Compound fertilizer for improving acidified soil of slope cropland by using biological crust and preparation method of compound fertilizer

Abstract

The invention discloses a compound fertilizer for improving slope cropland acidified soil by using biological crust and a preparation method thereof.The preparation method comprises the steps that straw chippings, smashed citrus imperfect fruits, cow dung, rape seed cakes and saccharomycetes powder are stirred and mixed and then fermented and composted, and an organic fertilizer A is prepared; mixing plant ash and a mixed bacteria solution to prepare an alkaline organic fertilizer; the preparation method comprises the following steps: crushing an alkaline organic fertilizer, fully and uniformly mixing the crushed alkaline organic fertilizer with urea, phosphogypsum, potassium sulfate and calcium superphosphate, granulating, sequentially spraying the green alga suspension and sodium alginate on the surface of the prepared organic-inorganic compound fertilizer, and drying at low temperature to obtain the compound fertilizer. The compound fertilizer disclosed by the invention can quickly form biological crust and reduce soil leaching after being spread into soil, organic fertilizers, inorganic fertilizers and microbial agents are organically combined and prepared into spherical fertilizers, mechanical fertilization is facilitated, the nutrient requirements of crops in the whole growth period are met while acidified soil is improved, and the yield of the crops is increased. Not only is the availability of the acidified soil improved, but also the sustainable development of farmland is promoted.

Description

Technical Field

[0001] The invention relates to the technical field of fertilizer production, and in particular to a compound fertilizer for improving acidified soil of sloping cultivated land by utilizing biological crust and a preparation method thereof. Background Art

[0002] Soil acidification is a deterioration of soil properties in the soil degradation category and is a global soil degradation problem. One of the main causes of soil acidification in humid areas is the intense leaching of soil caused by high rainfall, which leads to the increase of basic cations such as Ca in the soil. 2+ Mg 2+ The loss of soil ions, especially the relatively serious soil and water loss in sloping farmland, can easily take away a large number of cations in the soil, reduce the buffering capacity of soil acidification, and eventually form a stable acidified soil dominated by Al. + 、Al 3+ and Mn 2+ The increase in concentration and activity of toxic elements such as chlorine and chlorine leads to poor root development of crops, seriously affecting their growth and development.

[0003] The existing methods of improving acidified soil include chemical improvement, organic fertilizer improvement and microbial improvement, and the corresponding improvers include minerals, organic fertilizers, acid-inhibiting microbial agents, etc. However, mineral improvers such as quicklime are strongly alkaline substances, and direct application to the soil may cause a significant increase in local pH and damage the soil ecological environment; organic fertilizer improvers improve soil quality by inputting organic matter, among which alkaline organic fertilizers can increase soil pH, but the dosage is large, the short-term effect is not significant, and the cost is high; acid-inhibiting microbial agents have an inhibitory effect on soil acidification, but the effect is unstable and cannot be applied to various types of soils.

[0004] CN111943750 A discloses a biological organic fertilizer for preventing soil acidification and compaction. The biological organic fertilizer uses organic materials such as crop residues, mountain soil, poultry manure, livestock manure, etc. as raw material components of the organic fertilizer, but no inorganic materials are added. Although the biological organic fertilizer can improve the soil, it cannot increase the soil pH in a short period of time to achieve the effect of acidifying the soil.

[0005] CN108863636 A discloses an alkaline compound fertilizer for preventing and improving soil acidification and a preparation method thereof. The alkaline compound fertilizer is prepared from urea, diammonium phosphate, potassium sulfate, calcium oxide and calcium carbonate, but can only increase soil pH but cannot improve soil quality, and cannot meet the needs of improving and improving acidified soil.

[0006] CN115536476 A discloses a soil conditioning composition that can quickly and long-term improve soil acidification and a preparation method thereof. The composition is composed of a combination of humic acid substances, calcium-silicon-based minerals, decomposed organic matter and biochemical fulvic acid, which can increase soil pH in a short period of time, improve soil pH buffering capacity, and improve soil quality. However, its nutrient content is low and cannot meet the nutritional needs of crop growth.

