Fertilizer suitable for saline-alkali soil and preparation method and device thereof

Abstract

The invention discloses a fertilizer suitable for saline-alkali soil and a preparation method and device thereof, and relates to the field of saline-alkali soil fertilizers.The fertilizer particles are of at least N layers of core-shell structures, first compositions are arranged on the odd layers from inside to outside, second compositions are arranged on the even layers from inside to outside, N is an odd number larger than or equal to 3, and the core-shell structures are of a core-shell structure. The composition I is prepared from the following raw materials: an organic base fertilizer, a nitrogen-phosphorus-potassium base fertilizer, ammonium lignosulfonate, amino acid, a microbial agent and a mariculture product extract. The fertilizer particle has an odd-layer core-shell structure, the outermost layer is nutrient substances, the problem that the composition I on the surface is rapidly dissolved along with irrigation when the fertilizer is just put into the saline-alkali soil is solved, the effect of rapidly improving the saline-alkali soil is achieved, and the survival rate of seedlings is increased. After the irrigation period is finished, the composition II protects the composition I on the inner layer and waits for the next irrigation period, so that the excessive concentration of the fertilizer in a short time can be avoided, the purpose of slowly releasing the fertilizer can be achieved, and the fertilization frequency of the saline-alkali soil is reduced.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of saline-alkali soil fertilizers, and particularly relates to a fertilizer suitable for saline-alkali soil and a preparation method and device thereof. BACKGROUND

[0002] Traditional methods for improving saline-alkali soil include the following:

[0003] I. By establishing a good drainage system, excessive water and salt in the soil are timely removed, the underground water level is lowered, salt accumulation in the soil surface layer is prevented, scientific irrigation is used, and fresh water is used for leaching the saline-alkali soil, so that the salt in the soil is dissolved and removed with water, thereby reducing the salt content in the soil.

[0004] II. By using different tillage methods to increase the soil permeability and promote the upward and downward movement of soil salt and water, the leaching and removal of salt are facilitated, so that the salt accumulation in the soil surface layer is reduced, and the improvement purpose is achieved.

[0005] III. By adding gypsum, superphosphate, aluminum sulfate and other chemical improvers to the saline-alkali soil, the soil structure is improved, and the soil pH is adjusted.

[0006] IV. By planting salt-tolerant plants, applying organic fertilizer, microbial fertilizer or soil conditioner to the saline-alkali soil, the soil physical properties are improved, and the normal productivity of the saline-alkali soil is restored.

[0007] The above-mentioned combination of various methods has played a certain role in the treatment of saline-alkali soil, among which the selection of fertilizer is crucial. CN202410199985.9 discloses a fertilizer composition for improving saline-alkali soil, which adopts complex base fertilizer combined with humic acid, and enhances the nutrient elements of the composition by adding sodium lignosulfonate, hydroxyapatite, trace element agent and amino acid raw material, thereby providing a high-quality organic matter environment to optimize the soil improvement effect. However, the above-mentioned fertilizer contains sodium lignosulfonate with excellent water solubility, and other components are not suitable for storage. After being put into the soil and irrigated, the fertilizer will quickly dissolve, resulting in a high concentration of fertilizer in the saline-alkali soil in a short period, which is not suitable for crop growth. Moreover, the concentration of the fertilizer decreases rapidly due to the influence of loss and volatilization, which is not conducive to the improvement of saline-alkali soil. The prior art uses coating materials to coat the fertilizer to achieve the purpose of slow-release fertilizer, such as CN201910851329.1 discloses a slow-release compound fertilizer for improving saline-alkali soil, which uses a composite gel formed by polyacrylic acid, silica gel, sodium alginate and chitosan as a coating material for fertilizer particles, which can effectively improve the water retention performance of saline-alkali soil and has a certain slow-release effect. However, the coating material can only give the fertilizer a single slow-release effect. After the coating is damaged, the concentration of the fertilizer will first increase temporarily and then decrease rapidly. In addition, at the initial stage of applying the coated fertilizer to the saline-alkali soil, the soil environment cannot be improved quickly due to the blocking of the coating, resulting in the difficulty of survival of crop seedlings in the face of harsh conditions and nutrient deficiency. SUMMARY

[0008] The purpose of the present application is to solve the above-mentioned problems, and to provide a fertilizer suitable for saline-alkali soil and a preparation method and device thereof.

