Water-saving and water-retaining organic fertilizer and preparation method thereof

Abstract

The invention discloses a water-saving and water-retaining organic fertilizer and a preparation method thereof, and relates to the technical field of organic chemical fertilizers, the preparation method comprises the following steps: S1, uniformly mixing raw materials and water to obtain a mixture; s2, adding an EM bacterial solution which is 1-2.5% of the mass of the mixture, performing aerobic fermentation at 30-40 DEG C, turning over up and down once every day, adding 7-10 parts by weight of potato hydroxypropyl starch, and performing pile fermentation for anaerobic fermentation; s3, adding 3-5 parts by weight of starch grafted potassium acrylate, 2-5 parts by weight of trehalose and 10-30 parts by weight of unfermented plant straw into the fermentation product, uniformly mixing, and performing freeze-drying and crushing on the mixed product to obtain the water-saving and water-retaining organic fertilizer. The fertilizer can balance the release speed of nutrients, improve the utilization rate of the nutrients, provide more comprehensive and balanced nutrient supply for crops and promote the growth and development of the crops, and meanwhile, the improved soil structure is also beneficial to the root growth and nutrient absorption of the crops.

Description

Technical Field

[0001] The invention relates to the technical field of organic fertilizers, and in particular to a water-saving and water-retaining organic fertilizer and a preparation method thereof. Background Art

[0002] Organic-inorganic compound fertilizer refers to a compound fertilizer containing organic matter and inorganic nutrients. Most of the organic matter is processed organic fertilizer and matter containing organic matter. Some are added with microbial agents and substances that stimulate growth. They are called organic active fertilizers or biological slow-release fertilizers. The inorganic nutrient part is mainly chemical fertilizers. However, in arid areas, the soil water content is low, soil erosion is serious, and the soil is prone to compaction. Specifically, it refers to the phenomenon that the soil surface lacks organic matter and has a poor structure. Under the influence of external factors such as irrigation or rainfall, the structure is destroyed and the soil material is dispersed, and after drying, the soil surface becomes hard due to the action of cohesion; compaction reduces the soil's ability to absorb water, oxygen and nutrients, and the decreased permeability causes poor development of crop roots, affecting the growth and development of crops.

[0003] For example, the Chinese patent, application number, CN202410557832.7, is a water-saving and water-retaining organic fertilizer and its preparation method; starting from the composition of organic fertilizer, the natural polymer water-retaining agent potato hydroxypropyl starch is screened out, and a secondary fermentation process is adopted, that is, short-term aerobic fermentation combined with long-term anaerobic fermentation. During aerobic fermentation, only starch is added, and during anaerobic fermentation, potato hydroxypropyl starch is added. After the fermentation is completed, different degradable synthetic polymer water-retaining resins are further added to the fermentation product, and starch-grafted potassium acrylate matching the organic fertilizer is screened out, and the timing of adding different types of water-retaining agents is studied, so as to achieve the effect of not affecting the composting fermentation of organic fertilizer, and at the same time, the organic fertilizer has the effect of saving water and retaining water.

[0004] However, the large-scale aggregation of microorganisms accelerates the degradation of organic fertilizers, causing some of their nutrients to be utilized by microorganisms during use and reducing the time they take effect. Summary of the invention

[0005] The embodiment of the present application provides a water-saving and water-retaining organic fertilizer and a preparation method thereof, thereby solving the problem of short action time of organic fertilizer in the prior art and achieving a long-term effect of organic fertilizer. The embodiment of the present application provides a preparation method of water-saving and water-retaining organic fertilizer, and the preparation steps specifically include:

[0006] S1: 70-100 parts by weight of organic matter from cattle and sheep manure, 40-60 parts by weight of plant straw, 10-15 parts by weight of humic acid, 1-2 parts by weight of brown sugar, 10-20 parts by weight of starch, 1-5 parts by weight of urea, 2-5 parts by weight of calcium phosphate, 1-4 parts by weight of potassium chloride, and water are uniformly mixed to obtain a mixture;

