Olive residue organic fertilizer as well as preparation method and application thereof

Abstract

The invention discloses an olive residue organic fertilizer as well as a preparation method and application thereof, and belongs to the technical field of organic fertilizers. Comprising the following steps: S1, uniformly mixing olive residues, chicken manure, bone meal, plant ash, modified chitosan, modified sodium alginate, modified montmorillonite, a complex microbial inoculant, zinc sulfate and borax to prepare a fermentation mixture; s2, piling the fermentation mixture into a fermentation pile, and fermenting until the fermentation pile is thoroughly decomposed, so as to obtain the olive residue organic fertilizer. Wherein the modified chitosan is chitosan grafted with a disulfide bond, and the modified sodium alginate is sodium alginate grafted with polyethylene glycol; the modified montmorillonite is montmorillonite grafted with polyacrylic acid; wherein the complex microbial inoculant comprises bacillus subtilis, actinomycetes and saccharomycetes. The olive residues are fermented into the organic fertilizer, the olive residues can be fully utilized, meanwhile, in the fermentation process, the nitrogen loss can be greatly reduced, the nitrogen content of the organic fertilizer is increased, and the utilization value of the organic fertilizer is increased.

Description

Technical Field

[0001] The invention relates to the technical field of organic fertilizers, in particular to an olive pomace organic fertilizer and a preparation method and application thereof. Background Art

[0002] As the olive cultivation industry continues to grow in the agricultural sector, the disposal of olive pomace presents a significant challenge. Traditional disposal methods, such as direct disposal or landfill, not only waste resources but can also cause environmental pollution. Meanwhile, the market demand for organic fertilizers is growing, prompting a pressing need to convert agricultural waste, such as olive pomace, into high-value organic fertilizer. Furthermore, if the resulting organic matter can be reused in olive cultivation, this would effectively utilize resources.

[0003] Because olive pomace has a high carbon content and a relatively low nitrogen content, it is difficult to meet fermentation requirements. Therefore, nitrogen-rich substances such as urea, ammonium sulfate, and livestock and poultry manure are often added during the fermentation process to adjust the carbon-nitrogen ratio. However, during the fermentation process, most nitrogen-containing substances are converted into ammonia and escape, resulting in a significant loss of nitrogen-containing substances. This, in turn, leads to a low nitrogen content and nutritional imbalance in the prepared organic fertilizer, seriously affecting its utilization value. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art and provide an olive pomace organic fertilizer and a preparation method and application thereof. By fermenting the olive pomace into organic fertilizer and applying it again to olive planting, the olive pomace can be fully utilized. At the same time, during the fermentation process, nitrogen loss can be greatly reduced, thereby increasing the nitrogen content of the organic fertilizer and improving the utilization value of the organic fertilizer.

[0005] The object of the present invention is achieved through the following technical solutions:

[0006] Technical Solution 1: A method for preparing olive residue organic fertilizer, comprising the following steps:

[0007] S1. The olive residue, chicken manure, bone meal, wood ash, modified chitosan, modified sodium alginate, modified montmorillonite, composite bacterial agent, zinc sulfate and borax were mixed to obtain a fermentation mixture;

[0008] S2. piling the fermentation mixture into a fermentation pile and fermenting it until it is mature, thereby obtaining olive pomace organic fertilizer.

[0009] Wherein, the modified chitosan is chitosan grafted with disulfide bonds, the modified sodium alginate is sodium alginate grafted with polyethylene glycol; the modified montmorillonite is montmorillonite grafted with polyacrylic acid;

[0010] Wherein, the composite bacterial agent includes Bacillus subtilis, actinomycetes and yeast.

[0011] As some possible implementation methods of the present application, the montmorillonite in the modified montmorillonite is first heat-treated before being grafted with polyacrylic acid.

[0012] As some feasible embodiments of the present application, the mass ratio of the olive residue, chicken manure, bone meal, wood ash, modified chitosan, modified sodium alginate, modified montmorillonite, composite bacterial agent, zinc sulfate and borax is 1000:(20-50):(20-50):(25-50):(10-20):(10-20):(50-80):(1-4):(0.5-2):(0.3-0.8).

[0013] As some feasible implementation methods of the present application, the mass ratio of olive residue, chicken manure, bone meal, wood ash, modified chitosan, modified sodium alginate, modified montmorillonite, composite bacterial agent, zinc sulfate and borax is 1000:32:27:42:15:10:63:2:1:0.6.