[0009] The present application achieves the above-mentioned purposes by the following technical solutions:

[0010] The first purpose of the present application is to provide a fertilizer suitable for saline-alkali soil, wherein the particles of the fertilizer have at least N-layer core-shell structure, and the odd-numbered layers from the inside to the outside are composition one and the even-numbered layers are composition two, wherein N is an odd number greater than or equal to 3;

[0011] The preparation raw materials of the composition one include organic base fertilizer, nitrogen-phosphorus-potassium base fertilizer, ammonium lignosulfonate, amino acid, microbial agent and marine aquaculture product extract, and the preparation raw materials of the composition two include marine aquaculture product extract;

[0012] Among them, the marine aquaculture product includes shellfish and crustaceans;

[0013] The organic base fertilizer is obtained by mixing and fermenting humic acid, livestock manure, tea seed meal and fermentation bacteria liquid;

[0014] The microbial agent is composed of halophilic bacteria, Bacillus subtilis, nitrogen-fixing bacteria, phosphorus-solubilizing bacteria and potassium-solubilizing bacteria.

[0015] As a further optimization scheme of the present application, the composition one comprises 60-100 parts of organic base fertilizer, 40-60 parts of nitrogen, phosphorus and potassium base fertilizer, 10-20 parts of ammonium lignosulfonate, 5-10 parts of amino acid, 10-20 parts of microbial agent and 30-40 parts of marine aquaculture product extract by weight;

[0016] The organic base fertilizer comprises 30-40 parts of humic acid, 40-50 parts of livestock manure, 10-15 parts of tea seed meal and 10-15 parts of fermentation bacteria liquid.

[0017] The mass ratio of halophilic bacteria, bacillus subtilis, nitrogen-fixing bacteria, phosphorus-solubilizing bacteria and potassium-solubilizing bacteria in the microbial agent is (2-4):1:1:1:1.

[0018] As a further optimization scheme of the present application, the shellfish is one or more of scallops, mussels, clams and snails, and the crustacean is one or more of shrimps, crabs and barnacles.

[0019] A second object of the present application is to provide a preparation method of the above-mentioned fertilizer suitable for saline-alkali soil, comprising the following steps:

[0020] (1) The dry organic base fertilizer and nitrogen, phosphorus and potassium base fertilizer are crushed and mixed with ammonium lignosulfonate and microbial agent, then the mixture is added with a liquid mixture of amino acid and marine aquaculture product extract to obtain composition one, and the composition one is granulated and dried to obtain granules one with a first layer of core structure;

[0021] (2) The granules one are sprayed with composition two, i.e. marine aquaculture product extract, and dried to obtain granules two with a second layer of shell structure;

[0022] (3) The granules two are sprayed with composition one and granulated, and dried to obtain fertilizer granules with a third layer of shell structure, and the fertilizer granules are repeatedly subjected to the operations of steps (2) and (3) to obtain a fertilizer with N layers of core-shell structure.

[0023] As a further optimization scheme of the present application, the preparation process of the organic base fertilizer is as follows: the humic acid, livestock manure and tea seed meal are dried, crushed and sieved, then mixed uniformly, 3 times of water by volume is added, fermentation bacteria liquid is added, and fermentation treatment is carried out at 48-52℃, the pH is adjusted to 5.0-6.0 during the fermentation process, and the organic base fertilizer is obtained after drying and crushing after the fermentation is completed.

[0024] As a further optimization scheme of the present application, the preparation process of the marine aquaculture product extract is as follows:

[0025] The marine culture product is crushed, at least one volume of water is added for cooking, and after cooling, acid protease is added to the cooked liquid for enzymolysis, the enzymolysis temperature is 40-50 DEG C, the enzymolysis pH is 2.5-3.5, after enzymolysis, the enzymolysis liquid is centrifuged and filtered, the precipitate is dried to obtain a solid, and the solid is pulverized and ground, mixed with warm water to obtain a marine culture product extract.

[0026] The second object of the present application is to provide a preparation device for the above-mentioned fertilizer, comprising a shell and, from top to bottom, a stirring member, a spray pipe one, a granulating roller, a screen, a disc granulating structure and a particle collecting tank in the shell.

[0027] The upper end of the shell is provided with two feed ports, one of which is used for feeding solid raw materials in composition one, and the other is used for feeding fertilizer particles with an even number of core-shell structures, the stirring member and the spray pipe one are provided with several, the stirring member is located below the feed port, and the several spray pipes one are arranged alternately and obliquely, and the spray pipe one is used for feeding liquid raw materials in composition one.

[0028] The screen is inclined, and the lower end of the screen is provided with a discharge port one on the shell for discharging fertilizer particles with an odd number of core-shell structures, one side of the particle collecting tank is provided with a discharge port two for discharging fertilizer particles with an even number of core-shell structures, and the upper end of the disc granulating structure is provided with a spray pipe two above for spraying composition two.

[0029] As a further optimization scheme of the present application, one side of the discharge port two is provided with a conveying assembly for conveying the fertilizer particles with the even number of core-shell structures upward to the feed port.

[0030] As a further optimization scheme of the present application, the granulating roller comprises a roller body and a particle tank distributed on the surface of the roller body, the particle tank is provided with an air bag member along the tank surface, and the particle tank is provided with a channel communicating with the air bag member, the inside of the roller body is provided with a sealed annular cavity and an air pump, the air pump communicates with the annular cavity, and the channel extends to the annular cavity along the radial direction of the roller body.