[0007] S2, adding 1%-2.5% of the mixture by mass of EM bacterial solution, aerobically fermenting at 30-40°C for 1-2 days, turning upside down once a day, adding 7-10 parts by weight of potato hydroxypropyl starch, and anaerobically fermenting the pile for 15-25 days;

[0008] S3. Add 3-5 parts by weight of potassium starch grafted acrylate, 2-5 parts by weight of trehalose, and 10-30 parts by weight of unfermented plant straw to the fermentation product, mix them evenly, freeze-dry and crush the mixed product to obtain a water-saving and water-retaining organic fertilizer.

[0009] Furthermore, the mixture obtained in step S1 has a C / N ratio of 20:1-35:1, and a water content of the mixture of 45%-60%.

[0010] Furthermore, the plant straw is crushed and passed through an 80-mesh sieve.

[0011] Furthermore, the plant straw is coated with trehalose, and the specific steps are: melt the trehalose at 100-110°C, add the plant straw therein, mix and stir evenly, and slowly cool down while stirring, cool down to 50°C after 30 minutes, and then naturally cool down to room temperature, and crush the obtained plant straw through an 80-mesh sieve.

[0012] Furthermore, potato hydroxypropyl starch is added to the trehalose wrapping the fermented plant straw.

[0013] Furthermore, starch-grafted potassium acrylate is added to the trehalose that is not involved in the fermentation.

[0014] Furthermore, the trehalose contains 5 parts by weight of potato hydroxypropyl starch.

[0015] Furthermore, 3 parts by weight of potassium acrylate is grafted onto starch in the trehalose.

[0016] Furthermore, the unfermented plant straw is further wrapped twice to produce an inner shell and an outer shell, specifically:

[0017] When the temperature of the trehalose in the inner shell is lowered, the temperature is lowered to 50°C for 1 min, and then the temperature is naturally lowered to room temperature, and the obtained plant straw is crushed through an 80-mesh sieve;

[0018] The trehalose of the outer shell is also added with 0.5% by mass of sodium chloride to increase its aperture ratio, and the temperature is naturally lowered while stirring, and the obtained plant straw is crushed through an 80-mesh sieve;

[0019] The amount of starch grafted potassium acrylate added in the outer layer is 5 parts by weight, and the amount of starch grafted potassium acrylate added in the inner layer is 3 parts by weight.

[0020] A water-saving and water-retaining organic fertilizer is prepared by the preparation method of the water-saving and water-retaining organic fertilizer.

[0021] One or more technical solutions provided in the embodiments of the present application have at least the following technical effects or advantages:

[0022] First, the unfermented plant straw itself is rich in organic matter. Adding it to the fermentation product can further increase the organic matter content of the organic fertilizer. The unfermented plant straw contains a certain amount of carbon elements. The later addition can adjust the carbon-nitrogen ratio (C / N) of the organic fertilizer, making it more suitable for the growth and activity of microorganisms, which is beneficial for microorganisms to decompose organic matter and release nutrients needed by plants. The unfermented plant straw is first decomposed into smaller organic molecules by microorganisms in the soil. In the process of decomposing organic matter, microorganisms will release some cementing substances, such as polysaccharides and proteins. These substances are sticky and can bond soil particles together to form preliminary aggregates. As microbial metabolites and other components in the soil (such as calcium, magnesium ions, etc.) further combine with the aggregates, their stability is enhanced. Finally, these stable aggregates are interconnected to form soil aggregates with a porous structure. These aggregates are tightly bound through the interaction between soil particles and organic matter to form a stable soil structure.

