Special long-acting coated controlled-release fertilizer for summer corn and preparation method of special long-acting coated controlled-release fertilizer

Abstract

The invention relates to the technical field of agricultural fertilizers, in particular to a special long-acting coated slow / controlled-release fertilizer for summer corn and a preparation method of the special long-acting coated slow / controlled-release fertilizer. The preparation method of the special long-acting coated slow / controlled-release fertilizer for summer corn comprises the following steps: (1) preparing modified corn straw biochar powder: crushing corn straws, heating and soaking the crushed corn straws in a mixed aqueous solution of NaOH and Na2SO3 and a hydrogen peroxide solution in sequence, carbonizing and grinding; (2) preparing a coating solution: mixing polyethylene glycol 400 and glycerol, heating, adding the modified corn straw charcoal powder and concentrated sulfuric acid, continuing heating, adding nano silicon dioxide, polyvinylpyrrolidone and an isocyanate curing agent, and uniformly mixing; (3) granulating; and (4) coating: spraying the coating solution to the surfaces of fertilizer granules obtained by granulation, and drying to obtain the special long-acting coated slow / controlled-release fertilizer for summer corn. The special long-acting coated controlled-release fertilizer for summer corn prepared by the preparation method is used for field experiments, and the harvested summer corn is good in quality and high in yield.

Description

Technical Field

[0001] The invention relates to the technical field of agricultural fertilizers, and in particular to a long-acting coated slow-release fertilizer special for summer corn and a preparation method thereof. Background Art

[0002] Summer corn, also known as wheat stubble corn, is corn sown in summer. It is mainly distributed in the Huanghuaihai Plain in China, as well as in southern Shanxi and the Guanzhong Plain in Shaanxi. The growth cycle is generally 95 to 105 days, and the varieties are mainly early and mid-maturing. In the process of summer corn planting, fertilization is one of the most important measures to increase production and ensure income. At present, the existing commercially available coated slow-release fertilizer is one of the main fertilizer varieties used for summer corn, but coated slow-release fertilizer has at least the following problems: (1) Some coatings and nutrient configurations are unreasonable, which cannot achieve the long-term effect of slow-release fertilizers. The fertilizer utilization rate is low, and subsequent artificial topdressing is required, which increases production costs and labor costs.

[0003] (2) The coatings of some coated slow-release fertilizers will rupture early, causing the nitrogen, phosphorus and potassium elements to be released prematurely, resulting in nutrient loss and low nutrient utilization rate, which cannot achieve the long-term effect of the slow-release fertilizer. In addition, the soil frequently alternates between dry and wet in July and August, causing serious loss of nutrients in the soil, causing slow growth of corn seedlings and affecting the yield and quality of summer corn.

[0004] (3) Traditional controlled-release fertilizer membranes are mainly derived from petrochemical products and have high production costs. Fertilizers coated with bio-based materials have the advantages of being economical, environmentally friendly, and recyclable. They have gradually replaced petroleum-based membranes and become an important direction for the development of controlled-release fertilizers. However, bio-based membranes currently contain a large number of hydrophilic groups, are easy to absorb water, and have the problem of unstable controlled-release effects. Summary of the invention

[0005] Aiming at the technical problems that the coated slow-release fertilizer for summer corn in the prior art has unstable coating controlled-release effect, unreasonable coating and nutrient configuration, resulting in poor long-term slow-release effect and low summer corn yield, the present invention provides a preparation method of a special long-term coated slow-release fertilizer for summer corn, which uses modified bio-based materials as one of the raw material components of the coating, and the treated modified corn stalk biochar powder removes most of the lignin and cellulose, has a loose structure, and greatly improves the specific surface area and micropore volume. The pore structure of the biochar becomes complex, the adsorption capacity is strong, and it is not easy to absorb water and crack. When combined with other coating raw materials, after coating fertilizer particles with a certain ratio, the long-term slow-release effect is good, and the harvested summer corn is of good quality and high yield.

