Method for synergistically preparing high-calcium mineral organic water-soluble fertilizer and citrate-soluble mineral fertilizer from shellfish solid waste and agriculture and forestry biomass

Abstract

The invention discloses a method for synergistically preparing a high-calcium mineral organic water-soluble fertilizer and a citrate-soluble mineral fertilizer from shellfish solid waste and agriculture and forestry biomass. Through cooperation of multi-stage activation and catalysis, the conversion activity of calcium and the quality of humic acid are remarkably improved, the process route integration degree is high, and the technicality is high. The content of water-soluble calcium in the obtained product is more than or equal to 10%, the content of humic acid is more than or equal to 30%, medium trace elements are rich, quick-acting and long-acting fertility is achieved, crop growth can be remarkably promoted, the soil aggregate structure is improved, heavy metal is passivated, crop stress resistance is enhanced, and a new way is provided for high-added-value resource utilization of the two kinds of waste.

Description

Technical Field

[0001] This invention relates to the field of bio-fertilizer and solid waste resource utilization technology, and in particular to a method for synergistically producing high-calcium mineral organic water-soluble fertilizer and citrate-soluble mineral fertilizer from shellfish solid waste and agricultural and forestry biomass. Background Technology

[0002] Shellfish waste is a major solid waste generated from seafood processing. Its main component is calcium carbonate (CaCO3, typically containing over 90%), and it is rich in various trace elements such as magnesium, zinc, and selenium, making it a high-quality and inexpensive natural source of calcium. However, current methods of disposing of shellfish waste mainly involve landfilling or simple processing into low-value-added building materials. This not only leads to a serious waste of calcium resources and land accumulation, but its decomposition leachates may also pose potential risks to the surrounding soil and aquatic ecosystems.

[0003] On the other hand, agricultural and forestry biomass solid waste (such as straw, rice husks, and sawdust) has a huge annual output. It is rich in cellulose, hemicellulose, and lignin, and can be converted into humic acid and other high-value-added soil amendments through thermochemical transformation. However, biomass pyrolysis alone generally faces bottlenecks such as complex product composition, limited content of target functional groups, and non-concentrated fertilizer effects, which restrict its efficient agricultural application.

[0004] While existing technologies have explored co-pyrolysis of shells and biomass, most studies focus on the preparation of biochar materials for adsorption or soil passivation. However, there is a significant lack of systematic process design for a series of fertilizer products with both high calcium activity and high humic acid content. In particular, there is a lack of effective regulation of the directional transformation of calcium forms and the synergistic mechanism of organic component complexation during the reaction process, failing to achieve the goal of high-value utilization through "waste treatment and waste-to-waste integration." Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings and deficiencies of the prior art and to provide a method for the synergistic production of high-calcium mineral organic water-soluble fertilizer and citrate-soluble mineral fertilizer from shellfish solid waste and agricultural and forestry biomass.

[0006] The objective of this invention is achieved through the following technical solution: A method for co-producing high-calcium mineral organic water-soluble fertilizer and citrate-soluble mineral fertilizer from shellfish solid waste and agricultural and forestry biomass includes the following steps: (1) Mix the shell powder with an acid solution, heat and stir to react, filter, and dry the resulting solid to obtain activated shell powder; (2) Mix activated shell powder with biomass powder, add catalyst, grind and mix, heat and pyrolyze under a protective atmosphere, and obtain pyrolyzed solid after cooling; (3) Mix the pyrolysis solid obtained in step (2) with an alkaline solution, add a dispersant, stir and extract, filter, concentrate and dry the filtrate to obtain a high-calcium mineral organic water-soluble fertilizer, dry and pulverize the filter residue to obtain a citrate-soluble mineral fertilizer.

[0007] The shell powder mentioned in step (1) is obtained by drying, crushing and sieving the shells of shellfish; preferably, it includes oyster shells and mussel shells.

[0008] The sieving process mentioned refers to passing through a 100-200 mesh sieve.

[0009] The acid solution mentioned in step (1) is at least one of a 1-5 wt% citric acid solution, ascorbic acid solution, EDTA and malic acid mixture.

[0010] The heating and stirring reaction conditions described in step (1) are: heating in a water bath at 50-70°C for 1-3 hours.