[0031] As a further optimization scheme of the present application, the specific steps of the preparation device for preparing the fertilizer suitable for saline-alkali soil are as follows:

[0032] (1) The dry organic base fertilizer, nitrogen, phosphorus and potassium base fertilizer, ammonium lignosulfonate and microbial inoculum are mixed and put into the shell from one of the feed ports, the solid raw materials in composition one are dispersed by the stirring member, and the liquid mixed with amino acid and marine culture product extract is sprayed into the spray pipe one, and both fall into the relatively running granulating roller for granulation to obtain particles one with a first layer of core structure.

[0033] (2) the particle one falls into the screen, because the particle one is smaller than the screen diameter, the particle one falls into the disc granulation structure, and the composition two is sprayed by the spray pipe two, the composition two is mixed with the particle one by centrifugal force, and the particle two with a second layer shell structure is obtained, and falls into the particle collection tank from the gap;

[0034] (3) the particle two in the particle collection tank is put into another feeding port, and the step (1) is repeated to obtain the fertilizer particle with a third layer shell structure.

[0035] The beneficial effects of the present application are that:

[0036] 1. The fertilizer in the present application has an odd number of core-shell structures, and the outermost layer is a nutrient substance, which can solve the problem that the composition one on the surface of the fertilizer dissolves rapidly with irrigation when the fertilizer is just put into saline-alkali soil, so that the fertilizer can quickly improve the saline-alkali soil and provide sufficient nutrients for crops in the seedling stage, thereby increasing the survival rate. With the end of the irrigation period, the composition two protects the composition one in the inner layer, waits for the next irrigation period, and continues to release the internal nutrient substance, which can avoid excessive fertilizer concentration in a short time and achieve the purpose of slow-release fertilizer, and reduce the fertilization frequency of saline-alkali soil.

[0037] 2. The fertilizer in the present application uses marine product extract as a raw material for preparation in the composition one and the composition two, which can be used as an excellent coating agent on the one hand because the marine product extract contains a large amount of gum, and the marine product extract contains a large amount of calcium carbonate, which is excellent for improving saline-alkali soil, and on the other hand, the marine product extract can maintain excellent water retention in saline-alkali soil, thereby increasing the stability of the fertilizer. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 is a particle structure diagram of the fertilizer in the present application;

[0039] Figure 2 is an internal structure diagram of the preparation device of the fertilizer in the present application;

[0040] Figure 3 is a first partial schematic view of the granulating roller in the preparation device;

[0041] Figure 4 is a second partial schematic view of the granulating roller in the preparation device.

[0042] In the figure: 10, feed inlet; 20, stirring piece; 30, spray pipe one; 40, granulating roller; 41, roller body; 42, granulating tank; 43, air bag piece; 44, channel; 45, annular cavity; 46, air pump; 50, screen; 51, discharge port one; 60, disc granulating structure; 61, spray pipe two; 70, discharge port two; 80, collecting tank; 90, conveying assembly. DETAILED DESCRIPTION

[0043] It is necessary to point out here that the following detailed description is only used to further illustrate the present application and cannot be understood as limiting the scope of protection of the present application, and those skilled in the art can make some non-essential improvements and adjustments to the present application according to the above application content.

[0044] In the prior art, the fertilizer with ordinary coating material can only achieve one-time slow-release effect, and after the coating material is damaged, the concentration of the fertilizer will first increase temporarily and then decrease rapidly; and when the fertilizer with ordinary coating is just put into the saline-alkali soil, the surface coating of the fertilizer hinders the release of nutrients, affects the improvement of the saline-alkali soil, and causes the crop seedlings to be in a poor saline-alkali environment and difficult to survive due to insufficient nutrients. To solve this technical problem, the present application provides a fertilizer suitable for saline-alkali soil, and the fertilizer particle structure is as shown in Figure 1 The particle of the fertilizer has at least N-layer core-shell structure, and from inside to outside, the odd layers are composition one and the even layers are composition two, wherein N is an odd number greater than or equal to 3.

[0045] The composition one is the main nutrient substance, and the raw materials for preparation include organic base fertilizer, nitrogen-phosphorus-potassium base fertilizer, ammonium lignosulfonate, amino acid, microbial agent and marine cultivation product extract.

[0046] The composition two is a film material, which replaces the coating material in the prior art, and the raw materials for preparation include marine cultivation product extract.

[0047] The fertilizer in the present application has an odd-layer core-shell structure, and the outermost layer is a nutrient substance, which can solve the problem that when the fertilizer is just put into the saline-alkali soil, the composition one on the surface is quickly dissolved with irrigation, so that the fertilizer quickly improves the saline-alkali soil, and the crop seedlings can obtain sufficient nutrients and increase the survival rate. With the end of the irrigation period, the composition two protects the inner composition one, waits for the next irrigation period, and continues to release the internal nutrient substance, which can avoid excessive concentration of the fertilizer in a short time and achieve the purpose of slow-release fertilizer, and reduce the fertilization frequency in the saline-alkali soil.