[0007] Biological crust is a complex structure formed by the bonding of organisms with soil surface particles (for example, blue / green algae can form a symbiotic relationship with other microorganisms in the soil to form biological crust on the soil surface). It has multiple ecological functions, which can reduce rainfall infiltration and thus reduce soil erosion, retain soil cations, provide soil acid buffering capacity to improve soil acid buffering capacity, and can also fix the surface soil, reduce soil erosion, and contribute to the formation of a good soil structure; in addition, symbiosis with other microorganisms can increase the abundance of soil microorganisms and the stability of community structure, improve soil habitat, and is expected to further alleviate the problem of soil acidification. At present, most soil biological crusts rely on natural formation, and there is no research on the use of fertilizers to introduce biological crusts. There are few reports on the use of blue / green algae as precursor organisms for biological crusts. Usually, organic fertilizers use inactivated blue / green algae as raw materials or nutrients added to fertilizers to increase their fertility, but inactivated blue-green algae cannot form biological crusts in the soil and are used in large quantities, so the problem of algal toxins needs to be considered. In addition, compound fertilizers, as fertilizers with nutrients, will also affect the growth of microbial communities, thereby affecting the formation of biological crusts. Therefore, developing new fertilizers and using fertilizers as a medium to accelerate the formation of biological crusts on the soil surface while taking into account the fertilizer nutrient status and improving soil acidification is a difficult problem to overcome.

[0008] In summary, all kinds of existing products for acidifying soil improvement cannot fundamentally solve the problem of soil acidification, and cannot meet the comprehensive needs of increasing soil pH, improving soil quality and providing nutrients required by crops. It is even more difficult to solve the problems of cation loss and low soil acid buffering capacity caused by soil erosion in sloping farmland. Summary of the invention

[0009] The first purpose of the present invention is to provide a method for preparing a compound fertilizer for improving acidified soil in sloping farmland using biological crusts, which combines organic materials, inorganic improvers, inorganic fertilizers, acid-inhibiting microbial agents and algae to improve soil quality while ensuring that the soil pH is increased, and to supplement the missing base ions in the soil. At the same time, biological crusts are quickly formed on the soil surface based on green algae as a "protective film" to reduce the scouring and leaching of the soil by rainwater, improve the functional effectiveness and long-term nature of the organic-inorganic compound fertilizer, and fundamentally improve the acidified soil.

[0010] To achieve the above object, the present invention adopts the following technical solution: A method for preparing a compound fertilizer for improving acidified soil on sloping cultivated land using biological crusts comprises: The straw scraps, crushed citrus fruit residues, cow dung, rapeseed cake and yeast powder are mixed and stacked into strips for fermentation and composting to obtain organic fertilizer A; Adding plant ash to organic fertilizer A to adjust the pH to above 8.0 to obtain organic fertilizer B, and adding mixed bacterial liquid to organic fertilizer B to obtain alkaline organic fertilizer; The alkaline organic fertilizer is crushed, and then fully mixed with urea, phosphogypsum, potassium sulfate and superphosphate, and the mixture is added to a granulator for granulation to obtain an organic-inorganic compound fertilizer A; The organic-inorganic compound fertilizer A is placed in a rotating drum, and the green algae suspension is evenly sprayed with a spray gun. After the spraying is completed, sodium alginate is sprayed again, and the mixture is dried at low temperature to obtain the compound fertilizer for improving acidified soil using biological crust.

[0011] As a preferred implementation, the mass ratio of crop straw, cow dung, defective citrus fruit and rapeseed cake is 2-9:1-5:1:3:1-5; the added amount of yeast powder is 1‰-2‰ of the total mass of straw, cow dung, defective citrus fruit and rapeseed cake.

[0012] As a preferred embodiment, during composting, the temperature is controlled at 40-55°C and the humidity is controlled at 45-60%.