[0011] The ratio of seashell powder to acid solution in step (1) is 1g: 5-10mL.

[0012] The ratio of activated shell powder to biomass powder in step (2) is 1:1 to 5.

[0013] The biomass powder mentioned in step (2) includes at least one of rice straw powder and wood chip powder.

[0014] The catalyst mentioned in step (2) includes at least one of ferric chloride and ferric sulfate.

[0015] The amount of catalyst added in step (2) is 1 to 5% of the total mass.

[0016] The protective atmosphere described in step (2) is a high-purity nitrogen, carbon dioxide, or argon atmosphere.

[0017] The heating and pyrolysis conditions described in step (2) are to heat to 350-400℃ at a rate of 5-10℃ / min and pyrolyze for 90-150 minutes.

[0018] The alkaline solution mentioned in step (3) includes at least one of 1-5% ammonia water, 1-2 mol / L KOH solution, and 1-2 mol / L NaOH solution.

[0019] The ratio of the pyrolysis solid to the alkaline solution in step (3) is 1g:6-8mL.

[0020] The dispersant mentioned in step (3) includes at least one of pyrophosphate and sodium hexametaphosphate.

[0021] The amount of dispersant added in step (3) is 0.1 to 0.5% of the total mass.

[0022] The extraction in step (3) is performed at 70-90℃ and 200-400 r / min for 30-90 min.

[0023] The filtration described in step (3) is vacuum filtration through filter paper with a pore size of 10-20 μm.

[0024] A high-calcium mineral organic water-soluble fertilizer is prepared by the above-mentioned preparation method.

[0025] A citrate-soluble mineral fertilizer is prepared by the above-described preparation method.

[0026] The above-mentioned method for synergistically producing high-calcium mineral organic water-soluble fertilizer and citrate-soluble mineral fertilizer from shellfish solid waste and agricultural and forestry biomass is applied in fertilizer preparation.

[0027] The present invention has the following advantages and effects compared with the prior art: (1) Synergistic effect and turning waste into treasure: This invention innovatively combines marine solid waste (shell solid waste) with agricultural and forestry solid waste (biomass). Through the multi-step reaction design of organic acid pretreatment and transition metal catalytic pyrolysis, the efficiency of calcium dissolution and humic acid generation is significantly improved. Shells and biomass achieve synergistic transformation at the molecular level, overcoming the problems of insufficient calcium activation and low product activity in traditional processes, and significantly improving the agricultural value of the product.

[0028] (2) Diverse products with both fertilizer and fertilizer effects: Through simple solid-liquid separation, two products are obtained at once: the filtrate is a fast-acting high-calcium water-soluble fertilizer that can be directly used for drip irrigation and foliar spraying; the filter residue is a slow-acting citrate-soluble soil conditioner that can be used to improve soil structure, passivate heavy metals, and provide a long-term calcium source. This achieves a perfect combination of "fast-acting + slow-acting".

[0029] (3) The process is green and the cost is low: the whole process is carried out at a low temperature, the energy consumption is low, and the catalysts and dispersants used are inexpensive and readily available. Most of them can participate in the construction of the final product, and no harmful by-products are generated. The overall process conforms to the principles of green chemistry and has good industrialization prospects.

[0030] (3) Higher activity and easier absorption: The high-calcium humic acid fertilizer prepared by this invention is generated in situ during the pyrolysis process. Its molecular structure and complexation state are closer to natural soil humus. Compared with traditional physical mixing products, it has higher resistance to hard water and higher plant absorption efficiency. Attached Figure Description

[0031] Figure 1 This is a flowchart illustrating the technical process of the present invention.

[0032] Figure 2 The mixture of shellfish solid waste, catalyst, and biomass after pyrolysis catalysis in Example 1 is described.

[0033] Figure 3 This is the calcium-rich mineral organic water-soluble fertilizer obtained in Example 1.

[0034] Figure 4 The growth chart shows the cucumbers grown using the product from Example 1, calcium nitrate fertilizer, and a commercially available brand of organic calcium fertilizer.

