method or the above-mentioned liquid fertilizer. Leafy vegetables include lettuce, romaine lettuce, and spinach; the application rate is: 750~1000L / hectare for field crops, 900~950L / hectare for greenhouse agriculture, and 15~80mL / pot for potted plants in home gardening; the application method is drip irrigation or root irrigation, and it is applied 12 times during the seedling establishment period and the growth period. Attached Figure Description

[0022] Figure 1 This is a process flow diagram of one embodiment of the present invention; Figure 2 This is a graph showing the trend of effective viable bacteria count changes in liquid fertilizers with different S / Cl ratios in Examples 1-7 during different storage periods (0 months, 1 month, 3 months, 6 months). The horizontal axis represents the storage period, and the vertical axis represents the effective viable bacteria count (100 million / mL). The curves are labeled with 7 groups of formulations and a control of traditional fertilizers, visually demonstrating the storage stability advantage of the formulations of this invention. The treatment numbers in the graphs represent the mass ratio of sulfur (S) to chlorine (Cl) in the fertilizer. Except for total S and total Cl, the mass of chlorine is uniformly fixed at 100, presented in the format "S∶100", i.e., "23∶100" represents a mass ratio of S to Cl of 23∶100. The "∶" in the labels is a separator, used only for visual comparison of the relative masses of sulfur and chlorine, and is not a division operation symbol. Figure 3This is a bar chart comparing the effects of liquid fertilizer #2 (long-term storage type) treatment 1 in Example 2 and traditional fertilizer treatment 2 in Example 2 on the yield and quality indicators of lettuce. The horizontal axis represents the treatment group, and the vertical axis represents the indicator values. The sub-charts show the fresh weight of a single plant, vitamin C content, and nitrate content. Error bars and letters indicating significant differences are marked. Figure 4 This is a scatter plot showing the correlation between different sulfur / chlorine ratio treatments of the liquid fertilizer (Examples 1-7 of this invention) and the vitamin C content and nitrate reductase (NR) activity in lettuce during the second potted plant application experiment. The horizontal axis represents different S / Cl ratios, and the vertical axis represents the index values. A trend line is fitted and labeled R. 2 Value and P-value; Figure 5 This is a heatmap showing the distribution of dominant phyla in the soil microbial community after different sulfur-chlorine ratio treatments with the liquid fertilizers of Examples 1-7 of this invention in the second potted plant application experiment. The horizontal axis represents the different S / Cl ratios of the formulations of Examples 1-7, and the vertical axis represents the dominant bacterial phyla (Pseudomonadota, Actinomycetota, Bacteroidota, etc.) and dominant fungal phyla (Ascomycota, Basidiomycota, Olpidiomycota, etc.). The color depth represents the relative abundance (using log10 transformation). A color gradient scale is attached on the right to visually demonstrate the optimization effect of the formulations of the Examples of this invention on the soil microbial community structure. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased.

[0024] Unless otherwise stated, all percentages in this invention represent mass fractions. Ratios are mass percentages, and concentrations are mass concentrations.

[0025] Unless otherwise specified, all materials, instruments, and equipment used below are conventional materials, instruments, and equipment or obtained through commercial channels; all testing methods used are existing methods unless otherwise specified.

[0026] Based on the dynamic design of its nutritional requirements, and taking into account the water solubility and functionality of the fertilizer of this invention, unless otherwise specified, the parts in the following description are the mass percentages of each element when the fertilizer mass is 100 parts.

[0027] Existing microbial liquid fertilizer technology still has the following shortcomings: 1. Lack of synergistic design between sulfur and chloride, and underutilization of chloride ion characteristics. Existing technologies mostly focus on the independent application of single sulfur or chloride sources, failing to develop systematic synergistic sulfur-chloride schemes. Some technologies add salt (containing chloride ions) as a component of the culture medium, but without synergistic regulation with a sulfur source, nor optimizing the ratio to address the impact of chloride ions on microorganisms; most sulfur-containing microbial fertilizers only use potassium sulfate as a potassium source, without introducing a chloride source, leading to insufficient vitamin C synthesis and limited enhancement of nitrogen metabolism enzyme activity in crops. Existing research has clearly shown that chloride ions have a concentration-dependent "low-promoting, high-inhibiting" effect on microbial activity: when the chloride ion concentration is below 20 mmol / L, it can promote the catalytic activity of α-amylase in Bacillus amyloliquefaciens; when the concentration is above 20 mmol / L, it becomes inhibitory. However, existing technologies have not designed synergistic sulfur-chloride ratios based on this characteristic, either failing to achieve a synergistic effect due to insufficient chloride concentration, or inhibiting microbial activity due to excessively high concentration.

[0028] 2. The adaptability of microbial protection systems is poor, and the problem of chloride ion-specific stress remains unsolved. Osmotic pressure stress exerted by chloride ions on microorganisms is a key mechanism leading to the inactivation of microbial agents. High concentrations of chloride ions can damage the integrity of microbial cell membranes, alter enzyme structures, and thus interfere with microbial metabolic activities. While existing technologies attempt to enhance agent stability using protectants, they have not designed specific protection systems for chloride ion stress. Some products use trehalose or xanthan gum as a single protectant, which only alleviates the inactivation problem under conventional storage conditions; in chloride-containing potassium source systems, osmotic pressure changes caused by high salt concentrations still lead to a significant reduction in the number of viable bacteria. Existing technologies mostly construct low-temperature protection systems for microbial agents, without researching the reduction in agent activity during high-salt fertilizer storage, which aligns with the industry's common problem of short shelf life for microbial liquid fertilizers. Furthermore, the few studies involving chlorine-tolerant strains focus on pollutant degradation rather than the plant growth promotion and soil improvement functions required for agricultural production, making them unsuitable for direct application in leafy vegetable microbial liquid fertilizers.

[0029] 3. The chloride ion tolerance threshold is not clearly defined, and the formulation design lacks data support. Existing research confirms that different microorganisms have significantly different tolerances to chloride ions, with Bacillus microorganisms commonly used in agriculture being particularly sensitive to chloride ion concentrations. Related studies show that when the chloride ion concentration in the environment of Bacillus amyloliquefaciens exceeds 20 mmol / L, its enzyme activity is inhibited; if the concentration increases further, the number of viable bacteria will continue to decrease. Other studies have shown that high concentrations of chloride ions (e.g., above 40 mmol / L) can counteract the promoting effect of metal ions such as calcium and potassium on Bacillus enzyme activity, indirectly accelerating the inactivation of the microbial agent. However, existing technologies have not quantitatively defined the safe threshold for chloride ions in microbial liquid fertilizers specifically for leafy vegetables. Some studies only specify a salt mass percentage of 0.2%, without specifying an upper limit for chloride ion concentration in conjunction with the type of microbial agent; most patents for chlorine-containing microbial fertilizers only indicate the amount of potassium chloride used, without considering the impact of chloride ions on microbial activity, resulting in large fluctuations in product stability in actual applications, with viable bacteria count decline rates often exceeding 40%.

[0030] 4. The crude preparation process exacerbates localized salt concentration exceedances induced by chloride ions. Current technologies generally employ direct mixing and compounding of raw materials, without optimizing the process for the solubility characteristics of sulfur and chloride salts, further intensifying the stress of chloride ions on microorganisms. Studies have shown that excessively high salt concentrations in liquid water-soluble fertilizers can lead to microbial dehydration, interfering with nutrient absorption and inhibiting life activities; direct mixing processes easily cause a sudden increase in localized chloride concentration, creating a hypertonic environment. Existing studies often use a direct inoculation and fermentation model after mixing the culture medium, without incorporating adaptive steps such as gradient heating and intermittent stirring, which easily leads to localized chloride ion accumulation, affecting the colonization efficiency of the microbial agent. Most existing technologies do not consider the differences in the solubility rates of sulfur and chloride salts, easily resulting in localized salt concentration exceedances after mixing, which not only inhibits microbial activity but may also cause root burn in crops.

[0031] 5. Limited application scenarios and lack of precise formulations adapted to chloride ions. Existing technologies do not have specific formulations designed for the chloride ion tolerance requirements of different scenarios. Although some studies claim applicability to multiple fields such as crops, animal husbandry, and industrial waste treatment, they do not optimize the formulation for special soil types such as chloride-sensitive soils (sensitive to chloride ions and requiring controlled chloride input) and saline-alkali soils (containing high chloride content, requiring strict limits on fertilizer chloride concentration). Home gardening scenarios require precise control of fertilizer chloride ion concentration within safe thresholds, and must meet the requirements of low dosage and no risk of root burn, but existing technologies completely lack such low-chlorine, low-dosage formulations. In long-term storage scenarios, the synergistic stress of chloride and sulfur ions accelerates the inactivation of microbial agents, and existing technologies do not specifically optimize the formulation and protection system, resulting in a product shelf life of generally less than 3 months, which cannot meet the needs of large-scale storage and cross-regional transportation.

[0032] 6. Insufficient synergy among soil, crops, and microorganisms, neglecting the systemic impact of chloride ions. Existing technologies often focus on improving single functions without considering the synergistic effects of chloride ions on soil, crops, and microorganisms. Some studies only focus on increasing yield and improving soil function, without optimizing the sulfur-chlorine ratio to suit the nutritional needs of leafy vegetables, resulting in fertilizer utilization rates of less than 40%. Some technologies, while containing sulfur, chloride, potassium sources and microorganisms, fail to balance factors such as the sulfur-chlorine ratio, microbial colonization, and soil chloride uptake. In fact, selective crop uptake can reduce soil chloride accumulation, and sulfides can alleviate the inhibitory effect of chloride ions on microorganisms; these synergistic mechanisms have not been fully utilized. Relevant practical data show that after the application of traditional microbial liquid fertilizers, soil pH imbalance and improvement in microbial community diversity are not significant, and the effect of alleviating continuous cropping obstacles is limited. The core reason is that the systemic impact of chloride ions on soil physicochemical properties, crop uptake, and microbial colonization has not been comprehensively considered.

[0033] Based on this, the present invention addresses the above-mentioned technical deficiencies by designing a sulfur-chlorine ratio gradient to cover the chloride ion safety threshold, specifically alleviating chloride stress, constructing a composite protection system and processes such as gradient heating and microbial agent post-ripening adaptation, and providing technical support for the green and efficient planting of leafy vegetables.

[0034] In a first aspect, embodiments of the present invention propose a method for preparing a liquid fertilizer with synergistic sulfur and chlorine regulation, comprising the following steps: Step (1) Solid nutrient pretreatment: Nitrogen and phosphorus sources are crushed; soil conditioner is dried, cooled and then crushed; potassium source is ground; potassium source is potassium sulfate and / or potassium chloride; Step (2) Preparation of base solution: Add a portion of solvent, then add nitrogen source, phosphorus source, soil conditioner and compound potassium source in sequence, start stirring, gradually increase temperature, stir, adjust pH value, and add more solvent; Step (3) Protection system and carbon source addition: Add composite protective agent and carbon source additive to base solution, stir to form matrix solution without layering and precipitation; Step (4) Post-ripening and adaptation of microbial agent: Inoculate the microbial agent into the substrate solution and culture statically in the dark, stirring intermittently during the process; Step (5) Low temperature stabilization: Place the substrate solution containing the bacterial agent from step (4) above in a low temperature environment and let it stand. Sampling and testing of effective viable bacteria count, pH, and total nutrient deviation are performed. After passing the test, the solution is sealed and stored.

[0035] This invention, through the innovative construction of a sulfur-chlorine composite and composite stress-resistant protection system and gradient adaptation process, deeply explores the mechanism and system effect of sulfur-chlorine synergy, specifically addresses the core defects of existing technologies, and achieves multiple synergistic advantages such as crop quality improvement, microbial survival, soil improvement, and multi-scenario adaptation.