[0014] As some possible implementation methods of the present application, in the composite bacterial agent, the mass ratio of Bacillus subtilis, actinomycetes and yeast is 10:(5-10):(10-20).

[0015] In some embodiments of the present application, the water content of the fermentation mixture is 50% to 60%.

[0016] Technical Solution 2: An olive residue organic fertilizer, prepared by any method in Technical Solution 1.

[0017] Technical Solution 3: Use of the olive pomace organic fertilizer prepared by any method in Technical Solution 1 as a special fertilizer for olive cultivation.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The present invention adopts a fermentation process to convert olive residue into high-efficiency organic fertilizer, successfully realizing the resource utilization of olive residue and turning waste into treasure. In the construction of the fermentation system, chicken manure is rich in nitrogen, bone meal supplements phosphorus and calcium, and wood ash provides potassium and various trace elements. The three together constitute the basic nutrient source. At the same time, the addition of modified chitosan, modified sodium alginate, and modified montmorillonite significantly improves the soil pore structure and enhances the soil's water and fertilizer retention properties by virtue of their unique physical and chemical properties. In addition, the addition of composite bacterial agents activates the soil microbial community and accelerates nutrient circulation; zinc sulfate and borax, as key trace elements, accurately meet the special needs of olive growth. The synergistic effect of each component not only provides a full-cycle and diversified nutrient supply for the growth of olive trees, but also optimizes the physical and chemical properties of the soil, enhances the ecological vitality of the soil, and effectively improves the olive tree's ability to resist adversities such as drought and disease, ultimately achieving the dual goals of increasing olive yield and optimizing quality.

[0020] 2. The present invention innovatively incorporates modified chitosan, modified sodium alginate, and modified montmorillonite into the fermentation system. These three functional materials synergistically construct a nitrogen protection barrier that combines adsorption, retention, and sustained release, blocking nitrogen loss through different mechanisms and effectively reducing nitrogen loss by more than 30%.

[0021] 3. The present invention innovatively introduces modified sodium alginate and modified montmorillonite into the system in a synergistic manner, and successfully overcomes the problem of self-degradation of modified chitosan by constructing a multi-material interaction mechanism. DETAILED DESCRIPTION

[0022] A method for preparing olive pomace organic fertilizer comprises the following steps:

[0023] S1. The olive residue, chicken manure, bone meal, wood ash, modified chitosan, modified sodium alginate, modified montmorillonite, composite bacterial agent, zinc sulfate and borax were mixed to obtain a fermentation mixture;

[0024] S2. piling the fermentation mixture into a fermentation pile and fermenting it until it is mature, thereby obtaining olive pomace organic fertilizer.

[0025] Wherein, the modified chitosan is chitosan grafted with disulfide bonds, the modified sodium alginate is sodium alginate grafted with polyethylene glycol; the modified montmorillonite is montmorillonite grafted with polyacrylic acid;

[0026] Wherein, the composite bacterial agent includes Bacillus subtilis, actinomycetes and yeast.

[0027] In the above scheme, the functions of each component are as follows:

[0028] Olive pomace: Rich in organic components such as cellulose, hemicellulose and lignin, as well as a certain amount of nitrogen, phosphorus, potassium and trace elements, it can increase the organic matter content of the soil, improve the soil structure, and is beneficial to the growth and respiration of the olive tree roots, while providing a long-term nutrient supply for the olive tree.

[0029] Chicken manure: Rich in nitrogen, phosphorus, and potassium. Nitrogen promotes the growth of olive tree branches and leaves, phosphorus helps root development and flowering and fruiting, and potassium can enhance the olive tree's resistance to stress.

[0030] Bone meal: Rich in phosphorus and calcium. Phosphorus is essential for the flowering, fruiting and root development of olive trees. Calcium helps strengthen the cell walls of olive trees, improve the hardness and quality of the fruit, and reduce physiological diseases.

[0031] Wood ash: Rich in potassium, it enhances the olive tree's ability to resist lodging and resistance to diseases and pests.

[0032] Zinc sulfate: Zinc is one of the trace elements necessary for the growth and development of olive trees, and is involved in the composition and metabolic process of various enzymes in olive trees.

[0033] Borax: Boron plays an important role in the reproductive growth of olive trees. It can promote pollen germination and pollen tube elongation, increase the fruit setting rate of olive trees, and reduce flower and fruit drop.

