Compound fertilizer for planting crops in improved saline-alkali soil and preparation method of compound fertilizer

Abstract

The invention relates to a compound fertilizer for planting crops in improved saline-alkali soil and a preparation method thereof, and belongs to the technical field of compound fertilizers. The compound fertilizer is of a multi-layer granular structure and is composed of a slow release layer, a diaphragm and a quick release layer, wherein the diaphragm is wrapped outside the slow-release layer, and the quick-release layer is wrapped outside the diaphragm; the slow-release layer contains a nitrogen fertilizer, a phosphate fertilizer and a potash fertilizer; the material of the diaphragm is a mixture of polycaprolactone and a water-soluble polymer material in a ratio of 1: (1-2); the quick release layer is zeolite powder adsorbed with acidic substances. The invention provides a fertilizer with a multi-layer granular structure, which can improve the water-retaining property of soil by using the porous structure of zeolite while quickly adjusting the pH value of the soil. A layer of diaphragm is coated outside the slow-release layer, and the diaphragm is slowly dissolved under the action of water, so that the fertilizer in the internal slow-release layer is released outwards. The compound fertilizer provided by the invention not only neutralizes the pH value of soil, but also improves the water-retaining property of the soil; the internal fertilizer can be slowly released outwards, so that multiple effects are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of compound fertilizers, and in particular to a compound fertilizer used for planting crops in improved saline-alkali land and a preparation method thereof. Background Art

[0002] Saline-alkali land is a type of salt accumulation, which refers to land where the salt contained in the soil affects the normal growth of crops. Saline-alkali land can be divided into light saline-alkali land, moderate saline-alkali land and heavy saline-alkali land. The essence of its formation is mainly the horizontal and vertical redistribution of various soluble salts on the ground, so that salt gradually accumulates on the surface of the soil in the salt-collecting area. The formation of saline-alkali land is mostly related to the accumulation of carbonates in the soil, so the alkalinity is generally high, and plants can hardly survive in areas with severe saline-alkali soil. There are two conditions for the formation of saline-alkali soil: one is the dry climate and high groundwater level (above the critical water level); the other is low-lying terrain with no drainage outlet. Groundwater contains a certain amount of salt. If its water surface is close to the ground and the area is relatively dry, the water that rises to the surface due to capillary action evaporates, leaving salt behind: over time, the salt content of the soil gradually increases, forming saline-alkali soil. If it is a depression and there is no drainage outlet, the water in the depression evaporates and leaves salt behind, forming saline-alkali land.

[0003] The improvement of saline-alkali land is generally carried out in several steps: first, drain and wash the salt to reduce the salt content of the soil; then plant salt-tolerant plants to fertilize the soil; and finally plant crops. The improved saline-alkali land reduces the salt content in the soil and improves the fertility of the soil. However, there is still a small amount of salt in the improved saline-alkali land, which causes the soil pH value to be high, and there is still a risk of easy loss of water in the soil. These problems will lead to serious obstacles to the utilization of saline-alkali land. Summary of the invention

[0004] In view of the problems that the existing improved saline-alkali land still has high soil pH value and water is not easy to preserve, the present invention provides a compound fertilizer for planting crops in improved saline-alkali land and a preparation method thereof to solve the above problems. The present invention provides a multi-layer granular structure fertilizer, including a quick-release layer and a slow-release layer, which can quickly adjust the soil pH while using the porous structure of zeolite to improve the water retention of the soil. The outside of the slow-release layer is coated with a diaphragm, which slowly dissolves under the action of water, allowing the fertilizer in the internal slow-release layer to be released outward. The compound fertilizer of the present invention not only neutralizes the pH of the improved saline-alkali soil, but also improves the water retention of the soil; at the same time, the internal fertilizer can be slowly released outward, achieving multiple effects.

