Tea garden acidic soil conditioner and preparation method thereof

Abstract

The invention relates to a tea garden acidic soil conditioner, which is prepared from the following raw materials in parts by weight: 10 to 15 parts of alkaline conditioning materials, 10 to 30 parts of honey pomelo waste fruit fermented organic fertilizers, 4 to 6 parts of alkali modified biochar, 2 to 4 parts of biostimulant, 3 to 5 parts of graft modified chitosan, 0.25 to 0.6 part of dicyandiamide, 0.5 to 1 part of complex microbial inoculants, 0.25 to 0.5 part of binding agents and 0.006 to 0.012 part of trace element substances. The alkaline conditioning material is a mixture of magnesium-containing mineral substances and shell powder in a mass ratio of 10: (2-5); the graft modified chitosan is obtained by grafting and modifying chitosan through an unsaturated phosphorus-containing monomer and an unsaturated nitrogen-sulfur-containing monomer, and the grafting rate is 20-30%; the biostimulant comprises mineral source fulvic acid, magnesium sulfate, monopotassium phosphate and a seaweed extract. The tea garden acidic soil conditioner provided by the invention can effectively improve tea garden soil, so that the yield and quality of tea leaves are obviously improved.

Description

Technical Field

[0001] The invention relates to the technical field of soil remediation, and in particular to a tea garden acidic soil improver and a preparation method thereof. Background Art

[0002] Tea garden soil is generally over-acidified. The average pH value of tea garden soil is 4.73 nationwide. Only 41% of tea garden soil has a pH value between 4.5 and 5.5, and about 52% of tea garden soil has a pH value below 4.5. At present, the common method used to improve acidified soil is to apply chemicals such as lime. However, from a long-term perspective, it is not feasible to apply lime to solve the acidification of tea gardens. On the one hand, lime can cause greater soil compaction and soil fertility decline; on the other hand, tea trees have the characteristics of ammonium preference, aluminum polytropy, low chloride and calcium aversion. Tea trees have a much lower demand for calcium than general crops. When the active calcium content in the soil exceeds 0.5% (calculated as CaO), the growth of tea trees will be abnormal, and in severe cases, it will cause death. In addition, tea farmers pay more attention to nitrogen fertilizers, neglect phosphorus and potassium fertilizers, and do not apply trace element fertilizers; they only apply unit fertilizers, not compound fertilizers; they only apply chemical fertilizers, and rarely apply organic fertilizers, etc. These fertilization methods lead to unbalanced soil fertility in tea gardens, low fertilizer utilization, and even soil pollution problems. The soil fertility has declined, limiting the improvement of tea production efficiency. Simply adding some alkaline acid-adjusting materials can only adjust the pH of acidic soils, and the supplement of some trace elements, organic matter, nitrogen, phosphorus and potassium is negligible, and it cannot comprehensively improve the soil environmental quality.

[0003] Studies have shown that the dominant microorganisms in the soil are chemo-organic microorganisms, which obtain energy, carbon and other nutrients from decomposing plant-derived organic matter such as plant litter, root shedding, and root secretions. Maintaining the diversity of organic matter available to soil microorganisms is the key to maintaining soil microbial diversity. Adding available organic matter can greatly stimulate the activity of soil microorganisms. During the cultivation of honey pomelo, many honey pomelo fruits produce a certain amount of fallen fruits and defective fruits that are not suitable for fresh sale after sorting due to physiological or external environmental reasons during the growth, development and maturity of honey pomelo. These defective fruits are large in size and high in water content. Random stacking or landfill treatment not only takes up a lot of land, but also produces a large amount of leachate and odor. At present, there have been studies on the use of some peels for organic fertilizer fermentation. If the waste honey pomelo fruit can be used for organic fertilizer fermentation, it can not only effectively improve the resource utilization efficiency of the waste honey pomelo fruit, but also meet the demand for organic fertilizer in the process of soil conditioning in tea gardens. Therefore, the waste honey pomelo fruit can be used as a raw material for organic fertilizer fermentation to increase the organic matter in the tea garden soil, regulate the soil environment, and improve the soil quality.

[0004] In view of this, it is necessary to provide a safe and effective tea garden soil acidification improver or soil conditioner that meets the nutritional requirements of tea trees and improves the soil environment of tea gardens. Long-term application will not affect the tea garden soil. It can effectively regulate the acidity and alkalinity of the soil and improve soil quality. It can also effectively regulate the microbial environment in the soil and stimulate microbial activity.

