Slow-release agricultural green input and preparation method thereof

Abstract

The invention discloses a slow-release agricultural green input and a preparation method thereof, and belongs to the technical field of environmental engineering. According to the method, comprehensive resource utilization is carried out on the papermaking deinking sludge and the agriculture and forestry residues, resource utilization of waste is achieved, and healthy development of agriculture is achieved. The method comprises the following steps: loading water-soluble agricultural and forestry residue-based plant excitant and plant microbiosis excitant on sodium alginate gel balls, and carrying out hydrophobic modification on sodium alginate to further fix and slowly release nutrient substances and excitant components in the agricultural and forestry residue-based plant excitant and the plant microbiosis excitant. A long-acting nitrogen source is provided for crops, and the problem of soil acidification is relieved.

Description

Technical Field

[0001] The invention relates to a slow-release agricultural green input and a preparation method thereof, and belongs to the field of environmental engineering. Background Art

[0002] Currently, the total amount of inorganic fertilizers and pesticides used is high, but the cumulative risk of soil contamination in agricultural land is also high. Although the application of inorganic fertilizers and pesticides can increase crop yields and income, it can also lead to a decline in crop quality and pose potential health and ecological risks. Studies have found that the application of organic fertilizers and plant stimulants based on agricultural and forestry residues can improve soil quality, and the addition of biochar can help increase soil carbon storage capacity. Therefore, the research and development of organic fertilizers and plant stimulants based on agricultural and forestry residues, the application of organic fertilizers and plant stimulants produced from agricultural and forestry residues, and the coupling of biochar with enhanced carbon sequestration and emission reduction have become key priorities and key areas for industry development.

[0003] Green inputs include environmentally friendly agricultural inputs such as green, high-efficiency functional fertilizers, biofertilizers, soil conditioners, high-efficiency, low-toxicity, low-residue pesticides and veterinary drugs, green, high-efficiency feed additives, and biodegradable mulch films. Plant stimulants derived from agricultural and forestry residues are extracts of agricultural and forestry residues. These extracts are made through acid- and thermal-hydrolysis processes. The resulting product contains a large number of substances that provide nutrients and stimulate plant growth, such as proteins, peptides, amino acids, phosphates, and small organic molecules. Plant microbial stimulants are extracts of activated sludge, obtained through a thermal-alkaline reaction of activated sludge. When applied to plant surfaces or root soil, they not only enhance fertilizer efficiency but also prevent plant diseases and pests. Both plant stimulants and microbial stimulants are derived from the supernatant of thermal hydrolysis. The active substances in these stimulants are soluble, which can lead to loss during agricultural production and undermine their effectiveness. Therefore, there is a need to develop a green and environmentally friendly slow-release method for these green inputs to improve soil quality and increase crop yields. Summary of the Invention

[0004] When applied to soil, chemical fertilizers not only increase the content of heavy metals and toxic substances and reduce soil microbial activity, but also lead to nutrient imbalance, increased acidification, and nitrate accumulation. Therefore, finding new green inputs to replace chemical fertilizers has become a key focus. This invention prepares a sodium alginate-loaded material based on plant stimulants and plant microbial stimulants derived from agricultural and forestry residues. The sodium alginate gel spheres are modified through organic compounding and secondary coating to enhance the sustained-release performance of this green input.

[0005] The present invention provides a method for preparing a green input, comprising the following steps:

[0006] (1) Preparation of a mixed solution of plant stimulants based on agricultural and forestry residues and sodium alginate: taking a plant stimulant based on agricultural and forestry residues and sodium alginate to obtain a mixed solution, then heating the mixed solution, stirring it, and then adding Bacillus subtilis and Pseudomonas fluorescens after cooling and stirring evenly to obtain a mixed solution of stimulants;

[0007] (2) Treatment of papermaking deinking sludge: The papermaking deinking sludge is stirred with sodium hydroxide, and then the solid-liquid separation is carried out, the solid is crushed, and sieved to obtain pretreated sludge, and then the pretreated sludge is immersed in ethylene oxide and stirred evenly. The sludge is then taken out and washed with anhydrous ethanol and then washed with acetic acid solution. Finally, the washed sludge solid is immersed in a glyoxal aqueous solution, and then taken out and washed with water to obtain treated sludge;