[0013] As a preferred implementation, the composting process is adjusted according to the ratio of different organic materials; specifically, the compost turning and raking time is determined according to the carbon-nitrogen ratio (C / N ratio) of each material, the difficulty of decomposing the raw materials (such as the high content of cellulose and lignin in crop straw), the initial active organic carbon content (high content of active organic carbon composting has high fermentation efficiency), and the turning and raking frequency (to improve the air permeability and uniformity of the compost).

[0014] For example: the ratio of crop straw, cow dung, citrus fruit residues and rapeseed cake is 2:1:1:1, and the composting period is 3-5 months. In the early stage (the first 1-2 months), the composting should be done once a week, and in the later stage (3-5 months), the composting should be done once every 2-3 weeks. The ratio of crop straw, cow dung, citrus fruit residues and rapeseed cake is 3:3:2:2. The composting takes 2-4 months. In the early stage (first month), the compost is turned over once a week, and in the later stage (2-4 months), the compost is turned over once every 2-4 weeks. The ratio of crop straw, cow dung, citrus fruit residues and rapeseed cake is 7:5:3:5, and the composting takes 4-6 months. In the early stage (1-2 months), the composting should be done once a week, and in the later stage (3-6 months), the composting should be done once every 3-4 weeks. The ratio of crop straw, cow dung, defective citrus fruit and rapeseed cake is 9:3:3:5. Compost for a total of 3-6 months. Turn the soil over once a week in the early stage (1st-2nd month) and once every 2-3 weeks in the later stage (3rd-6th month).

[0015] As a preferred embodiment, the mixed bacterial solution is obtained by mixing and diluting bacterial powders of Bacillus subtilis, Bacillus megaterium, Pseudomonas and yeast in a mass ratio of 3-7: 3-7: 2-6: 2-7.

[0016] As a preferred embodiment, the amount of the mixed bacterial liquid is such that the amount of mixed bacterial powder added per ton of organic fertilizer B reaches 5-7.5 kg.

[0017] As a preferred embodiment, 15-25 kg of urea, 20-40 kg of phosphogypsum, 15-35 kg of potassium sulfate and 10-30 kg of superphosphate are added to each ton of alkaline organic fertilizer.

[0018] As a preferred embodiment, the green algae suspension is obtained by diluting the green algae concentrate with water, and the amount of the green algae concentrate is 30-100 g / t organic-inorganic compound fertilizer A; The dry weight of biomass in the green algae suspension is 700-800 g / L. The green algae concentrate is diluted for easy uniform spraying.

[0019] As a preferred embodiment, the concentration of the sodium alginate solution is 1-3%, and the dosage is 20-50 L / t organic-inorganic compound fertilizer A.

[0020] As a preferred embodiment, after spraying sodium alginate, drying is performed at 30-40°C.

[0021] Another object of the present invention is to provide a compound fertilizer prepared by the above method.

[0022] The organic-inorganic compound fertilizer provided by the present invention can quickly form a biological crust when spread in the soil while ensuring fertility, and can effectively improve soil acidity, improve soil quality, and reduce nutrients and soil erosion. The biological crust can effectively prevent rainfall infiltration, reduce soil nutrient leaching, and prevent or delay the soil acidification process; the organic matter in the fertilizer, including humic acid, can not only improve the air permeability and water retention of the soil, but also promote the formation and maintenance of the soil mass structure, thereby creating a more suitable crop growth environment; Bacillus subtilis and Bacillus megaterium can produce a large amount of extracellular enzymes, which can effectively decompose organic matter in the soil, release amino acids and alkaline substances to neutralize soil acidity, promote the release of soil nutrients, and at the same time can produce substances similar to cytokinins and plant growth hormones that can improve plant immune function; Pseudomonas can produce alkaline substances such as ammonia, which is conducive to loosening the soil structure, especially in soils with low nitrogen and phosphorus content, it can increase the effectiveness of nutrients; yeast mainly participates in the fermentation process of organic matter in the soil, which helps to increase the diversity and biological activity of microorganisms in the soil. Inorganic materials in organic-inorganic compound fertilizers also play a positive role in improving fertilizer nutrient supply capacity and improving soil acidification. The main component of gypsum is CaSO4. When added to variable charge soil, SO4 2- The ions are specifically adsorbed, releasing OH - Neutralize H in soil + , while the released Ca 2+ Can replace Al in soil colloids 3+ and H + , replenishing the basic cations in the soil, increasing the soil cation exchange capacity (CEC), and improving soil acidity in a relatively stable and continuous manner; potassium sulfate can replenish the K that has been leached from the soil in large quantities due to high temperature and rainy conditions. + It can also increase soil CEC, improve soil physical structure, promote the formation of soil aggregate structure, and increase soil permeability and water retention. Superphosphate can not only provide the P required for plant growth, but also bring a large amount of Ca into the soil. 2+ , improve soil acidification.