[0005] In a first aspect, the present invention provides a compound fertilizer for planting crops in improved saline-alkali land, wherein the compound fertilizer is a multi-layer granular structure, consisting of a slow-release layer, a diaphragm and a quick-release layer; wherein the slow-release layer is wrapped with the diaphragm on the outside, and the quick-release layer is wrapped with the quick-release layer on the outside of the diaphragm; the slow-release layer contains nitrogen fertilizer, phosphorus fertilizer and potassium fertilizer; the diaphragm material is a mixture of polycaprolactone: water-soluble polymer material = 1:1~2; the quick-release layer is zeolite powder adsorbed with acidic substances.

[0006] Furthermore, the acidic substance is a humic acid aqueous solution or a fermentation liquid of Aspergillus niger.

[0007] Furthermore, the water-soluble polymer material is at least one of starch, sodium alginate, carboxymethyl cellulose or polyvinyl alcohol.

[0008] Furthermore, the slow-release layer accounts for 60% to 72% of the total weight of the compound fertilizer, and the quick-release layer accounts for 25% to 37% of the total weight of the compound fertilizer; wherein the nitrogen, phosphorus and potassium nutrients are proportioned by weight as N:P2O5:K2O=(1 to 2.5):(0.6 to 1):(2 to 3.5).

[0009] Furthermore, the nitrogen fertilizer is at least one of urea, ammonium nitrate and ammonium sulfate; the phosphate fertilizer is at least one of monoammonium phosphate or diammonium phosphate; and the potash fertilizer is at least one of potassium sulfate or potassium chloride.

[0010] Furthermore, the particle size of the particles in the sustained-release layer is 3-5 mm.

[0011] In a second aspect, the present invention provides a method for preparing the above-mentioned compound fertilizer for planting crops in improved saline-alkali land, comprising the following steps: (1) Preparation of the slow-release layer: nitrogen fertilizer, phosphate fertilizer and potassium fertilizer are put into a stirring mixer according to a certain proportion, mixed evenly, granulated, dried and sieved to prepare slow-release layer fertilizer granules; (2) Preparation of a diaphragm solution: dissolving polycaprolactone in a solvent, wherein the amount of the solvent used is 10-15 kg / kg based on the weight of the polycaprolactone; adding a water-soluble polymer material according to a ratio and stirring the mixture evenly at room temperature to obtain a homogeneous diaphragm solution; (3) Preparation of the immediate-release layer: Take an aqueous solution of an acidic substance, then add zeolite powder at a concentration of 5 to 20 kg / kg based on the weight of the acidic substance, stir evenly, and then spray-dry to obtain the immediate-release layer; (4) Preparation of compound fertilizer: spray the membrane solution prepared in step (2) onto the surface of the slow-release fertilizer particles prepared in step (1), then spray the quick-release layer onto the membrane surface, and dry naturally to obtain the compound fertilizer.

[0012] Furthermore, in step (1), the solvent is acetone or chloroform.

[0013] The beneficial effects of the present invention are: The present invention provides a multi-layer granular structure fertilizer. In the initial stage of fertilization, the acidic substances attached to the zeolite pores in the quick-release layer are rapidly released under the action of water in the soil, and while neutralizing the alkaline substances in the soil, the water is also adsorbed in the pores, thereby improving the water retention of the soil water. The diaphragm contains water-soluble substances, which can quickly adjust the soil pH while also adsorbing and releasing water to adjust the soil moisture content, reduce soil consolidation, and increase soil porosity. In addition, zeolite powder can also provide trace elements, improve soil fertility, and promote plant growth. The outside of the slow-release layer is coated with a diaphragm, and the water-soluble substances in the diaphragm are slowly dissolved under the action of water. The diaphragm produces holes so that the fertilizer in the internal slow-release layer can be slowly released into the soil, thereby increasing the action time of the fertilizer. The water-insoluble polycaprolactone used in the diaphragm can be completely decomposed within 3 to 6 months, and there is no risk of polluting the land. DETAILED DESCRIPTION