[0008] (3) Preparation of excitant-sodium alginate gel balls: adding the sludge treated in step (2) to the excitant mixture prepared in step (1), mixing them evenly to obtain a sludge excitant mixture; mixing microbial nutrient excitant, CaCl2 and water to obtain a microbial nutrient excitant dilution; adding the microbial nutrient excitant dilution dropwise to the sludge excitant mixture, allowing it to stand to separate the gel balls at the bottom, and then washing with water to obtain excitant-sodium alginate gel balls;

[0009] (4) Preparation of green inputs: Stearic acid and water are mixed, heated and stirred until completely dissolved to obtain a stearic acid solution. After cooling, the excitogen-sodium alginate gel balls prepared in step (3) are immersed in the stearic acid solution. After a period of reaction, the gel balls are taken out and washed with water to obtain the green inputs.

[0010] Furthermore, the agricultural and forestry residue-based plant stimulant in step (1) is prepared according to the following steps:

[0011] Take 1800-2000g of an algae-water mixture with a moisture content of 96-98%, add 30-40g of bamboo powder and 30-40g of oxalic acid, and adjust the pH to 0.8-1. After hydrolysis at 90-100°C for 20-24 hours, discharge the residue, add 40-50g of cyanobacteria and hydrolyze again. Repeat 3-4 times to increase the concentration of nutrients in the liquid phase to obtain an agricultural and forestry residue-based plant stimulant.

[0012] Furthermore, the mass fraction of sodium alginate in the mixed solution in step (1) is 1 to 3%.

[0013] Furthermore, the heating temperature in step (1) is 70-90°C.

[0014] Furthermore, in step (1), the mass ratio of the agricultural and forestry residue-based phytostimulant to the Bacillus subtilis is 1 kg:100-300 mg.

[0015] Furthermore, in step (1), the mass ratio of the agricultural and forestry residue-based plant stimulant to the fluorescing Pseudomonas is 1 kg:100-300 mg.

[0016] Furthermore, the water content of the papermaking deinking sludge in step (2) is 90-95%.

[0017] Furthermore, in step (2), the mass ratio of papermaking deinking sludge to agricultural and forestry residue-based plant stimulants is 50-100 g:1 kg.

[0018] Furthermore, in step (2), the mass ratio of papermaking deinking sludge to sodium hydroxide is 10:2-5.

[0019] Furthermore, the concentration of the acetic acid solution in step (2) is 5 to 10‰.

[0020] Furthermore, the concentration of the glyoxal aqueous solution in step (2) is 15-20 g / L.

[0021] Furthermore, in step (3), the ratio of the volume of the microbial nutrient stimulant to the mass of the agricultural and forestry residue-based plant stimulant is 10 mL: 0.8-1 kg.

[0022] Furthermore, in step (3), the ratio of the volume of the micronutrient stimulant to the mass of CaCl2 is 10 mL:75-80 g.

[0023] Furthermore, in step (3), the volume ratio of the microbial nutrient stimulus to water is 1:8-9.

[0024] Furthermore, in step (4), the mass ratio of stearic acid to water is 1:20-25.

[0025] Furthermore, the reaction time in step (4) is 20 to 30 minutes.

[0026] The present invention provides green input products prepared by the above method.

[0027] The green input provided by the present invention is used in the agricultural field.

[0028] Beneficial effects

[0029] 1. The present invention makes comprehensive resource utilization of papermaking deinking sludge and agricultural and forestry residues, thereby realizing resource utilization of waste and healthy development of agriculture.

[0030] 2. The present invention loads water-soluble agricultural and forestry residue-based plant stimulants and plant microorganism stimulants on sodium alginate gel balls, and hydrophobically modifies the sodium alginate to further fix and slowly release the nutrients and stimulant components in the agricultural and forestry residue-based plant stimulants and plant microorganism stimulants, providing a long-term nitrogen source for crops and alleviating the problem of soil acidification.

[0031] 3. Beneficial bacteria are also added to the green input of the present invention. The bacteria can not only use the substances in the gel balls to reproduce, but also convert large molecules into small molecules, providing nutrition for plants. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Nutrient release rate of green inputs.

[0033] Figure 2 Nutrient release rate; a is the green input after hydrophobic modification, and b is the green input without hydrophobic modification.

[0034] Figure 3 Nutrient release rate; a refers to paraffin secondary coating modification, and b refers to sodium alginate acylation modification.