[0048] 1. Materials and methods

[0049] 1.1 Materials

[0050] The reagents and materials used in the preparation of the fertilizer in the experiment are as follows:

[0051] The preparation process of the organic-based fertilizer is as follows: 30-40 parts of humic acid, 40-50 parts of livestock manure, and 10-15 parts of tea seed meal (cake left after oil extraction from tea oil fruits) are respectively dried, crushed, and sieved, and then uniformly mixed, 3 times the volume of water is added, 10-15 parts of fermentation liquid (yeast bacteria, cellulose-decomposing bacteria, and actinomycetes mixed bacteria liquid in equal volume) is added, fermentation treatment is carried out at 48-52 DEG C, the pH is adjusted to 5.0-6.0 during the fermentation process, after the fermentation is completed, drying, crushing, and sieving through a 100-mesh sieve are carried out to obtain the organic-based fertilizer.

[0052] In the nitrogen, phosphorus and potassium-based fertilizer, the nitrogen fertilizer is urea, ammonium sulfate or ammonium nitrate, the phosphorus fertilizer is superphosphate, diammonium phosphate or calcium magnesium phosphate fertilizer, the potassium fertilizer is potassium sulfate, dihydrogen potassium phosphate or potassium nitrate, and the mass ratio of the nitrogen fertilizer, the phosphorus fertilizer and the potassium fertilizer is 5:5:10.

[0053] The ammonium lignosulfonate is purchased from Shanghai Tingruo Chemical Co., Ltd., and the amino acid liquid fertilizer is purchased from Heze Kangpu Fertilizer Co., Ltd.

[0054] The mass ratio of the halophilic bacteria, bacillus subtilis, nitrogen-fixing bacteria, phosphorus-decomposing bacteria and potassium-decomposing bacteria in the microbial agent is (2-4):1:1:1:1, the halophilic bacteria, bacillus subtilis and nitrogen-fixing bacteria in the microbial agent are purchased from Shanghai Jiachu Biological Engineering Co., Ltd., and the phosphorus-decomposing bacteria and potassium-decomposing bacteria are purchased from Weifang Yihao Biological Technology Co., Ltd.

[0055] The preparation process of the sea farming product extract is as follows:

[0056] The sea farming product is soaked overnight, the sand is spit out, and after being washed, it is put into a crusher for crushing treatment, all the crushed tissues are added to a cooking pot, at least one time the volume of water is added for 100 DEG C cooking, and when the volume is concentrated to 1 / 2, the cooking is ended and natural cooling is started, after cooling, 5wt% acid protease is added to the cooked liquid for enzymolysis for 1-2h, the enzymolysis temperature ranges from 40 DEG C to 50 DEG C, the enzymolysis pH ranges from 2.5 to 3.5, after enzymolysis, the mixture is put into a centrifugal device for overall centrifugal filtration (500-800 revolutions / minute), after the enzymolysis liquid is filtered, the precipitate is dried to obtain solid, the solid is crushed and ground through a 100-mesh sieve, and after being mixed with 2 times the volume of 50 DEG C-60 DEG C warm water, the sea farming product extract is obtained, wherein the acid protease is purchased from Anhui Xingsheng Biological Technology Co., Ltd., the shellfish is one or more of sea-farmed scallops, mussels, clams and snails, and the crustacean is one or more of sea-water shrimps, crabs and barnacles.

[0057] 1.2 Preparation of the fertilizer

[0058] The preparation process of the fertilizer in the application is as follows:

[0059] (1) dry 60-100 parts of organic-based fertilizer, 40-60 parts of nitrogen, phosphorus and potassium-based fertilizer, and 10-20 parts of ammonium lignosulfonate and 10-20 parts of microbial agent are crushed and mixed, then 5-10 parts of amino acid and 30-40 parts of marine cultivation product extract mixed liquid are added to the mixture to obtain composition one, the composition one is granulated and dried to obtain granules one with a first layer core structure;

[0060] (2) spray composition two, i.e. marine cultivation product extract, on the granules one, and dry to obtain granules two with a second layer shell structure; wherein the amount of composition two is equal to the total mass of granules one, and spraying is stopped after completion;

[0061] (3) spray composition one on the granules two, then granulate, and dry to obtain fertilizer granules with a third layer shell structure. Repeating steps (2) and (3) on the fertilizer granules can obtain fertilizer with N-layer core-shell structure.