[0034] Modified sodium alginate: It has good hydrophilicity and water retention, and contains some natural plant growth regulators and trace elements, which can stimulate the growth of olive tree roots and enhance the stress resistance of olive trees.

[0035] Modified chitosan: can inhibit harmful microorganisms, improve the structure of soil microbial communities, enhance soil biological activity, and enhance the resistance of olive trees to diseases and pests and their adaptability to adverse environments.

[0036] Modified montmorillonite: It has a large specific surface area and ion exchange capacity, can absorb nutrient ions in the soil, reduce nutrient loss and leaching, play a fertilizer retention role, and is beneficial to the growth and development of olive tree roots.

[0037] Through the synergistic effect of the above components, it can provide comprehensive nutrient supply for olive planting, improve soil structure, enhance soil water and fertilizer retention capacity, promote soil microbial activity, improve the stress resistance of olive trees, and ultimately achieve the goal of increasing olive yield and quality.

[0038] Furthermore, in the modified chitosan, the chitosan itself has a certain adsorption capacity, which can fix the nitrogen-containing substances produced during the fermentation process through adsorption, reducing their volatilization into the external environment in the form of ammonia, thereby reducing nitrogen loss. After the introduction of disulfide bonds, the types and number of functional groups on the molecular chain increase, providing more adsorption sites for nitrogen, allowing the modified chitosan molecules to bind to nitrogen through various effects such as electrostatic attraction, hydrogen bonding, and complexation, further improving the nitrogen adsorption capacity. At the same time, the disulfide bonds have a certain rigidity and stability. After being grafted onto the chitosan molecules, the chitosan molecules are further stretched or form a specific spatial structure, which is conducive to the proximity and adsorption of nitrogen molecules, thereby increasing the adsorption amount.

[0039] Modified sodium alginate has a large number of functional groups, such as carboxyl groups, which can interact with nitrogen-containing compounds through ion exchange and complexation, resulting in a certain adsorption capacity for nitrogen. Polyethylene glycol has good hydrophilicity and flexibility. After grafting polyethylene glycol, on the one hand, it can increase the stretchability and steric hindrance of the sodium alginate molecular chain, enabling it to better contact with nitrogen-containing substances and improving adsorption efficiency. On the other hand, functional groups such as hydroxyl groups of polyethylene glycol can further enhance the adsorption capacity of nitrogen through hydrogen bonding and other interactions. In addition, after polyethylene glycol is grafted onto sodium alginate, it can form a gel-like substance with certain elasticity and stability in the fermentation system. This gel structure can form a physical barrier between the fermentation substrate and the external environment, preventing the nitrogen-containing gases produced by fermentation from escaping directly into the air, thereby reducing nitrogen volatilization losses.

[0040] Modified montmorillonite itself has a certain adsorption capacity and can adsorb ammonium ions through ion exchange. At the same time, polyacrylic acid contains a large number of carboxyl groups. During the fermentation process, the carboxyl groups can dissociate, making the modified surface more negatively charged, thereby enhancing the electrostatic attraction to cationic nitrogen. At the same time, the polymer chain of polyacrylic acid has a certain degree of flexibility and stretchability, which can increase the contact area between montmorillonite and nitrogen-containing substances, helping to improve the efficiency of nitrogen adsorption.

[0041] Based on this, adding modified chitosan, modified sodium alginate and modified montmorillonite during the fermentation process can significantly reduce nitrogen loss.

[0042] However, the introduction of disulfide bonds in modified chitosan will hinder the binding of microbial enzymes to chitosan molecules, thereby reducing the rate of enzymatic hydrolysis. Based on this, the degradation rate of chitosan grafted with disulfide bonds is slower than that of ungrafted chitosan. In this way, the nutrients bound in the structure of modified chitosan are difficult to be released in time, and at the same time the soil structure is damaged, which seriously affects the cultivation of olives.

[0043] Compared to sodium alginate, the hydrophilicity of modified sodium alginate is significantly improved, allowing it to better interact with modified chitosan. When in contact with modified chitosan, it can more quickly penetrate into the interior of the modified chitosan, promoting the dispersion of the modified chitosan molecular chains, thereby improving its ability to self-degrade chitosan. At the same time, the carboxyl groups of modified sodium alginate interact with groups such as amino groups in the modified chitosan. This interaction changes the molecular conformation of the modified chitosan, making it more susceptible to enzyme attack. At the same time, it may also destroy the hydrogen bonds and other forces between the modified chitosan molecules, making the structure of the modified chitosan loose, thereby improving its self-degradation ability.