[0023] Secondly, by wrapping trehalose around the plant straw to form a hard shell, the trehalose shell has a controlled release effect, so that the release rate of nutrients in the plant straw can be adjusted during the fermentation process, so that nutrients are continuously and stably supplied during the growth of crops. Trehalose and its decomposition products have a selective promoting effect on microorganisms, which can guide the growth of beneficial microorganisms and inhibit the reproduction of harmful microorganisms during the fermentation process, thereby optimizing the fermentation environment. Through the controlled release effect of the trehalose shell, nutrients in the plant straw can be released on demand, the utilization rate of nutrients can be improved, and the waste of nutrients can be reduced. The survival ability of fermentation bacteria is increased in the initial stage of fermentation. The fermentation products of trehalose can adjust the pH value, humidity, temperature and other parameters of the fermentation environment, create an environment that is more conducive to the growth and reproduction of beneficial microorganisms, and improve the fermentation efficiency and quality of organic fertilizers.

[0024] Third, adding potato hydroxypropyl starch to the trehalose wrapping the fermented plant straw not only improves the toughness and strength of the trehalose shell, but also improves the processing performance of the trehalose shell because of its good solubility and film-forming properties, making it easier to shape and wrap the plant straw and improving its chemical stability. The potato hydroxypropyl starch makes the trehalose shell have better water retention and nutrient slow-release properties, so that it can maintain a suitable humidity during the fermentation of the plant straw and slowly release nutrients for crops to absorb and utilize. In addition, the special components of trehalose help to improve the permeability of the cell membrane of the fermentation bacteria, making it easier for the fermentation bacteria to absorb other nutrients, accelerating the metabolic utilization of the potato hydroxypropyl starch by the fermentation bacteria, decomposing it, and increasing the growth rate of bacteria. The thickening and film-forming properties of the potato hydroxypropyl starch reduce the loss of active ingredients such as total phosphorus and total potassium during the fermentation process, maintain the nutrient content of the fertilizer, and allow microorganisms to be distributed in large quantities on the trehalose shell.

[0025] Fourthly, the double-layer structure provides a more suitable growth environment for bacteria by adjusting the porosity and water retention capacity, which not only improves the metabolic activity and reproduction efficiency of bacteria, but also promotes the decomposition and utilization of organic matter in plant straw by bacteria, thereby improving the fermentation effect and product quality of organic fertilizer.

[0026] The double-layer sugar shell structure provides bacteria with a growth environment that gradually changes from the outer layer to the inner layer. The larger pores and air permeability of the outer shell are conducive to the rapid diffusion and penetration of bacteria. As the bacteria penetrate into the inner shell, they use the richer organic matter in the inner shell to grow and reproduce, thereby improving the overall bacterial utilization efficiency. DETAILED DESCRIPTION

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which the present invention belongs; the terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention; the term "and / or" used herein includes any and all combinations of one or more related listed items.

[0028] Embodiment 1

[0029] The present application discloses a method for preparing a water-saving and water-retaining organic fertilizer, comprising:

[0030] S1: 70-100 parts by weight of organic matter from cattle and sheep manure, 40-60 parts by weight of plant straw, 10-15 parts by weight of humic acid, 1-2 parts by weight of brown sugar, 10-20 parts by weight of starch, 1-5 parts by weight of urea, 2-5 parts by weight of calcium phosphate, 1-4 parts by weight of potassium chloride, and water are uniformly mixed to obtain a mixture, wherein the C / N of the mixture is controlled to be 20:1-35:1, and the water content of the mixture is 45%-60%;

[0031] S2, adding 1%-2.5% of the mixture by mass of EM bacterial solution, aerobically fermenting at 30-40°C for 1-2 days, turning upside down once a day, adding 7-10 parts by weight of potato hydroxypropyl starch, and anaerobically fermenting the pile for 15-25 days;

[0032] S3. Add 3-5 parts by weight of potassium starch grafted acrylate, 2-5 parts by weight of trehalose, and 10-30 parts by weight of unfermented plant straw to the fermentation product, mix them evenly, freeze-dry and crush the mixed product to obtain a water-saving and water-retaining organic fertilizer.

[0033] Among them, the plant straw was crushed and passed through an 80-mesh sieve.