[0023] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention targets the main cause of soil acidification in sloping farmland by introducing green algae into fertilizers. When the fertilizer is spread, the green algae are used as precursor organisms to promote the rapid formation of a biological crust on the soil surface, effectively reducing the infiltration of rainwater and other substances, and reducing the leaching of soil base particles, thereby fundamentally preventing or delaying the soil acidification process.

[0024] (2) The present invention strictly controls the proportion of inorganic matter in compound fertilizer granulation and sprays sodium alginate on the surface to keep the green algae alive, so that the green algae can be applied to the soil as a precursor of biological crust through fertilizer. At the same time, the soil habitat can be improved and the formation of biological crust on the soil surface can be accelerated, which is more conducive to preventing soil acidification.

[0025] (3) The present invention is designed for acidified soil in sloping cultivated land. Gypsum, plant ash and the like are used to neutralize soil acidity and increase soil pH. Potassium sulfate and superphosphate are used as the supply of potassium and phosphorus in the soil. Calcium, potassium and the like are introduced to supplement the missing basic cations in the acidified soil and exchange Al on the surface of the soil colloid. 3+ and H + , allowing it to flow away with water, which can not only reduce soil acidity but also increase soil CEC and improve nutrient supply capacity.

[0026] (4) The present invention combines a variety of organic and inorganic materials and microbial agents to provide a more comprehensive nutrient supply capacity for crop growth and better meet the diverse nutritional needs of plants. The materials used are all relatively mild ingredients, which can continuously improve the physical and chemical properties of the soil, and can increase the stability and abundance of soil microbial communities, avoiding strong stimulation to soil organisms in the native environment of the soil.

[0027] (5) The present invention combines organic materials and inorganic materials to increase the nutrient content in the fertilizer. The disc granulation can be used for one-time mechanized fertilization, avoiding the secondary fertilization after the application of traditional organic fertilizers. The inorganic matter in the fertilizer provides a large amount of quick-acting nutrients, and the nutrients in the organic fertilizer are released through slow decomposition, which can meet the nutrient needs of crops throughout the entire growth period. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is the situation of biological crust on the soil surface of each treatment in the corn pot experiment. DETAILED DESCRIPTION

[0029] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0030] In order to enable those skilled in the art to more clearly understand the technical solution of the present application, the technical solution of the present application will be described in detail below in conjunction with specific embodiments.

[0031] The test materials used in the examples of the present invention are all conventional test materials in the art and can be purchased through commercial channels.

[0032] Bacillus subtilis, Bacillus megaterium, Pseudomonas and yeast (all bacterial powder) used in the examples were purchased from Hubei Xingdongcheng Chemical Co., Ltd.

[0033] The green algae concentrate in the embodiment was purchased from Foster Biotechnology (Taizhou) Co., Ltd., of which 60-70% was Chlorella, and the dry weight of the green algae concentrate was 700-800 g / L, and the dry weight was the weight of biomass obtained after drying the unit volume of the concentrate to a constant weight.