[0035] Figure 5 The image shows a comparison of the product in Example 3 and the hydroponic tomato experiment using calcium nitrate fertilizer. Detailed Implementation

[0036] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0037] Unless otherwise specified in the following implementation plan, the test conditions are generally as per standard test conditions or the test conditions recommended by the reagent company. Unless otherwise specified, all materials and reagents used are commercially available.

[0038] Processing of shellfish raw materials: Shellfish solid waste is selected from common oyster shells and mussel shells. After manually removing any remaining meat, the shells are rinsed thoroughly with tap water and then dried in an oven at 105℃ to constant weight (usually ≥12 hours). The shells are then crushed using a high-efficiency pulverizer and passed through a 100-mesh standard sieve to obtain uniform shell powder, which is then sealed and stored for later use. Agricultural and forestry biomass is selected from rice straw, sawdust, and cotton stalks. After rinsing with tap water to remove soil, the materials are also dried at 105℃ to constant weight. The biomass is then crushed using a plant pulverizer and passed through a 100-mesh standard sieve to obtain biomass powder, which is then sealed and stored for later use.

[0039] Example 1: Citric Acid Activated Rice Straw System (1) Take 100g of oyster shell powder (passed through a 100-mesh sieve) and mix it with 800mL of 5wt% citric acid solution. Stir the mixture in a water bath at 60℃ for 2 hours. After the reaction is complete, filter the mixture, wash the filter cake with deionized water until neutral, and dry it at 105℃ to obtain activated shell powder; (2) Take 100g of the above activated oyster shell powder and 100g of rice straw powder (passed through a 100-mesh sieve) and mix them evenly. Then add 4g of ferric chloride (FeCl3·6H2O) as a catalyst and grind and mix thoroughly. (3) Place the mixture in a tube furnace, introduce high-purity N2 (99.99%) to purge the air, and raise the temperature to 380°C at a rate of 10°C / min under the N2 atmosphere. Pyrolyze at this temperature for 2 hours and obtain the pyrolyzed solid after natural cooling. (4) Mix the pyrolysis solid with 800 mL of 1 mol / L KOH solution (solid-liquid ratio 1:8), add 0.4 g of sodium pyrophosphate as a dispersant, and extract by stirring at 300 r / min at 80 °C for 1 hour; (5) Filter while hot to obtain extract and extract residue. Concentrate the extract to 1 / 4 of its original volume at 70°C, then spray dry to obtain a brownish-black powdery high-calcium mineral organic water-soluble fertilizer. Dry the extract residue at 105°C and then pulverize to obtain a grayish-black citrate-soluble mineral fertilizer product.

[0040] Example 2: Mixed acid activated wood chip system (1) Take 75g of oyster shell powder (passed through a 100-mesh sieve) and 1000mL of a mixed solution containing 3wt% EDTA and 2wt% malic acid and place it in a reactor. Stir the mixture at 200r / min for 3 hours under a constant temperature water bath at 50℃. After the reaction is completed, perform vacuum filtration and wash the filter cake repeatedly with deionized water until the washing liquid is neutral. Transfer the filter cake to an oven and dry it at 105℃ to constant weight to obtain activated shell powder for later use. (2) Weigh the above activated oyster shell powder and 75g of sawdust powder (passed through a 100-mesh sieve) and place them in a mixer. Mix at 30r / min for 15 minutes until homogeneous. Then add 3g of ferric sulfate catalyst and continue mixing for 20 minutes to ensure that the catalyst is evenly dispersed in the mixture. (3) Transfer the mixed material to a tubular pyrolysis furnace, introduce high-purity CO2 gas (purity ≥ 99.99%) to purge air, and maintain a gas flow rate of 100 mL / min. Heat to 400℃ at a programmed heating rate of 5℃ / min, and maintain pyrolysis at this temperature for 1.5 hours. After pyrolysis, allow to cool naturally to room temperature to obtain the pyrolysis solid product; (4) The pyrolysis solid and 750 mL of 2% ammonia solution (solid-liquid ratio 1:10) were placed in an extraction reactor, and 0.3 g of sodium pyrophosphate was added as a dispersant. The mixture was stirred and extracted at 300 r / min for 1 hour under constant temperature of 70℃. After extraction, vacuum filtration was performed while hot to separate the dark brown extract and gray-black extract residue. (5) The extract was placed in a rotary evaporator and concentrated to 1 / 5 of its original volume, and then spray-dried to obtain a brown powdery high-calcium mineral organic water-soluble fertilizer product. The extract residue was dried in an oven at 105°C for 12 hours and then processed by an ultra-micro pulverizer to pass through a 200-mesh sieve to obtain a citrate-soluble mineral fertilizer product.