[0034] The technical solutions in the above embodiments of the present application have at least the following technical effects or advantages:

[0035] Unfermented plant straw is rich in organic matter. Adding it to the fermentation product can further increase the organic matter content of the organic fertilizer. Unfermented plant straw contains a certain amount of carbon. Adding it later can adjust the carbon-nitrogen ratio (C / N) of the organic fertilizer, making it more suitable for the growth and activity of microorganisms, which is beneficial for microorganisms to decompose organic matter and release nutrients needed by plants.

[0036] Unfermented plant straw is first decomposed into smaller organic molecules by microorganisms in the soil. In the process of decomposing organic matter, microorganisms release some cementing substances, such as polysaccharides and proteins. These substances are sticky and can bind soil particles together to form preliminary aggregates. As microbial metabolites and other components in the soil (such as calcium and magnesium ions) further combine with aggregates, their stability is enhanced. Finally, these stable aggregates are interconnected to form soil aggregates with a porous structure. These aggregates are tightly bound together through the interaction between soil particles and organic matter, forming a stable soil structure.

[0037] The porosity of the aggregate structure allows air and water in the soil to flow freely, thereby improving soil aeration and facilitating the root respiration and growth of crops. The aggregate structure can retain moisture in the soil and reduce evaporation and loss of water, which enables the soil to provide sufficient moisture for crops even in drought periods. The organic matter and microbial activities in the aggregate structure provide a rich source of nutrients for crops. At the same time, the aggregate structure can also protect the nutrients in the soil from being leached and lost, thereby improving soil fertility.

[0038] Since unfermented plant straw is rich in organic matter and nutrients, it can increase the nutrient content of organic fertilizer and improve the utilization rate of fertilizer. At the same time, the presence of organic matter can also promote the activity of soil microorganisms, accelerate the release and conversion of nutrients, and make it easier for crops to absorb and utilize. When unfermented plant straw decomposes in the soil, it will release water-soluble organic matter and colloidal substances, which can absorb and retain soil moisture and enhance the water retention capacity of the soil, which is particularly important for crop growth in arid areas or dry seasons; the nutrients of fermented plant straw are released more rapidly, while unfermented straw can slowly decompose in the soil and continuously release nutrients. The mixed use of the two can balance the release rate of nutrients and improve the utilization rate of nutrients. In addition, the fermented product contains a large number of fermentation bacteria, which is conducive to the decomposition of unfermented plant straw. The mixed use of fermented and unfermented straw can provide crops with a more comprehensive and balanced nutrient supply and promote the growth and development of crops. At the same time, the improved soil structure is also conducive to the root growth and nutrient absorption of crops.

[0039] The performance of the organic fertilizer was tested by the detection and planting test of the organic fertilizer. Four samples of the organic fertilizer were set, and the only difference was that samples 1-3 were selected from different weight portions of unfermented plant straw in the present embodiment, and sample 4 was unfermented plant straw; the remaining ingredients and conditions were 100 weight portions of organic matter from cattle and sheep manure, 60 weight portions of plant straw, 15 weight portions of humic acid, 2 weight portions of brown sugar, 20 weight portions of starch, 5 weight portions of urea, 5 weight portions of calcium phosphate, 4 weight portions of potassium chloride, 10 weight portions of potato hydroxypropyl starch, 5 weight portions of potassium acrylate, 5 weight portions of trehalose, and 1% of the total weight of EM bacterial solution, which was aerobically fermented at 35° C. for 2 days and anaerobic fermented in a pile for 20 days;

[0040] The experimental plants used in the planting experiment were honeysuckle seedlings. After the tree holes were dug, organic fertilizer and backfill soil were mixed in a ratio of 1:2 and backfilled into the afforestation tree holes. Watering was done once on the day of afforestation and no watering was done later. The survival rate and dry weight were investigated the following year. The results are shown in Table 1:

[0041] Unfermented plant straw weight Dry weight / g Survival rate / % Sample 1 10 5.86±0.31 91.21±4.31 Sample 2 20 6.15±0.28 93.24±4.21 Sample 3 30 6.22±0.30 92.86±4.68 Sample 4 0 5.48±0.25 89.61±5.35

[0042] Table 1

[0043] Embodiment 2

[0044] The above embodiment further improves the input and output of the first embodiment by mixing unfermented plant straw into the fermented organic fertilizer to increase the stability and sustainability of the nutrient release of the organic fertilizer, thereby increasing the effect of the organic fertilizer and extending its effective time.