[0035] Figure 4 Nutrient release rate; a is stearic acid secondary coating modification, b is microcrystalline wax secondary coating modification. DETAILED DESCRIPTION

[0036] Source of raw materials

[0037] Microbial nutrient stimulants were purchased from Shanxi Jinlian Environmental Technology Co., Ltd., with a pH of approximately 10.42, a nitrogen content of approximately 0.1225 g / L, and Ca 2+ The mass fraction is 2-2.5%; the preservation number of Bacillus subtilis is CMCC(B)63501; the preservation number of Pseudomonas fluorescens is BWCC29202; the papermaking deinking sludge comes from a sewage treatment plant supporting a papermaking enterprise in Wuxi City; the agricultural and forestry residue-based plant stimulant is prepared by the following preparation process: take 2000g of an algae-water mixture with a moisture content of 98%, add 40g of bamboo powder, add 40g of oxalic acid, and use sulfuric acid to adjust the pH to 0.8, set the temperature to 100℃, set the stirring speed to 90-100rpm, after hydrolysis for 24h, discharge the residue, and add 40g of fresh cyanobacteria to hydrolyze again, then repeat the steps of adding cyanobacteria and hydrolysis 3 times to increase the concentration of nutrients in the liquid phase to obtain the agricultural and forestry residue-based plant stimulant.

[0038] Example 1

[0039] (1) Preparation of a mixed solution of plant stimulants based on agricultural and forestry residues and sodium alginate: 1 kg of plant stimulants based on agricultural and forestry residues was taken, sodium alginate was added to obtain a mixed solution, the mass fraction of sodium alginate in the mixed solution was 2%; the mixed solution was heated in a water bath to 70-90°C, and stirred continuously until the sodium alginate was completely dissolved. After cooling to room temperature, 200 mg each of Bacillus subtilis and Pseudomonas fluorescens were added and stirred evenly to obtain a mixed solution of stimulants.

[0040] (2) Treatment of papermaking deinking sludge: 50 g of papermaking deinking sludge with a moisture content of 95% was taken, 15 g of sodium hydroxide was added, stirred evenly and allowed to stand for 30 min; solid-liquid separation was performed, the solid was crushed, and passed through a 20-mesh sieve to obtain pretreated sludge; the pretreated sludge was then immersed in ethylene oxide, stirred evenly at 4°C, and allowed to stand at low temperature for 3 h. After that, the sludge was taken out and washed twice with anhydrous ethanol, and then washed twice with 5‰ acetic acid solution; the washed sludge solid was immersed in a 15 g / L glyoxal aqueous solution, allowed to stand for 5 min, taken out, and washed twice with ultrapure water to obtain treated sludge.

[0041] (3) Preparation of excitant-sodium alginate gel balls: Add the sludge treated in step (2) to the excitant mixture prepared in step (1) and mix them evenly; add 10 mL of microbial nutrient excitant and 75-80 g of CaCl2 to 90 mL of water so that the CaCl2 in the diluted microbial nutrient excitant is 0.1%; 2+ The mass fraction is 3%; a mixture of agricultural and forestry residue-based plant stimulant-sodium alginate and paper deinking sludge is added dropwise to the diluted microbial nutrient stimulant using a syringe and allowed to stand for 8 hours; the gel balls at the bottom are separated and then washed three times with ultrapure water to obtain stimulant-sodium alginate gel balls.

[0042] (4) Preparation of green input (hydrophobic modification): Place 4 g of stearic acid in a beaker, add 100 mL of ultrapure water, heat to 40-50°C, stir until completely dissolved, and cool for later use; immerse the excitogen-sodium alginate gel balls prepared in step (3) in the stearic acid solution and react for 30 minutes; take out the gel balls and rinse them once with ultrapure water to obtain the green input.

[0043] Nutrient release rate detection process:

[0044] The nutrient release rate detection method refers to the national standard GB / T23348-2009 method to determine the total nitrogen content in the extract at 1, 3, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55 and 60 days respectively.