[0014] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0015] Example 1 A method for preparing compound fertilizer for planting crops on improved saline-alkali land comprises the following steps: (1) Preparation of slow-release layer: 46 parts of urea, 42 parts of monoammonium phosphate and 50 parts of potassium sulfate (N: P2O5: K2O = 1:1:2) were put into a stirring mixer, mixed evenly, granulated, dried, and sieved to prepare slow-release layer fertilizer granules with a particle size of 3-5 mm; (2) Preparation of diaphragm solution: Dissolve 5 parts of polycaprolactone in 500 parts of acetone; add 5 parts of starch and stir evenly at room temperature to obtain a homogeneous diaphragm solution; (3) Preparation of the immediate-release layer: 150 parts of a 3% humic acid aqueous solution was added with 57.5 parts of zeolite powder, stirred evenly, and then spray-dried to obtain the immediate-release layer; (4) Preparation of compound fertilizer: spray the membrane solution prepared in step (2) onto the surface of the slow-release fertilizer particles prepared in step (1), then spray the quick-release layer onto the membrane surface, and dry naturally to obtain the compound fertilizer.

[0016] Example 2 A method for preparing compound fertilizer for planting crops on improved saline-alkali land comprises the following steps: (1) Preparation of the slow-release layer: 20 parts of ammonium sulfate, 21 parts of monoammonium phosphate and 100 parts of potassium sulfate (N: P2O5: K2O = 1.2: 0.6: 2.4) are put into a stirring mixer, mixed evenly, granulated, dried, sieved, and made into slow-release layer fertilizer granules with a particle size of 3-5 mm; (2) Preparation of diaphragm solution: Dissolve 5 parts of polycaprolactone in 500 parts of acetone; add 5 parts of sodium alginate and stir evenly at room temperature to obtain a homogeneous diaphragm solution; (3) Preparation of the immediate-release layer: 160 parts of a 2.5% humic acid aqueous solution were added with 55 parts of zeolite powder, stirred evenly, and then spray-dried to obtain the immediate-release layer; (4) Preparation of compound fertilizer: spray the membrane solution prepared in step (2) onto the surface of the slow-release fertilizer particles prepared in step (1), then spray the quick-release layer onto the membrane surface, and dry naturally to obtain the compound fertilizer.

[0017] Example 3 A method for preparing compound fertilizer for planting crops on improved saline-alkali land comprises the following steps: (1) Preparation of slow-release layer: 34 parts of ammonium nitrate, 14 parts of diammonium phosphate and 84 parts of potassium chloride (N: P2O5: K2O = 2.5:1:3.5) are put into a stirring mixer, mixed evenly, granulated, dried, sieved, and made into slow-release layer fertilizer granules with a particle size of 3-5 mm; (2) Preparation of diaphragm solution: Dissolve 5 parts of polycaprolactone in 500 parts of acetone; add 5 parts of carboxymethyl cellulose and stir evenly at room temperature to obtain a homogeneous diaphragm solution; (3) Preparation of the quick-release layer: 200 parts of an aqueous solution of a 3% Aspergillus niger fermentation liquid was taken, and then 62 parts of zeolite powder was added, stirred evenly, and spray-dried to obtain a quick-release layer; the Aspergillus niger fermentation liquid was the fermentation liquid of Aspergillus niger 22HQ, and the Aspergillus niger 22HQ was disclosed in the patent application number CN202310329236.9; (4) Preparation of compound fertilizer: spray the membrane solution prepared in step (2) onto the surface of the slow-release fertilizer particles prepared in step (1), then spray the quick-release layer onto the membrane surface, and dry naturally to obtain the compound fertilizer.

[0018] Test Case The compound fertilizers prepared in Examples 1 to 3 were used for field tests.

[0019] Test variety: Corn variety Lainong 14 Test location: Binzhou City, Shandong Province Trial period: June 2022 to July 2022.