[0045] The plant straw is coated with trehalose before being added to the fermentation mixture and the unfermented plant straw is coated with trehalose before being added to the fermentation mixture, specifically:

[0046] Melt trehalose at 100-110°C, add plant straw, mix and stir evenly, and slowly cool down while stirring, cool to 50°C after 30 minutes, and then naturally cool to room temperature, and crush the obtained plant straw through an 80-mesh sieve.

[0047] The technical solutions in the above embodiments of the present application have at least the following technical effects or advantages:

[0048] By wrapping trehalose on the outside of plant straw to form a hard shell, the trehalose shell has a controlled release effect, so that the release rate of nutrients in the plant straw can be adjusted during the fermentation process, so that nutrients are continuously and stably supplied during the growth of crops. Trehalose and its decomposition products have a selective promotion effect on microorganisms, which can guide the growth of beneficial microorganisms in the fermentation process and inhibit the reproduction of harmful microorganisms, thereby optimizing the fermentation environment; through the controlled release effect of the trehalose shell, nutrients in the plant straw can be released on demand, the utilization rate of nutrients is improved, and the waste of nutrients is reduced; and the survival ability of fermentation bacteria is increased in the initial stage of fermentation. The fermentation products of trehalose can adjust the pH value, humidity and temperature of the fermentation environment, create an environment that is more conducive to the growth and reproduction of beneficial microorganisms, and improve the fermentation efficiency and quality of organic fertilizers;

[0049] During the fermentation process, the cellulose, hemicellulose and other organic substances in the plant straw that are difficult to use directly are gradually decomposed into small molecular organic matter and humus under the action of beneficial microorganisms. Trehalose is fermented first, and a group of microbial groups adapted to the fermentation environment are cultivated in advance to effectively decompose the organic matter in the plant straw and improve its utilization rate. Trehalose and its fermentation products are rich in various nutrients and bioactive substances, such as amino acids, vitamins, growth regulators, etc., which promote crop growth and improve crop resistance. Trehalose is fermented first so that these beneficial substances can be better retained and utilized in organic fertilizers.

[0050] At the same time, the trehalose in the shell of the unfermented plant straw is retained, and the sugar shell formed after the trehalose melts and cools can wrap the plant straw, enhance its stability, and increase the stability of the organic fertilizer during storage and transportation; the trehalose coating layer can prevent the nutrients in the plant straw from being lost, and ensure the effective release of nutrients during the use of the organic fertilizer; trehalose itself has excellent moisture retention and stability, can improve the soil environment, and improve the water retention capacity and air permeability of the soil; the organic fertilizer made from the plant straw coated with trehalose is rich in various nutrients and bioactive substances, can promote the growth and development of crops, and improve the yield and quality of crops; the trehalose coating layer can control the release rate of nutrients in the plant straw and realize the continuous supply of nutrients. Trehalose itself has biological activity, can stimulate the growth of crop roots, and improve the stress resistance and immunity of crops. Through the trehalose coating treatment, the nutrients in the plant straw are effectively maintained and slowly released, thereby improving the utilization rate of the organic fertilizer; the trehalose coating layer can prevent microbial erosion and nutrient loss, and extend the shelf life of the organic fertilizer.

[0051] The finished product tested the number of viable bacteria, total phosphorus and total potassium retention rates of the organic fertilizer. The total phosphorus and total potassium retention rates refer to the loss of phosphorus and potassium during the fermentation process, specifically the percentage of phosphorus and potassium at the end of fermentation to the beginning of fermentation. The difference between the sample and Example 1 is that the plant straw is wrapped with trehalose. The results are shown in Table 2;

[0052]

[0053] Table 2

[0054] Embodiment 3

[0055] Example 2: By wrapping trehalose on plant straw, the growth capacity of fermentation bacteria is increased and the effective time is prolonged, and further improvement is made on the basis of Example 2 to increase the water retention capacity.