[0036] Based on the cost differences and complementary performance of sulfur and chlorine raw materials, a synergistic mechanism of low cost and high performance is constructed: the ratio of low-cost potassium chloride to high-performance potassium sulfate reduces the cost by 15% to 20% compared to commercially available single high-sulfur fertilizers, while avoiding the quality defects of single potassium chloride; the preparation process does not require special high-end equipment, and the gradient dissolution of sulfur and chlorine salts and the adaptation process of microbial agent post-ripening can be directly connected to existing liquid fertilizer production lines, reducing energy consumption by more than 12% in large-scale production; the product is free of heavy metal pollution, and the synergistic effect of sulfur and chlorine reduces the risk of soil salinization, reducing the total salt content by 17.2%, and there are no problems such as crop root burn or soil degradation after application, which is in line with the policy orientation of green agriculture and low-carbon cultivation, and has broad prospects for promotion and application.

[0037] As one implementation method, in step (1), based on 1000L of liquid fertilizer product, the amount of nitrogen source, phosphorus source and soil conditioner added in step (1) is 60~325kg, 55~300kg and 100~125kg respectively. In the potassium source, the ratio of potassium sulfate to potassium chloride is (0~720kg): (670~0kg), and the ratio of potassium element provided by potassium sulfate and potassium chloride is (0~120): (120~0). The nitrogen source is one or more of urea, ammonium nitrate phosphorus, or ammonium nitrate. The phosphorus source is one or more of ammonium polyphosphate, ammonium dihydrogen phosphate, and diammonium hydrogen phosphate; The soil conditioner is one or more of the following: humic acid, fulvic acid, alginic acid, and polyglutamic acid.

[0038] The potassium source is a composite potassium source, and it provides different sulfur-chlorine ratios. It is composed of potassium sulfate and / or potassium chloride in a mass ratio of (0~720):(0~670). In step (1), the nitrogen source and phosphorus source are crushed to 80-100 mesh; the soil conditioner is dried at 60℃ to a moisture content of ≤8%, cooled and crushed to 60-80 mesh; and the composite potassium source is ground to 100-120 mesh.

[0039] This invention, through precise sulfur-chlorine ratio design, constructs a synergistic mechanism based on the "low-promoting and high-inhibiting" characteristics of chloride ions on inoculants and the crop nutritional function of sulfur: low concentration of Cl... -This product activates the activity of α-amylase and phosphorus- and potassium-solubilizing enzymes by 30%, promoting soil nutrient transformation and crop absorption while avoiding the inhibition of nitrogen metabolism enzymes by high chlorine levels. Sulfur participates in the synthesis pathways of cysteine ​​and vitamin C in crops, enhancing the activity of nitrogen metabolism enzymes and mitigating the negative impact of chloride ions on crop quality. Specifically, nitrate reductase activity is increased by 28.5%. Multiple gradient ratios are precisely matched to different scenarios. The high-sulfur formula corrects the imbalance of sulfur and chloride ratios, reducing nitrate accumulation in crops by ≥27.0%. The high-chlorine formula, supplemented with sulfur, avoids leaf edge scorching caused by chloride ions, reducing it by 75%. In practical applications, the fresh weight of each plant increases by 20.2%~31.1%, vitamin C content increases by 22.8%~31.3%, soil microbial diversity increases by more than 14%, and the colonization rate of Bacillus subtilis reaches over 90%, completely resolving the contradiction between high chlorine inhibiting quality and high sulfur inhibiting viable bacteria.

[0040] In one implementation, in step (2), the stirring rate is 100~150 r / min, the temperature is increased to 30℃ at a rate of 1℃ every 10 min, and the stirring is carried out for 30~45 min. The pH is then adjusted to 6.7~7.2. For example, the target pH values ​​are: 7.2 for group 1, 6.7 for group 7, and 6.8~7.0 for groups 2 and 6; the stirring time is: 45 min for groups 1 and 7, 35 min for groups 2 and 4, and 30~40 min for groups 3, 5, and 6.

[0041] In step (2), 520~770kg of solvent is added to the mixing tank, and the raw materials are added in sequence. Stirring is started at 25℃, and the solvent is added to 1000L to obtain the base liquid of the product.

[0042] This invention allows for the adaptation of different stirring times and pH values ​​to different formulations. Gradual temperature rise and post-ripening culture processes can induce Bacillus subtilis to express chlorine-resistant genes, achieving gradient adaptation between the inoculant and the sulfur-chlorine system.

[0043] In one embodiment, in step (3), the composite protective agent is composed of glycerol and xanthan gum in a mass ratio of 2~3:1~2, and the amount added is 6.0~9.0 kg; the stirring speed is 100~150 r / min, and the stirring time is 20~25 min. The carbon source additive is one or more of mannitol, sorbitol, xylitol, erythritol, and arabinitol, and the amount added is 0.1~0.2 kg.

[0044] The stirring rate for groups 5, 6, and 7 was 140-150 r / min, and the stirring time was 24-25 min; the stirring rate for the remaining groups was 100-130 r / min, and the stirring time was 20-23 min.

[0045] This invention presents a composite protective system combining a compound protectant and a carbon source additive, specifically mitigating chloride ion osmotic pressure stress. Combined with a gradient heating and post-ripening adaptation process for the microbial agent, it avoids the problem of localized excessive salt concentrations caused by traditional direct compounding. By controlling the ratio of potassium sulfate to potassium chloride, the system's osmotic pressure is maintained within the suitable range for the microbial agent, preventing cell membrane rupture caused by high chloride levels and reducing intracellular leakage by 60%. Sulfur enhances the cell's osmotic pressure regulation capacity by promoting the synthesis of compatible solutes such as betaine and proline by microorganisms, forming a synergistic effect with the compound protectant. The gradient heating and post-ripening culture process induces Bacillus subtilis to express chloride-resistant genes, achieving gradient adaptation between the microbial agent and the sulfur-chlorine system.

[0046] In one embodiment, in step (4), the bacterial agent is inoculated into the substrate solution and statically cultured at 28-30°C in the dark for 27-32 hours, with stirring for 10-12 minutes every 7-8 hours during this period, at a stirring rate of 100-110 r / min. The bacterial agent is one or more of Bacillus subtilis, Trichoderma harzianum, Bacillus amyloliquefaciens, Bacillus megaterium, Bacillus lilacinus, and Paecilomyces lilacinus.

[0047] Group 1 was cultured for 32 hours, Group 2 for 30 hours, Group 3 for 29 hours, Group 4 for 30 hours, Group 5 for 28 hours, Group 6 for 28 hours, and Group 7 for 27 hours.

[0048] This invention enables integrated improvement of crops, soil, and microorganisms. It establishes a synergistic mechanism for sulfur and chloride ion balance, soil physicochemical improvement, and microbial colonization: sulfur forms a soluble complex with calcium and magnesium ions in the soil, avoiding precipitation problems caused by high sulfur content alone, and improving soil nutrient availability, increasing calcium and magnesium ion utilization by 35%; chloride ions at low concentrations (≤78~400mg / L) can regulate soil pH towards neutrality, alleviating acid-base imbalances in saline-alkali and acidic soils; sulfur and chloride work synergistically with humic acid and Bacillus subtilis to improve soil aggregate structure, enhance water and fertilizer retention, and promote the proliferation of beneficial soil bacteria such as nitrogen-fixing and phosphorus-solubilizing bacteria; nutrient release rhythm is precisely matched with the crop growth period: low chloride and high sulfur during the seedling stage promote root development; medium sulfur and medium chloride during the growth period ensure nutrient supply; and high sulfur and low chloride during the harvest period improve quality, increasing fertilizer utilization from less than 40% to over 65%. Application in saline-alkali soil can reduce the total salt content of the soil by 17.2% and the pH to 7.9; application in acidic soil can adjust the pH to be more neutral and increase the soil organic matter content by more than 12%; application in continuously cropped soil can increase the proportion of bacterial generalized species by 14.9%, effectively alleviating the obstacles of continuous cropping.

[0049] Secondly, the present invention also provides a liquid fertilizer with synergistic regulation of sulfur and chlorine, comprising 60-325 kg of nitrogen source, 55-300 kg of phosphorus source, 0-720 kg of potassium source, 100-125 kg of soil conditioner, 0.3-0.8 kg of microbial agent, 6.0-9.0 kg of compound protective agent, 0.1-0.2 kg of carbon source additive and 520-770 kg of solvent.

[0050] This invention's liquid fertilizer, through precise formulation design, construction of a composite stress-resistant protection system, and gradient adaptation process innovation, deeply explores the molecular mechanism and system effect of sulfur-chlorine synergy, specifically addresses the core defects of existing technologies, and achieves multiple synergistic advantages such as crop quality improvement, microbial stability, soil improvement, and multi-scenario adaptability.

[0051] In one implementation method, the potassium source is potassium sulfate and / or potassium chloride, with a potassium sulfate:potassium chloride ratio of (0~720kg):(670~0kg). The following seven groups of composite potassium source formulations have different sulfur-to-chlorine ratios: Group 1, all-chlorine sulfur-free formula, S / Cl ratio 0:100, K2O provided by potassium sulfate and potassium chloride ratio 0:120, mass ratio of potassium sulfate to potassium chloride can be 0:(200~670). Group 2, high chlorine and low sulfur formula, S / Cl ratio 9:100, K2O provided by potassium sulfate and potassium chloride ratio 20:100, and the mass ratio of potassium sulfate to potassium chloride can be (40~120):(166.7~500). Group 3, medium chlorine and low sulfur type formula, S / Cl ratio 23:100, K2O provided by potassium sulfate and potassium chloride ratio 40:80, and the mass ratio of potassium sulfate to potassium chloride can be (80~240):(133.3~400). Group 4, medium chlorine and medium sulfur type formula, the ratio of K2O provided by potassium sulfate and potassium chloride is 60:60, the S / Cl ratio is 45:100, and the mass ratio of potassium sulfate to potassium chloride can be (120~360):(100~300). Group 5, a sulfur-chlorine balanced formula, with an S / Cl ratio of 95:100, a K2O ratio of 80:40 provided by potassium sulfate and potassium chloride, and a mass ratio of potassium sulfate to potassium chloride of (160~480):(66.7~200). Group 6, high-sulfur medium-chlorine type formula, S / Cl ratio 227:100, K2O provided by potassium sulfate and potassium chloride ratio 100:20, and the mass ratio of potassium sulfate to potassium chloride can be (200~600):(33.3~100). Group 7, all-sulfur, chlorine-free formula, S / Cl ratio 100:0, K2O provided by potassium sulfate and potassium chloride ratio 120:0, and potassium sulfate to potassium chloride mass ratio can be (240~720):0.

[0052] Once the sulfur-chlorine ratio is determined, the sulfur content is fixed, which also fixes the chlorine content. The usage amounts of potassium sulfate and potassium chloride are also relatively fixed. Within the mass range of potassium sulfate and potassium chloride, there are many different formulations, but due to the limitation of the sulfur-chlorine ratio, the mass ratio between groups will not overlap.

[0053] Based on the concentration-dependent effect of chloride ions on bacterial agents, this invention precisely controls the mass ratio of potassium sulfate and potassium chloride, and clarifies the safe threshold of chloride ions under different scenarios. It not only meets the nutritional requirements of lettuce and similar leafy vegetables for sulfur, but also adapts to the tolerance of Bacillus subtilis to chloride. It breaks through the technical bottleneck of high chloride inhibiting quality and high sulfur inhibiting live bacteria, achieving high-quality and high-yield crops, with a yield increase of over 20%, a nitrate content reduction of over 27%, and an increase in soil microbial diversity of over 14%.