[0041] Example 3 Ascorbic Acid Activated Cotton Stalk System (1) 50g of oyster shell powder (100 mesh) was stirred with 600mL of 4wt% ascorbic acid solution at 70℃ for 1.5 hours. After the reaction, the mixture was filtered, washed until neutral, and dried under vacuum at 80℃ to obtain activated shell powder; (2) Mix the above activated oyster shell powder with 150g cotton stalk powder (100 mesh), add 5g ferric nitrate catalyst, and mix thoroughly. (3) Under an argon atmosphere, the temperature was increased to 350°C at 8°C / min and pyrolyzed for 2.5 hours. After cooling, the pyrolyzed solid was obtained. (4) Mix the pyrolysis solid with 900 mL of 1.5 mol / L NaOH solution (solid-liquid ratio 1:6), add 0.45 g of sodium hexametaphosphate, stir and extract at 90 °C for 0.5 hours, and hot filter to obtain extract and extract residue; (5) After the extract is concentrated, it is freeze-dried to obtain a high-calcium mineral organic water-soluble fertilizer; after the extract residue is dried, it is air-jet pulverized and passed through a 300-mesh sieve to obtain a citric acid-soluble mineral fertilizer.

[0042] Example 4: Mussel shell-rice straw system This embodiment aims to verify the universality of the process of the present invention for shells from different sources. Mussel shells, which differ from those in Example 1 (oyster shells) in structure and composition, were selected as raw materials, and fertilizer products were prepared according to the same process. Key indicators were then compared.

[0043] (1) Take 100g of mussel shell powder (passed through a 100-mesh sieve) and mix it with 800mL of 5wt% citric acid solution. Stir the mixture in a water bath at 60℃ for 2 hours. After the reaction, filter and wash until neutral, and dry at 105℃ to obtain activated mussel shell powder; (2) Mix 100g of activated mussel shell powder with 100g of rice straw powder (passed through a 100-mesh sieve), add 4.0g of ferric chloride (FeCl3·6H2O) catalyst, and mix thoroughly. (3) Under N2 atmosphere, the temperature is increased to 380℃ at 10℃ / min, and pyrolyzed for 2 hours. After cooling, the pyrolyzed solid is obtained. (4) Mix the pyrolysis solid with 800 mL of 1 mol / L KOH solution (solid-liquid ratio 1:8), add 0.4 g of sodium pyrophosphate, stir and extract at 80 °C for 1 hour, and hot filter to obtain extract and extract residue; (5) After the extract is concentrated, it is spray-dried to obtain a high-calcium mineral organic water-soluble fertilizer; after the extract residue is dried and pulverized, a citric acid-soluble mineral fertilizer is obtained.

[0044] Comparative Example 1: Replacing shellfish solid waste with pure calcium carbonate In this comparative example, the oyster shell powder in Example 1 was replaced with common chemical reagent calcium carbonate. The specific steps were exactly the same as in Example 1, except that "100g oyster shell powder" was replaced with "100g analytical grade calcium carbonate powder".

[0045] Comparative Example 2: Pretreatment using hydrochloric acid instead of citric acid In this comparative example, the organic acid pretreatment reagent in Example 1 was replaced with an inorganic strong acid. The specific steps were exactly the same as in Example 1, except that "5wt% citric acid solution" was replaced with "5wt% hydrochloric acid solution".

[0046] Comparative Example 3 (transition metal catalyst omitted) This comparative example investigated the effect of omitting the catalyst. The specific steps were exactly the same as in Example 1, except that ferric chloride catalyst was not added.