[0006] In a first aspect, the present invention provides a method for preparing a long-acting coated slow-release fertilizer for summer corn, comprising the following steps: (1) Preparation of modified corn straw biochar powder: crush corn straw, heat and soak it in a mixed aqueous solution of NaOH and Na2SO3 and a hydrogen peroxide solution, and then carbonize and grind it; (2) Preparing a coating solution: Mix polyethylene glycol 400 and propylene glycol, heat to 70-100°C, add modified corn straw biochar powder and concentrated sulfuric acid, continue to heat to 150-180°C, react for 1-2 hours to obtain a mixed solution, add nano-silica, polyvinyl pyrrolidone and isocyanate curing agent to the mixed solution, mix well to obtain a coating solution; (3) Granulation: After the kernel components are mixed evenly, they are added into a coating machine and heated and melted by blowing air, and then cooled and granulated to obtain fertilizer granules; (4) Coating: Spray the coating solution onto the surface of the fertilizer particles and dry them at room temperature to obtain a long-acting coated slow-release fertilizer for summer corn; Among them, the core ingredients include the following raw materials: Urea, potassium dihydrogen phosphate, potassium nitrate, 2,4-dichlorophenoxyacetic acid, 4-iodophenoxyacetic acid, borax, magnesium ammonium phosphate, zinc sulfate, manganese sulfate, ferrous sulfate and calcium ammonium nitrate.

[0007] Urea, potassium dihydrogen phosphate and potassium nitrate provide nitrogen, phosphorus and potassium for summer corn.

[0008] The main function of 2,4-dichlorophenoxyacetic acid is that it is a highly effective herbicide and is often used for weeding in corn fields.

[0009] 4-iodophenoxyacetic acid can promote the growth, development, flowering and fruiting of corn plants and shorten the corn development cycle.

[0010] Zinc sulfate, borax, calcium ammonium nitrate, magnesium ammonium phosphate, manganese sulfate, and ferrous sulfate provide corn with trace elements such as zinc, boron, calcium, magnesium, manganese, and iron.

[0011] Furthermore, step (1) prepares modified corn straw biochar powder: the dried corn straw is crushed and sieved, heated and soaked in a mixed aqueous solution of NaOH and Na2SO3 at 90-100°C for 2-3h, washed with water, and then heated and soaked in a 4wt%-5wt% hydrogen peroxide aqueous solution at 70-80°C for 2-3h, dried, placed in a tubular furnace, heated to 580-600°C at a heating rate of 10-15°C / min under nitrogen atmosphere, kept warm for pyrolysis for 3-4h, cooled naturally to room temperature, and ground and sieved.

[0012] Furthermore, in step (2), the mass ratio of the mixed solution: the mixture of nano-silicon dioxide, polyvinyl pyrrolidone and isocyanate curing agent is 15-18:381-382.

[0013] Furthermore, in step (2), the mass ratio of modified corn straw biochar powder, polyethylene glycol 400, propylene glycol, and concentrated sulfuric acid is 10-12:5-6:1-2:1-2; The mass ratio of nano silicon dioxide, polyvinyl pyrrolidone and isocyanate curing agent is 280-300:1-2:80-100.

[0014] Furthermore, the isocyanate curing agent is monoisocyanate, diisocyanate or polyisocyanate.

[0015] Further, the core composition includes the following raw materials in parts by weight: 60-90 parts of urea, 30-50 parts of potassium dihydrogen phosphate, 50-60 parts of potassium nitrate, 1-2 parts of 2,4-dichlorophenoxyacetic acid, 1-2 parts of 4-iodophenoxyacetic acid, 1-2 parts of borax, 1-2 parts of magnesium ammonium phosphate, 1-3 parts of zinc sulfate, 1-2 parts of manganese sulfate, 1-2 parts of ferrous sulfate, and 1-2 parts of calcium ammonium nitrate.

[0016] Furthermore, in step (4), the mass ratio of the coating solution to the fertilizer particles is 3-5:15-20.

[0017] In a second aspect, the present invention provides a long-acting coated slow-release fertilizer for summer corn, which is prepared according to the preparation method of the long-acting coated slow-release fertilizer for summer corn.

[0018] The beneficial effects of the present invention are: The preparation method of the special long-acting coated slow-release fertilizer for summer corn provided by the invention is simple to operate and has reasonable component matching. The prepared special long-acting coated slow-release fertilizer for summer corn can control nitrogen, stabilize phosphorus and potassium, and is matched with trace elements such as zinc and boron to provide sufficient nutrients for the entire growth cycle of summer corn. When used before sowing, the fertilizer requirement of corn in the entire growth season can be met, the inconvenience caused by topdressing in the high temperature of midsummer is avoided, the labor intensity is reduced, labor is saved, and the harvested summer corn has a high yield and good corn kernel quality. DETAILED DESCRIPTION

[0019] 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.