[0054] This invention's liquid fertilizer employs different formulations based on the chloride ion tolerance threshold and sulfur nutrient requirements of different scenarios. For example, in saline-alkali soil scenarios, a medium-chloride, low-sulfur formulation is used (chloride concentration in the liquid fertilizer product is 60g / L~180g / L, sulfur concentration is 13.6g / L~40.8g / L) to avoid chloride accumulation in the soil, while sulfur alleviates salt stress. In chloride-sensitive soil scenarios, a group 7 chloride-free, high-sulfur formulation is used (chloride concentration in the liquid fertilizer product is 0g / L, sulfur concentration is 40.8g / L~122.4g / L) to completely avoid chloride ion accumulation. The harmful effects of chloride ions on sensitive crops are addressed. For long-term storage, a medium-chlorine, low-sulfur formulation (75g / L~225g / L chlorine and 6.8g / L~20.4g / L sulfur in liquid fertilizer products) is used. This balances the beneficial effects of medium chlorine on bacterial activity while maintaining stable bacterial metabolism through sulfur. For home gardening, a high-chlorine, medium-sulfur formulation (45g / L~135g / L chlorine and 20.4g / L~61.2g / L sulfur in liquid fertilizer products) is employed. This eliminates the risk of root burn with low dosages while ensuring crop quality. The application rate is precisely controllable across different scenarios, and the application method is convenient. This addresses the issues of poor efficacy or high risk associated with traditional fertilizers in chloride-sensitive soils, saline-alkali lands, and special cultivation methods such as potted plants. Its adaptability and practicality are significantly superior to existing technologies.

[0055] In one embodiment, the nitrogen source is one or more of urea, ammonium nitrate, or ammonium nitrate; The phosphorus source is one or more of ammonium polyphosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, and urea phosphate; The soil conditioner is one or more of humic acid, fulvic acid, alginic acid, and polyglutamic acid; The carbon source additive is one or more of mannitol, sorbitol, xylitol, erythritol, and arabinitol; The microbial agent is one or more of the following: Bacillus subtilis, Trichoderma harzianum, Bacillus amyloliquefaciens, Bacillus megaterium, Bacillus mucilaginosus, and Paecilomyces lilacinus.

[0056] The composite protective agent is composed of glycerin and xanthan gum in a mass ratio of 2~3:1~2.

[0057] In the liquid fertilizer of this invention, the composite protective system of compound protectant and carbon source additive specifically alleviates chloride ion osmotic pressure stress. Combined with gradient heating and microbial agent post-ripening adaptation process, it avoids the problem of local salt concentration exceeding the standard caused by traditional direct compounding.

[0058] As one implementation method, the liquid fertilizer is sampled and tested to ensure that the effective viable bacteria count is ≥1 billion / mL, the pH is 6.5~7.5, and the total nutrient N:P2O5:K2O deviation is ≤±2%. After passing the test, it is sealed and stored. The storage conditions are 5~25℃, protected from light and sealed. After 6 months of storage, the effective viable bacteria count is ≥800 million / mL, which meets the needs of large-scale storage and cross-regional transportation.

[0059] This invention involves standing at 10-15℃ for 12-15 hours, sampling and testing for effective viable bacteria count ≥1 billion / mL, pH 6.5-7.5, and total nutrient N:P2O5:K2O deviation ≤±2%. After passing the test, the sample is sealed and stored.

[0060] After being stored at 5~25℃ under light-proof and sealed conditions for 6 months, the effective viable bacteria count of the product of this invention is still ≥850 million / mL, and the viable bacteria attenuation rate is only 15%~25%, which far exceeds the standard for agricultural microbial agents (≥200 million / mL). Traditional microbial liquid fertilizers have an attenuation rate of more than 40% after 3 months of storage. Compared with traditional microbial liquid fertilizers, the storage period of this invention is extended by 100%, and the viable bacteria stability is improved by more than 60%, which fully meets the needs of large-scale storage and cross-regional transportation.

[0061] Thirdly, the present invention also proposes the application of a sulfur-chlorine synergistic liquid fertilizer in leafy vegetable cultivation, wherein the liquid fertilizer is obtained by the above-mentioned preparation method; Leafy vegetables include lettuce, romaine lettuce, and spinach; the application rate is: 750-1000 L / hectare in field cultivation, 900-950 L / hectare in greenhouse agriculture, and 15-80 mL / pot for home gardening; the application method is drip irrigation or root irrigation, applied 12 times during the seedling stage and growth period. This invention is particularly suitable for the green cultivation of leafy vegetables such as lettuce, romaine lettuce, and spinach. This invention constructs a synergistic system of precise nutrient supply, efficient microbial colonization, and soil chlorine absorption, and develops multi-scenario-specific formulas to precisely adapt to core scenarios such as short-term immediate application, long-term large-scale storage, saline-alkali land, acidic soil improvement, chlorine-sensitive soil greenhouse cultivation, and home gardening, providing integrated technical support for the green and low-carbon cultivation of leafy vegetables.

[0062] To further illustrate the present invention, the following describes in detail, with reference to embodiments, a liquid fertilizer with synergistic regulation of sulfur and chlorine, its preparation method, and its application.

[0063] The purity / performance requirements for each raw material in the examples are as follows: Urea: Nitrogen content ≥46%, agricultural grade, free of mechanical impurities; Ammonium nitrate phosphorus: water solubility ≥95%, nutrient ratio N-P2O5-K2O=30:10:0; Ammonium nitrate: nitrogen content ≥35%, agricultural grade, free of mechanical impurities; Ammonium polyphosphate: P2O5 content ≥58%, water solubility ≥95%, nutrient ratio N-P2O5-K2O=18:58:0; Potassium sulfate: K2O content ≥50%, sulfur content ≥17%, moisture ≤2.0%, purity ≥92.5%, agricultural grade; Potassium chloride: K2O content ≥60%, chlorine content ≥45%, moisture ≤2.0%, purity ≥95%, agricultural grade; Humic acid, fulvic acid, alginic acid, polyglutamic acid: agricultural grade; Xanthan gum: viscosity ≥1200 mPa·s (25℃, 1% aqueous solution), food grade; Glycerin: Food grade, purity ≥99.0%; Mannitol, sorbitol, xylitol, erythritol, arabinitol: purity ≥99.5%, industrial grade; Deionized water: conductivity ≤10μS / cm, Pb≤0.01mg / L, Cd≤0.001mg / L, pH 6.5~7.5, free from heavy metal pollution.

[0064] The measurement methods involved in this invention refer to T / CPFIA-0017-2025 "Water-soluble Fertilizers Containing Microorganisms" and T / CPFIA-0016-2025 "Compound Fertilizers Containing Microorganisms".

[0065] like Figure 1 As shown, one preparation method of this embodiment has the following specific steps: Step (1) Solid nutrient pretreatment: Urea and ammonium polyphosphate are pulverized to 80-100 mesh using a universal pulverizer, sieved and sealed for later use; humic acid is dried in a 60℃ constant temperature drying oven until the moisture content is ≤8%, cooled and pulverized to 60-80 mesh to avoid clumping; potassium sulfate and potassium chloride are ground to 100-120 mesh using a planetary grinder to ensure water solubility and reduce the problem of excessively high local salt concentration during dissolution.

[0066] Step (2) Preparation of base solution: First, add deionized water to the mixing tank, then add urea, ammonium polyphosphate, humic acid and potassium sulfate and potassium chloride of the corresponding formula in sequence. Start the stirrer and stir at a rate of 100~150 r / min. The initial temperature is 25℃. The temperature is gradually increased to 30℃ at a rate of 1℃ every 10 min. Stir for 30~45 min to ensure that the solid raw materials are completely dissolved. Adjust the pH to the target value with 0.1mol / L hydrochloric acid or potassium hydroxide solution, and add deionized water to the 1000L mark to obtain a homogeneous base solution.

[0067] Step (3) Protection system and carbon source addition: Add glycerol, xanthan gum and mannitol to the base solution, and keep the stirring rate at 100~150r / min to form a stable matrix solution without layering and precipitation.

[0068] Step (4) Post-maturation adaptation of bacterial agent: Inoculate the bacterial agent into the substrate solution and transfer it to a constant temperature incubator at 28~30℃ in the dark for static culture for 27~32h; during the culture period, start the stirrer for 10min every 8h, with a stirring rate of 100r / min, to promote full contact between the bacterial agent and sulfur and chloride ions, induce the bacterial agent to synthesize proline, polysaccharides and other stress-resistant metabolic products, and avoid the large-scale inactivation of the bacterial agent caused by direct inoculation; the bacterial solution is uniformly turbid with no obvious precipitation, and the bacterial cells are observed to be intact and have good activity under a microscope.

[0069] Step (5) Low temperature stabilization: Place the substrate solution containing the bacterial agent from step (4) above in a low temperature environment and let it stand. Sampling and testing of effective viable bacteria count, pH, and total nutrient deviation are performed. After passing the test, the solution is sealed and stored.

[0070] Examples of a stable microbial liquid fertilizer with synergistic sulfur and chlorine regulation in Examples 1-7 include a nitrogen source, a phosphorus source, a potassium source, a soil conditioner, a functional microbial agent, a protective agent, a carbon source additive, and a solvent. Based on a 1000L finished product, the total nutrient content strictly meets the N:P₂O₅:K₂O ratio of 40:40:120. In Examples 1-7, the nitrogen source is a fixed amount of 60kg urea, the phosphorus source is a fixed amount of 68.97kg ammonium polyphosphate, the soil conditioner is a fixed amount of 100.00kg humic acid, the functional microbial agent is 0.51kg Bacillus subtilis inoculant, the protective agent is 6-9kg of a compound protective agent, the carbon source additive is 0.1-0.2kg mannitol, and the solvent is deionized water, replenished to 1000L. The composite protectant is composed of glycerol and xanthan gum in a mass ratio of 3:1. The potassium source is a composite potassium source composed of potassium sulfate and potassium chloride in a mass ratio of (0~240):(200~0). The initial effective viable count of Bacillus subtilis inoculant is ≥1 billion / mL.

[0071] Example 1

[0072] The method for preparing liquid fertilizer with synergistic sulfur and chlorine regulation in this embodiment includes the following steps: Liquid fertilizer 1# (Group 1 all-chlorine, sulfur-free formula, for short-term immediate application). Step (1) Crush 60kg of urea and 68.97kg of ammonium polyphosphate to 90 mesh; dry 100.00kg of humic acid at 60℃ to a moisture content of 6%, cool and crush to 70 mesh; grind 0.00kg of potassium sulfate and 200.00kg of potassium chloride to 110 mesh.

[0073] Step (2) Add 770L of deionized water to the mixing tank, and add the above solid raw materials in sequence, with a total mass of 428.95kg. Start stirring at 25℃, stirring rate 120r / min, and gradually increase the temperature to 30℃ at a rate of 1℃ every 10min. Stir for 45min, and adjust the pH to 7.2 with 0.1mol / L potassium hydroxide solution.

[0074] Step (3) Add 6.84 kg of composite protective agent and 0.15 kg of mannitol, and stir at 120 r / min for 22 min to form a uniform matrix solution without precipitation. The composite protective agent contains 5.13 kg of glycerol and 1.71 kg of xanthan gum.

[0075] Step (4) Inoculate with 0.8 kg of Bacillus subtilis inoculum with an initial viable count of 1 billion / mL, add deionized water to 1000L, and statically culture at 29℃ in the dark for 32h, stirring for 10min every 8h during the period, with a stirring rate of 100r / min.

[0076] Step (5) Place the bacterial solution in a low temperature environment of 12℃ and let it stand for 15 hours. Take a sample for testing. The effective viable bacteria count is 1.08 billion / mL, pH 7.2, N:P2O5:K2O=40:40:120, all chlorine elements, no sulfur elements. After passing the test, seal and store in a light-proof environment of 20℃ for 1 month for future use.

[0077] Example 2

[0078] The method for preparing liquid fertilizer with synergistic sulfur and chlorine regulation in this embodiment, for preparing liquid fertilizer No. 2 (Group 2 high-chlorine, low-sulfur type, for long-term storage), includes the following steps: Step (1) Crush 60kg of urea and 68.97kg of ammonium polyphosphate to 90 mesh; dry 100.00kg of humic acid at 60℃ to a moisture content of 6%, cool and crush to 70 mesh; grind 40.00kg of potassium sulfate and 166.67kg of potassium chloride to 110 mesh.

[0079] Step (2) Add 770L of deionized water to the mixing tank, and add the above solid raw materials in sequence, with a total mass of 435.62kg. Start stirring at 25℃, stirring rate 120r / min, and gradually increase the temperature to 30℃ at a rate of 1℃ every 10min. Stir for 35min, and adjust the pH to 7.0 with 0.1mol / L potassium hydroxide solution.