[0044] Compared with montmorillonite, the hydrophilicity of modified montmorillonite is greatly enhanced, which is beneficial to improve its self-degradation ability.

[0045] Due to its hydrophilicity, a moist environment can be formed around the montmorillonite-polyacrylic acid-modified chitosan composite, which is beneficial to the swelling of the modified chitosan and the hydrolysis of disulfide bonds.

[0046] On the other hand, the presence of the polyacrylic acid segments creates a certain steric hindrance effect, giving the modified chitosan molecular chains more room to stretch on the montmorillonite surface, making it less likely to agglomerate or accumulate tightly. This makes the disulfide bonds on the modified chitosan molecular chains more exposed to the external environment, increasing their contact with bioactive substances such as hydrolases, facilitating the enzyme's action on the disulfide bonds and promoting self-degradation.

[0047] The self-degradation effect of modified chitosan can be effectively improved through the synergistic effect of modified sodium alginate and modified montmorillonite.

[0048] In order to further improve the nitrogen adsorption effect, the self-degradation ability of the modified chitosan, and the air permeability of the fermentation pile, as some feasible embodiments of the present application, the structure of the modified montmorillonite is further limited, that is, the montmorillonite in the modified montmorillonite is first heat-treated before being grafted with polyacrylic acid. Heat treatment can effectively increase the pore size of the montmorillonite, providing more space and sites for the grafting of polyacrylic acid, so that polyacrylic acid can be more fully grafted onto the surface and pores of the montmorillonite. Due to the increase in the pore size of the montmorillonite, the modified chitosan can more easily enter the pores of the montmorillonite, fully contacting the grafted material on the surface of the montmorillonite and the environment within the pores, effectively improving the self-degradation effect of the modified chitosan. At the same time, the increase in pore size can improve the adsorption of nitrogen and reduce nitrogen loss.

[0049] In order to further improve the role of organic fertilizer in olive cultivation, as some feasible embodiments of the present application, the amount of each component in the organic fertilizer is further limited, that is, the mass ratio of the olive residue, chicken manure, bone meal, wood ash, modified chitosan, modified sodium alginate, modified montmorillonite, composite bacterial agent, zinc sulfate and borax is 1000:(20~50):(20~50):(25~50):(10~20):(10~20):(50~80):(1~4):(0.5~2):(0.3~0.8).

[0050] In order to further improve the role of organic fertilizer in olive cultivation, as some feasible implementation methods of this application, the amount of each component in the organic fertilizer is further limited, that is, the mass ratio of olive residue, chicken manure, bone meal, wood ash, modified chitosan, modified sodium alginate, modified montmorillonite, composite bacterial agent, zinc sulfate and borax is 1000:32:27:42:15:10:63:2:1:0.6.

[0051] In order to further improve the fermentation effect, as some feasible embodiments of the present application, the dosage of each component in the composite bacterial agent is further limited, that is, in the composite bacterial agent, the mass ratio of Bacillus subtilis, actinomycetes and yeast is 10:(5-10):(10-20).

[0052] In order to further improve the fermentation effect, as some possible implementation methods of the present application, the moisture content of the fermentation mixture is further limited, that is, as some possible implementation methods of the present application, the moisture content of the fermentation mixture is 50% to 60%.

[0053] The preparation of the organic fertilizer described in the present application is further described in detail below in conjunction with specific embodiments; it is worth noting that: the various raw materials in the examples are commercially available products.

[0054] Example 1

[0055] S1. Grind the olive pomace and pass it through a 10-mesh sieve, wherein the moisture content of the olive pomace is less than 45%. By weight, evenly mix 1000 parts of olive pomace, 30 parts of chicken manure, 25 parts of bone meal, 45 parts of wood ash, 13 parts of modified chitosan, 12 parts of modified sodium alginate, 65 parts of modified montmorillonite, 1 part of zinc sulfate, and 0.5 part of borax, and adjust the moisture content of the materials to 50% to 60%; then add 2 parts of a composite microbial agent (a mixture of Bacillus subtilis, actinomycetes, and yeast, with a mass ratio of 1:1:1 and a concentration of ≥2 billion / g) and mix thoroughly to obtain a fermentation mixture;

[0056] S2. The fermented mixture is piled into a trapezoidal or conical pile, generally about 1.5 meters high and 2 meters wide, with the length depending on the site and processing capacity. After stacking, the pile should be turned regularly, turning once every day for the first 5 days of fermentation and every 3 days thereafter. Olive pomace fermentation is complete when the volume of the compost no longer decreases significantly, the color changes to dark brown or dark brown, the odor changes from the original sour smell to a lighter earthy smell, and the compost temperature drops to room temperature with no significant temperature increase.