[0034] Example 1 The compound fertilizer is prepared by the following steps: (1) The crop straw is dried at 50-55°C to a moisture content of about 4%, and then cut into 1-3 cm pieces using a grass cutter. At the same time, the defective citrus fruits are crushed in a special crushing device. Subsequently, the processed crop straw, cow dung, defective citrus fruits and rapeseed cake are mixed in a weight ratio of 3:3:2:2, and yeast powder is added in a ratio of 1‰ (mass ratio, diluted with water to ensure uniform mixing), and fully stirred in a mixing container to ensure uniform distribution of the ingredients.

[0035] The mixed materials are piled into long strips and fermented for a three-month composting process. During the fermentation period, the temperature and humidity of the compost are regularly checked using a temperature and humidity monitor to ensure that the test depth is 20 cm. During the fermentation process, the compost temperature is controlled at 40-55°C and the humidity is controlled at 45%-60%. In the early stage of composting (the first month), the compost is turned over once a week; in the later stage (the second and third months), it is adjusted to turn over once every three weeks to promote full fermentation and decomposition of the materials. After the fermentation is completed, the compost is dried to control the final moisture content between 30-40% to obtain organic fertilizer A.

[0036] (2) Add wood ash to organic fertilizer A to adjust the pH value of organic fertilizer A to 8.0 to obtain organic fertilizer B. Then, mix the powders of Bacillus subtilis, Bacillus megaterium, Pseudomonas and yeast in a ratio of 5:5:6:4, add 5 kg of mixed powder per ton of organic fertilizer B, dilute the mixed powder and evenly add it to organic fertilizer B and stir it thoroughly to ensure that the microorganisms are evenly distributed in the entire compost, thereby obtaining an alkaline organic fertilizer.

[0037] (3) The alkaline organic fertilizer was dried to a moisture content of about 30% and then crushed. Urea, potassium sulfate, superphosphate and phosphogypsum (all in powder form) were added in an amount of 15, 30, 25 and 30 kg per ton, respectively. The mixture was fully mixed in a mixer and added to a disc granulator. Conventional granulation was adopted. The inclination angle of the disc granulator was adjusted to 45° and the speed was adjusted to 21 r / min. During the granulation process, a binder was sprayed into the disc granulator. The granulation time was 20 min. At the same time, the thickness of the material layer in the disc was ensured to be 20 cm. After completion, the fertilizer was passed through a 2-7 mm steel sieve and dried to obtain a spherical organic-inorganic compound fertilizer A.

[0038] (4) Place the spherical organic-inorganic compound fertilizer A into a rotating drum and use a spray gun to evenly spray the green algae suspension. The green algae suspension is prepared by diluting the purchased green algae concentrate with water 100 times at a dosage of 50 g / t of organic-inorganic compound fertilizer A (the dry weight of the green algae concentrate is 730 g / L). After spraying, in order to ensure the stability and activity of the green algae on the fertilizer surface, use a spray gun to spray sodium alginate again. The concentration of the sodium alginate solution is set to 2% (mass ratio). The spraying amount per ton of organic-inorganic compound fertilizer A is 35 L. After spraying, dry it at 30-40°C to obtain an organic-inorganic compound fertilizer specially used for acidified soil improvement.

[0039] Example 2 The compound fertilizer is prepared by the following steps: (1) The crop straw is dried at 50-55°C to a moisture content of about 3%, and then cut into 1-3 cm pieces using a grass cutter. At the same time, the defective citrus fruits are crushed in a special crushing device. Subsequently, the processed crop straw, cow dung, defective citrus fruits and rapeseed cake are mixed in a weight ratio of 7:5:3:5, and yeast powder is added in a ratio of 1.5‰ (mass ratio, diluted with water to ensure uniform mixing), and fully stirred in a mixing container to ensure uniform distribution of the ingredients.