[0047] Comparative Example 4 (omitted agricultural and forestry biomass) This comparative study investigated the effect of omitting biomass. The specific steps were as follows: 100g of activated oyster powder obtained in Example 1 was taken, 4g of ferric chloride catalyst was added and mixed, and the same pyrolysis, alkaline extraction and post-treatment steps as in Example 1 were carried out directly without adding rice straw powder.

[0048] Comparative Example 5: Simple Acid Treatment + Physical Mixing Method This comparative example represents a "simple acid treatment + physical mixing" scheme that a person skilled in the art might use, in order to compare its essential differences with the overall synergistic process of this invention.

[0049] (1) Take 100g of oyster shell powder and react it with excess 5% hydrochloric acid solution until no bubbles are produced. Filter to obtain a filtrate rich in calcium chloride. (2) Weigh 40g of commercially available humic acid powder (its humic acid content is equivalent to that of the product in Example 1), add it to the above filtrate, and mechanically stir for 2 hours to mix it thoroughly. (3) The mixture is concentrated at 70°C and spray-dried to obtain a physically mixed "organic calcium fertilizer" product.

[0050] Example 5: Component Detection 5.1 Detection Method The water-soluble calcium content was determined by atomic absorption spectrometry according to "NY / T 1117-2010 Determination of Calcium, Magnesium, Sulfur and Chlorine Content in Water-soluble Fertilizers"—the result is expressed as CaO; the humic acid content was determined according to "GB / T 34766-2017 Determination of Humic Acid Content from Mineral Sources"; the fulvic acid content was determined by volumetric method or ultraviolet spectrophotometry after separation and extraction under acidic conditions; plant height and stem diameter were measured using a ruler and vernier calipers; the SPAD value of chlorophyll was measured using a SPAD-502 chlorophyll meter; root activity was determined using the TTC (triphenyltetrazolium chloride) method; the disease incidence rate was calculated by surveying and statistically analyzing the number of diseased leaves / total number of leaves; for hard water stability testing, 1g of the product of this invention and the product of Comparative Example 5 were dissolved in 100mL of 500mg / L hard water (expressed as CaCO3), and after standing for 2 hours, the flocculation was observed and the calcium retention rate of the supernatant was measured.

[0051] 5.2 Test Results Table 1 Comparison of key component indicators between the examples and comparative examples.

[0052] Note: "—" indicates that the ratio could not be calculated or was not meaningful to calculate due to low or undetectable humic acid content. Total trace elements include elements such as Mg, Zn, Fe, and Se (calculated as oxides). Water-insoluble matter content refers to the proportion of solid impurities in the product that are insoluble in water. pH value is determined after diluting the product at a ratio of 1:250 (mass / volume). Hard water stability: The calcium retention rate in the supernatant after dissolving the product in 500 mg / L (calculated as CaCO3) of hard water and allowing it to stand for 2 hours.

[0053] 5.3 Results Analysis Based on the data in Table 1, the following analysis examines the embodiments and comparative examples from different perspectives: (1) Effects of different organic acid pretreatment systems (Examples 1-3) Citric acid (Example 1), processed under mild conditions, yielded a product with a balanced content of water-soluble calcium (13.8%) and humic acid (39.2%), a moderate pH (8.5), and excellent overall product performance, with a cost advantage. EDTA-malic acid mixed acid (Example 2), pyrolyzed at 400℃ in a CO2 atmosphere, although the water-soluble calcium (12.5%) and humic acid (36.4%) were slightly lower than in Examples 1 and 3, this system had a significant effect on integrating trace elements in shells (total trace elements 1.9%), and the product was richer in various nutrients. Ascorbic acid (Example 3), pyrolyzed at a relatively low temperature of 350℃, yielded the highest content of water-soluble calcium (14.6%) and humic acid (41.3%), and also the highest proportion of fulvic acid (44.1%), indicating that ascorbic acid has unique advantages in promoting low-temperature high-efficiency conversion and generating highly active components.

[0054] All three organic acid systems can successfully achieve the objectives of this invention, but each has its own characteristics. The appropriate acid activation system can be selected according to the focus of the target product (high calcium, high humic acid, rich in trace elements), which reflects the flexibility and universality of the process.