[0057] Wherein, the preparation method of modified chitosan is as follows:

[0058] Chitosan is added to a 1% to 2% aqueous acetic acid solution and stirred until completely dissolved to obtain a chitosan solution. The chitosan is then passed through a dialysis bag to retain chitosan with a molecular weight cutoff of 8,000 to 14,000 Da. The solution is then freeze-dried. The dried material is then fully dissolved in an appropriate amount of DMSO. A certain amount of cystamine, EDC·HCl, and NHS are then added. The reaction vessel is sealed and reacted at 45 to 50°C for 20 hours. The reaction is then cooled and an appropriate amount of acetone is added to precipitate. The precipitate is then centrifuged, washed, and vacuum-dried to a constant weight to obtain modified chitosan.

[0059] The preparation method of modified sodium alginate is as follows:

[0060] Sodium alginate is dissolved in an appropriate amount of deionized water to prepare a solution of a certain concentration, and then insoluble impurities are removed by filtration or centrifugation to obtain a clear sodium alginate solution. Thereafter, an appropriate amount of N-hydroxysuccinimide (NHS) and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) are added to the sodium alginate solution and stirred continuously at room temperature for 1.5 hours to obtain an activated solution.

[0061] Polyethylene glycol (molecular weight 3000-10000Da) is dissolved in an appropriate amount of dimethyl sulfoxide to prepare a polyethylene glycol solution, and then the PEG solution is slowly added dropwise to the activation solution, followed by reaction at 50°C for 7 hours; then excess ethanol is added to the reaction system to precipitate, and the precipitate is centrifuged, washed, and vacuum-dried to constant weight to obtain modified sodium alginate.

[0062] Among them, the molar ratio of EDC to carboxyl groups in sodium alginate is 2:1; the molar ratio of NHS to EDC is 1:1; and the mass ratio of polyethylene glycol to sodium alginate is 2:1.

[0063] The preparation method of modified montmorillonite is as follows:

[0064] ① Heat treatment: the montmorillonite is dried, ground, passed through a 200-mesh sieve, and then calcined at 600°C for 2 hours. After cooling, the heat-treated montmorillonite is obtained;

[0065] ② Grafting polyacrylic acid: Add heat-treated montmorillonite to deionized water, mix thoroughly and prepare a montmorillonite suspension with a mass fraction of 3%; measure a certain volume of acrylic acid and slowly add it to a certain concentration of sodium hydroxide solution, and carry out neutralization reaction under stirring conditions, controlling the neutralization degree at 70%.

[0066] The neutralized acrylic acid solution was added to the montmorillonite suspension and stirred thoroughly. The mixture was then transferred to a three-necked flask and purged with nitrogen for 30 minutes. A certain amount of potassium persulfate was then weighed, dissolved in a small amount of deionized water, and added to the flask to initiate graft polymerization. The reaction temperature was 60°C, the stirring speed was 400 rpm, and the reaction time was 3.5 hours. The mixture was then cooled, washed, and vacuum dried at 60-80°C to constant weight to obtain the modified montmorillonite.

[0067] The mass ratio of acrylic acid to montmorillonite is 2:1, and the amount of potassium persulfate used is 1.5% of the mass of acrylic acid.