[0005] CN115505402A discloses a conditioner for improving acidified soil in tea gardens, which is composed of the following raw materials in parts by weight: 22-44 parts of biochar, 12-24 parts of commercial organic fertilizer, 18-36 parts of "popcorn" organic fertilizer, 20-40 parts of dolomite powder, and 28-56 parts of lime nitrogen. "Popcorn" organic fertilizer is an organic fertilizer formed by puffing technology, which can quickly change the physical, chemical and biological properties of the soil, especially the improvement effect on compacted soil is obvious.

[0006] CN114507531A discloses a tea garden acidic soil conditioner, comprising 10-20 parts of dolomite powder, 40-60 parts of modified biochar, 5-10 parts of humic acid, 5-10 parts of earthworm castings, 5-10 parts of organic fertilizer, 6-12 parts of composite bacterial agent, 3-8 parts of nitrification inhibitor, and 10-15 parts of lignin-based super absorbent resin.

[0007] However, the tea garden soil conditioner provided by the above patent cannot effectively improve the quality and yield of tea. Summary of the invention

[0008] The purpose of the present invention is to effectively alleviate the acidification problem of tea garden soil, improve soil quality without excessive application of calcium source substances, which affects the quality of tea leaves; add beneficial organic matter, trace elements, and biostimulants to effectively improve the microbial environment of tea garden soil, stimulate the activity of microorganisms in acidified tea garden soil, and improve the resource utilization efficiency of the soil, thereby improving the quality of tea leaves.

[0009] In order to achieve the above technical objectives, the present invention provides the following technical solutions:

[0010] A tea garden acidic soil conditioner comprises the following raw materials in parts by weight: 10-15 parts of alkaline conditioning materials, 10-30 parts of fermented organic fertilizer from honey pomelo waste fruit, 4-6 parts of alkali-modified biochar, 2-4 parts of biostimulants, 3-5 parts of grafted modified chitosan, 0.25-0.6 parts of dicyandiamide, 0.5-1 parts of composite bacterial agents, 0.25-0.5 parts of binders, and 0.006-0.012 parts of trace elements; the alkaline conditioning materials are a mixture of magnesium-containing minerals and shell powder in a mass ratio of 10:2-5; the grafted modified chitosan is obtained by grafting chitosan with unsaturated phosphorus-containing monomers and unsaturated nitrogen-sulfur-containing monomers, with a grafting rate of 20-30%; the biostimulants include mineral-source humic acid, magnesium sulfate, potassium dihydrogen phosphate and seaweed extract.

[0011] Preferably, the magnesium-containing ore powder is selected from at least one of sepiolite, magnesite ore powder, and silicon-calcium-potassium-magnesium fertilizer.

[0012] Preferably, the honey pomelo waste fruit fermented organic fertilizer is prepared by a preparation method comprising the following steps:

[0013] (S1) Evenly mixing animal feces and waste pomelo fruit after juicing;

[0014] (S2) adjusting the moisture content to 55% to 65% using rice husks and mushroom soil residue;

[0015] (S3) adjusting the pH of the mixture to 6-7 with lime;

[0016] (S4) adding activated high temperature aerobic fermentation bacteria, intermittently turning the compost in a fermentation tank for fermentation for 12-15 days, and drying to obtain the fermented organic fertilizer of honey pomelo waste fruit.

[0017] In step (S1), the animal manure is not particularly limited, such as sheep manure, cow manure, pig manure, horse manure, etc. The mass ratio of animal manure to the waste pomelo fruit after juicing is 1-2:1; in step (S2), the ratio of rice husk to mushroom soil residue is 3-5:1-2; in step S(4), the thermophilic aerobic fermentation and decomposition bacteria include at least one of Bacillus subtilis, Bacillus licheniformis, Lactobacillus, yeast, and Aspergillus.

[0018] The high-temperature aerobic fermentation and decomposition bacteria are Bacillus subtilis, Bacillus licheniformis, Lactobacillus, yeast and Aspergillus mixed in a mass ratio of 1-2:1-2:1-2:1-2:1-2, and then inoculated in 0.5-2wt% brown sugar water at a ratio of bacterial agent: water of 1:20-30, cultured at 37°C for 4-5 hours, and after the bacterial species are activated, the bacterial agent is sprayed or mixed into the material at a ratio of 1-2wt%.