[0062] Composition one includes composition two, which facilitates the formation of strong bonding force between adjacent core-shell structures. According to the above preparation method of the fertilizer, a specific device for preparing the fertilizer is also provided, as shown in Figure 2 which includes a shell and, from top to bottom, a stirring piece 20, a spray pipe one 30, a granulating roller 40, a screen 50, a disc granulating structure 60 and a particle collecting tank 80 inside the shell;

[0063] Two feed ports 10 are provided on the upper end of the shell, one of which is used for feeding solid raw materials (crushed organic-based fertilizer, nitrogen, phosphorus and potassium-based fertilizer, and ammonium lignosulfonate and microbial agent) in composition one, and the other is used for feeding fertilizer granules with an even number of core-shell structures;

[0064] The stirring piece 20 and the spray pipe one 30 are both provided with several, the stirring piece 20 is located below the feed port 10 (the stirring piece 20 is arranged side by side, composed of a shaft and a stirring rod located on the shaft);

[0065] The several spray pipes one 30 are arranged alternately and obliquely, and the spray pipe one 30 is used for feeding liquid raw materials (liquid mixture of liquid amino acid and marine cultivation product extract, with a certain viscosity) in composition one;

[0066] The screen 50 is obliquely arranged, preferably detachably arranged inside the shell, different aperture screens 50 can be replaced according to the specifications of the fertilizer granules, or screens 50 with variable apertures can be arranged, and a discharge port one 51 is provided on the shell at the low end of the screen 50 for discharging fertilizer granules with an odd number of core-shell structures;

[0067] The side of the particle collecting tank 80 is provided with a discharge port two 70 for discharging fertilizer particles with an even number of core-shell structures. The high end of the disc granulation structure 60 is provided with a spray pipe two 61 for spraying marine aquaculture product extract. The disc granulation structure 60 can adopt the structure of a disc granulator in the prior art and use centrifugal force for granulation. The disc granulation structure 60 can be adjusted in angle and has a gap with the shell. After granulation, the particles fall into the particle collecting tank 80 through the gap.

[0068] The structures not shown in the figure include power equipment such as structures for driving the granulation roller 40 and the stirring member 20 (the rotation speed of the granulation roller is 50-100 r / min, and the power of the stirring member is 0.5-1.5 kW). The shell is provided with driving equipment, a gearbox, and a transmission member to enable the relative rotation of the granulation roller 40 and the rotation of the stirring member 20. This part of the power equipment should belong to the prior art.

[0069] The structures not shown include raw material tanks (organic-based fertilizer, nitrogen-phosphorus-potassium-based fertilizer, ammonium lignosulfonate, microbial agent, amino acid, and marine aquaculture product extract) and pipe valve members connecting the raw material tanks with the feed inlet 10 and the spray pipe one 30 and the spray pipe two 61. The specifications (volume size, installation site) of the device can be reasonably set.

[0070] The specific steps for preparing the fertilizer are as follows:

[0071] (1) Mix dry organic-based fertilizer, nitrogen-phosphorus-potassium-based fertilizer, ammonium lignosulfonate, and microbial agent and pour them into the shell from one of the feed inlets 10. Spray a mixture of amino acid and marine aquaculture product extract into the spray pipe one 30, and both fall into the granulation roller 40 that is running relatively to be granulated, thereby obtaining particles one with a first layer of core structure.

[0072] (2) The particles one fall onto the screen 50 and fall into the disc granulation structure 60 because the particle size of the particles one is smaller than the mesh diameter of the screen 50. At the same time, the spray pipe two 61 sprays composition two, which is mixed with the particles one by centrifugal force to obtain particles two with a second layer of shell structure. After the spraying of the composition two is completed, the particles two fall into the particle collecting tank 80 from the gap.

[0073] (3) Pour the particles two in the particle collecting tank 80 into the other feed inlet 10 and repeat step (1) to obtain fertilizer particles with a third layer of shell structure. Repeat steps (2) and (3) to obtain fertilizer with N layers of core-shell structure. When the fertilizer particles meet the requirements, the fertilizer particles with an odd number of layers of core-shell structure are accumulated on the screen 50. Open the closure on the discharge port one 51 to discharge the fertilizer from the discharge port one 51.

[0074] Preferably, when the processing capacity is large and the device size is too large, an upward conveying assembly 90, such as a bucket elevator or a screw conveyor, is arranged on one side of the discharge port two 70 to convey the fertilizer particles of the even layer core-shell structure upward to the feeding port 10.