[0068] Example 2

[0069] S1. Grind the olive pomace and pass it through a 10-mesh sieve, wherein the moisture content of the olive pomace is less than 45%. By weight, evenly mix 1000 parts of olive pomace, 32 parts of chicken manure, 27 parts of bone meal, 42 parts of wood ash, 15 parts of modified chitosan, 10 parts of modified sodium alginate, 63 parts of modified montmorillonite, 1 part of zinc sulfate and 0.6 parts of borax, and adjust the moisture content of the materials to 50% to 60% by adding water; then add 2 parts of a composite bacterial agent (a mixture of Bacillus subtilis, actinomycetes and yeast, the mass ratio of the three is 1:1:1, and the concentration of the three bacterial agents is ≥2 billion / g) and mix thoroughly to obtain a fermentation mixture;

[0070] S2. The fermented mixture is piled into a trapezoidal or conical pile, generally about 1.5 meters high and 2 meters wide, with the length depending on the site and processing capacity. After stacking, the pile should be turned regularly, turning once every day for the first 5 days of fermentation and every 3 days thereafter. Olive pomace fermentation is complete when the volume of the compost no longer decreases significantly, the color changes to dark brown or dark brown, the odor changes from the original sour smell to a lighter earthy smell, and the compost temperature drops to room temperature with no significant temperature increase.

[0071] Comparative Example 1

[0072] Compared with Example 2, modified chitosan was not added, and the rest were the same as Example 2.

[0073] Comparative Example 2

[0074] Compared with Example 2, modified sodium alginate was not added, and the rest were the same as Example 2.

[0075] Comparative Example 3

[0076] Compared with Example 2, modified montmorillonite was not added, and the rest were the same as Example 2.

[0077] Comparative Example 4

[0078] Compared with Example 2, modified montmorillonite and modified sodium alginate are not added, and the rest are the same as Example 2.

[0079] Comparative Example 5

[0080] Compared with Example 2, modified chitosan, modified sodium alginate and modified montmorillonite were not added, and the rest were the same as Example 2.

[0081] Comparative Example 6

[0082] Compared with Example 2, the modified chitosan was replaced with chitosan, and the rest was the same as Example 2.

[0083] Comparative Example 7

[0084] Compared with Example 2, the modified chitosan was changed to chitosan, and the modified montmorillonite and modified sodium alginate were not added. The rest were the same as Example 2.

[0085] 1. Determine the nitrogen loss of organic fertilizers.

[0086] The nitrogen loss of the organic fertilizers prepared in Examples 1 to 2 and Comparative Examples 1 to 6 was measured, wherein the nitrogen content determination method (such as the Kjeldahl method), the determination formula, and the nitrogen loss determination formula are all prior art. The results are shown in Table 1.

[0087] Table 1:

[0088]

[0089]

[0090] It can be seen from Table 1 that the nitrogen loss of the organic fertilizer prepared according to the fermentation method and fermentation components of the present invention is less than 10%, which is much lower than the nitrogen loss of Comparative Example 5.

[0091] Comparing Comparative Examples 1 to 4 with Comparative Example 5, it can be seen that adding any component of modified chitosan, modified sodium alginate and modified montmorillonite will reduce the nitrogen loss, but only when the three are added in combination can the nitrogen loss of organic fertilizer be reduced to the greatest extent.

[0092] In Comparative Example 6, chitosan was not modified, which would result in an increase in nitrogen loss.

[0093] 2. Determine the self-degradation ability of modified chitosan.

[0094] Sandy loam soil from the planting base of Sichuan Zhongyi Olive Development Co., Ltd. was used. The soil pH was 6.8, and the soil moisture content was 65% of the field water holding capacity.

[0095] Then proceed as follows:

[0096] Take 5 parts of the above soil, and the organic fertilizers in Example 2, Comparative Example 2, Comparative Example 3, Comparative Example 4 and Comparative Example 7 are respectively evenly mixed into 5 parts of the soil at a mass of 1 wt%. Then, the 5 parts of soil mixed with the organic fertilizer are placed in culture containers to simulate the actual conditions of the soil, so that the soil always maintains 60% to 70% of the field water holding capacity and maintains the temperature at 25 to 30 ° C.

[0097] During the incubation process, soil samples were collected from each soil group at predetermined time intervals (e.g., 5th day, 10th day, 15th day, 20th day, etc.), and then the content of the modified chitosan remaining in the soil was determined by high performance liquid chromatography, ultraviolet spectrophotometry, or other existing methods.

[0098] After testing, it took 25 days for the modified chitosan in Example 2 to be completely degraded;

[0099] In Comparative Example 2, it took 34 days for the modified chitosan to be completely degraded;

[0100] In Comparative Example 3, it took 36 days for the modified chitosan to be completely degraded;

[0101] In Comparative Example 4, it took 46 days for the modified chitosan to be completely degraded;

[0102] In Comparative Example 7, it took 27 days for chitosan to be completely degraded.