[0019] Preferably, the unsaturated phosphorus-containing monomer is selected from at least one of ethyl (meth) acrylate phosphate, propyl (meth) acrylate phosphate, and butyl (meth) acrylate phosphate; the unsaturated nitrogen-sulfur-containing monomer is N-vinyl-thio-pyrrolidone. More preferably, the mass ratio of the unsaturated phosphorus-containing monomer to the unsaturated nitrogen-sulfur-containing monomer is 3.5-4.5:1.5-2.5.

[0020] Preferably, the grafted modified chitosan is obtained by a preparation method comprising the following steps:

[0021] Chitosan is dissolved in acetic acid solution, unsaturated phosphorus-containing monomers and unsaturated nitrogen-sulfur-containing monomers are added, in-situ polymerization occurs under the action of an initiator, and after cooling, the reaction solution is precipitated with alcohol, and the precipitate is vacuum dried to obtain grafted modified chitosan.

[0022] More preferably, in step (P1), the concentration of the acetic acid solution is 1-4wt%, such as 2wt%; the molecular weight of chitosan is 50-100kDa, and the degree of deacetylation is 70-85%. The total amount of unsaturated phosphorus-containing monomers and unsaturated sulfonic acid / sulfonate monomers added is 50-80% of the mass of chitosan, preferably 50-65%. The initiator is a water-soluble redox initiation system of persulfate (such as ammonium persulfate, sodium persulfate, potassium persulfate) and bisulfite (such as sodium bisulfite, potassium bisulfite) in a mass ratio of 1-2:1. The initiation temperature is 50-70°C; anhydrous ethanol is selected for alcohol precipitation.

[0023] The inventors found that chitosan can be grafted and polymerized with unsaturated phosphorus-containing monomers and unsaturated nitrogen-containing sulfur monomers, and then added as a component to soil conditioners to significantly improve tea garden soil, so that tea yield and beneficial ingredients (such as tea polyphenol content) are significantly increased. The possible reason is that on the one hand, phosphorus, sulfur, and nitrogen are nutrients needed by the soil, and on the other hand, chitosan after polymer grafting can enhance the metabolic activities of microorganisms, such as soil phosphatase activity, dehydrogenase activity, etc., which can effectively enhance the absorption of nutrients by tea trees.

[0024] Preferably, the alkali-modified biochar is prepared by a preparation method comprising the following steps:

[0025] (T1) washing the biomass raw material, drying it, and crushing it to obtain a granular raw material, and then maintaining the granular raw material at 400-600° C. for 2-4 hours under a nitrogen atmosphere, and taking it out after cooling to obtain biochar;

[0026] (T2) adding the biochar to an alkaline solution containing 0.5-1 mol / L MOH and 2-4 mol / L M2CO3, where M is Na and K, mixing and stirring or shaking and soaking for 12-24 hours to obtain an alkaline biochar mixture, and then filtering, washing and drying to obtain the alkali-modified biochar.

[0027] The biomass in step (T1) is selected from at least one of pomelo peel, corn stalks, wheat stalks and bamboo.

[0028] Preferably, the biostimulant is a compound of mineral humic acid, magnesium sulfate, potassium dihydrogen phosphate, and seaweed extract. Among them, mineral humic acid, magnesium sulfate, and potassium dihydrogen phosphate can be purchased commercially; seaweed extract is purchased from the seaweed essence product of Mingyue Seaweed Group. More preferably, the biostimulant is a compound of mineral humic acid, magnesium sulfate, potassium dihydrogen phosphate, and seaweed extract according to 10-30:5-10:15-20:30-50. The inventors have found that the biostimulant compounded with the above four ingredients can increase soil enzyme activity, increase soil microbial activity, thereby increasing the release of effective nutrients in the soil, increase the absorption of nutrients by tea trees, significantly increase tea yield and improve tea quality.

[0029] Preferably, the composite microbial agent is capable of improving acidic soil microbial bacteria, such as at least two of Bacillus subtilis, Bacillus gelatinous, Bacillus licheniformis, and Bacillus megaterium. More preferably, the weight ratio of any two of the two or more bacteria in the composite microbial agent is 1-3:1-3.

[0030] The binder is at least one of carboxymethyl cellulose and starch; the trace element substance is at least one of zinc sulfate, ammonium molybdate and manganese sulfate, preferably zinc sulfate and ammonium molybdate are compounded in a mass ratio of 5-9:1.