[0040] The mixed materials are piled into long strips and subjected to a 4-month fermentation and composting process. During the fermentation period, the temperature and humidity of the compost are regularly checked using a temperature and humidity monitor to ensure that the test depth is 20 cm. During the fermentation process, the compost temperature is controlled at 40-55°C and the humidity is controlled at 45%-60%. In the early stage of composting (the first 1.5 months), the compost is turned over and raked once a week; in the later stage (2.5-4 months), it is adjusted to turn over and raked once every three weeks to promote full fermentation and decomposition of the materials. After the fermentation is completed, the compost is dried to control the final moisture content between 30-40% to obtain organic fertilizer A.

[0041] (2) Add wood ash to organic fertilizer A to adjust the pH value of organic fertilizer A to 8.0 to obtain organic fertilizer B. Then, mix Bacillus subtilis, Bacillus megaterium, Pseudomonas and yeast in a ratio of 3:7:2:2, add 7.5 kg of mixed bacterial powder per ton of organic fertilizer B, dilute the mixed bacterial powder and evenly add it to organic fertilizer B and stir it thoroughly to ensure that the microorganisms are evenly distributed in the entire compost, thereby obtaining an alkaline organic fertilizer.

[0042] (3) The alkaline organic fertilizer was dried to a moisture content of about 35% and then crushed. Urea, potassium sulfate, superphosphate and phosphogypsum (all in powder form) were added in an amount of 25, 15, 30 and 40 kg per ton, respectively. The mixture was fully mixed in a mixer and added to a disc granulator. Conventional granulation was adopted. The inclination angle of the disc granulator was adjusted to 45° and the speed was adjusted to 18 r / min. During the granulation process, a binder was sprayed into the disc granulator. The granulation time was 25 min. At the same time, the material layer thickness in the disc was ensured to be 20 cm. After completion, the mixture was passed through a 2-7 mm steel sieve and dried to obtain a spherical organic-inorganic compound fertilizer A.

[0043] (4) Place the spherical organic-inorganic compound fertilizer A into a rotating drum and use a spray gun to evenly spray the green algae suspension. The green algae suspension is prepared by diluting the purchased green algae concentrate with water 100 times according to the dosage of 100 g / t organic-inorganic compound fertilizer A (the dry weight of the green algae concentrate is 730 g / L). After spraying, in order to ensure the stability and activity of the green algae on the fertilizer surface, use a spray gun to spray sodium alginate again. The concentration of the sodium alginate solution is set to 1%. The spraying amount per ton of organic-inorganic compound fertilizer A is 50 L. After spraying, dry it at 30-40°C to obtain the organic-inorganic compound fertilizer specially used for acidified soil improvement.

[0044] Example 3 The compound fertilizer is prepared by the following steps: (1) The crop straw is dried at 50-55°C to a moisture content of about 3%, and then cut into 1-3 cm pieces using a grass cutter. At the same time, the defective citrus fruits are crushed in a special crushing device. Subsequently, the processed crop straw, defective citrus fruits, cow dung and rapeseed cake are mixed in a weight ratio of 2:1:1:1, and yeast powder is added in a ratio of 2‰ (mass ratio, diluted with water to ensure uniform mixing), and fully stirred in a mixing container to ensure uniform distribution of the ingredients.

[0045] The mixed materials are piled into long strips and subjected to a 4-month fermentation and composting process. During the fermentation period, the temperature and humidity of the compost are regularly checked using a temperature and humidity monitor to ensure that the test depth is 20 cm. During the fermentation process, the compost temperature is controlled at 40-55°C and the humidity is controlled at 45%-60%. In the early stage of composting (the first 1.5 months), the compost is turned over and raked once a week; in the later stage (2.5-4 months), it is adjusted to turn over and raked once every three weeks to promote full fermentation and decomposition of the materials. After the fermentation is completed, the compost is dried to control the final moisture content between 30-40% to obtain organic fertilizer A.