[0103] The above data show that the synergistic effect of modified sodium alginate and modified montmorillonite can significantly improve the self-degradation ability of modified chitosan.

[0104] 3. Experiment on the application of organic fertilizer in olive cultivation.

[0105] The organic fertilizers prepared in Examples 1 and 2 were tested at the olive planting base of Sichuan Zhongyi Olive Development Co., Ltd.

[0106] Three fertilizer groups were set up in the experiment, namely the organic fertilizers in Examples 1 and 2, and a commercially available potassium sulfate compound fertilizer.

[0107] The amount of fertilizer applied was based on the standard that the total nutrient content of nitrogen, phosphorus and potassium in each treatment was the same.

[0108] 60 olive trees of the same age, similar growth and fruit yield of 100 to 110 kg per tree were randomly selected and divided into three groups on average. The fertilizers of the three fertilizer groups mentioned above were applied to each group.

[0109] The fertilization method adopts the existing technology. The amount of commercial potassium sulfate type compound fertilizer is applied according to the instructions. The fertilizer in Examples 1 and 2 is applied 2 to 5 kg per plant each time. The specific amount of fertilizer is adjusted according to actual conditions, but the fertilization frequency is the same as that of the commercial potassium sulfate type compound fertilizer.

[0110] Except for the type and amount of fertilizer, all other external conditions are the same.

[0111] Two years later, in the Example 1 group, the fruit yield of three trees decreased compared with two years ago (an average decrease of 2.4 kg), while the fruit yield of the rest increased, with an average increase of 9.2 kg;

[0112] In the Example 2 group, the fruit yield of one tree decreased compared with two years ago (decreased by 1.9 kg), while the fruit yields of the others increased, with an average increase of 10.0 kg;

[0113] In the commercial fertilizer group, the fruit yield of three trees decreased compared with two years ago (an average decrease of 2.1 kg), while the fruit yield of the rest increased, with an average increase of 7.8 kg.

[0114] It can be seen from this that the organic fertilizer prepared by the present invention can significantly increase olive yield, and the overall effect is better than that of commercially available potassium sulfate type compound fertilizer.

Claims

1. A method for preparing olive pomace organic fertilizer, characterized in that, The steps include: S1. The olive residue, chicken manure, bone meal, wood ash, modified chitosan, modified sodium alginate, modified montmorillonite, composite bacterial agent, zinc sulfate and borax were mixed to obtain a fermentation mixture; S2. piling the fermentation mixture into a fermentation pile and fermenting it until it is mature, thereby obtaining olive pomace organic fertilizer. Wherein, the modified chitosan is chitosan grafted with disulfide bonds, the modified sodium alginate is sodium alginate grafted with polyethylene glycol; and the modified montmorillonite is montmorillonite grafted with polyacrylic acid. Wherein, the composite bacterial agent includes Bacillus subtilis, actinomycetes and yeast.

2. the preparation method of a kind of olive residue organic fertilizer according to claim 1, is characterized in that, The montmorillonite in the modified montmorillonite is first heat-treated before being grafted with polyacrylic acid.

3. The preparation method of an olive residue fertilizer according to claim 1, wherein The mass ratio of the olive residue, chicken manure, bone meal, wood ash, modified chitosan, modified sodium alginate, modified montmorillonite, composite bacterial agent, zinc sulfate and borax is 1000:(20-50):(20-50):(25-50):(10-20):(10-20):(50-80):(1-4):(0.5-2):(0.3-0.8).

4. The preparation method of an olive residue fertilizer according to claim 3, wherein The mass ratio of olive residue, chicken manure, bone meal, wood ash, modified chitosan, modified sodium alginate, modified montmorillonite, composite bacterial agent, zinc sulfate and borax is 1000:32:27:42:15:10:63:2:1:0.

6.

5. The preparation method of a kind of olive residue organic fertilizer according to claim 3, is characterized in that, In the composite bacterial agent, the mass ratio of Bacillus subtilis, actinomycetes and yeast is 10:(5-10):(10-20).

6. The preparation method of an olive residue organic fertilizer according to claim 1, wherein The water content of the fermentation mixture is 50% to 60%.

7. An olive pomace organic fertilizer, characterized in that: Prepared by the method according to any one of claims 1 to 7.

8. Use of the olive pomace organic fertilizer prepared by the preparation method according to any one of claims 1 to 6 as a special fertilizer for olive cultivation.

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