[0080] Step (3) Add 6.96 kg of composite protective agent and 0.15 kg of mannitol, and stir at 120 r / min for 22 min to form a uniform matrix solution. The composite protective agent contains 5.22 kg of glycerol and 1.74 kg of xanthan gum.

[0081] Step (4) Inoculate with 0.8 kg of Bacillus subtilis inoculum with an initial viable count of 1.2 billion / mL, add deionized water to 1000L, and statically culture at 29℃ in the dark for 30h, stirring for 10min every 8h during the period, with a stirring rate of 100r / min.

[0082] Step (5) Place the bacterial solution in a low temperature environment of 12℃ and let it stand for 12 hours. Take samples for testing. The effective viable bacteria count is 1.15 billion / mL, pH 7.0, N:P2O5:K2O=40:40:120, sulfur-chlorine ratio is 9:100. After passing the test, seal and store in a light-proof environment at 20℃.

[0083] Example 3

[0084] The method for preparing liquid fertilizer with synergistic sulfur and chlorine regulation in this embodiment, for preparing liquid fertilizer No. 3 (group 3, medium chlorine and low sulfur type, suitable for saline-alkali land), includes the following steps: Step (1) Crush 60kg of urea and 68.97kg of ammonium polyphosphate to 90 mesh; dry 100.00kg of humic acid at 60℃ to a moisture content of 6%, cool and crush to 70 mesh; grind 96.00kg of potassium sulfate and 133.33kg of potassium chloride to 110 mesh. Step (2) Add 770L of deionized water to the mixing tank, and add the above solid raw materials in sequence, with a total mass of 458.28kg. Start stirring at 25℃, stirring rate 130r / min, and gradually increase the temperature to 30℃ at a rate of 1℃ every 10min. Stir for 40min, and adjust the pH to 6.9 with 0.1mol / L hydrochloric acid.

[0085] Step (3) Add 7.32 kg of composite protective agent and 0.15 kg of mannitol, and stir at 130 r / min for 23 min to form a uniform matrix solution without precipitation. The composite protective agent contains 5.49 kg of glycerol and 1.83 kg of xanthan gum.

[0086] Step (4) Inoculate with 0.8 kg of Bacillus subtilis inoculum with an initial viable count of 1 billion / mL, add deionized water to 1000L, and statically culture at 28.5℃ in the dark for 29h, stirring for 10min every 8h during the period, with a stirring rate of 100r / min.

[0087] Step (5) Place the bacterial solution in a low temperature environment of 13℃ and let it stand for 13 hours. Take a sample for testing. The effective viable bacteria count is 1.15 billion / mL, pH 7.0, N:P2O5:K2O=40:40:120, sulfur-chlorine ratio is 23:100. After passing the test, it can be used for future use.

[0088] Example 4

[0089] The method for preparing liquid fertilizer with synergistic sulfur and chlorine regulation in this embodiment, for preparing liquid fertilizer #4 (group 4, medium chlorine and medium sulfur type, suitable for neutral soil), includes the following steps: Step (1) Crush 60kg of urea and 68.97kg of ammonium polyphosphate to 90 mesh; dry 100.00kg of humic acid at 60℃ to a moisture content of 6%, cool and crush to 70 mesh; grind 144.00kg of potassium sulfate and 100.00kg of potassium chloride to 110 mesh.

[0090] Step (2) Add 770L of deionized water to the mixing tank, and then add the above solid raw materials in sequence, with a total mass of 472.95kg. Start stirring at 25℃, stirring speed 120r / min, and gradually increase the temperature to 30℃ at a rate of 1℃ every 10min. Stir for 35min, and naturally adjust the pH to 7.0 without additional acid or alkali adjustment.

[0091] Step (3) Add 7.56 kg of composite protective agent and 0.15 kg of mannitol, and stir at 120 r / min for 22 min to form a uniform matrix solution without precipitation. The composite protective agent contains 5.67 kg of glycerol and 1.89 kg of xanthan gum.

[0092] Step (4) Inoculate with 0.8 kg of Bacillus subtilis inoculum with an initial viable count of 600 million / mL, add deionized water to 1000L, and statically culture at 29℃ in the dark for 30h, stirring for 10min every 8h during the period, with a stirring rate of 100r / min.

[0093] Step (5) Place the bacterial solution in a low temperature environment of 12℃ and let it stand for 12 hours. Take samples for testing. The effective viable bacteria count is 1.01 billion / mL, pH is 7.0, N:P2O5:K2O=40:40:120, sulfur-chlorine ratio is 45:100. After passing the test, it can be used for future use.

[0094] Example 5

[0095] The method for preparing liquid fertilizer with synergistic sulfur and chlorine regulation in this embodiment, for preparing liquid fertilizer #5 (group 5, sulfur-chlorine balanced type, suitable for acidic soils), includes the following steps: Step (1) Crush 60kg of urea and 68.97kg of ammonium polyphosphate to 90 mesh; dry 100.00kg of humic acid at 60℃ to a moisture content of 6%, cool and crush to 70 mesh; grind 192.00kg of potassium sulfate and 66.67kg of potassium chloride to 100 mesh. Step (2) Add 770L of deionized water to the mixing tank, and add the above solid raw materials in sequence, with a total mass of 487.62kg. Start stirring at 25℃, stirring rate 125r / min, and gradually increase the temperature to 30℃ at a rate of 1℃ every 10min. Stir for 40min, and adjust the pH to 7.0 with 0.1mol / L potassium hydroxide solution.

[0096] Step (3) Add 7.8 kg of composite protective agent and 0.15 kg of mannitol, and stir at 125 r / min for 25 min to form a uniform matrix solution without precipitation. The composite protective agent contains 5.85 kg of glycerol and 1.95 kg of xanthan gum.

[0097] Step (4) Inoculate with 0.8 kg of Bacillus subtilis inoculum with an initial viable count of 800 million / mL, add deionized water to 1000L, and statically culture at 30℃ in the dark for 28h, stirring for 10min every 8h during the period, with a stirring rate of 100r / min.

[0098] Step (5) Place the bacterial solution in a low temperature environment of 15℃ and let it stand for 15 hours. Take samples for testing. The effective viable bacteria count is 1.05 billion / mL, pH 7.0, N:P2O5:K2O=40:40:120, sulfur-chlorine ratio is 95:100. After passing the test, it can be used for future use.

[0099] Example 6

[0100] The method for preparing liquid fertilizer with synergistic sulfur and chlorine regulation in this embodiment, for preparing liquid fertilizer No. 6 (Group 6, high sulfur and medium chlorine type), includes the following steps: Step (1) Crush 60kg of urea and 68.97kg of ammonium polyphosphate to 90 mesh; dry 100.00kg of humic acid at 60℃ to a moisture content of 6%, cool and crush to 70 mesh; grind 244.00kg of potassium sulfate and 33.33kg of potassium chloride to 110 mesh. Step (2) Add 770L of deionized water to the mixing tank, and add the above solid raw materials in sequence, with a total mass of 506.28kg. Start stirring at 25℃, stirring rate 130r / min, and gradually increase the temperature to 30℃ at a rate of 1℃ every 10min. Stir for 45min, and adjust the pH to 7.0 with 0.1mol / L potassium hydroxide solution.

[0101] Step (3) Add 8.08 kg of composite protective agent and 0.15 kg of mannitol, and stir at 130 r / min for 25 min to form a uniform matrix solution without precipitation. The composite protective agent contains 6.06 kg of glycerol and 2.02 kg of xanthan gum.

[0102] Step (4) Inoculate with 0.8 kg of Bacillus subtilis inoculum with an initial viable count of 1 billion / mL, add deionized water to 1000L, and statically culture at 30℃ in the dark for 30h, stirring for 10min every 8h during the period, with a stirring rate of 100r / min.

[0103] Step (5) Place the bacterial solution in a low temperature environment of 12℃ and let it stand for 12 hours. Take samples for testing. The effective viable bacteria count is 1.12 billion / mL, pH 7.0, N:P2O5:K2O=40:40:120, sulfur-chlorine ratio is 227:100. After passing the test, it can be used for future use.

[0104] Example 7

[0105] The method for preparing liquid fertilizer with synergistic sulfur and chlorine regulation in this embodiment, for preparing liquid fertilizer #7 (Group 7, all-sulfur and chlorine-free type, suitable for chlorine-sensitive soils), includes the following steps: Step (1) Crush 60kg of urea and 68.97kg of ammonium polyphosphate to 100 mesh; dry 100.00kg of humic acid at 60℃ to a moisture content of 6%, cool and crush to 80 mesh; grind 288.00kg of potassium sulfate and 0.00kg of potassium chloride to 120 mesh. Step (2) Add 770L of deionized water to the mixing tank, and add the above solid raw materials in sequence, with a total mass of 516.95kg. Start stirring at 25℃, stirring rate 150r / min, and gradually increase the temperature to 30℃ at a rate of 1℃ every 10min. Stir for 45min, and adjust the pH to 6.7 with 0.1mol / L potassium hydroxide solution.

[0106] Step (3) Add 8.28 kg of composite protective agent and 0.15 kg of mannitol, and stir at 150 r / min for 25 min to form a uniform matrix liquid without precipitation. The composite protective agent contains 6.21 kg of glycerol and 2.07 kg of xanthan gum.

[0107] Step (4) Inoculate with 0.8 kg of Bacillus subtilis inoculum with an initial viable count of 400 million / mL, add deionized water to 1000L, and incubate statically at 30℃ in the dark for 27h, stirring for 10min every 8h during the period, with a stirring rate of 100r / min.

[0108] Step (5) Place the bacterial solution in a low temperature environment of 10℃ and let it stand for 15 hours. Take a sample for testing. The effective viable bacteria count is 1.03 billion / mL, pH 6.7, N:P2O5:K2O=40:40:120, full sulfur element, no chlorine element. After passing the test, it can be used for future use.

[0109] Example 8

[0110] This embodiment describes a stable microbial liquid fertilizer with synergistic sulfur and chlorine regulation, comprising a nitrogen source, a phosphorus source, a potassium source, a soil conditioner, functional microbial agents, a protective agent, a carbon source additive, and a solvent. Based on a 1000L production volume, the total nutrients strictly meet the N:P₂O₅:K₂O ratio of 130:130:130. The nitrogen source is a multi-form nitrogen source, the phosphorus source is a multi-form phosphorus source, the soil conditioner is a fixed amount of 125.00 kg of humic acid, the functional microbial agents are multi-functional microbial agents, the protective agent is a composite protective agent, the carbon source additive includes multiple carbon sources, and the solvent is deionized water, replenished to 1000L. The composite protective agent consists of glycerol and xanthan gum in a 3:1 mass ratio, and the potassium source is a composite potassium source composed of potassium sulfate and potassium chloride in a mass ratio of (0~240):(200~0). The initial effective viable count of each individual microbial agent is ≥1 billion / mL.

[0111] The method for preparing liquid fertilizer with synergistic sulfur and chlorine regulation in this embodiment, for preparing liquid fertilizer #4 (group 4, medium sulfur and medium chlorine type, suitable for neutral soil), includes the following steps: Step (1) Crush 100kg ammonium nitrate, 225kg ammonium nitrate, 100kg ammonium dihydrogen phosphate, and 100kg diammonium hydrogen phosphate to 90 mesh; mix 70.00kg humic acid, 20.00kg fulvic acid, 5.00kg alginic acid, and 5.00kg polyglutamic acid and dry them at 60℃ to a moisture content of 6%, then cool and crush them to 70 mesh; grind 194.00kg potassium sulfate and 55.00kg potassium chloride to 110 mesh.

[0112] Step (2) Add 626 L of deionized water to the mixing tank, and add the above solid raw materials in sequence, with a total mass of 774 kg. Start stirring at 25°C and a stirring rate of 120 r / min. Increase the temperature to 30°C at a rate of 1°C every 10 min. Stir for 35 min and adjust the pH to 7.0 naturally. No additional acid or alkali adjustment is required.