[0055] (2) Applicability of different biomass raw materials (Examples 1, 2, 3) Rice straw, sawdust, and cotton stalks, three common agricultural and forestry wastes, all exhibited good synergistic effects in this process. The cotton stalk system (Example 3) obtained the best organic matter activity indicators (humic acid and fulvic acid), which may be related to the cellulose / lignin composition of the cotton stalks themselves. The sawdust system (Example 2) produced a product with relatively high total trace element content. This indicates that the present invention has broad applicability to biomass from different sources, which is beneficial for the localized acquisition of raw materials in industrialization.

[0056] (3) Synergistic effect of catalyst and pyrolysis conditions All examples used iron-based catalysts, but operated under different pyrolysis temperatures and atmospheres. For example, Example 2, catalytic pyrolysis was performed in a CO2 atmosphere at 400°C, and the product had a slightly higher water-insoluble content (1.1%) than other examples, possibly due to fine-tuning of the degree of carbonization under different atmospheres. Example 3, conducted in an Ar atmosphere at 350°C, achieved highly efficient conversion, demonstrating that the catalyst can effectively drive the reaction under relatively mild conditions, helping to reduce energy consumption.

[0057] (4) Verification of the universality of seashell raw materials (Example 4 and Example 1) Using mussel shells (Example 4) and oyster shells (Example 1) under the same process, the key indicators of the products (water-soluble calcium 13.1% and 13.8%, respectively, and humic acid 38.5% and 39.2%, respectively) were highly similar. The total amount of trace elements in the mussel shell product (2.9%) was even slightly higher than that in the oyster shell product (2.3%), which may be due to the natural differences in trace element composition among different shell species. This result strongly demonstrates that the process of the present invention has a stable conversion effect on different types of shell solid waste, ensuring a reliable source of raw materials for industrialization.

[0058] (5) Analysis of the effect of the proportion Comparative Example 1 (pure calcium carbonate): This invention utilizes natural seashells with unique multi-level structures and rich in trace elements, rather than pure chemicals. This is not only a manifestation of "using waste to treat waste," but also a physicochemical basis for the product to have abundant trace elements (≥1.8% in the example, only 0.4% in Comparative Example 1).

[0059] Comparative Example 2 (hydrochloric acid pretreatment): Organic acid pretreatment (such as citric acid) not only activates calcium dissolution, but also allows the organic acid or its derivatives to participate in molecular complexation during subsequent pyrolysis. This is the key to obtaining low water-insoluble matter (≤1.2% in the example, 8.5% in Comparative Example 2), suitable pH value and high humic acid quality.

[0060] Comparative Example 3 (without catalyst): Transition metal catalysts (such as FeCl3) are the driving force for bridging the inorganic calcium of shellfish and the organic components of biomass, achieving "in-situ molecular-level complexation" under mild pyrolysis conditions. Without it, the calcium dissolution rate and the efficiency and activity (proportion of fulvic acid) of humic acid formation are all significantly reduced.

[0061] Comparative Example 4 (without biomass): Agricultural and forestry biomass is the only source of humic acids, and the active intermediates produced by its pyrolysis are necessary reactants for "organizing" and "activating" the calcium in seashells. Without biomass, it is impossible to produce the core product of this invention—high-calcium mineral organic water-soluble fertilizer.

[0062] Comparative Example 5 (Physical Mixing): The in-situ complexation achieved by the present invention through catalytic co-pyrolysis is fundamentally different from simple physical mixing. This is directly reflected in the product's hard water resistance (calcium retention rates >92% and <30%, respectively) and the proportion of active components (fulvic acid / humic acid ratios >41.8% and 22.0%, respectively). This difference determines that the product of the present invention is less likely to clog pipes in actual agricultural irrigation, and has higher plant absorption and utilization efficiency, as well as better disease prevention and stress resistance effects.

[0063] Example 6: Planting Application Experiment 6.1 Cucumber Cultivation Experiment Experimental Design: A pot experiment was conducted in an artificial climate chamber using the cucumber variety "Jinchun No. 4". Three treatments were set up: T1, applied with the water-soluble fertilizer from Example 1 (diluted 600 times); CK1, applied with an equivalent amount of calcium nitrate solution; CK2, applied with a commercially available brand of organic calcium water-soluble fertilizer (with equivalent calcium content). Each treatment was replicated three times in a randomized block design. Except for the calcium source, all other nutrient management was consistent.