[0020] Assume that there are 4 treatments of compound fertilizers of Examples 1 to 3 and a comparative example (ordinary fertilizer), and the fertilizer dosage of the examples is the same as that of the comparative example. The fertilizer dosage of the comparative example is determined according to the usual dosage of local farmers, and the fertilization method is the usual method of farmers, that is, diammonium phosphate compound fertilizer and urea are evenly spread on the field surface at the time of sowing, and then deeply plowed into the soil. The compound fertilizer in the example is evenly spread on the field surface at the time of corn sowing, and then deeply plowed into the soil. The content of each component in the soil is detected 15 days after fertilization. The average results are shown in Table 1: Table 1 - Test results

[0021] It can be clearly seen that the compound fertilizer of the present invention can continuously release fertilizer into the soil after fertilization, and at the same time improve the pH of the soil and reduce the salt content and alkalinity in the soil.

[0022] Although the present invention has been described in detail by way of preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, a person of ordinary skill in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and such modifications or substitutions shall be within the scope of the present invention. Any person of ordinary skill in the art may easily conceive of changes or substitutions within the technical scope disclosed by the present invention, and such changes or substitutions shall be within the scope of protection of the present invention.

Claims

1. A compound fertilizer for planting crops on improved saline-alkali land, characterized in that: The compound fertilizer is a multi-layer granular structure, consisting of a sustained-release layer, a diaphragm and a quick-release layer; the sustained-release layer is wrapped with a diaphragm, and the quick-release layer is wrapped with a quick-release layer on the outside of the diaphragm; the sustained-release layer contains nitrogen fertilizer, phosphate fertilizer and potassium fertilizer; the diaphragm material is a mixture of polycaprolactone: water-soluble polymer material = 1:1~2; the quick-release layer is zeolite powder adsorbed with acidic substances.

2. The compound fertilizer for planting crops in improved saline-alkali land according to claim 1, characterized in that: The acidic substance is a humic acid aqueous solution or a fermentation liquid of Aspergillus niger.

3. The compound fertilizer for planting crops in improved saline-alkali land according to claim 1, characterized in that: The water-soluble polymer material is at least one of starch, sodium alginate, carboxymethyl cellulose or polyvinyl alcohol.

4. The compound fertilizer for planting crops in improved saline-alkali land according to claim 1, characterized in that: The slow-release layer accounts for 60% to 72% of the total weight of the compound fertilizer, and the quick-release layer accounts for 25% to 37% of the total weight of the compound fertilizer; wherein the nitrogen, phosphorus and potassium nutrients are proportioned by weight as N:P2O5:K2O=(1 to 2.5):(0.6 to 1):(2 to 3.5).

5. The compound fertilizer for planting crops in improved saline-alkali land according to claim 4, characterized in that: The nitrogen fertilizer is at least one of urea, ammonium nitrate and ammonium sulfate; the phosphate fertilizer is at least one of monoammonium phosphate or diammonium phosphate; and the potash fertilizer is at least one of potassium sulfate or potassium chloride.

6. The compound fertilizer for planting crops in improved saline-alkali land according to claim 1, characterized in that: The particle size of the particles in the sustained-release layer is 3-5 mm.

7. A method for preparing the compound fertilizer for planting crops in improved saline-alkali land as claimed in claim 1, characterized in that: The following steps are involved: (1) Preparation of the slow-release layer: nitrogen fertilizer, phosphate fertilizer and potassium fertilizer are put into a stirring mixer according to a certain proportion, mixed evenly, granulated, dried and sieved to prepare slow-release layer fertilizer granules; (2) Preparation of a diaphragm solution: dissolving polycaprolactone in a solvent, wherein the amount of the solvent used is 10-15 kg / kg based on the weight of the polycaprolactone; adding a water-soluble polymer material according to a ratio and stirring the mixture evenly at room temperature to obtain a homogeneous diaphragm solution; (3) Preparation of the immediate-release layer: Take an aqueous solution of an acidic substance, then add zeolite powder at a concentration of 5 to 20 kg / kg based on the weight of the acidic substance, stir evenly, and then spray-dry to obtain the immediate-release layer; (4) Preparation of compound fertilizer: spray the membrane solution prepared in step (2) onto the surface of the slow-release fertilizer particles prepared in step (1), then spray the quick-release layer onto the membrane surface, and dry naturally to obtain the compound fertilizer.

8. The method according to claim 7, characterized in that The solvent in step (1) is acetone or chloroform.

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