[0031] The present invention also provides a method for preparing the above tea garden acidic soil conditioner, comprising the following steps:

[0032] (1) dispersing a binder and trace element substances in water to obtain a binder dispersion system;

[0033] (2) weighing the biostimulant, the composite bacterial agent, and the fermented organic fertilizer of honey pomelo waste fruit and uniformly mixing them to obtain a mixture a;

[0034] (3) The mixture a is placed at the bottom of the disc, and after the disc is started, 50-70% of the binder dispersion system is sprayed on the surface of the mixture in a spraying manner, and finally granulated in a granulator to form an internal core material b;

[0035] (4) weighing alkaline conditioning material, alkali-modified biochar, and dicyandiamide, and uniformly mixing them to obtain a mixture c;

[0036] (5) The mixture c is added to the disc in a powdering manner, and the remaining binder dispersion system is sprayed in a spraying manner. After drying, the acidic soil conditioner for tea gardens is finally obtained.

[0037] Preferably, in step (1), in the binder dispersion system, the concentration of trace elements is 0.1-0.3 wt %, and the concentration of the binder is 1.5-6 wt %.

[0038] The present invention also provides the use of the tea garden acidic soil conditioner in improving tea garden soil. The amount of the conditioner is 150-300 kg / mu, and it is applied 1-2 months before tea farmers apply base fertilizer every year. The application method is consistent with that of conventional tea farmers.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] (1) The present invention effectively solves the problem of arbitrarily stacking and environmental pollution of waste pomelo fruit generated during pomelo production, and effectively utilizes pomelo waste resources by mixing and fermenting the waste with livestock and poultry excrement such as sheep manure and cow manure, rice husks, and mushroom soil residues, thereby effectively combining the characteristics of plant-based and animal-based organic fertilizer raw materials, making the organic fertilizer more nutritionally balanced and improving the utilization rate of waste resources such as sheep manure, pomelo waste, and mushroom residues.

[0041] (2) The present invention prepares a grafted modified chitosan, which can significantly improve the effectiveness of the modifier after chitosan is grafted and modified by unsaturated phosphorus-containing monomers and unsaturated sulfonic acid / sulfonate monomers.

[0042] (3) The improver provided by the present invention has a significant effect. The possible reason is that the improver of the present invention is a granular double-layer coating structure. It uses fermented organic fertilizer from waste pomelo fruit and alkaline conditioning materials as the main raw materials, and adds alkali-modified biochar, biostimulants and other ingredients to make a granular double-layer coating material. It not only effectively adjusts the pH of acidic soil in tea gardens after application, alleviates the acidification trend of tea gardens, but also has the characteristics of rich nutrition and long-lasting fertilizer effect. After application to the soil, the outer layer of the material can first adjust the soil pH and effectively improve the soil quality; as the coating is decomposed by soil microorganisms, the nutrients and composite microorganisms inside the material are slowly released, and the microorganisms use organic fertilizers and various organic nutrients to effectively colonize, which can optimize the community structure and community quantity of beneficial bacteria in acidified soil microorganisms, and the compounded biostimulants can effectively improve the quality of tea.

[0043] (4) Existing soil conditioners or improvers for tea gardens are generally in powder form, which can easily cause dust problems when applied. In addition, most tea garden application methods are to apply them on the surface of tea bushes and then sweep them down to the roots of the tea trees. The powder easily sticks to the surface of tea leaves, making it inconvenient to use. In this study, the soil conditioners or improvers were prepared into granules using an organic binder containing trace elements. After application, the soil conditioners or improvers can be dropped to the roots of tea trees by simply patting the materials, which increases the convenience of application.

[0044] Specific implementation method

[0045] In order to make the technical means, creative features, objectives and effects of the present invention easy to understand, the tea garden soil conditioner and its application provided by the present invention are further described in conjunction with specific embodiments. The embodiments described below are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0046] Preparation Example 1 Preparation of organic fertilizer from fermented pomelo waste fruit

[0047] ① Evenly mix fresh sheep manure and the waste pomelo fruit after juicing in a mass ratio of 1:1;

[0048] ② Use rice husks and mushroom residue to adjust the moisture content to 60%, and the mass ratio of rice husks to mushroom residue is 3:1;

[0049] ③ Use lime to adjust the pH of the mixture to 7;

[0050] ④ Add activated high-temperature aerobic fermentation and decomposition bacteria, intermittently turn the compost in the fermentation tank for 12-15 days, and then dry to obtain the fermented organic fertilizer of honey pomelo waste fruit; the high-temperature aerobic fermentation and decomposition bacteria are Bacillus subtilis, Bacillus licheniformis, Lactobacillus, yeast, and Aspergillus niger, which are mixed in equal mass proportions and inoculated in 2% brown sugar water at a ratio of 1:30 of bacterial agent: water for 5 hours at 37°C, and after the activation of the strains is completed, spray the bacterial agent at a ratio of 1wt% into the material after pH adjustment in step ③. The bacterial agent ratio of 1wt% refers to the mass ratio of the composite bacteria and the material before inoculation.