[0075] The existing granulating roller 40 includes a roller body 41 and a particle groove 42 (hemispherical or other concave) distributed on the surface of the roller body 41. Since the multi-layer wrapping of the fertilizer particles will continuously increase the particle size of the fertilizer particles, the existing granulating roller 40 can be improved on the basis of fixing the particle groove 42. For example, an air bag part 43 (which can be an air bag corresponding to the shape of the particle groove 42, or an elastic surface with an edge fixed to the edge of the particle groove 42) is arranged on the particle groove 42 along the groove surface, and the particle groove 42 is provided with a channel 44 in communication with the air bag part 43. The inside of the roller body 41 is provided with a sealed annular cavity 45 and an air pump 46, the air pump 46 is in communication with the annular cavity 45, and all the channels 44 extend to the annular cavity 45 along the radial direction of the roller body 41. When preparing fertilizer cores, the air bag part 43 is in a bulging state, and the particle size of the particle groove 42 is small. After the fertilizer has a shell structure, the air pump 46 is started to pump the annular cavity 45, so that the air bag part 43 is concave downward, so as to increase the particle size of the particle groove 42 and provide space for multi-layer coating. Until the air bag part 43 completely fits the wall surface of the particle groove 42, that is, the maximum fertilizer particle size of the device, which can be reasonably set according to needs.

[0076] The methods used in the present application are conventional methods known to those skilled in the art unless otherwise specified. The reagents and other materials used are commercially available unless otherwise specified.

[0077] 2. Verification test

[0078] 2.1, the application method of fertilizers with different components in saline-alkali land

[0079] The test was conducted in early April 2021 in Mingji Township, Lijin County, Dongying City, Shandong Province. The physicochemical properties of the test field soil are shown in Table 1.

[0080] Table 1. Physicochemical properties of test field soil (0-20 cm)

[0081] The test adopts a randomized block design, and sets up a test group and a control group (Table 2). According to the shape of the test field, the size of the block is divided, and the area of each field is about 9m 2 The field ridge between adjacent test fields is paved with mulch film to prevent seepage, and the test crops are corn and soybean mixed planting, the corn variety is Lushan 510, and the soybean variety is Qihuang 34.

[0082] Table 2. Test treatment design

[0083] Note: Composition I: ① organic base fertilizer (40 parts of humic acid, 50 parts of human and livestock manure, 15 parts of tea seed meal, 15 parts of fermentation bacteria liquid); ② nitrogen, phosphorus and potassium base fertilizer; ③ ammonium lignosulfonate; ④ amino acid; ⑤ microbial agent (mass ratio of halophilic bacteria, bacillus subtilis, nitrogen-fixing bacteria, phosphorus-solubilizing bacteria, potassium-solubilizing bacteria is 2:1:1:1:1, and the number of viable bacteria in the microbial agent is ≥1.0×10 8 CFU / g); ⑥: A1 scallop extract, A2 mussel extract, A3 sea shrimp extract (mixed with an unspecified amount of spotty shrimp, white shrimp and Procambarus clarkii), A4 (mixed with an unspecified amount of flower crab, green crab and Portunus sanguinolentus), B1 sea fish extract, B2 freshwater clam extract, B3 xanthan gum. Composition II is the same as ⑥, and the preparation method is the same (some adaptive adjustments are made according to the different properties of the substances).

[0084] The fertilizer samples prepared in the test group and the control group were uniformly applied to the test field after deep loosening at a dosage of 150 kg / mu. Then the test field was rotary tilled, and after the rotary tillage was completed, the test field was irrigated. The irrigation amount can be confirmed according to the local experience value, and the soil 20 cm deep is kept moist. Corn seedlings and soybean seedlings are alternately planted in the test field before the Gu Yu period in April. The planting method can be carried out by conventional methods, and the irrigation amount is set without fertilization after planting according to the local situation.

[0085] 2.2 Determination of soil water holding capacity and water retention rate

[0086] The fertilizer samples prepared in the test group and the control group were uniformly applied to the test field after deep loosening at a dosage of 150 kg / mu. Then the test field was rotary tilled, and after the rotary tillage was completed, the test field was irrigated. The irrigation amount can be confirmed according to the local experience value, and the soil 20 cm deep is kept moist. Corn seedlings and soybean seedlings are alternately planted in the test field before the Gu Yu period in April. The planting method can be carried out by conventional methods, and the irrigation amount is set without fertilization after planting according to the local situation.

[0087] The soil was mixed with the fertilizer sample at a ratio of 2wt% and dried, and the mixture was filled into a transparent organic glass tube with a diameter of 6 cm and a length of 25 cm. The bottom of the tube was sealed with 300 mesh nylon cloth, and the weight was recorded as W0. The glass tube was hung on an iron stand, and tap water was slowly sprayed until water seeped out of the bottom of the tube. When there was no water seeped out of the bottom of the tube, the weight was recorded as W1, and the soil without adding the fertilizer sample was used as a blank control group. The water holding rate (WH%) of the soil was calculated.

[0088] Similarly, the prepared soil mixture was stored in a glass beaker and weighed as W2. Then tap water was slowly sprayed and the mixture was soaked until saturated, and then weighed again as W3. The beaker was placed at room temperature, and on the 30th day, the weight was recorded as W i , and the soil without containing the fertilizer sample was used as a blank control group, and the water retention rate (WR%) of the soil containing the fertilizer sample after 30 days was calculated;

[0089] The water retention rate (WR%) of the soil was calculated.