[0113] Step (3) Add 7.56 kg of composite protective agent and 0.03 kg of mannitol, 0.03 kg of sorbitol, 0.03 kg of xylitol, 0.03 kg of erythritol and 0.03 kg of arabinitol, and stir at 120 r / min for 22 min to form a uniform matrix liquid without precipitation. The composite protective agent contains 5.67 kg of glycerol and 1.89 kg of xanthan gum.

[0114] Step (4) Inoculate with 0.8 kg of Bacillus subtilis, Trichoderma harzianum, Bacillus amyloliquefaciens, Bacillus megaterium, Bacillus jellyoides, and Paecilomyces lilacinus with an initial viable count of 100 million / mL, add deionized water to 1000L, and statically culture at 29℃ in the dark for 30h, stirring for 10min every 8h during the period at a stirring rate of 100r / min.

[0115] Step (5) Place the bacterial solution in a low temperature environment of 12℃ and let it stand for 12 hours. Take samples for testing. The effective viable bacteria count is 1.01 billion / mL, pH is 7.0, N:P2O5:K2O=130:130:130, sulfur-chlorine ratio is 133:100. After passing the test, it can be used for future use.

[0116] Example 9

[0117] The method for preparing liquid fertilizer with synergistic sulfur and chlorine regulation in this embodiment, for preparing liquid fertilizer #7 (Group 7, all-sulfur and chlorine-free type, suitable for chlorine-sensitive soils), includes the following steps: Step (1) Crush 70kg of urea and 66kg of monoammonium phosphate (N 12%, P 2O 5 61%) to 100 mesh; dry 125.00kg of humic acid at 60℃ to a moisture content of 6%, cool and then crush to 80 mesh; grind 720.00kg of potassium sulfate and 0.00kg of potassium chloride to 120 mesh. Step (2) Add 520L of deionized water to the mixing tank, and add the above solid raw materials in sequence, with a total mass of 856kg. Start stirring at 25℃, stirring rate 150r / min, and gradually increase the temperature to 30℃ at a rate of 1℃ every 10min. Stir for 45min, and adjust the pH to 6.7 with 0.1mol / L potassium hydroxide solution.

[0118] Step (3) Add 8.28 kg of composite protective agent and 0.15 kg of mannitol, and stir at 150 r / min for 25 min to form a uniform matrix liquid without precipitation. The composite protective agent contains 6.21 kg of glycerol and 2.07 kg of xanthan gum.

[0119] Step (4) Inoculate with 0.8 kg of Bacillus subtilis inoculum with an initial viable count of 400 million / mL, add deionized water to 1000L, and incubate statically at 30℃ in the dark for 27h, stirring for 10min every 8h during the period, with a stirring rate of 100r / min.

[0120] Step (5) Place the bacterial solution in a low temperature environment of 10℃ and let it stand for 15 hours. Take a sample for testing. The effective viable bacteria count is 1.03 billion / mL, pH is 6.7, N:P2O5:K2O=40:40:360, and there is no chlorine. After passing the test, it can be used for future use.

[0121] Comparative Example 1 To prepare liquid fertilizer 1#-0 that is free of bacteria, preservatives, and carbon sources, follow these steps: 59.98 kg of urea and 68.97 kg of ammonium polyphosphate were pulverized to 90 mesh; 100.00 kg of humic acid was dried at 60℃ to a moisture content of 6%, cooled, and then pulverized to 70 mesh; 0.00 kg of potassium sulfate and 200.00 kg of potassium chloride were ground to 110 mesh.

[0122] Add 800L of deionized water to the mixing tank, then add the above solid raw materials sequentially. Start stirring at 25℃ (120r / min), gradually increase the temperature to 30℃, and stir for 45min. Adjust the pH to 7.2 with 0.1mol / L potassium hydroxide solution. Add deionized water to 1000L, let stand at 12℃ for 12h, and take samples for testing. The effective viable bacteria count is 0 billion / mL, pH is 7.2, and N:P2O5:K2O=40:40:120. After passing the test, seal and store in a light-proof environment at 20℃ for 1 month for future use.

[0123] This comparative example lacks microbial-related functions and can only provide basic nutrients. Its crop growth promotion and soil improvement effects are significantly weaker than those of Example 1.

[0124] Comparative Example 2 To prepare liquid fertilizer 2-0# that is sterile and retains the protective agent and carbon source, follow these steps: 59.98 kg of urea and 68.97 kg of ammonium polyphosphate were pulverized to 90 mesh; 100.00 kg of humic acid was dried at 60℃ to a moisture content of 6%, cooled, and then pulverized to 70 mesh; 40.00 kg of potassium sulfate and 166.67 kg of potassium chloride were ground to 110 mesh.

[0125] Add 800L of deionized water to the mixing tank, then add the above solid raw materials (total mass 435.62kg). Start stirring at 25℃ (120r / min), gradually increase the temperature to 30℃, and stir for 35min. Adjust the pH to 7.0 with 0.1mol / L potassium hydroxide solution. Add 6.96kg of composite protective agent (5.22kg of glycerol + 1.74kg of xanthan gum) and 0.15kg of mannitol, and stir at 120r / min for 22min to form a homogeneous matrix solution. Add deionized water to 1000L, and incubate statically at 29℃ in the dark for 30h, stirring for 10min (100r / min) every 8h. Let it stand at 12℃ for 12h, and take samples for testing. The effective viable bacteria count is 0.00 billion / mL, pH is 7.0, and N:P2O5:K2O=40:40:120. After passing the test, seal and store in a dark environment at 20℃.

[0126] Because this comparative example does not contain functional microbial agents, it cannot achieve the functions of promoting microbial growth and improving soil microecology. Therefore, the effect of improving lettuce yield and quality is weaker than that of Example 2.

[0127] Comparative Example 3 To prepare liquid fertilizer 3#-0 that is free of bacteria and humic acid, follow these steps: 59.98 kg of urea and 68.97 kg of ammonium polyphosphate were crushed to 90 mesh; 96.00 kg of potassium sulfate and 133.33 kg of potassium chloride were ground to 110 mesh.

[0128] Add 800L of deionized water to the mixing tank, then add the above solid raw materials (total mass 358.28kg). Start stirring at 25℃ (120r / min), gradually increase the temperature to 30℃, and stir for 35min. Adjust the pH to 7.0 with 0.1mol / L potassium hydroxide solution. Add 5.72kg of composite protective agent (4.29kg of glycerol + 1.43kg of xanthan gum) and 0.15kg of mannitol, and stir at 120r / min for 22min to form a homogeneous, precipitate-free matrix solution. Add deionized water to 1000L. Let stand at 12℃ for 12h, and take samples for testing. The effective viable bacteria count is 0 billion / mL, pH is 7.0, and N:P2O5:K2O=40:40:120. If qualified, it can be used for future use.

[0129] This comparative example does not contain any inoculants or humic acid, and its soil improvement effect is significantly insufficient. In the application of saline-alkali land, its effect on improving soil pH and total salt content is weaker than that of Example 3.

[0130] Comparative Example 4 To prepare commercially available traditional single-type potassium sulfate liquid fertilizer 4#-0 containing bacteria but without protectants, carbon sources, or other additives, follow these steps: 59.98 kg of urea and 68.97 kg of ammonium polyphosphate were pulverized to 100 mesh; 100.00 kg of humic acid was dried at 60℃ to a moisture content of 6%, cooled, and then pulverized to 80 mesh; 288.00 kg of potassium sulfate and 0.00 kg of potassium chloride were ground to 120 mesh; 800 L of deionized water was added to a mixing tank, followed by the above solid raw materials. Stirring was started at 25℃ (150 r / min), and the temperature was gradually increased to 30℃. Stirring was continued for 45 min, and then 0. The pH was adjusted to 6.7 with 0.1 mol / L potassium hydroxide solution; the mixture was stirred at 150 rpm for 25 min to form a homogeneous, precipitate-free substrate solution; 0.8 kg (initial viable count 400 million / mL) of Bacillus subtilis inoculum was added, and deionized water was added to a final volume of 1000 L. The mixture was statically cultured at 30°C in the dark for 27 h, with stirring for 10 min (100 rpm) every 8 h; after incubation at 10°C for 15 h, samples were taken for testing. The effective viable count was 620 million / mL, pH 6.7, and N:P₂O₅:K₂O = 40:40:120. After passing the tests, the samples were sealed and stored. This comparative example, lacking a protective system, had insufficient microbial stability; after 6 months of storage, the viable count was significantly lower than in Example 7, and the application effect was correspondingly weakened.

[0131] Effect verification test 1. First trial of potted plant application Experimental materials: Experimental pots with a diameter of 25cm and a height of 20cm were selected. Each pot contained 10kg of non-chlorine-sensitive soil with a pH of 7.3, an organic matter content of 1.2%, and an exchangeable calcium content of 150mg / kg. 26-day-old "Butter Lettuce" seedlings were selected.

[0132] Experimental design: Two treatment groups were set up, with 3 pots and replicates in each group. One seedling was planted in each pot and placed in a greenhouse (temperature 18~28℃, light 12h / d).

[0133] Treatment 1: Apply liquid fertilizer No. 1 of Example 1 of the present invention, which has been stored for 1 month, at a rate of 80 mL / pot, by root irrigation. Apply once during the seedling establishment period (5 days after transplanting) and once during the growth period (20 days after transplanting).

[0134] Treatment 2: Apply liquid fertilizer 1#-0 (containing no bacteria, no protectant, no carbon source, and total nutrients N:P2O5:K2O=40:40:120) as in Treatment 1, with the same application rate and method as Treatment 1.

[0135] Cultivation and management: The trial period was 35 days (short-term fast-growing harvest scenario). Water was applied once every 5 days to maintain soil moisture at 60-70%. No pest or disease control measures were implemented.

[0136] The results showed that the average height of lettuce plants in treatment 1 was 27.8 cm, an increase of 18.3% compared to 23.5 cm in treatment 2; the average fresh weight of the above-ground parts was 62.5 g / plant, an increase of 22.1% compared to 51.2 g / plant in treatment 2. Within a short-term fast-growing cultivation cycle of 35 days, it can rapidly accelerate the longitudinal growth and biomass accumulation of plants, significantly shorten the harvesting cycle of lettuce, meet the planting needs of fast-growing vegetables for early harvesting and market access, and directly achieve improved quality and increased yield.

[0137] The average fresh weight of the roots was 15.8g / plant, which was 28.4% higher than that of treatment 2 (12.3g / plant). The root-promoting effect was far better than that of the above-ground growth. The developed root system can expand the range of soil nutrients and water absorption, lay a solid foundation for nutrient absorption in the middle and late stages of plant growth, and fundamentally enhance the growth potential of crops.

[0138] The average exchangeable calcium content in the soil was 186.5 mg / kg, which was 22.5% higher than that in treatment 2 (152.3 mg / kg). Appropriate chloride ions can promote the activation and release of calcium in the soil and improve the bioavailability of calcium. This can not only meet the calcium requirements for lettuce growth and prevent physiological diseases such as lettuce heart burn and heart leaf malformation, but also overcome the shortcomings of traditional high-chlorine fertilizers that only supply macronutrients and ignore the activation of micronutrients, thus achieving a balanced supply of nutrients.

[0139] The average chlorophyll content (SPAD) of the leaves was 43.2, which was 11.9% higher than that of treatment 2 (38.6). The leaves had better green retention. The increase in chlorophyll content can significantly enhance the plant's photosynthetic efficiency and increase the accumulation of photosynthetic products. At the same time, it can effectively alleviate cultivation adversities such as weak light and diurnal temperature fluctuations in the facility, reduce problems such as yellowing leaves, premature aging, and weak growth, strengthen the plant's physiological resistance to adversity, and improve its adaptability to the field environment.

[0140] Seven days after application, the number of viable bacteria in the soil was 8.6 × 10⁶. 8 The effective viable bacteria count in soil treated with cfu / g was only 2.1 × 10⁻⁶. 5 The fertilizer contains functional microbial flora, which can quickly colonize and proliferate after being applied to the soil. It effectively regulates the microecological structure of the rhizosphere soil, inhibits the growth of harmful bacteria, reduces micro-soil obstacles caused by continuous cropping in potted plants, improves soil biological activity, improves the soil environment through the action of microorganisms, and enhances the soil's self-buffering and stress resistance.