[0051] Preparation Example 2 Preparation of alkali-modified biochar

[0052] ① Wash the corn stalks, dry them and crush them to obtain pellets, then keep the pellets at 400-600° C. for 2-4 hours in a nitrogen atmosphere, and take them out after cooling to obtain biochar;

[0053] ② Add the biochar to an alkali solution containing 1 mol / L KOH solution and 2 mol / L Na2CO3, with the mass ratio of alkali solution to biochar being 5:1. Shake and soak for 12 hours. Filter the mixed solution, wash the solid phase with water to neutrality, and dry to constant weight to obtain alkali-modified biochar.

[0054] Preparation Example 3 Preparation of modified chitosan

[0055] 10 parts by mass of chitosan (molecular weight 80 kDa, deacetylation degree 80%) was dissolved in 200 parts by mass of 2% acetic acid solution, 3.5 parts by mass of ethyl acrylate phosphate, 1.5 parts by mass of N-vinyl-thio-pyrrolidone, and 0.1 parts by mass of sodium persulfate and sodium bisulfite in a mass ratio of 2:1 as redox initiator were added, the temperature was raised to 60°C for reaction for 5 hours, after cooling, the reaction solution was precipitated with anhydrous alcohol, the precipitate was washed with anhydrous ethanol to remove unreacted monomers and polymers not grafted on chitosan, and then vacuum dried to obtain grafted modified chitosan. According to the formula Wherein M1 is the mass of chitosan after graft modification, and M2 is the mass of unmodified chitosan. The grafting rate of graft modified chitosan obtained in Preparation Example 3 is 21.6%.

[0056] Preparation Example 4 Preparation of modified chitosan

[0057] Other conditions were the same as those in Preparation Example 3, except that the mixed monomers were 4 parts by mass of ethyl acrylate phosphate and 2.5 parts by mass of N-vinyl-thio-pyrrolidone. The grafting rate of the grafted modified chitosan obtained in Preparation Example 4 was 26.4%.

[0058] Comparative Preparation Example 1

[0059] The other conditions were the same as those in Preparation Example 3, except that the monomer was 5 parts by mass of ethyl acrylate phosphate. The grafting rate of the obtained modified chitosan was 22.1%.

[0060] Comparative Preparation Example 2

[0061] The other conditions were the same as those in Preparation Example 3, except that the monomer was 5 parts by mass of N-vinyl-thio-pyrrolidone. The grafting rate of the obtained modified chitosan was 21.4%.

[0062] Example 1

[0063] Prepare the materials according to the following weight proportions: 13.75 kg of alkaline conditioning materials (including 10 kg of sepiolite and 3.75 kg of shell powder, i.e., sepiolite and shell powder are compounded in a mass ratio of 10:3.75), 22.38 kg of fermented organic fertilizer from waste pomelo fruit obtained in Preparation Example 1, 5 kg of alkali-modified biochar obtained in Preparation Example 2, 3.5 kg of grafted modified chitosan obtained in Preparation Example 3, 3.625 kg of biostimulant (mineral humic acid, magnesium sulfate, potassium dihydrogen phosphate, and seaweed extract are compounded in a mass ratio of 20:10:15:40), 0.5 kg of dicyandiamide, 0.75 kg of composite microbial agent (Bacillus subtilis and Bacillus gelatinus are compounded in a mass ratio of 1:2), 0.25 kg of binder carboxymethyl cellulose, and 6.25 g of trace elements (zinc sulfate and ammonium molybdate are compounded in a mass ratio of 9:1).

[0064] Raw material preparation: mineral humic acid, magnesium sulfate, potassium dihydrogen phosphate, and seaweed extract are weighed according to a ratio, and mixed evenly to obtain a biostimulant; Bacillus subtilis and Bacillus gelatinus are mixed evenly in a weight ratio of 1:2 to obtain a composite microbial agent.