[0090] ​The results are shown in Table 3.

[0091] Table 3. Test results statistics of water holding capacity and water retention

[0092] As can be seen from Table 3, compared with the control group, the fertilizers provided by test groups 1-4 have a certain degree of improvement on the water holding capacity and water retention capacity of saline-alkali soil, and test groups 1 and 2 have the best effect. The setting of the fertilizer can improve the water holding rate of the soil and improve the soil hardening state after being applied to the soil. With the increase of application time, the soil water retention rate still remains above 18%, which is about three times of the blank control group (6.52%). Obviously, adding the fertilizer prepared by the present application to the soil can not only improve the water holding performance of the saline-alkali soil, but also improve its water retention performance, thereby effectively improving the soil hardening state of the saline-alkali soil, prolonging the irrigation period, reducing the irrigation frequency, and also enhancing the drought resistance of crops during subsequent planting. It provides a theoretical basis for improving saline-alkali soil and has good application prospect.

[0093] 2.3 Soil detection

[0094] The dead seedling rates of corn and soybeans in different test fields were counted, and the soil of the test fields was measured and analyzed at the end of July (the maturity period of corn and soybeans). The results are shown in Tables 4 and 5.

[0095] Table 4. Dead seedling rate (%)

[0096] Through the statistics of the dead seedling rates of corn and soybeans in the test fields, it can be seen that the fertilizer prepared by the present application can significantly reduce the dead seedling rate. Through test groups 1-4, it can also be concluded that the fertilizer prepared by using the extract of marine culture products with shells as raw material has a better effect on improving the dead seedling rate than the fertilizer prepared by using the extract of marine culture products without shells as raw material.

[0097] Table 5. Test results statistics of soil analysis

[0098] Through the detection and analysis of the test field soil at the end of the corn and soybean planting period, it is found that the fertilizer prepared by the application can increase the nitrogen, phosphorus, potassium and organic matter in the saline-alkali soil, and can obviously reduce the pH and soluble salt of the saline-alkali soil, and improve the alkalization degree of the saline-alkali soil. As can be seen from the comparison of the test groups 1-4 and the control group 4, compared with the commercially available coated organic fertilizer, the fertilizer prepared by the application can improve the nutrients in the saline-alkali soil to different degrees, so that the saline-alkali soil tends to be normal, and through the comparison of the test groups 1-4 and the control groups 1-2, it is found that the fertilizer prepared by using the marine aquaculture products as raw materials has a high survival rate, and the calcium carbonate in the marine product extract is more excellent in improving the saline-alkali soil. Through the control group 3, xanthan gum is used as a coating agent, and the effect is equivalent to that of ordinary fertilizer, and the defect still exists.

[0099] The above-described embodiments only express several embodiments of the application, which are described in detail and specifically, but cannot be understood as the limitation of the patent scope of the application. It should be pointed out that for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the application, and these all belong to the protection scope of the application.

Claims

1. A fertilizer suitable for saline-alkali land, characterized in that: The fertilizer particles have a core-shell structure of at least N layers, with odd-numbered layers from the inside to the outside being composition one and even-numbered layers being composition two, wherein N is an odd number greater than or equal to 3; The raw materials for preparing the first composition include organic base fertilizer, nitrogen, phosphorus and potassium base fertilizer, ammonium lignin sulfonate, amino acids, microbial agents and marine aquaculture product extracts, and the raw materials for preparing the second composition include marine aquaculture product extracts; Among them, marine aquaculture products include shellfish and crustaceans; The organic base fertilizer is obtained by mixed fermentation of humic acid, human and livestock manure, tea seed meal and fermentation bacteria liquid; The microbial agent consists of halophilic bacteria, Bacillus subtilis, nitrogen-fixing bacteria, phosphate-solubilizing bacteria and potassium-solubilizing bacteria.

2. A fertilizer suitable for saline-alkali land according to claim 1, characterized in that: The composition comprises, by weight, 60-100 parts of organic base fertilizer, 40-60 parts of nitrogen, phosphorus and potassium base fertilizer, 10-20 parts of ammonium lignin sulfonate, 5-10 parts of amino acids, 10-20 parts of microbial agents and 30-40 parts of marine aquaculture product extract; The organic base fertilizer comprises 30-40 parts of humic acid, 40-50 parts of human and livestock manure, 10-15 parts of tea seed meal and 10-15 parts of fermentation bacteria liquid; The mass ratio of halophilic bacteria, Bacillus subtilis, nitrogen-fixing bacteria, phosphate-solubilizing bacteria and potassium-solubilizing bacteria in the microbial agent is (2-4): 1:1:1:

1.

3. The fertilizer suitable for saline-alkali land according to claim 1, characterized in that: The shellfish is one or more of scallops, mussels, clams and snails, and the crustaceans is one or more of shrimps, crabs and barnacles.