[0141] The liquid fertilizer #1 in Example 1 of this invention, as a high-chlorine formula, maintains high viable bacterial activity even after one month of storage. Its bacterial flora exhibits good storage tolerance, is not easily inactivated, and is unaffected by short-term storage. Farmers can stockpile this fertilizer in advance and use it as needed, meeting the immediate application requirements of small-scale, individual farmers. In terms of storage, transportation, and field application, its stability is significantly better than traditional high-chlorine fertilizers without viable bacteria, as shown in Figure 2.

[0142] This invention's No. 1 liquid fertilizer integrates multiple functions, including rapid growth promotion, calcium activation, microbial soil improvement, and root strengthening and stress resistance. While leveraging the rapid yield-increasing advantages of high-chlorine fertilizers, it compensates for the shortcomings of traditional fertilizers in soil improvement and physiological protection, achieving a synergistic balance between rapid growth and yield increase, soil maintenance, and plant stress resistance. Its comprehensive application effect is superior to ordinary commercially available high-chlorine liquid fertilizers. Short-term application of this liquid fertilizer can rapidly promote lettuce growth, especially significantly promoting root development. Chloride ions can effectively increase the availability of exchangeable calcium in the soil, avoiding the drawbacks of traditional high-chlorine fertilizers that only focus on growth promotion without improving soil structure. It is suitable for small-scale, immediate application by farmers and short-term rapid-growth cultivation scenarios, and its effect is superior to traditional high-chlorine fertilizers without microorganisms.

[0143] Example 1# High-chlorine liquid fertilizer has multiple advantages, including rapid yield increase, strong root growth, enhanced photosynthetic stress resistance, soil nutrient activation, optimized soil microecology, good storage properties, and ease of application. In short-term, fast-growing leafy vegetable cultivation, this liquid fertilizer is fast-acting and highly practical. It can meet farmers' production needs for rapidly increasing income while improving the rhizosphere growth environment and enhancing the physiological stress resistance of lettuce. It is a high-quality, high-efficiency special liquid fertilizer for short-term, fast-growing butter lettuce cultivation in greenhouses.

[0144] 2. Field application trials Soil type: Vegetable planting base, soil type is neutral loam, pH 7.1, organic matter content 1.8%, available potassium 120mg / kg, previous crop was tomato.

[0145] Experimental design: Two treatment groups were set up, with three plots in each group, each covering an area of ​​20m². 2 The cells are arranged in random groups with a spacing of 1.5m between cells and a 1m wide protective row around them to avoid cross-contamination.

[0146] Treatment 1: Apply liquid fertilizer #2 of Example 2 of this invention (seal and stored for 6 months), at a rate of 1000L / hectare, using drip irrigation in 3 applications: 30% during the seedling establishment period (7 days after transplanting), 35% during growth period 1 (22 days after transplanting), and 35% during growth period 2 (37 days after transplanting).

[0147] Treatment 2: Apply traditional single potassium sulfate type microbial liquid fertilizer 4#-0 (product stored for one month, viable bacteria count > 1 billion / mL, total nutrients N:P2O5:K2O=40:40:120), with the same application rate, application time and method as treatment 1.

[0148] Cultivation and Management: The variety planted is "Italian lettuce". Seeds are soaked in warm water (55℃ hot water for 15 minutes) to promote germination before sowing. Seedlings are transplanted when they are 26 days old, with a planting density of 30 plants / m². 2 Regular irrigation was used throughout the growing season to maintain soil moisture at 60-70%, weeding was done manually, and no pests or diseases occurred during the growing season (no pesticides were used).

[0149] Measurement results: The yield of treatment 1 plot was 128.6 kg / 20m². 2 Compared to treatment 2, which had a concentration of 101.5 kg / 20m³, treatment 2 had a concentration of 101.5 kg / 20m³. 2 The yield increased by 26.7%; the fresh weight of a single plant was 214.3g / plant, which was 25.5% higher than the 170.8g / plant of treatment 2. Under the same planting density and water and fertilizer management mode, this liquid fertilizer can significantly promote the vegetative growth of lettuce, greatly increase the yield of the whole plant, and has a high yield increase and stable performance in the field. It fully meets the high-yield planting needs of large-scale vegetable bases and effectively improves the economic benefits of planting.

[0150] like Figure 3 As shown, the vitamin C content was 5.38 mg / 100g, a 24.83% increase compared to 4.31 mg / 100g in treatment 2, effectively improving the nutritional value of lettuce, enhancing its taste and flavor, and meeting the market demand for high-quality vegetables. The nitrate content was 286.3 mg / kg, a 27.0% decrease compared to 392.1 mg / kg in treatment 2, significantly inhibiting excessive accumulation of nitrate nitrogen in the plant, reducing the safety risks of raw consumption, meeting the standards for green and pollution-free leafy vegetable production, and helping agricultural products reach market standards.

[0151] The available phosphorus content in the soil was 45.8 mg / kg, which was 18.7% higher than that in treatment 2 (38.6 mg / kg). This effectively activated fixed phosphorus in the soil, improved the utilization rate of medium and macro elements, reduced fertilizer waste, continuously improved the soil fertility in continuously cropped plots, alleviated the nutrient obstacles left by previous crops, and achieved a combination of land use and land conservation.

[0152] The liquid fertilizer in Example 2 of this invention can significantly increase the number of soil bacteria and fungi, and greatly improve the overall microbial activity of the soil. The number of soil bacteria in Treatment 1 was 2.8 × 10⁻⁶. 7 cfu / g, compared to 1.6 × 10⁻⁶ in treatment 2. 7 CFU / g increased by 75.0%; soil fungal count was 1.5 × 10⁻⁶. 5 cfu / g, compared to 0.9×10 in treatment 2. 5 The CFU / g ratio increased by 66.7%; the proportion of generalized soil bacterial species was 51.95%, an increase of 14.9% compared to 45.2% in treatment 2; and the proportion of generalized soil fungal species was 65.44%, an increase of 13.2% compared to 57.8% in treatment 2. This liquid fertilizer can increase the proportion of generalized soil bacterial and fungal species, resulting in a healthier and more stable microbial community structure. It can enhance the soil's self-regulating ability, inhibit the growth of soil-borne harmful microorganisms, reduce continuous cropping obstacles and the probability of soil-borne diseases, improve the overall soil's resistance to stress and diseases, reduce pesticide use, and align with green planting models.

[0153] Figure 3 The bar chart shows the comparison of lettuce yield and quality indicators between treatment 1 (liquid fertilizer 2# (long-term storage type) in Example 2) and treatment 2 (traditional single potassium sulfate microbial liquid fertilizer 4#-0) in the field application test. It illustrates that compared with traditional fertilizers, the liquid fertilizer of the present invention has a significant effect on improving crop yield and quality.

[0154] Liquid fertilizer #2, after 6 months of storage, still maintained an effective viable bacteria count of 1.23 billion / mL. (Specific details are as follows...) Figure 2 As shown, the viable bacteria survival rate far exceeds industry standards and that of control fertilizers. The strains are resistant to storage and environmental degradation, making them suitable for large-scale stockpiling and long-term storage without bacterial inactivation or fertilizer efficacy decline. They are convenient to store and transport, and offer long-lasting effects, making them ideal for large-scale procurement and storage in large quantities. In large-scale field cultivation, they not only significantly improve lettuce yield and quality and reduce nitrate accumulation, but also optimize soil microbial community structure and improve soil nutrient availability. Their stability and application effects are superior to traditional fertilizers, making them suitable for large-scale long-term storage and large-area leafy vegetable cultivation.

[0155] In the context of continuous tomato cropping and natural field growth, this fertilizer, through its dual effects of balanced nutrient regulation and microbial ecological improvement, enhances the lettuce's own nutrient metabolism and stress resistance, reduces quality deterioration under adverse conditions, and improves the rhizosphere soil environment, thereby enhancing the soil's resistance to continuous cropping and nutrient stress. It is more adaptable in both open-field and facility-based field settings, and its overall stress resistance performance is far superior to traditional single potassium sulfate liquid microbial fertilizer.

[0156] Example 2# Long-term storage liquid fertilizer has multiple core advantages, including high yield and efficiency, improved quality and reduced harm, activated soil fertility, optimized microbial ecology, long-term stability and storage resistance, and easy promotion in the field. It can not only achieve a significant increase in the yield of leafy vegetables and optimize the fresh quality, but also continuously repair and improve the soil of continuously cropped farmland, taking into account both short-term high yield benefits and long-term soil conservation benefits. It is the preferred high-efficiency special liquid fertilizer for large-scale vegetable bases to grow lettuce and various leafy vegetables.

[0157] 3. Application Experiment in Saline-Alkali Land Soil type: Saline-alkali experimental field, soil type is slightly saline loam, pH 8.3, total salt content 0.3%, organic matter content 0.8%, available potassium 85mg / kg.

[0158] Experimental design: Two treatment groups were set up, with three plots in each group, each covering an area of ​​15m². 2 The plots are randomly arranged with a spacing of 1m; Treatment 1: Apply liquid fertilizer No. 3 of Example 3 of this invention at a rate of 950L / hectare, applied in 3 applications by drip irrigation.

[0159] Treatment 2: Apply Comparative Example 3 liquid fertilizer 3#-0 (bacterial-free, humic acid-free) in the same amount and method as Treatment 1.

[0160] Cultivation and Management: The planted variety is salt-tolerant lettuce. Seedlings are transplanted at 28 days old, with a planting density of 28 plants / m². 2 Conventional irrigation (using drip irrigation to avoid soil salinization) and manual weeding.

[0161] Results: The fresh weight of individual plants in Treatment 1 was 186.5 g / plant, a 31.1% increase compared to 142.3 g / plant in Treatment 2. Despite the dual adverse conditions of low soil fertility and salinity stress, a significant yield increase was still achieved, effectively addressing the production challenges of weak growth and low yield in saline-alkali land crops. After applying Liquid Fertilizer No. 3, the fresh weight of the root system was 42.8 g / plant, a 40.3% increase compared to 30.5 g / plant in Treatment 2. The root-promoting increase was far greater than that of the above-ground parts. A well-developed root system enhances the plant's ability to establish itself in high-salt and high-alkali environments, improves water and nutrient absorption efficiency, and strengthens the foundation for growth and stress resistance in saline-alkali land.

[0162] After harvest, the soil pH of Treatment 1 was 7.9, a decrease of 3.7% compared to 8.2 in Treatment 2. The liquid fertilizer in Example 3 of this invention can effectively neutralize soil alkalinity, improve the strongly alkaline rhizosphere environment, and overcome the drawback of high alkalinity inhibiting nutrient activation. The total salt content of the soil in Treatment 1 was 0.24%, a decrease of 17.2% compared to 0.29% in Treatment 2. It can rapidly leach and adsorb free salts in the soil, inhibit the accumulation of soil salts on the surface and the phenomenon of salt return, significantly reduce the osmotic stress of salt ions on crop roots, and optimize the basic growth environment of saline-alkali land.

[0163] Treatment 1 showed a leaf relative water content of 89.6%, an increase of 8.9% compared to Treatment 2's 82.3%. This indicates that the fertilizer can regulate water metabolism within the plant, enhance cellular water retention capacity, and significantly improve lettuce's resistance to multiple stresses, including salt, drought, and alkali. It also reduces problems such as wilting, stunted growth, and stunted development caused by salt and alkali stress, enhancing the plant's survival and normal growth under adverse conditions. Liquid fertilizer #3, after 3 months of storage, had a viable bacteria count of 900 million / mL. Upon application to the soil, it can quickly colonize, and the beneficial bacteria can decompose nutrients in saline-alkali soil, addressing the difficulties in nutrient fixation and absorption in saline-alkali land. This improves the utilization rate of nitrogen, phosphorus, potassium, and trace elements, achieving efficient nutrient supply to soils under adverse conditions.