[0064] Cultivation and management: Treatment begins at the three-leaf and one-heart stage of seedlings, with watering every 7 days for a total of 6 treatments. Various indicators are measured 45 days after cultivation.

[0065] Results and Analysis: As shown in the table below, the product of this invention is significantly superior to the two control groups in promoting growth, improving quality, and enhancing stress resistance.

[0066] Table 2. Results of the determination of main indicators in the cucumber cultivation experiment.

[0067] Note: Different letters after the same row of data indicate significant differences at the P<0.05 level.

[0068] 6.2 Hydroponic Tomato Experiment Experimental design: Hoagland's nutrient solution was used as the basal medium, with the product of Example 3 replacing the calcium source (calcium nitrate) in the nutrient solution. The control group (CK) used an equal amount of calcium nitrate. Measurements were taken after 35 days of hydroponics.

[0069] The results are shown in the table below. The product of this invention can significantly promote tomato growth and improve physiological activity and fruit quality.

[0070] Table 3 Comparison of key indicators in the hydroponic tomato experiment (improvement rate relative to the control group)

[0071] 6.3 Experimental Conclusions Based on the results of the cucumber cultivation experiment and the tomato hydroponic experiment, the following conclusions can be drawn: (1) Significant effect in promoting growth and improving quality The high-calcium mineral organic water-soluble fertilizer prepared by this invention has a comprehensive and significant promoting effect on the growth and development of cucumbers and tomatoes under the same calcium content conditions. Specifically, it significantly increases plant height, stem diameter, leaf chlorophyll content (SPAD value), and the number of fruits per plant; at the same time, it greatly improves fruit quality, with significantly higher calcium content, vitamin C, and lycopene content in fruits compared to treatments with calcium nitrate and commercially available organic calcium fertilizers. This indicates that the product of this invention not only provides highly efficient calcium nutrition, but its rich content of humic acid, fulvic acid, and other active organic substances also synergistically exerts multiple functions such as stimulating growth, enhancing photosynthesis, and improving quality.

[0072] (2) Enhance the ability to resist adversity and disease The powdery mildew disease index of cucumbers using the product of this invention (12.5%) was significantly lower than that of the two control groups, and the relative resistance of tomatoes to early blight was also increased by 45.2%. Simultaneously, tomato root activity (TTC reduction) was significantly increased (+63.4%). This strongly demonstrates that the product of this invention, by providing organically bound calcium and active humic acid substances, effectively activates the crop's own physiological metabolism and defense system, enhances root activity, and thus significantly improves the crop's resistance to biotic stress (diseases).

[0073] (3) Product advantages The superior agronomic effects of this invention stem from its unique preparation process. Through in-situ molecular-level complexation achieved via "organic acid pretreatment-transition metal catalytic co-pyrolysis," calcium exists in an organically chelated state that is more easily absorbed and utilized by plants. Simultaneously, the generated humic acid and fulvic acid possess higher bioactivity. This differs from the single inorganic nutrient of calcium nitrate, and also from the simple coexistence of components in physically mixed organic calcium fertilizers. Therefore, this invention achieves an organic combination of "nutrient supply" and "physiological regulation," demonstrating a synergistic fertilizer effect of "1+1>2."

[0074] Based on the comparison results of the above embodiments and comparative examples, this invention, by constructing a multi-step synergistic process system of "organic acid pretreatment - transition metal catalytic co-pyrolysis - alkaline extraction," not only effectively destroys the dense structure of shells and increases reactive sites, but more importantly, achieves in-situ molecular-level complexation of shell calcium with biomass organic components under the action of a catalyst, thereby successfully converting two types of solid waste into high-calcium mineral organic water-soluble fertilizer and citrate-soluble mineral fertilizer. This overall process route exhibits significant synergistic effects and indivisibility. The prepared products are significantly superior to conventional calcium fertilizers and any comparative schemes that omit or replace key steps in terms of nutrient activity, hard water resistance, and actual agronomic effects, fully demonstrating the substantial characteristics and technological progress of this invention.