4. A method for preparing a fertilizer suitable for saline-alkali land according to any one of claims 1 to 3, characterized in that: The following steps are involved: (1) crushing dried organic base fertilizer and nitrogen, phosphorus and potassium base fertilizer, mixing them with ammonium lignin sulfonate and microbial agent, and then adding a liquid mixed with amino acids and marine aquaculture product extract to the mixture to obtain composition 1, granulating the composition 1, and drying to obtain particles 1 having a first layer core structure; (2) spraying composition 2, i.e., a marine aquaculture product extract, into the particles 1 to obtain particles 2 having a second shell structure after drying; (3) Spraying composition 1 into granules 2 and granulating the granules, and obtaining fertilizer granules having a third-layer shell structure after drying. Repeating steps (2) and (3) on the fertilizer granules can obtain a fertilizer having an N-layer core-shell structure.

5. The method for preparing a fertilizer suitable for saline-alkali land according to claim 4, wherein: The preparation process of the organic base fertilizer is as follows: humic acid, human and livestock manure, and tea seed meal are dried, crushed, sieved, and then evenly mixed; 3 times the volume of water is added thereto; and fermentation liquid is added thereto; fermentation is carried out at 48-52° C., the pH is adjusted to 5.0-6.0 during the fermentation process, and after fermentation, the organic base fertilizer is dried and crushed to obtain the organic base fertilizer.

6. The method for preparing a fertilizer suitable for saline-alkali land according to claim 4, characterized in that: The preparation process of the marine aquaculture product extract is as follows: The marine aquaculture product is crushed, and at least one volume of water is added for boiling. After cooling, acidic protease is added to the boiled liquid for enzymatic hydrolysis. The enzymatic hydrolysis temperature is 40-50°C, and the enzymatic hydrolysis pH is 2.5-3.

5. After the enzymatic hydrolysis, the enzymatic hydrolysis liquid is centrifuged and filtered, and the precipitate is dried to obtain a solid. The solid is crushed and ground, and mixed with warm water to obtain a marine aquaculture product extract.

7. A device for preparing fertilizer suitable for saline-alkali land according to any one of claims 1 to 3, characterized in that: It includes a shell and a stirring element, a nozzle, a granulating roller, a screen, a disc granulating structure and a granulation tank located inside the shell from top to bottom; Two feed ports are provided at the upper end of the shell, wherein one feed port is used to feed the solid raw materials in the first composition, and the other feed port is used to feed the fertilizer particles having an even-layer core-shell structure. A plurality of stirring members and nozzles are provided, and the stirring members are located below the feed ports. The plurality of nozzles are arranged in an alternating and inclined manner, and the nozzles are used to feed the liquid raw materials in the first composition. The screen is inclined, and a discharge port 1 is provided on the shell at the lower end of the screen for discharging fertilizer particles with an odd-numbered core-shell structure. A discharge port 2 is provided on one side of the particle collecting trough for discharging fertilizer particles with an even-numbered core-shell structure. A nozzle 2 is provided above the high end of the disc granulation structure for spraying composition 2.

8. The preparation device according to claim 7, characterized in that: A conveying assembly is provided on one side of the second discharge port for conveying the fertilizer particles with an even number of core-shell structures upward to the feed port.

9. The preparation device according to claim 7, characterized in that: The granulating roller includes a roller body and granule grooves distributed on the surface of the roller body. The granule grooves are provided with airbags along the groove surfaces, and the granule grooves are provided with channels connected to the airbags. A sealed annular cavity and an air pump are provided inside the roller body. The air pump is connected to the annular cavity, and the channel extends radially along the roller body to the annular cavity.

10. The preparation device according to any one of claims 7 to 9, characterized in that: The specific steps of the preparation device for preparing fertilizer suitable for saline-alkali land are as follows: (1) Dry organic base fertilizer, nitrogen, phosphorus and potassium base fertilizer, ammonium lignin sulfonate and microbial agent are mixed and fed into the shell from one of the feed ports. The mixture is dispersed by the stirring element and a liquid mixed with amino acids and marine aquaculture product extract is sprayed into the nozzle 1. The liquid mixed with amino acids and marine aquaculture product extract falls into the granulating rollers running opposite to each other at the same time and is granulated to obtain granules 1 having a first layer core structure. (2) Particle 1 falls onto the screen. Since the particle size of particle 1 is smaller than the mesh size of the screen, particle 1 falls into the disc granulation structure. At the same time, nozzle 2 sprays composition 2. Composition 2 is mixed with particle 1 by centrifugal force to obtain particle 2 with a second shell structure. Particle 2 falls into the particle collecting tank through the gap. (3) Particle 2 in the collecting trough is fed into another feed port, and step (1) is repeated to obtain fertilizer particles having a third-layer shell structure. Repeating steps (2) and (3) on the fertilizer particles can obtain a fertilizer having an N-layer core-shell structure.

Images