[0065] The steps for preparing soil conditioner are as follows:

[0066] (1) zinc sulfate and ammonium molybdate are weighed in a mass ratio of 9:1 to prepare a trace element substance aqueous solution with a concentration of 0.1 wt %, and 0.25 kg of a binder carboxymethyl cellulose is added and dispersed in the trace element solution. The binder concentration is 4 wt %, to obtain a binder dispersion system;

[0067] (2) weighing the biostimulant, the composite bacterial agent, and the fermented organic fertilizer of honey pomelo waste fruit according to the formula and uniformly mixing them to obtain a mixture a;

[0068] (3) The mixture a is placed at the bottom of the disc, and after the disc is started, 60% of the binder dispersion system is sprayed on the surface of the mixture by spraying, and finally granulated in a granulator to form an internal core material b;

[0069] (4) weighing alkaline conditioning materials, alkali-modified biochar and dicyandiamide according to the formula, and uniformly mixing them to obtain a mixture c;

[0070] (5) The mixture c is added to the disc in a powdering manner, and the remaining binder dispersion system is sprayed in a spraying manner, so that the mixture c forms a coating on the surface of the internal core material b, and finally forms a granular double-layer coating material. After drying, the tea garden acidic soil conditioner 1 is finally obtained.

[0071] Example 2

[0072] The other conditions are the same as those in Example 1, except that the raw materials are: 12 kg of alkaline conditioning material (including 10 kg of sepiolite and 2 kg of shell powder, i.e., sepiolite and shell powder are compounded in a mass ratio of 10:2), 25.48 kg of fermented organic fertilizer from waste pomelo fruit obtained in Preparation Example 1, 4.3 kg of alkali-modified biochar obtained in Preparation Example 2, 4.1 kg of grafted modified chitosan obtained in Preparation Example 3, 3.5 kg of biostimulant (mineral humic acid, magnesium sulfate, potassium dihydrogen phosphate, and seaweed extract are compounded in a mass ratio of 10:10:20:30), 0.5 kg of dicyandiamide, 0.65 kg of composite microbial agent (Bacillus licheniformis and Bacillus megaterium are compounded in a mass ratio of 1:1), 0.25 kg of binder carboxymethyl cellulose, and 10.5 g of trace elements (zinc sulfate and ammonium molybdate are compounded in a mass ratio of 6:1).

[0073] Example 3

[0074] The other conditions are the same as those in Example 1, except that the raw materials are: 15 kg of alkaline conditioning material (including 10 kg of sepiolite and 5 kg of shell powder, i.e., sepiolite and shell powder are compounded in a mass ratio of 10:5), 29.5 kg of fermented organic fertilizer of honey pomelo waste fruit obtained in Preparation Example 1, 6 kg of alkali-modified biochar obtained in Preparation Example 2, 4.7 kg of grafted modified chitosan obtained in Preparation Example 3, 4 kg of biostimulant (mineral humic acid, magnesium sulfate, potassium dihydrogen phosphate, seaweed extract are compounded in a mass ratio of 20:10:20:50), 0.5 kg of dicyandiamide, 0.65 kg of composite microbial agent (Bacillus subtilis, Bacillus megaterium, Bacillus licheniformis are compounded in a mass ratio of 1:1:2), 0.3 kg of binder carboxymethyl cellulose, and 12 g of trace element substance (zinc sulfate and ammonium molybdate are compounded in a mass ratio of 7:1).

[0075] Comparative Example 1

[0076] The other conditions were the same as those in Example 1, except that the grafted modified chitosan prepared in Preparation Example 3 was replaced by the modified chitosan prepared in Comparative Preparation Example 1 of equal mass.

[0077] Comparative Example 2

[0078] The other conditions were the same as those in Example 1, except that the grafted modified chitosan prepared in Preparation Example 3 was replaced by the modified chitosan prepared in Comparative Preparation Example 2 of equal mass.

[0079] Comparative Example 3

[0080] The other conditions are the same as those in Example 1, except that the biostimulant is a compound of mineral humic acid, magnesium sulfate, and potassium dihydrogen phosphate in a mass ratio of 20:10:15, that is, no seaweed extract is added.

[0081] Comparative Example 4

[0082] The other conditions were the same as those in Example 1, except that no biostimulant was added.