[0046] (2) Adjust the pH value of organic fertilizer A to 8.0 by adding wood ash to organic fertilizer A to obtain organic fertilizer B. Then, mix Bacillus subtilis, Bacillus megaterium, Pseudomonas and yeast in a ratio of 7:3:3:7, add 7.5 kg of mixed bacterial powder per ton of compost organic fertilizer B, dilute the mixed bacterial powder and evenly add it to organic fertilizer B and stir thoroughly to ensure that the microorganisms are evenly distributed in the entire compost, thereby obtaining an alkaline organic fertilizer.

[0047] (3) The alkaline organic fertilizer was dried to a moisture content of about 35% and then crushed. Urea, potassium sulfate, superphosphate and phosphogypsum (all in powder form) were added in an amount of 20, 35, 10 and 20 kg per ton, respectively. The mixture was fully mixed in a mixer and added to a disc granulator. Conventional granulation was adopted. The inclination angle of the disc granulator was adjusted to 45° and the speed was adjusted to 18 r / min. During the granulation process, a binder was sprayed into the disc granulator. The granulation time was 25 min. At the same time, the thickness of the material layer in the disc was ensured to be 20 cm. After completion, the fertilizer was passed through a 2-7 mm steel sieve and dried to obtain a spherical organic-inorganic compound fertilizer A.

[0048] (4) Place the spherical organic-inorganic compound fertilizer A into a rotating drum and use a spray gun to evenly spray the green algae suspension. The green algae suspension is prepared by diluting the purchased green algae concentrate with water 100 times at a dosage of 30 g / t of organic-inorganic compound fertilizer A (the dry weight of the green algae concentrate is 730 g / L). After spraying, in order to ensure the stability and activity of the green algae on the fertilizer surface, use a spray gun to spray sodium alginate again. The concentration of the sodium alginate solution is set to 3%. The spraying amount per ton of organic-inorganic compound fertilizer A is 20 L. After spraying, dry it at 30-40°C to obtain an organic-inorganic compound fertilizer specially used for acidified soil improvement.

[0049] Example 4 Corn field plot test In order to verify the effect of the advantageous combination of microorganisms, inorganic materials and organic materials in improving soil acidification in sloping farmland, corn pot and field plot tests were conducted, as follows: 1. Test method: Potted experiment: There were five treatments in the experiment, CKC (conventional fertilizer with green algae), MC (self-made organic fertilizer with green algae); GBC (conventional fertilizer with gypsum, acid-inhibiting microorganisms and green algae); MBC (self-made organic compost with acid-inhibiting organisms and green algae) and MGBC (organic-inorganic compound fertilizer for acidified soil prepared according to Example 1) (Note: except for the MGBC treatment, all other treatments were sprayed with green algae on the fertilizer surface and then applied to the soil immediately). Each treatment was repeated 3 times, the pot used for potted plants was 40 cm high and 48 cm in diameter, one corn was planted in each pot, and a randomized block design was used. All groups were managed under the same conditions, and the growth of biological crusts on the soil surface was observed during the planting process.

[0050] Field test: Six treatments were set up in the test, namely CK (conventional fertilizer treatment); CKC (conventional fertilizer combined with green algae), MC (alkaline organic fertilizer combined with green algae in Example 1); GBC (conventional fertilizer combined with gypsum, acid-inhibiting microorganisms and green algae); MBC (self-made organic compost combined with acid-inhibiting organisms and green algae) and MGBC (organic-inorganic compound fertilizer for acidified soil prepared according to Example 1) (Note: except for MGBC treatment, the other green algae-containing treatments were sprayed on the fertilizer surface and then applied to the soil immediately). Each treatment was repeated 3 times, and the area of ​​each plot was set to 50 m 2 , randomized block design. The corn planting density was 4000 plants / mu. Each group was managed under the same conditions, the soil pH was measured during the planting process, and the yield of each group was counted after the corn was harvested.

[0051] In this experiment, the organic fertilizer treated with MBC was the alkaline organic fertilizer (not granulated) prepared according to steps (1) and (2) in Example 1, and the organic fertilizer in MC was the alkaline organic fertilizer (not granulated and without adding mixed bacterial solution) prepared according to steps (1) and (2) in Example 1.