[0020] Example 1 A method for preparing a long-acting coated slow-release fertilizer for summer corn comprises the following steps: (1) Preparation of modified corn straw biochar powder: The dried corn stalks were crushed, passed through a 40-mesh sieve, heated and soaked in a mixed aqueous solution of NaOH and Na2SO3 at 100°C for 2 h, wherein the concentration of NaOH in the mixed aqueous solution was 1 mol / L and the concentration of Na2SO3 was 0.2 mol / L. After washing with water, the mixed aqueous solution was heated and soaked in a 5 wt% hydrogen peroxide solution at 70°C for 2 h, dried in a drying oven, placed in a tubular furnace, heated to 600°C at a heating rate of 10°C / min under nitrogen atmosphere protection, and pyrolyzed for 3 h at this temperature. After cooling naturally to room temperature, the mixed aqueous solution was taken out, ground and passed through an 80-mesh sieve to obtain modified corn stalk biochar powder. (2) Preparation of coating solution: Mix 5 parts of polyethylene glycol 400 and 2 parts of propylene glycol, heat to 100°C, add 10 parts of modified corn straw biochar powder and 2 parts of concentrated sulfuric acid, continue to heat to 150°C, react for 1 hour, and obtain a mixed solution; add 300 parts of nano-silicon dioxide, 1 part of polyvinyl pyrrolidone and 80 parts of curing agent PM200 to 15 parts of the mixed solution and mix evenly to obtain a coating solution; (3) Granulation: After the kernel components are mixed evenly, they are added into a coating machine and heated and melted by blowing air, and then cooled and granulated to obtain fertilizer granules; (4) Coating: The coating solution is evenly sprayed onto the surface of the fertilizer particles using a spraying device, and after drying at room temperature, a long-acting coated slow-release fertilizer specifically for summer corn is obtained; The core composition includes the following components by mass: 90 parts of urea, 40 parts of potassium dihydrogen phosphate, 50 parts of potassium nitrate, 2 parts of 2,4-dichlorophenoxyacetic acid, 2 parts of 4-iodophenoxyacetic acid, 1 part of borax, 1 part of magnesium ammonium phosphate, 3 parts of zinc sulfate, 1 part of manganese sulfate, 1 part of ferrous sulfate, and 2 parts of calcium ammonium nitrate; The mass ratio of the coating solution to the fertilizer particles is 5:20.

[0021] Example 2 A method for preparing a long-acting coated slow-release fertilizer for summer corn comprises the following steps: (1) Preparation of modified corn straw biochar powder: Same as Example 1; (2) Preparation of coating solution: 6 parts of polyethylene glycol 400 and 1 part of propylene glycol were mixed, heated to 100°C, 12 parts of modified corn straw biochar powder and 1 part of concentrated sulfuric acid were added, and the mixture was further heated to 150°C and reacted for 1 hour to obtain a mixed solution; 280 parts of nano-silicon dioxide, 2 parts of polyvinyl pyrrolidone and 100 parts of curing agent PM200 were added to 18 parts of the mixed solution and mixed evenly to obtain a coating solution; (3) Granulation: After the kernel components are mixed evenly, they are added into a coating machine and heated and melted by blowing air, and then cooled and granulated to obtain fertilizer granules; (4) Coating: The coating solution is evenly sprayed onto the surface of the fertilizer particles using a spraying device, and after drying at room temperature, a long-acting coated slow-release fertilizer specifically for summer corn is obtained; The core composition includes the following components by mass: 60 parts of urea, 30 parts of potassium dihydrogen phosphate, 60 parts of potassium nitrate, 1 part of 2,4-dichlorophenoxyacetic acid, 1 part of 4-iodophenoxyacetic acid, 2 parts of borax, 2 parts of magnesium ammonium phosphate, 2 parts of zinc sulfate, 2 parts of manganese sulfate, 2 parts of ferrous sulfate, 1 part of calcium ammonium nitrate; The mass ratio of the coating solution to the fertilizer particles is 2:15.

[0022] Example 3 A method for preparing a long-acting coated slow-release fertilizer for summer corn comprises the following steps: (1) Preparation of modified corn straw biochar powder: Same as Example 1; (2) Preparation of coating solution: Mix 5 parts of polyethylene glycol 400 and 2 parts of propylene glycol, heat to 100°C, add 11 parts of modified corn straw biochar powder and 1 part of concentrated sulfuric acid, continue to heat to 150°C, react for 1 hour, and obtain a mixed solution; add 290 parts of nano-silicon dioxide, 1 part of polyvinyl pyrrolidone and 90 parts of curing agent PM200 to 17 parts of the mixed solution and mix evenly to obtain a coating solution; (3) Granulation: After the kernel components are mixed evenly, they are added into a coating machine and heated and melted by blowing air, and then cooled and granulated to obtain fertilizer granules; (4) Coating: The coating solution is evenly sprayed onto the surface of the fertilizer particles using a spraying device, and after drying at room temperature, a long-acting coated slow-release fertilizer specifically for summer corn is obtained; The core composition includes the following components by mass: 75 parts of urea, 50 parts of potassium dihydrogen phosphate, 50 parts of potassium nitrate, 1 part of 2,4-dichlorophenoxyacetic acid, 2 parts of 4-iodophenoxyacetic acid, 1 part of borax, 2 parts of magnesium ammonium phosphate, 1 part of zinc sulfate, 1 part of manganese sulfate, 2 parts of ferrous sulfate, and 1 part of calcium ammonium nitrate; The mass ratio of the coating solution to the fertilizer particles is 3:18.