[0056] Adding potato hydroxypropyl starch to the trehalose wrapped in the fermented plant straw, and adding starch-grafted potassium acrylate to the trehalose wrapped in the unfermented plant straw, with 5 parts by weight of potato hydroxypropyl starch and 3 parts by weight of starch-grafted potassium acrylate;

[0057] The technical solutions in the above embodiments of the present application have at least the following technical effects or advantages:

[0058] Adding potato hydroxypropyl starch to the trehalose wrapped in the fermented plant straw not only improves the toughness and strength of the trehalose shell, but also improves the processing performance of the trehalose shell because of its good solubility and film-forming properties, making it easier to shape and wrap plant straw and improving its chemical stability. The trehalose shell has better water retention and nutrient slow-release properties, so that it can maintain a suitable humidity during the fermentation of plant straw and slowly release nutrients for crops to absorb and utilize. In addition, the special composition of trehalose helps to improve the permeability of the cell membrane of the fermentation bacteria, making it easier for the fermentation bacteria to absorb other nutrients, accelerating the metabolic utilization of potato hydroxypropyl starch by the fermentation bacteria, decomposing it, and increasing the growth rate of bacteria. The thickening and film-forming properties of potato hydroxypropyl starch reduce the total The loss of active ingredients such as phosphorus and total potassium, maintains the nutrient content of the fertilizer, and makes the microorganisms distributed in large quantities on the trehalose shell; after adding starch grafted potassium acrylate to the trehalose wrapped in the unfermented plant straw and adding the fermented mixture, new nutrition is provided for the whole microorganism, and the microorganism is transferred to the trehalose wrapped in the unfermented plant straw as much as possible, so that the fermentation bacteria are more located near the trehalose shell during the whole fermentation process, and the water retaining agent is added to the sugar shell, which can maximize the use of the water retaining agent, improve the water retention effect, save the dosage, transfer the microorganism to the trehalose shell, optimize the distribution of microorganisms in the organic fertilizer, make the microorganisms more fully utilize the nutrients in the organic fertilizer, improve the fermentation efficiency and the quality of the organic fertilizer, and because the microorganisms are more located near the trehalose shell, the water retaining agent plays a more direct and effective role. This helps to reduce the dosage of water retaining agent and reduce production costs. The addition of trehalose and starch grafted potassium acrylate, as well as the redistribution of microorganisms, enhance the biological activity of organic fertilizers, improve soil structure, improve soil fertility, and promote the growth and development of crops.

[0059] The finished product tested the number of viable bacteria, total phosphorus and total potassium retention rates of the organic fertilizer. The total phosphorus and total potassium retention rates refer to the loss of phosphorus and potassium during the fermentation process, specifically the percentage of phosphorus and potassium at the end of fermentation to the beginning of fermentation. The only difference between the sample and Example 2 is that trehalose also contains a water retaining agent. The results are shown in Table 3;

[0060]

[0061]

[0062] Table 3

[0063] Embodiment 4

[0064] The above embodiment further improves on the basis of the third embodiment by adding a water retaining agent to trehalose to improve the aggregation environment of the fermentation bacteria in order to optimize the preparation steps and increase the fertilizer efficiency.

[0065] The unfermented plant straw is further wrapped twice to produce an inner shell and an outer shell, specifically:

[0066] When the temperature of the trehalose in the inner shell is lowered, the temperature is lowered to 50°C for 1 min, and then the temperature is naturally lowered to room temperature, and the obtained plant straw is crushed through an 80-mesh sieve;

[0067] The trehalose of the outer shell is also added with 0.5% by mass of sodium chloride to increase its aperture ratio, and the temperature is naturally lowered while stirring, and the obtained plant straw is crushed through an 80-mesh sieve;

[0068] The amount of starch grafted potassium acrylate added in the outer layer is 5 parts by weight, and the amount of starch grafted potassium acrylate added in the inner layer is 3 parts by weight.