[0083] Application Examples

[0084] The tea garden acidic soil conditioner prepared in the above examples and comparative examples was used in Hua'an Tea Garden, Zhangzhou City, Fujian Province. At the same time, the test area without any tea garden soil conditioner was used as the control, named CK. The experimental time was in early August, the tea garden had a planting period of about 15 to 20 years, and the cycle was 60 days. Each experimental treatment group was set up with 3 replicates, and the area of ​​each experimental replicate was about 20m 2The dosage of tea garden soil conditioner is 300kg / mu. The fertilizer application is the same as farmers' conventional fertilization, and the fertilizer application location is the effective planting area within the drip line of the tea tree. 60 days after the application of the conditioner, the soil and tea leaves were collected for testing, and the soil pH value, CEC, soil alkaline nitrogen, tea quality parameters and other related indicators were measured respectively. The test methods are shown in Table 1-2 below.

[0085] Table 1 Soil testing indicators, methods and reference standards

[0086]

[0087] Table 2 Tea index detection methods and reference standards

[0088]

[0089] Based on the above experimental settings, the results of the sampling test are shown in Tables 3-5 below.

[0090] Table 3 Effects of different soil conditioners on soil properties and nutrient content

[0091]

[0092]

[0093] Table 4 Tea production survey results

[0094] deal with Tea yield (kg / mu) 100 bud weight(g) CK 61.52 46.06 Example 1 103.05 62.98 Example 2 97.37 59.32 Example 3 100.08 63.87 Comparative Example 1 104.92 61.06 Comparative Example 2 102.75 63.28 Comparative Example 3 92.62 58.47 Comparative Example 4 76.48 52.75

[0095] Table 5 Tea quality test results

[0096]

[0097]

[0098] The experimental results show that compared with not applying soil conditioner (CK), after applying the tea garden acidic soil conditioner of the present invention, the pH of the tea garden soil will increase significantly, and the content of various nutrients in the soil will also increase significantly, effectively improving soil fertility. The use of tea garden acidic soil conditioner can also increase tea yield and quality. The inventor believes that the combination of the two unsaturated monomer grafted modified chitosan and biostimulant of the present invention plays a key role. Comparative Example 1 and Comparative Example 2 respectively modify chitosan with a separate phosphorus-containing monomer and a nitrogen-sulfur monomer. The yield of tea is basically unaffected, but the quality of tea is reduced. The biostimulant in Comparative Example 3 lacks seaweed extract, and Comparative Example 4 does not add biostimulants. The yield and quality of tea are affected, among which Comparative Example 4 is the most affected.

Claims

1. A tea garden acidic soil conditioner, characterized in that: The invention comprises the following raw materials in parts by weight: 10-15 parts of alkaline conditioning materials, 10-30 parts of organic fertilizer fermented from waste pomelo fruit, 4-6 parts of alkali-modified biochar, 2-4 parts of biostimulants, 3-5 parts of grafted modified chitosan, 0.25-0.6 parts of dicyandiamide, 0.5-1 parts of composite bacterial agent, 0.25-0.5 parts of adhesive, and 0.006-0.012 parts of trace elements; the alkaline conditioning materials are a mixture of magnesium-containing minerals and shell powder in a mass ratio of 10:2-5; the grafted modified chitosan is obtained by grafting chitosan with unsaturated phosphorus-containing monomers and unsaturated nitrogen-sulfur monomers, with a grafting rate of 20-30%; the biostimulants include mineral humic acid, magnesium sulfate, potassium dihydrogen phosphate and seaweed extract.

2. The tea garden acidic soil conditioner according to claim 1, characterized in that: The magnesium-containing ore powder is selected from at least one of sepiolite, magnesite ore powder, and silicon-calcium-potassium-magnesium fertilizer.

3. The tea garden acidic soil conditioner according to claim 1, characterized in that: The honey pomelo waste fruit fermented organic fertilizer is prepared by a preparation method comprising the following steps: (S1) Evenly mixing animal feces and waste pomelo fruit after juicing; (S2) adjusting the moisture content to 55% to 65% using rice husks and mushroom soil residue; (S3) adjusting the pH of the mixture to 6-7 with lime; (S4) adding activated thermophilic aerobic fermentation and decomposition composite bacteria, intermittently turning the compost in a fermentation tank for fermentation for 12-15 days, and drying to obtain honey pomelo waste fruit fermentation organic fertilizer; Preferably, in step (S1), the animal manure is selected from sheep manure, cow manure, pig manure, and horse manure; the mass ratio of animal manure to waste pomelo fruit after juicing is 1-2:1; in step (S2), the ratio of rice husk to mushroom soil residue is 3-5:1-2; in step S(4), the thermophilic aerobic fermentation and decomposition bacteria include at least one of Bacillus subtilis, Bacillus licheniformis, Lactobacillus, yeast, and Aspergillus.