[0023] Comparative Example 1 A method for preparing a coated slow-release fertilizer comprises the following steps: (1) Preparation of corn straw powder: The dried corn stalks were crushed, passed through a 40-mesh sieve, heated and soaked in a mixed aqueous solution of NaOH and Na2SO3 at 100°C for 2 hours, wherein the concentration of NaOH in the mixed aqueous solution was 1 mol / L and the concentration ratio of Na2SO3 was 0.2 mol / L, washed with water, and then heated and soaked in a 5 wt% hydrogen peroxide solution at 70°C for 2 hours, dried in a drying oven, and then ground and passed through an 80-mesh sieve to obtain corn stalk powder; (2) Preparation of coating solution: Mix 5 parts of polyethylene glycol 400 and 2 parts of propylene glycol, heat to 100°C, add 10 parts of corn straw powder and 2 parts of concentrated sulfuric acid, continue to heat to 150°C, react for 1 hour, and obtain a mixed solution; add 300 parts of nano-silicon dioxide, 1 part of polyvinyl pyrrolidone and 80 parts of curing agent PM200 to 15 parts of the mixed solution and mix evenly to obtain a coating solution; (3) Granulation: The core components (the same as the core components in Example 1) are mixed evenly and added to a coating machine for heating and melting by blowing air, and then cooled and granulated to obtain fertilizer granules; (4) Coating: The coating solution is evenly sprayed onto the surface of the fertilizer particles using a spraying device, and then dried at room temperature to obtain a coated slow-release fertilizer; Among them, the mass ratio of the coating solution to the fertilizer particles is 5:20.

[0024] Comparative Example 2 A method for preparing a coated slow-release fertilizer is the same as that in Example 1, except that in step (4), the mass ratio of the coating solution to the fertilizer particles is 6:10.

[0025] Comparative Example 3 A method for preparing a coated slow-release fertilizer is the same as that in Example 1, except that in step (3), the core component includes the following raw materials in parts by weight: 100 parts of urea, 60 parts of potassium dihydrogen phosphate, 70 parts of potassium nitrate, 4 parts of 2,4-dichlorophenoxyacetic acid, 2 parts of 4-iodophenoxyacetic acid, 1 part of borax, 1 part of magnesium ammonium phosphate, 5 parts of zinc sulfate, 1 part of manganese sulfate, 1 part of ferrous sulfate, and 2 parts of calcium ammonium nitrate.

[0026] Comparative Example 4 A coated slow-release fertilizer comprises the following steps: (1) Preparation of modified corn straw biochar powder: Same as Example 1; (2) Granulation: The core components (the same as the core components in Example 1) are mixed evenly and added to a coating machine for heating and melting by blowing air, and then cooled and granulated to obtain fertilizer granules; (3) Coating: Add ammonium sulfate into water to dissolve, heat until melted, and evenly spray it onto the surface of fertilizer particles using a spraying device. After drying at room temperature, a coated slow-release fertilizer is obtained; Among them, the mass ratio of the coating solution to the fertilizer particles is 5:20.

[0027] Experimental Example 1 In order to illustrate the effect of the long-acting coated slow-release fertilizer for summer corn prepared by the present invention, field experiments were carried out on the long-acting coated slow-release fertilizer for summer corn of Examples 1-3 and the coated slow-release fertilizer of Comparative Examples 1-4.

[0028] The experimental site was in Linshu County, Shandong Province. The summer corn variety was Zhengdan 958. The summer corn experimental group was divided into 7 groups, each with an area of ​​1 mu, and was divided into Example 1 to Example 3 and Comparative Example 1 to Comparative Example 4. The long-acting coated slow-release fertilizer specially provided for summer corn in Examples 1-3 and the coated slow-release fertilizer provided in Comparative Examples 1-4 were applied respectively.