[0069] The technical solutions in the above embodiments of the present application have at least the following technical effects or advantages:

[0070] The trehalose in the inner shell is rapidly cooled to 50°C within 1 minute, and then naturally cooled to room temperature, resulting in the formation of a denser pore structure of trehalose, because rapid cooling will limit the diffusion and rearrangement of sugar molecules, thereby forming smaller pores, which is conducive to the initial attachment and aggregation of bacteria, providing a more compact growth environment for bacteria;

[0071] The amount of starch-grafted potassium acrylate added to the inner layer is 3 parts by weight. This polymer water-retaining agent has good water absorption and water-retaining capacity. During the bacterial aggregation process, it maintains the moisture of the inner shell, provides a moist growth environment for the bacteria, and is conducive to the metabolic activity and reproduction of the bacteria. The fine pore structure of the inner shell and the appropriate amount of water-retaining agent can maintain the moisture in the shell, providing a moist growth environment for the bacteria.

[0072] The larger pore structure and more water-retaining agents of the outer shell can allow more water and air exchange while retaining moisture. 0.5% by mass of sodium chloride is added to the trehalose of the outer shell to increase the porosity of the sugar shell. As an inorganic salt, sodium chloride acts as a pore former during the solidification process, helping to form a larger pore structure, which is conducive to the penetration of oxygen and nutrients, as well as the discharge of metabolic waste, thereby promoting the growth and metabolic activities of bacteria; the natural cooling process allows the sugar molecules to have enough time to rearrange themselves and form a stable pore structure;

[0073] The amount of starch-grafted potassium acrylate added to the outer layer is 5 parts by weight, which is more than that of the inner layer. This can further enhance the water absorption and water retention capacity of the outer layer, providing more sufficient water for the bacteria. At the same time, the larger pore structure and stronger water retention capacity of the outer layer are conducive to the penetration and diffusion of bacteria into the interior of the plant straw, improving the utilization rate of bacteria;

[0074] The fine pore structure of the inner shell is conducive to the initial attachment and aggregation of bacteria, providing a stable growth environment for bacteria, while the larger pore structure and stronger water retention capacity of the outer shell are conducive to the further diffusion and penetration of bacteria, improving the aggregation efficiency of bacteria;

[0075] The double-layer structure provides a more suitable growth environment for bacteria by adjusting the porosity and water retention capacity, which not only improves the metabolic activity and reproduction efficiency of bacteria, but also promotes the decomposition and utilization of organic matter in plant straw by bacteria, thereby improving the fermentation effect and product quality of organic fertilizer.

[0076] The double-layer sugar shell structure provides bacteria with a growth environment that gradually changes from the outer layer to the inner layer. The larger pores and air permeability of the outer shell are conducive to the rapid diffusion and penetration of bacteria. As the bacteria penetrate into the inner shell, they use the richer organic matter in the inner shell to grow and reproduce, thereby improving the overall bacterial utilization efficiency.

[0077] Through the design of the double-layer sugar shell structure, the amount of water-retaining agent is reduced while ensuring the water-retaining effect. The fine pores of the inner shell and the appropriate amount of water-retaining agent are sufficient to maintain a moist environment inside the shell, while the outer shell enhances the overall water-retaining capacity through a larger pore structure and more water-retaining agents, optimizes the fermentation process of organic fertilizer, improves the metabolic activity and reproduction efficiency of bacteria, and thus promotes the decomposition and transformation of organic matter.