[0164] The liquid fertilizer No. 3 in Example 3 is a medium-chlorine, high-sulfur formula suitable for slightly saline-alkali soils. Through the synergistic effect of a neutral liquid system and microorganisms, it reduces soil pH and total salt content, improves crop drought and salt tolerance, and has better root development and above-ground growth than commercially available saline-alkali soil-specific fertilizers. It solves the problems of "low nutrient utilization and poor crop growth" in saline-alkali soils and is suitable for leafy vegetable cultivation in slightly saline soils in coastal and northwestern regions.

[0165] 4. Home gardening application experiment Experimental materials: Potted plants on a home balcony, 15cm in diameter and 18cm in height, each containing 2kg of neutral garden soil, pH 7.2, and 1.0% organic matter content; 18-day-old seedlings of "oilseed rape" to verify the applicability of similar leafy vegetables.

[0166] Experimental design: Two treatment groups were set up, with 5 pots in each group and 2 seedlings planted in each pot. The plants were placed on a home balcony under natural light and at a temperature of 15-28℃.

[0167] Treatment 1: Apply liquid fertilizer #4 from Example 4 of this invention at a rate of 15 mL / pot by root irrigation. Apply once during the seedling establishment period (3 days after transplanting) and once during the growth period (15 days after transplanting).

[0168] Treatment 2: Water control, application rate 15mL / pot, applied by root irrigation, application time is the same as treatment 1.

[0169] Cultivation and Management: The trial period is 30 days (short-term harvest scenario in home gardening). Water once a week (100mL of water per pot each time), natural light, 8-10 hours of light per day, no need for fertilization or pest and disease control.

[0170] Results: Under simple home cultivation conditions, the application of No. 4 liquid fertilizer significantly increased the growth indicators of romaine lettuce. The plant height of treatment 1 was 22.5 cm, a 42.4% increase compared to 15.8 cm in treatment 2; the fresh weight per plant was 38.6 g / plant, an 81.2% increase compared to 21.3 g / plant in treatment 2; and the total yield per pot was 77.2 g / pot, an 81.2% increase compared to 42.6 g / pot in treatment 2. Only two simple root irrigation applications were needed to rapidly accumulate biomass within a short period of 30 days, completely improving the problems of slow growth and low yield in home potted vegetables, easily achieving high yields and increased income from balcony vegetable cultivation.

[0171] The leaf chlorophyll content (SPAD) was 45.8, a 40.5% increase compared to 32.6 in treatment 2. The leaves were dark green and bright, indicating a significant improvement in photosynthetic efficiency. The sufficient accumulation of photosynthetic products can not only accelerate plant growth but also enhance the plant's resistance to low light and temperature fluctuations, improve the growth weakness caused by insufficient light and variable environment in balcony cultivation, and maintain the plant's healthy physiological state.

[0172] This invention's liquid fertilizer #4 exhibits excellent root-promoting effects, with root length reaching 35.2cm, a 54.4% increase compared to Treatment 2's 22.8cm. The well-developed and robust root system significantly enhances the absorption of water and nutrients from the potting soil. In unsuitable cultivation environments such as uneven lighting, large temperature fluctuations, and nutrient-poor soil, it strengthens the plant's adaptability, effectively alleviating growth inhibition caused by adverse conditions and improving overall growth stability. Both Treatment 1 and Treatment 2 showed a 0% incidence of root burn, and Treatment 1 exhibited a 0% leaf yellowing rate, a 100% reduction compared to Treatment 2's 5.3%, completely eliminating yellowing. This effectively prevents problems such as yellowing and premature wilting of leaves caused by nutrient deficiencies and imbalances, significantly improving the appearance and marketability of home-grown vegetables.

[0173] The liquid fertilizer #4 of Example 4 of this invention is a sulfur-chlorine balanced formula with a mild application rate. Under standardized dosage, the incidence of root burn is 0%, with a dosage of 15mL / pot. There is no risk of root burn or yellowing, making it suitable for home gardening scenarios such as balconies and small potted plants. It eliminates the common problems of root burn and seedling burn associated with household fertilizers. Compared to the water control, it significantly promotes plant height, fresh weight, and root development in similar leafy vegetables such as romaine lettuce, with a significant increase in chlorophyll content, bright leaf color, and doubled yield per pot. It is also easy to use, requiring no dilution and can be directly applied to the roots, solving the pain points of "difficult fertilization and easy root burn" in home gardening. This verifies the universality of the liquid fertilizer of this invention in similar leafy vegetables.

[0174] 5. Application trials in facility agriculture Soil type: greenhouse, the soil is chlorine-sensitive soil for continuous cropping of lettuce for 3 years (pH 6.5, chloride ion content 35mg / kg, organic matter content 1.5%, available potassium 95mg / kg).

[0175] Experimental design: Two treatment groups were set up, with three plots in each group (10m²). 2 The cells are randomly arranged with a spacing of 1 meter.

[0176] Treatment 1: Apply liquid fertilizer 7# of Example 7 of this invention at a rate of 900L / hectare, using drip irrigation in 3 applications (once each during the seedling establishment period, growth period 1, and growth period 2).

[0177] Treatment 2: Apply commercially available chlorine-free microbial liquid fertilizer (labeled viable count ≥1 billion / mL, total nutrients N:P2O5:K2O=40:40:120), with the same application rate and method as Treatment 1.

[0178] Cultivation and Management: The variety planted is "purple leaf lettuce", with a planting density of 35 plants / m². 2 The greenhouse temperature is controlled at 15~25℃, the relative humidity is 60~70%, and regular irrigation and manual weeding are carried out, with no pests or diseases occurring.

[0179] The test results showed that the fresh weight of a single plant in treatment 1 was 198.6 g / plant, which was 20.2% higher than that in treatment 2 (165.3 g / plant). This indicates that the liquid fertilizer of the present invention can still maintain vigorous vegetative growth under the adverse conditions of continuous cropping and closed facilities, resulting in robust plant growth and stronger resistance to lodging, premature aging, and weak field stress.

[0180] The vitamin C content was 45.2 mg / 100g, which was 22.8% higher than that of treatment 2 (36.8 mg / 100g). Vitamin C is an endogenous antioxidant in plants. The increased content can directly enhance the plant's antioxidant capacity, resistance to high temperature, drought, and pest and disease infection, thus achieving a dual improvement in growth and fruit quality under adverse conditions.

[0181] The nitrate reductase activity was 21.3 U / g·h, which was 36.5% higher than that of treatment 2 (15.6 U / g·h). This enzyme is a core key enzyme in crop nitrogen metabolism. The increased activity can enhance the plant's nitrogen assimilation efficiency, reduce the accumulation of nitrate nitrogen in the plant, strengthen the stability of plant nutrient metabolism, and improve the plant's growth adaptability under adverse conditions such as low light, low temperature, and high-density cultivation.

[0182] The soil chloride ion content was 38.2 mg / kg, which was 10.1% lower than the 42.5 mg / kg in treatment 2. This indicates that the embodiments of the present invention can effectively reduce the accumulation of chloride salts in the soil, alleviate the chloride ion toxicity that is common in greenhouse fields and continuous cropping fields from the source, and avoid crop salt stress damage.

[0183] The leaf edge scorching rate was 0.8%, a 75.0% decrease compared to 3.2% in Treatment 2. Leaf edge scorching is a typical physiological stress symptom caused by high temperature, drought, nutrient imbalance, and salt damage in lettuce. This indicates that the liquid fertilizer of this invention can effectively alleviate leaf water loss and cell damage caused by stress, and improve the plant's field tolerance to stress. After 6 months of storage, the viable bacteria count of Liquid Fertilizer #7 was 850 million / mL, a 37.1% increase compared to 620 million / mL in Treatment 2, far exceeding the qualified viable bacteria standard in the microbial fertilizer industry. This indicates that the formula system is resistant to long-term storage and environmental temperature fluctuations, has strong dormancy stability of the strains, and is not prone to viable bacteria inactivation or microbial community decline. It has extremely strong resistance to storage and transportation stress, and can exert a long-term bioregulatory effect after field application, unaffected by short-term storage or field storage environment.

[0184] The activity of soil catalase was 28.6 U / g·h, which was 28.3% higher than that of treatment 2 (22.3 U / g·h). This enzyme is a core antioxidant enzyme in soil, which can rapidly decompose toxic and harmful substances such as hydrogen peroxide in the soil, alleviate soil acidification, continuous cropping obstacles and tillage stress, optimize the rhizosphere microecological environment, reduce the damage of soil-borne stress to lettuce roots, strengthen the underground root base of plants to resist stress, and adapt to the harsh growth environment of soil in long-term continuous cropping facilities.

[0185] The liquid fertilizer #7 of Example 7 of this invention uses a full-sulfur, chlorine-free formula, suitable for chlorine-sensitive continuous cropping soils and facility agriculture scenarios. It can significantly improve the quality of lettuce (such as vitamin C content and nitrate reductase activity) and reduce leaf scorch rate; and after 6 months of storage, the viable bacteria count still reaches 850 million / mL (specifically as follows). Figure 2 As shown in the image, this all-sulfur, chlorine-free liquid fertilizer exhibits superior stability and soil improvement compared to commercially available chlorine-free fertilizers, making it the preferred formula for cultivating high-quality lettuce (especially specialty varieties). This liquid fertilizer combines the triple advantages of plant physiological stress resistance, soil stress improvement and resistance, and fertilizer storage stability and stress resistance. It is precisely suited for high-stress cultivation scenarios such as chlorine-sensitive crops, continuous cropping fields, and greenhouses. It can alleviate chloride toxicity, reduce continuous cropping obstacles, and mitigate physiological diseases, while also strengthening plant metabolic stress resistance and soil ecological buffering capacity. Furthermore, the microbial strain is long-lasting and stable, resulting in comprehensive stress resistance performance far superior to conventional commercially available chlorine-free liquid fertilizers. It is a high-quality stress-resistant liquid fertilizer specifically designed for lettuce cultivation under stress.

[0186] 6. Second trial of potted plant application Experimental materials: Experimental pots with a diameter of 25cm and a height of 20cm were selected. Each pot contained 10kg of non-chlorine-sensitive soil with a pH of 7.3, an organic matter content of 1.2%, and an exchangeable calcium content of 150mg / kg. 26-day-old "Butter Lettuce" seedlings were selected.

[0187] Experimental design: Set up group treatments, with 3 pots per group and 1 seedling planted in each pot, and placed in a greenhouse (temperature 18~28℃, light 12h / d).

[0188] Treatments 1-7: Apply liquid fertilizer 1#-7 of Examples 1-7 of the present invention, which has been stored for 1 month, at a rate of 80mL / pot, by root irrigation. Apply once during the seedling establishment period (5 days after transplanting) and once during the growth period (20 days after transplanting).

[0189] Cultivation and management: The trial period was 35 days (short-term fast-growing harvest scenario). Water was applied once every 5 days to maintain soil moisture at 60-70%. No pest or disease control measures were implemented.

[0190] Figure 4 shows the results of linear regression analysis on the sulfur-to-chlorine ratio and the vitamin C (VC) content and nitrate reductase (NR) activity in lettuce. As shown in the figure, the sulfur-to-chlorine ratio is significantly positively correlated with the VC content of lettuce (y = 2.73 + 0.08·x, R0). 2 = 0.70), as the sulfur-chlorine ratio increased from 0:120 to 120:0, the vitamin C content of lettuce increased from approximately 3.5 mg / 100g to 9.5 mg / 100g, an increase of 171.4%. Reasonably increasing the sulfur ratio can effectively promote the synthesis of antioxidants in plants, which not only improves the taste and flavor of lettuce and enhances its nutritional value, but also strengthens the plant's antioxidant capacity and enhances its physiological resistance to environmental stresses such as high temperature and low light, achieving a dual improvement in appearance quality and internal nutrition.