[0052] 2. Test results: The biological crust on the soil surface of each treatment in the potted experiment is as follows Figure 1 As shown in the figure, the application of organic fertilizer significantly increases the coverage of biological crust on the soil surface. MGBC that has been kept alive is more conducive to the growth of biological crust. It can form a "protective film" on the soil surface, reducing soil leaching caused by rainfall, etc., thereby fundamentally delaying or solving soil acidification.

[0053] The pH and yield results of corn in each treatment stage in the field are shown in Table 1. It can be seen that after applying the organic-inorganic compound fertilizer specially used for acidified soil improvement of the present invention, the soil pH of each corn period can be significantly improved, and the corn yield can be increased by 35.48% compared with the application of chemical fertilizers alone.

[0054] Table 1 Soil pH and corn yield in corn field plots at seedling and grain filling stages deal with Soil pH at seedling stage Soil pH during grain filling period Yield (kg / mu) CK 4.28 3.94 476.83 CKC 4.28 3.96 473.55 MC 4.43 4.39 448.16 GBC 4.41 4.62 465.82 MBC 4.38 4.36 479.92 MGBC 4.63 5.01 646.01 The above are all preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a compound fertilizer for improving acidified soil in sloping cultivated land using biological crust, characterized in that: include: The straw scraps, crushed citrus fruit residues, cow dung, rapeseed cake and yeast powder are mixed and stacked into strips for fermentation and composting to obtain organic fertilizer A; Adding plant ash to organic fertilizer A to adjust the pH to above 8.0 to obtain organic fertilizer B, and adding mixed bacterial liquid to organic fertilizer B to obtain alkaline organic fertilizer; The alkaline organic fertilizer is crushed, and then fully mixed with urea, phosphogypsum, potassium sulfate and superphosphate, and the mixture is added to a granulator for granulation to obtain an organic-inorganic compound fertilizer A; The organic-inorganic compound fertilizer A is placed in a rotating drum, and the green algae suspension is evenly sprayed with a spray gun. After the spraying is completed, sodium alginate is sprayed again, and the mixture is dried at low temperature to obtain the compound fertilizer for improving acidified soil using biological crust.

2. The method according to claim 1, characterized in that The mass ratio of the crop straw, cow dung, defective citrus fruit and rapeseed cake is 2-9:1-5:1:3:1-5; the added amount of yeast powder is 1‰-2‰ of the total mass of the straw, cow dung, defective citrus fruit and rapeseed cake.

3. The method according to claim 1, characterized in that During composting, the temperature is controlled at 40-55℃ and the humidity is controlled at 45-60%.

4. The method according to claim 1, characterized in that The mixed bacterial liquid is obtained by mixing bacterial powders of Bacillus subtilis, Bacillus megaterium, Pseudomonas and yeast in a mass ratio of 3-7: 3-7: 2-6: 2-7 and then diluting the mixture.

5. The method according to claim 4, characterized in that The dosage of the mixed bacterial liquid is such that the amount of mixed bacterial powder added per ton of organic fertilizer B reaches 5-7.5 kg.

6. The method according to claim 1, characterized in that Add 15-25kg urea, 20-40kg phosphogypsum, 15-35kg potassium sulfate and 10-30kg superphosphate to every ton of alkaline organic fertilizer.

7. The method according to claim 1, characterized in that The green algae suspension is obtained by diluting the green algae concentrate with water, and the amount of the green algae concentrate is 30-100 g / t of organic-inorganic compound fertilizer A; The dry weight of biomass in the green algae concentrated liquid is 700-800 g / L.

8. The method according to claim 1, characterized in that The concentration of the sodium alginate solution is 1-3%, and the dosage is 20-50 L / t organic-inorganic compound fertilizer A.

9. The method according to claim 1, characterized in that: After spraying sodium alginate, it is dried at 30-40℃.

10. A compound fertilizer prepared by the method according to any one of claims 1 to 9.

Images