[0045] The national standard for slow-release fertilizers, GB / T23348-2009, stipulates that the initial nutrient release rate should be ≤15%, the cumulative nutrient release rate over 28 days should be ≤80%, and the cumulative nutrient release rate over the nutrient release period should be ≥80%. The chemical industry standard, HG / T 4215-2011, also stipulates that the initial nutrient release rate should be ≤12%, the cumulative nutrient release rate over 28 days should be ≤75%, and the cumulative nutrient release rate over the nutrient release period should be ≥80%.

[0046] like Figure 1As shown, the prepared green input product is less than 1% on the first day, the nutrient release is less than 15% in the first three days, the nutrient release rate is less than 60% in the first 28 days, and the highest nutrient release rate can reach 90%, indicating that the slow-release fertilizer prepared by the green input product meets the national standard and the chemical industry standard.

[0047] Example 2: Comparison before and after hydrophobic modification

[0048] The nutrient release rate detection was performed on the phytostimuline-sodium alginate gel balls prepared in step (3) and the green input product prepared in step (4) in Example 1, and the detection process referred to Example 1.

[0049] The results are shown in Figure 2 As shown, the stearic acid hydrophobic modification hinders the water from infiltrating into the gel balls, reduces the nutrient release rate of sodium alginate, and makes the nutrient release rate more gentle, which is beneficial to plant absorption and utilization and reduces nutrient loss.

[0050] Comparative Example 1: Different modification methods

[0051] The nutrient release rate detection was performed on the stearic acid hydrophobic modified sodium alginate gel balls and the acylated modified gel balls of sodium alginate in Example 1, and the detection process referred to Example 1.

[0052] The steps (1) and (2) in the acylated modification of sodium alginate referred to Example 1, and the subsequent operations were as follows:

[0053] (3) The paper deinking sludge and the agricultural and forestry residual plant phytostimuline-sodium alginate mixed solution were mixed uniformly, 4g of 1-(3-dimethylaminopropyl)-3-ethyl carbodiimide hydrochloride and 4g of N-hydroxysuccinimide were added and mixed uniformly, and the mixture was recorded as solution A. 50mg of aminated polylactic acid was dissolved in 10mL of tetrahydrofuran to form solution B, and solution B was added dropwise to solution A using a syringe, and after stirring at 40℃ for 24h, freeze-drying was performed, and the solid was collected, thereby obtaining the acylated modified gel balls of sodium alginate.

[0054] Based on Figure 3 It was found that the stearic acid hydrophobic modified green input product can release nutrients more fully, and the nutrient release rate reaches 90% after 60 days, while the acylated modified sodium alginate has a nutrient release rate of about 80%, which does not meet the industry standard of the chemical industry.

[0055] Comparative Example 2

[0056] The nutrient release rate detection was performed on the stearic acid hydrophobic modified sodium alginate gel balls and the microcrystalline wax secondary film modified gel balls in Example 1, and the detection process referred to Example 1.

[0057] The steps (1) and (2) in the microcrystalline wax secondary film modification referred to Example 1, and the subsequent operations were as follows:

[0058] (3) Put 40 g microcrystalline wax in a beaker, heat in a 70℃ water bath until the microcrystalline wax is completely melted; immerse the gel ball in the microcrystalline wax for 10 s; immerse the gel ball in ice water quickly, and after solidification, rinse once with ultrapure water, which is the green input product. The green input product prepared is subjected to a nutrient release rate experiment in pure water.

[0059] Based on Figure 4 It can be seen that the nutrient release rate of the microcrystalline wax after modification meets the national standard "GB / T23348-2009" and the chemical industry standard "HG / T 4215-2011", but the microcrystalline wax is an inorganic coating material, which cannot be biodegraded and may affect the environment, and does not meet the green and pollution-free characteristics of the green input product to be prepared in the present application.

[0060] Comparative Example 3: Planting effect of chemical fertilizer and green input product

[0061] The green input product prepared in Example 1 and chemical fertilizer (urea) are respectively used for planting soybeans, and the application amount is 0.1175 g (calculated as N). Table 1 is the fat and protein yield of soybeans planted by the two.

[0062] After using the green input product, the bioactive substances and nutrient substances in the agroforestry residual plant stimulins and plant microbiostimulins can be fixed in the soil, so that the TN in the rhizosphere soil and non-rhizosphere soil is significantly improved. Since microorganisms decompose macromolecular substances and slowly release, they provide a long-acting nitrogen source for soybeans, so the nitrogen fertilizer agronomic efficiency and nitrogen fertilizer partial productivity of soybeans are significantly improved compared with chemical fertilizer. The conversion of matter also leads to an increase in soil pH, slowing down the problem of soil acidification.