[0078] In this embodiment, the experimental plant is selected as honeysuckle seedlings through planting test. After the tree hole is dug, the organic fertilizer and backfill soil are mixed in a ratio of 1:2 and backfilled into the afforestation tree hole. Watering is done once on the day of afforestation, and no watering is done in the later period. The survival rate, dry weight and preservation rate are investigated in the following year. The other conditions are the same as those in the embodiment. The results are shown in Table 4:

[0079] Unfermented plant straw weight Dry weight / g Survival rate / % Preservation rate / % Sample 1 10 6.14±0.28 92.87±4.36 89.14±4.45 Sample 2 20 6.34±0.24 93.43±3.86 90.58±3.85 Sample 3 30 6.83±0.24 94.22±4.61 91.43±4.18

[0080] Table 4

[0081] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a water-saving and water-retaining organic fertilizer, characterized in that: The preparation steps specifically include: S1: 70-100 parts by weight of organic matter from cattle and sheep manure, 40-60 parts by weight of plant straw, 10-15 parts by weight of humic acid, 1-2 parts by weight of brown sugar, 10-20 parts by weight of starch, 1-5 parts by weight of urea, 2-5 parts by weight of calcium phosphate, 1-4 parts by weight of potassium chloride, and water are uniformly mixed to obtain a mixture; S2, adding 1%-2.5% of the mixture by mass of EM bacterial solution, aerobically fermenting at 30-40°C for 1-2 days, turning upside down once a day, adding 7-10 parts by weight of potato hydroxypropyl starch, and anaerobically fermenting the pile for 15-25 days; S3. Add 3-5 parts by weight of potassium starch grafted acrylate, 2-5 parts by weight of trehalose, and 10-30 parts by weight of unfermented plant straw to the fermentation product, mix them evenly, freeze-dry and crush the mixed product to obtain a water-saving and water-retaining organic fertilizer.

2. The method for preparing a water-saving and water-retaining organic fertilizer according to claim 1, wherein: The mixture obtained in step S1 has a C / N ratio of 20:1-35:1, and a water content of the mixture of 45%-60%.

3. The method for preparing a water-saving and water-retaining organic fertilizer according to claim 1, wherein: The plant straw was crushed and passed through an 80-mesh sieve.

4. The method for preparing a water-saving and water-retaining organic fertilizer according to claim 1, wherein: The plant straw is coated with trehalose, and the specific steps are: melting the trehalose at 100-110° C., adding the plant straw therein, mixing and stirring evenly, and slowly cooling while stirring, cooling to 50° C. after 30 minutes, and then naturally cooling to room temperature, and crushing the obtained plant straw through an 80-mesh sieve.

5. The method for preparing a water-saving and water-retaining organic fertilizer according to claim 4, wherein: Potato hydroxypropyl starch was added to the trehalose coating of fermented plant straw.

6. The method for preparing a water-saving and water-retaining organic fertilizer according to claim 4, characterized in that: Starch-grafted potassium acrylate was added to the trehalose that was not involved in the fermentation.

7. The method for preparing a water-saving and water-retaining organic fertilizer according to claim 5, characterized in that: 5 parts by weight of potato hydroxypropyl starch in trehalose.

8. The method for preparing a water-saving and water-retaining organic fertilizer according to claim 6, wherein: 3 parts by weight of starch grafted with potassium acrylate in trehalose.

9. The method for preparing a water-saving and water-retaining organic fertilizer according to claim 8, wherein: The unfermented plant straw is further wrapped twice to produce an inner shell and an outer shell, specifically: When the temperature of the trehalose in the inner shell is lowered, the temperature is lowered to 50°C for 1 min, and then the temperature is naturally lowered to room temperature, and the obtained plant straw is crushed through an 80-mesh sieve; The trehalose of the outer shell is also added with 0.5% by mass of sodium chloride to increase its aperture ratio, and the temperature is naturally lowered while stirring, and the obtained plant straw is crushed through an 80-mesh sieve; The amount of starch grafted potassium acrylate added in the outer layer is 5 parts by weight, and the amount of starch grafted potassium acrylate added in the inner layer is 3 parts by weight.

10. A water-saving and water-retaining organic fertilizer, characterized in that: The organic fertilizer is prepared by the method for preparing the water-saving and water-retaining organic fertilizer according to any one of claims 1 to 9.

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