[0075] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for co-producing high-calcium mineral organic water-soluble fertilizer and citrate-soluble mineral fertilizer from shellfish solid waste and agricultural and forestry biomass, characterized in that... Includes the following steps: (1) Mix the shell powder with an acid solution, heat and stir to react, filter, and dry the resulting solid to obtain activated shell powder; (2) Mix activated shell powder with biomass powder, add catalyst, grind and mix, heat and pyrolyze under a protective atmosphere, and obtain pyrolyzed solid after cooling; (3) The pyrolysis solid obtained in step (2) is mixed with an alkaline solution, a dispersant is added, the mixture is stirred and extracted, filtered, the filtrate is concentrated and dried to obtain a high-calcium mineral organic water-soluble fertilizer, and the filter residue is dried and pulverized to obtain a citrate-soluble mineral fertilizer.

2. The method for co-producing high-calcium mineral organic water-soluble fertilizer and citrate-soluble mineral fertilizer from shellfish solid waste and agricultural and forestry biomass according to claim 1, characterized in that: The shell powder mentioned in step (1) is obtained by drying, crushing and sieving the shells of shellfish. The sieving process mentioned refers to passing through a 100-200 mesh sieve.

3. The method for co-producing high-calcium mineral organic water-soluble fertilizer and citrate-soluble mineral fertilizer from shellfish solid waste and agricultural and forestry biomass according to claim 1, characterized in that: The acid solution mentioned in step (1) is at least one of 1-5 wt% citric acid solution, ascorbic acid solution, EDTA and malic acid mixture; The heating and stirring reaction conditions described in step (1) are: heating in a water bath at 50-70°C for 1-3 hours; The ratio of seashell powder to acid solution in step (1) is 1g: 5-10mL.

4. The method for co-producing high-calcium mineral organic water-soluble fertilizer and citrate-soluble mineral fertilizer from shellfish solid waste and agricultural and forestry biomass according to claim 1, characterized in that: The ratio of activated shell powder to biomass powder in step (2) is 1:1 to 5; The biomass powder mentioned in step (2) includes at least one of rice straw powder and wood chip powder.

5. The method for co-producing high-calcium mineral organic water-soluble fertilizer and citrate-soluble mineral fertilizer from shellfish solid waste and agricultural and forestry biomass according to claim 1, characterized in that: The catalyst mentioned in step (2) includes at least one of ferric chloride and ferric sulfate; The amount of catalyst added in step (2) is 1 to 5% of the total mass.

6. The method for co-producing high-calcium mineral organic water-soluble fertilizer and citrate-soluble mineral fertilizer from shellfish solid waste and agricultural and forestry biomass according to claim 1, characterized in that: The protective atmosphere described in step (2) is a high-purity nitrogen, carbon dioxide, or argon atmosphere; The heating and pyrolysis conditions described in step (2) are to heat to 350-400℃ at a rate of 5-10℃ / min and pyrolyze for 90-150 minutes.

7. The method for co-producing high-calcium mineral organic water-soluble fertilizer and citrate-soluble mineral fertilizer from shellfish solid waste and agricultural and forestry biomass according to claim 1, characterized in that: The alkaline solution mentioned in step (3) includes at least one of 1-5% ammonia water, 1-2 mol / L KOH solution, and 1-2 mol / L NaOH solution; The ratio of pyrolysis solid to alkaline solution in step (3) is 1g:6-8mL; The dispersant mentioned in step (3) includes at least one of pyrophosphate and sodium hexametaphosphate; The amount of dispersant added in step (3) is 0.1% to 0.5% of the total mass; The extraction in step (3) is performed at 70-90℃ and 200-400 r / min for 30-90 min; The filtration described in step (3) is vacuum filtration through filter paper with a pore size of 10-20 μm.

8. A high-calcium mineral organic water-soluble fertilizer, prepared by any one of the preparation methods described in claims 1 to 7.

9. A citrate-soluble mineral fertilizer, prepared by any one of the preparation methods described in claims 1 to 7.

10. The method for co-producing high-calcium mineral organic water-soluble fertilizer and citrate-soluble mineral fertilizer from shellfish solid waste and agricultural and forestry biomass as described in any one of claims 1 to 7 is applied in fertilizer preparation.

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