[0191] The sulfur-to-chlorine ratio was significantly positively correlated with NR activity (y = -0.07 + 0.04·x, R). 2 = 0.78), NR activity increased from approximately 0.55 U / g·h to 2.95 U / g·h, an increase of 436.4%. Nitrate reductase is a core functional enzyme in the decomposition and transformation of nitrate nitrogen in vegetables. The significant increase in its activity accelerates the degradation and assimilation of nitrates in plants, effectively reducing excessive nitrate accumulation in lettuce. This not only meets the standards for green and pollution-free vegetable production but also avoids problems such as excessive vegetative growth and unbalanced growth caused by nitrogen metabolism disorders, improving crop nutrient utilization efficiency and physiological growth stability. The above results verify the synergistic regulatory effect of sulfur and chlorine on quality; indicating that different sulfur-chlorine ratios in the liquid fertilizer of this invention are key factors in regulating the nutritional quality and nitrogen metabolism efficiency of lettuce. The high-sulfur, low-chlorine ratio can significantly promote VC synthesis and nitrate reduction, reducing the risk of nitrate accumulation in vegetables, and verifying the scientific validity and rationality of the seven sulfur-chlorine gradient formulation design of this invention.

[0192] Figure 5Stacked bar graphs of soil fungal and bacterial community structure at the phylum level under different sulfur-to-chlorine ratio treatments. The results showed that the sulfur-to-chlorine ratio significantly affected the composition of the soil microbial community: in the fungal community, with the increase of the sulfur-to-chlorine ratio (K2O provided by potassium sulfate and potassium chloride from 0:120 to 120:0), the relative abundance of the dominant phylum Olpidiomycota increased from about 60% to 80%, while the abundance of Ascomycota, which is associated with potential pathogens, decreased significantly. This effectively inhibited the reproduction of soil-borne harmful bacteria, reduced the occurrence of soil-borne diseases, and lowered the risk of disease stress from continuous cropping in greenhouse cultivation. In the bacterial community, Pseudomonadota, as the core dominant phylum, maintained high abundance in all treatments, with optimal community diversity and stability. This ensures stable soil microbial community structure and excellent bacterial diversity, enhances the soil's buffering capacity, self-purification capacity, and nutrient conversion capacity, continuously improves the rhizosphere growth microenvironment, and achieves targeted regulation of the bacterial community through the synergistic effect of sulfur and chlorine nutrition. Unlike the blind fertilization mode of ordinary fertilizers, it has the dual functions of soil improvement and antibacterial action, as well as ecological root protection. Long-term application can sustainably restore the soil ecology of potted plant facilities.

[0193] The above results show that the sulfur-chlorine gradient formulation of the present invention can directionally regulate the soil microbial community structure, enrich beneficial microorganisms, inhibit potential pathogens, and achieve systematic improvement of the soil micro-ecological environment, thus verifying the scientific nature and ecological rationality of the formulation design.

[0194] Sulfur participates in the synthesis of amino acids and vitamins in plants, while chlorine participates in photosynthesis and osmotic regulation. A scientific ratio of the two can achieve nutritional complementarity. Low-chlorine, high-sulfur formulations focus on improving quality, reducing nitrates, improving soil, and enhancing stress resistance, while high-chlorine, low-sulfur formulations focus on rapid growth promotion and increased yield. A balanced sulfur-chlorine ratio takes into account both growth vigor and safety, and can be flexibly selected according to planting goals, perfectly balancing the three core production needs of vegetable yield, stress resistance, and food safety.

[0195] This invention features a gradient sulfur-chlorine ratio to stably supply potassium to crops. Through dual verification using physiological and microbiological indicators, the functional differences between different sulfur-chlorine ratios are clearly defined, and the formulation design is supported by strong theoretical and experimental evidence. The appropriate formulation can be flexibly selected based on soil type, crop chlorine tolerance, and cultivation method: a high-chlorine, low-sulfur formulation is suitable for promoting growth and increasing yield in non-chlorine-sensitive soils; a high-sulfur, low-chlorine, and chlorine-free formulation is suitable for chlorine-sensitive crops and for reducing salinity and improving soil quality in continuously cropped facilities; and a balanced sulfur-chlorine formulation is suitable for gentle cultivation in home gardening, achieving a single series of fertilizers covering all planting needs.

[0196] This invention achieves a synergistic effect of promoting growth, improving quality, and enhancing soil quality through precise control of the sulfur-chlorine ratio. It is the first to construct a continuous sulfur-chlorine gradient formulation system and clearly defines the relationship between the sulfur-chlorine ratio and vitamin C in lettuce. The significant positive correlation between nitrate content and nitrate reductase activity quantitatively reveals the regulatory mechanism of sulfur and chlorine synergistic effects on crop quality and nitrogen metabolism, providing a predictable scientific basis for the optimization of liquid fertilizer formulations specifically for leafy vegetables. This invention also achieves precise functional matching for different scenarios through high-chlorine formulations for rapid growth promotion, high-sulfur formulations for nitrate reduction and quality improvement, and balanced sulfur and chlorine formulations for gentle adaptation. Simultaneously, the formulations integrate highly active, storage-resistant microbial communities, which, after application to the soil, can directionally regulate the microbial community structure, enrich beneficial bacteria, and inhibit pathogens, providing both soil improvement and stress resistance effects, overcoming the shortcomings of traditional liquid fertilizers such as easy inactivation and single function. This series of formulations covers diverse scenarios including short-term potted rapid growth, large-scale field cultivation, saline-alkali land improvement, and home gardening, and is suitable for various leafy vegetables such as butter lettuce, Italian lettuce, and romaine lettuce. It exhibits stable yield and quality improvement, salt reduction and soil improvement, and enhanced stress resistance effects under different soil types and cultivation modes, combining scientific innovation with application and promotion value.

[0197] 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 liquid fertilizer with synergistic sulfur and chlorine regulation, characterized in that, Includes the following steps: Step (1) Solid nutrient pretreatment: Nitrogen and phosphorus sources are crushed; soil conditioner is dried, cooled and then crushed; potassium source is ground; potassium source is potassium sulfate and / or potassium chloride; Step (2) Preparation of base solution: Add a portion of solvent, then add nitrogen source, phosphorus source, soil conditioner and potassium source in sequence, start stirring, gradually increase temperature, stir, adjust pH, and add more solvent; Step (3) Protection system and carbon source addition: Add composite protective agent and carbon source additive to base solution, stir to form matrix solution without layering and precipitation; Step (4) Post-ripening and adaptation of microbial agent: Inoculate the microbial agent into the substrate solution and culture statically in the dark, stirring intermittently during the process; Step (5) Low temperature stabilization: Place the substrate solution containing the bacterial agent from step (4) above in a low temperature environment and let it stand. Sampling and testing of effective viable bacteria count, pH, and total nutrient deviation are performed. After passing the test, the solution is sealed and stored.

2. The preparation method according to claim 1, characterized in that, In step (1), based on 1000L of liquid fertilizer product, the amounts of nitrogen source, phosphorus source and soil conditioner added are 60~325kg, 55~300kg and 100~125kg respectively. In the potassium source, the ratio of potassium sulfate to potassium chloride is (0~720kg): (670~0kg), and the ratio of sulfur to chlorine is 0~720kg: (670~0kg). The nitrogen source is one or more of urea, ammonium nitrate phosphorus, or ammonium nitrate. The phosphorus source is one or more of ammonium polyphosphate, ammonium dihydrogen phosphate, and diammonium hydrogen phosphate; Soil conditioners are one or more of humic acid, fulvic acid, alginic acid, and polyglutamic acid.

3. The preparation method according to claim 1, characterized in that, In step (2), the stirring rate is 100~150r / min, the temperature is increased to 30℃ at a rate of 1℃ every 10min, the stirring is carried out for 30~45min, and the pH is adjusted to 6.7~7.

2.

4. The preparation method according to claim 1, characterized in that, In step (3), the amount of the composite protective agent added is 6.0~9.0 kg, which is composed of glycerol and xanthan gum in a mass ratio of 2~3:1~2; the stirring speed is 100~150 r / min, and the stirring time is 20~25 min; the amount of the carbon source additive added is 0.1~0.2 kg, and the carbon source additive is one or more of mannitol, sorbitol, xylitol, erythritol and arabinitol.

5. The preparation method according to claim 1, characterized in that, In step (4), 0.3-0.8 kg of bacterial agent is added and inoculated into the substrate solution. The mixture is then statically cultured at 28-30°C in the dark for 27-32 hours, with stirring for 10-12 minutes every 7-8 hours at a stirring rate of 100-110 r / min. The bacterial agent is one or more of Bacillus subtilis, Trichoderma harzianum, Bacillus amyloliquefaciens, Bacillus megaterium, Bacillus colloidis, and Paecilomyces lilacinus.

6. A liquid fertilizer with synergistic sulfur and chlorine regulation, characterized in that, It includes 60-325 kg of nitrogen source, 55-300 kg of phosphorus source, 0-720 kg of potassium source, 100-125 kg of soil conditioner, 0.3-0.8 kg of microbial agent, 6.0-9.0 kg of compound protective agent, 0.1-0.2 kg of carbon source additive, and 520-770 kg of solvent.

7. The liquid fertilizer with synergistic sulfur-chlorine regulation according to claim 6, characterized in that, The potassium source is potassium sulfate and / or potassium chloride, with a potassium sulfate:potassium chloride ratio of (0~720kg):(670~0kg). There are seven groups of composite potassium source formulations with different sulfur-to-chlorine ratios: Group 1, S / Cl ratio 0:100, K2O provided by potassium sulfate and potassium chloride in ratio 0:120; Group 2, S / Cl ratio 9:100, K2O provided by potassium sulfate and potassium chloride in ratio 20:100; Group 3, S / Cl ratio 23:100, K2O provided by potassium sulfate and potassium chloride ratio 40:80; Group 4, S / Cl ratio 45:100, K2O provided by potassium sulfate and potassium chloride in ratio 60:60; Group 5, S / Cl ratio 95:100, K2O provided by potassium sulfate and potassium chloride in ratio 80:40; Group 6, S / Cl ratio 227:100, K2O provided by potassium sulfate and potassium chloride ratio 100:20; Group 7 has an S / Cl ratio of 100:0 and a K2O ratio of 120:0 provided by potassium sulfate and potassium chloride.

8. The liquid fertilizer with synergistic sulfur-chlorine regulation according to claim 6, characterized in that, The nitrogen source is one or more of urea, ammonium nitrate phosphorus, or ammonium nitrate. The phosphorus source is one or more of ammonium polyphosphate, ammonium dihydrogen phosphate, and diammonium hydrogen phosphate; The soil conditioner is one or more of humic acid, fulvic acid, alginic acid, and polyglutamic acid; The composite protective agent is composed of glycerin and xanthan gum in a mass ratio of 2~3:1~2; The microbial agent is one or more of Bacillus subtilis, Trichoderma harzianum, Bacillus amyloliquefaciens, Bacillus megaterium, Bacillus mucilaginosus, and Paecilomyces lilacinus. The carbon source additive is one or more of mannitol, sorbitol, xylitol, erythritol, and arabinitol.

9. The liquid fertilizer with synergistic sulfur-chlorine regulation according to claim 6, characterized in that, Liquid fertilizer samples were tested for effective viable bacteria count ≥ 1 billion / mL, pH 6.5~7.5, and total nutrient N:P2O5:K2O deviation ≤ ±2%. After passing the test, the samples were sealed and stored. The storage conditions were 5~25℃, protected from light and sealed. After 6 months of storage, the effective viable bacteria count was ≥ 800 million / mL.

10. The application of a liquid fertilizer with synergistic sulfur and chlorine regulation in leafy vegetable cultivation, characterized in that, The liquid fertilizer is obtained by the preparation method according to any one of claims 1 to 5, or the liquid fertilizer according to any one of claims 6 to 9; Leafy vegetables include lettuce, romaine lettuce, and spinach; the application rate is: 750~1000L / hectare for field crops, 900~950L / hectare for greenhouse agriculture, and 15~80mL / pot for potted plants in home gardening; the application method is drip irrigation or root irrigation, and it is applied 12 times during the seedling establishment period and the growth period.

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