4. The tea garden acidic soil conditioner according to claim 1, characterized in that: The unsaturated phosphorus-containing monomer is selected from at least one of ethyl (meth) acrylate phosphate, propyl (meth) acrylate phosphate, and butyl (meth) acrylate phosphate; the unsaturated nitrogen-sulfur-containing monomer is N-vinyl-thio-pyrrolidone. More preferably, the mass ratio of the unsaturated phosphorus-containing monomer to the unsaturated nitrogen-sulfur-containing monomer is 3.5-4.5:1.5-2.

5.

5. The tea garden acidic soil conditioner according to claim 1, characterized in that: The grafted modified chitosan is obtained by a preparation method comprising the following steps: Chitosan is dissolved in acetic acid solution, unsaturated phosphorus-containing monomers and unsaturated nitrogen-sulfur-containing monomers are added, in-situ polymerization occurs under the action of an initiator, and after cooling, the reaction solution is precipitated with alcohol, and the precipitate is vacuum dried to obtain grafted modified chitosan.

6. The tea garden acidic soil conditioner according to claim 5, characterized in that: In step (P1), the concentration of acetic acid solution is 1-4wt%; the molecular weight of chitosan is 50-100kDa, and the degree of deacetylation is 70-85%. The total amount of unsaturated phosphorus-containing monomers and unsaturated sulfonic acid / sulfonate monomers added is 50-80% of the mass of chitosan, preferably 50-65%; the initiator is a water-soluble redox initiation system of persulfate (such as ammonium persulfate, sodium persulfate, potassium persulfate) and bisulfite (such as sodium bisulfite, potassium bisulfite) in a mass ratio of 1-2:1; the initiation temperature is 50-70°C; and anhydrous ethanol is selected as the alcohol precipitation.

7. The tea garden acidic soil conditioner according to claim 1, characterized in that: The alkali-modified biochar is prepared by a preparation method comprising the following steps: (T1) washing the biomass raw material, drying it, and crushing it to obtain a granular raw material, and then maintaining the granular raw material at 400-600° C. for 2-4 hours under a nitrogen atmosphere, and taking it out after cooling to obtain biochar; (T2) adding the biochar to an alkali solution containing 0.5-1 mol / L MOH and 2-4 mol / L M2CO3, where M is Na and K, mixing and stirring or shaking and impregnating for 12-24 hours to obtain an alkaline biochar mixture, and then filtering, washing, and drying to obtain the alkali-modified biochar; Preferably, the biomass in step (T1) is selected from at least one of pomelo peel, corn stalks, wheat stalks and bamboo.

8. The tea garden acidic soil conditioner according to claim 1, characterized in that: The biostimulant is a compound of mineral humic acid, magnesium sulfate, potassium dihydrogen phosphate and seaweed extract in the ratio of 10-30:5-10:15-20:30-50.

9. The tea garden acidic soil conditioner according to claim 1, characterized in that: The composite microbial agent is capable of improving acidic soil microbial bacteria, such as at least two of Bacillus subtilis, Bacillus gelatinus, Bacillus licheniformis, and Bacillus megaterium; preferably, the weight ratio of any two bacteria in the composite microbial agent is 1-3:1-3; More preferably, the binder is at least one of carboxymethyl cellulose and starch, and the trace element substance is at least one of zinc sulfate, ammonium molybdate and manganese sulfate. Preferably, zinc sulfate and ammonium molybdate are compounded in a mass ratio of 5-9:

1.

10. The method for preparing the tea garden acidic soil conditioner according to any one of claims 1 to 9, characterized in that: The steps include: (1) dispersing a binder and trace element substances in water to obtain a binder dispersion system; (2) weighing the biostimulant, the composite bacterial agent, and the fermented organic fertilizer of honey pomelo waste fruit and uniformly mixing them to obtain a mixture a; (3) The mixture a is placed at the bottom of the disc, and after the disc is started, 50-70% of the binder dispersion system is sprayed on the surface of the mixture in a spraying manner, and finally granulated in a granulator to form an internal core material b; (4) weighing alkaline conditioning material, alkali-modified biochar, and dicyandiamide, and uniformly mixing them to obtain a mixture c; (5) Mixture c is continuously added to the disc in a powdering manner, and the remaining binder dispersion system is sprayed in a spraying manner, and then dried to finally obtain a tea garden acidic soil conditioner; Preferably, in step (1), in the binder dispersion system, the concentration of trace elements is 0.1-0.3 wt %, and the concentration of the binder is 1.5-6 wt %.

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