[0029] The fertilization method was in accordance with the conventional method of the masses, and the field management was in accordance with the existing technology. All management measures were the same. On a certain day during the filling period, 3 corn plants were randomly selected from each group to measure their plant height and chlorophyll content (0.1 g of leaf tissue from the middle of the ear leaf was weighed, soaked in 10 mL of 95% ethanol solution in the dark until the leaves turned completely white, and then the volume was fixed to 25 mL with 95% ethanol solution, and the chlorophyll content was determined by spectrophotometry). The results were averaged. After the corn fruits were harvested, the corn yield and 100-grain weight per mu of each group were calculated. The results are shown in Table 1.

[0030] Table 1 Corn quality and yield results of each group

[0031] As can be seen from Table 1, the corn grown using the long-acting coated slow-release fertilizer specifically for summer corn of Examples 1-3 has high growth, high yield, and good corn fruit quality.

[0032] 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 method for preparing a long-acting coated slow-release fertilizer for summer corn, characterized in that: The following steps are involved: (1) Preparation of modified corn straw biochar powder: crush corn straw, heat and soak it in a mixed aqueous solution of NaOH and Na2SO3 and a hydrogen peroxide solution, and then carbonize and grind it; (2) Preparing a coating solution: Mix polyethylene glycol 400 and propylene glycol, heat to 70-100°C, add modified corn straw biochar powder and concentrated sulfuric acid, continue to heat to 150-180°C, react for 1-2 hours to obtain a mixed solution, add nano-silica, polyvinyl pyrrolidone and isocyanate curing agent to the mixed solution, mix well to obtain a coating solution; (3) Granulation: After the kernel components are mixed evenly, they are added into a coating machine and heated and melted by blowing air, and then cooled and granulated to obtain fertilizer granules; (4) Coating: Spray the coating solution onto the surface of the fertilizer particles and dry them at room temperature to obtain a long-acting coated slow-release fertilizer for summer corn; Among them, the core ingredients include the following raw materials: Urea, potassium dihydrogen phosphate, potassium nitrate, 2,4-dichlorophenoxyacetic acid, 4-iodophenoxyacetic acid, borax, magnesium ammonium phosphate, zinc sulfate, manganese sulfate, ferrous sulfate and calcium ammonium nitrate.

2. The method for preparing the long-acting coated slow-release fertilizer for summer corn according to claim 1, characterized in that: Step (1) preparing modified corn straw biochar powder: crushing the dried corn straw and sieving it, heating and soaking it in a mixed aqueous solution of NaOH and Na2SO3 at 90-100°C for 2-3h, washing it with water, and then heating and soaking it in a 4wt%-5wt% hydrogen peroxide aqueous solution at 70-80°C for 2-3h, drying it and placing it in a tubular furnace, heating it to 580-600°C at a heating rate of 10-15°C / min under nitrogen atmosphere protection, keeping it warm for 3-4h, cooling it naturally to room temperature, and grinding and sieving it.

3. The method for preparing the long-acting coated slow-release fertilizer for summer corn according to claim 1, characterized in that: In step (2), the mass ratio of the mixed solution: the mixture of nano-silicon dioxide, polyvinyl pyrrolidone and isocyanate curing agent is 15-18:381-382.

4. The method for preparing the long-acting coated slow-release fertilizer for summer corn as claimed in claim 3, characterized in that: In step (2), the mass ratio of modified corn straw biochar powder, polyethylene glycol 400, propylene glycol and concentrated sulfuric acid is 10-12:5-6:1-2:1-2; The mass ratio of nano silicon dioxide, polyvinyl pyrrolidone and isocyanate curing agent is 280-300:1-2:80-100.

5. The method for preparing the long-acting coated slow-release fertilizer for summer corn according to claim 1, characterized in that: The isocyanate curing agent is a monoisocyanate, a diisocyanate or a polyisocyanate.

6. The method for preparing the long-acting coated slow-release fertilizer for summer corn according to claim 1, characterized in that: The core composition includes the following raw materials in parts by weight: 60-90 parts of urea, 30-50 parts of potassium dihydrogen phosphate, 50-60 parts of potassium nitrate, 1-2 parts of 2,4-dichlorophenoxyacetic acid, 1-2 parts of 4-iodophenoxyacetic acid, 1-2 parts of borax, 1-2 parts of magnesium ammonium phosphate, 1-3 parts of zinc sulfate, 1-2 parts of manganese sulfate, 1-2 parts of ferrous sulfate, and 1-2 parts of calcium ammonium nitrate.

7. The method for preparing the long-acting coated slow-release fertilizer for summer corn according to claim 1, characterized in that: In step (4), the mass ratio of the coating solution to the fertilizer particles is 3-5:15-20.

8. A long-acting coated slow-release fertilizer for summer corn, characterized in that: The fertilizer is prepared according to the method for preparing the long-acting coated slow-release fertilizer for summer corn as described in any one of claims 1 to 7.

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