[0063] Table 1 Planting effect of chemical fertilizer and green input product

[0064]

[0065] The examples provided above are not intended to limit the scope covered by the present application, and the described steps are not intended to limit the execution order. Those skilled in the art can make obvious improvements to the present application in combination with existing common knowledge, which also falls within the protection scope defined by the claims of the present application.

Claims

1. A method for preparing green inputs, characterized in that: The following steps are involved: (1) Preparation of a mixed solution of plant stimulants based on agricultural and forestry residues and sodium alginate: taking a plant stimulant based on agricultural and forestry residues and sodium alginate to obtain a mixed solution, then heating the mixed solution, stirring it, and then adding Bacillus subtilis and Pseudomonas fluorescens after cooling and stirring evenly to obtain a mixed solution of stimulants; (2) Treatment of papermaking deinking sludge: The papermaking deinking sludge is stirred with sodium hydroxide, and then the solid-liquid separation is carried out, the solid is crushed, and sieved to obtain pretreated sludge, and then the pretreated sludge is immersed in ethylene oxide and stirred evenly. The sludge is then taken out and washed with anhydrous ethanol and then washed with acetic acid solution. Finally, the washed sludge solid is immersed in a glyoxal aqueous solution, and then taken out and washed with water to obtain treated sludge; (3) Preparation of excitant-sodium alginate gel balls: adding the sludge treated in step (2) to the excitant mixture prepared in step (1), mixing them evenly to obtain a sludge excitant mixture; mixing the microbial nutrient excitant, CaCl2 and water to obtain a microbial nutrient excitant dilution solution; Add the diluted microbial nutrient stimulant solution dropwise to the sludge stimulant mixture, let it stand, separate the gel balls at the bottom, and then wash with water to obtain the stimulant-sodium alginate gel balls; (4) Preparation of green inputs: Stearic acid and water are mixed, heated and stirred until completely dissolved to obtain a stearic acid solution. After cooling, the excitogen-sodium alginate gel balls prepared in step (3) are immersed in the stearic acid solution. After a period of reaction, the gel balls are taken out and washed with water to obtain the green inputs.

2. The method according to claim 1, wherein The agricultural and forestry residue-based plant stimulant in step (1) is prepared according to the following steps: Take 1800-2000g of an algae-water mixture with a moisture content of 96-98%, add 30-40g of bamboo powder and 30-40g of oxalic acid, and adjust the pH to 0.8-1. After hydrolysis at 90-100°C for 20-24 hours, discharge the residue, add 40-50g of cyanobacteria and hydrolyze again. Repeat 3-4 times to increase the concentration of nutrients in the liquid phase to obtain an agricultural and forestry residue-based plant stimulant.

3. The method according to claim 1, wherein In step (1), the mass fraction of sodium alginate in the mixed solution is 1 to 3%.

4. The method according to claim 1, wherein In step (1), the mass ratio of the agricultural and forestry residue-based plant stimulant to Bacillus subtilis is 1kg:100-300mg; the mass ratio of the agricultural and forestry residue-based plant stimulant to Pseudomonas fluorescens is 1kg:100-300mg.

5. The method according to claim 1, wherein In step (2), the mass ratio of papermaking deinking sludge to agricultural and forestry residue-based plant stimulants is 50-100 g:1 kg; the mass ratio of papermaking deinking sludge to sodium hydroxide is 10:2-5; and the concentration of the glyoxal aqueous solution is 15-20 g / L.

6. The method according to claim 1, wherein In step (3), the ratio of the volume of the microbial nutrient stimulant to the mass of the agricultural and forestry residue-based plant stimulant is 10 mL: 0.8-1 kg.

7. The method according to claim 1, wherein In step (3), the volume ratio of the microbial nutrient stimulant to the mass of CaCl2 is 10mL:75-80g; the volume ratio of the microbial nutrient stimulant to water is 1:8-9.

8. The method according to claim 1, wherein In step (4), the mass ratio of stearic acid to water is 1:20-25; and the reaction time is 20-30 min.

9. A green input product prepared according to the method according to any one of claims 1 to 8.

10. Use of the green input product according to claim 9 in the agricultural field.

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