Coated slow-release chemical fertilizer and preparation method thereof

Abstract

The invention discloses a coated slow-release chemical fertilizer and a preparation method thereof. The preparation method comprises the following steps: S1, obtaining a growth cycle of a plant; s2, acquiring environmental conditions of a plant growth site; s3, analyzing the chemical fertilizer application amount required by the plant in each growth cycle in combination with the growth environment; s4, determining the addition amount of the coating material in each growth period of the plant; and S5, preparing the slow-release chemical fertilizer. According to the invention, the fertilizing amount required by each growth period of the plant and the thickness of the coating material required by each period of the plant are calculated through the manufacturing method, so that data support is provided for manufacturing the slow-release fertilizer; through calculation, an adaptive amount of chemical fertilizer can be provided in each growth period of the plants, excessive topdressing is avoided, normal growth of the plants is facilitated, and waste of material resources and financial resources is also avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of fertilizers, and in particular relates to a coated slow-release fertilizer and a manufacturing method thereof. Background Art

[0002] Different types of crops, or the same type of crops, require different amounts of fertilizers in different growth cycles. A large portion of the fertilizers used in the early stage are lost due to the small amount absorbed by crops. Due to the loss of fertilizers in the early stage, crops will grow poorly in the middle and late stages of growth due to insufficient fertilizers. Therefore, people usually add fertilizers in the middle and late stages of crop growth. When farmers apply fertilizers, they often apply excessive amounts of fertilizers to ensure sufficient fertilizers, which may destroy the normal development of the plant's root system and affect the normal growth of the plant. Therefore, this method of fertilization not only wastes a lot of manpower, material and financial resources, but also reduces agricultural production efficiency to a certain extent.

[0003] Slow-release fertilizers meet the requirements of environmental protection and social sustainable development, and will become the mainstream of agricultural fertilizers in the future and the development direction of agricultural fertilizers in the world. However, current slow-release fertilizer products are only for a certain season, and the sustainable release time is 1-3 months, which cannot cover all the growth cycles of crops. Fertilization must be carried out one or two times in the middle, which still consumes a lot of manpower, material and financial resources, and the efficiency is not high. Summary of the invention

[0004] In order to solve the above problems, the present invention proposes a coated slow-release fertilizer and a manufacturing method thereof, which can calculate the amount of fertilizer required for each growth cycle of the plant and the thickness of the coating material for each cycle according to the growth cycle and environmental conditions of the plant, thereby producing a coated slow-release fertilizer suitable for the entire life cycle of the plant from planting to harvesting.

[0005] The coated slow-release fertilizer of the present invention comprises multiple layers of fertilizer raw materials and coating materials which are alternately arranged from inside to outside, wherein the innermost layer is the fertilizer raw materials and the outermost layer is the coating material.

[0006] The method for producing the coated slow-release fertilizer of the present invention comprises the following steps:

[0007] S1. Obtain the growth cycle of the plant;

[0008] S2. Obtain the environmental conditions of the plant growth area;

[0009] S3. Analyze the amount of fertilizer required for the plant in each growth cycle based on the growth environment;

[0010] S4. Determine the amount of coating material added to each growth cycle of the plant;

[0011] S5. Make slow-release fertilizer.

[0012] The growth periods of the plants in step S1 are respectively marked as P 1 , P 2 ,...P n , the number of growth cycles is 3-5.

[0013] The step S2 of obtaining the environmental conditions of the plant growth area refers to obtaining the environmental conditions corresponding to each cycle of the plant: soil type T, accumulated temperature H, light intensity L, precipitation M and crop density PD.

[0014] The step S3 specifically refers to analyzing the amount of fertilizer required by the plant in each growth cycle per unit area under the conditions of S2. The amount of fertilizer includes N, P, K, Ca, Mg, S and trace elements required by the plant in each growth cycle. The calculation formula for the amount of fertilizer is:

[0015] P n (Amount of fertilizer applied) = P n (N)+P n (P)+P n (K)+P n (Ca)+P n (Mg)+P n (S)+P n (Trace Elements)

[0016] Where P n (fertilizer amount) refers to the amount of fertilizer required for the nth growth cycle, P n (N) refers to the amount of nitrogen fertilizer required for the nth growth cycle, P n (P) refers to the amount of phosphorus fertilizer required for the nth growth cycle, P n (K) refers to the amount of potassium fertilizer required for the nth growth cycle, P n (Ca) refers to the amount of calcium fertilizer required for the nth growth cycle, P n (Mg) refers to the amount of magnesium fertilizer required for the nth growth cycle, P n (S) refers to the amount of sulfur fertilizer required for the nth growth cycle, P n (Trace elements) refers to the amount of trace elements required for the nth growth cycle.

[0017] The amount of fertilizer P of any element required for the nth growth cycle n The calculation formula of (R) is,

[0018]

[0019] In the formula, X represents the environmental conditions, X is 1 , ..., or X x, including accumulated temperature H, light intensity L, precipitation M and crop density PD; (X x ) 0 represents the standard value under one of the environmental conditions in the nth growth cycle suitable for plant growth, (X x ) n is the actual value of one of the environmental conditions in the nth growth cycle; R 0 It means that the environmental conditions are all standard values ​​(X x ) 0 T is the standard value of the fertilizer amount of the element required to maintain plant growth in the nth growth cycle, x is the number of non-standard environmental conditions suitable for plant growth in the nth growth cycle; T 0 Refers to the coefficient of the standard soil type suitable for plant growth, T n is the coefficient of soil type in the nth growth period, P n (R) means P n (N) or P n (P) or P n (K) or P n (Ca) or P n (Mg) or P n (S) or P n (trace elements);

[0020] Soil types are arranged in order from fertile to poor as follows: black soil, loam, brown soil, loess, red soil, white soil, sandy soil, saline-alkali soil, peat soil and clay. The soil type coefficient increases gradually in the order from fertile to poor. The difference between the coefficients of two adjacent soil types is 0.1. Loam is the standard soil type with a coefficient of 1.

[0021] According to the fertilizer amount P of any of the above elements n The calculation formula for N, P, K, Ca, Mg and S required for the nth growth cycle is as follows:

[0022] The amount of nitrogen fertilizer required for the nth growth cycle P n The calculation formula for (N) is,

[0023]

[0024] In the formula, X represents the environmental conditions, X is 1 , ..., or X x , including accumulated temperature H, light intensity L, precipitation M and crop density PD; (X x ) 0 represents the standard value under one of the environmental conditions in the nth growth cycle suitable for plant growth, (X x ) n is the actual value of one of the environmental conditions in the nth growth cycle; N0 It means that the environmental conditions are all standard values ​​(X x ) 0 The standard value of nitrogen fertilizer required to maintain plant growth in the nth growth cycle, T 0 Refers to the coefficient of the standard soil type suitable for plant growth, T n is the coefficient of soil type in the nth growth period;

[0025] Soil types are arranged in order from fertile to poor as follows: black soil, loam, brown soil, loess, red soil, white soil, sandy soil, saline-alkali soil, peat soil and clay. The soil type coefficient increases gradually in the order from fertile to poor. The difference between the coefficients of two adjacent soil types is 0.1. Loam is the standard soil type with a coefficient of 1.

[0026] The amount of phosphorus fertilizer required for the nth growth cycle P n The calculation formula of (P) is,

[0027]

[0028] In the formula, X represents the environmental conditions, X is 1 , ..., or X x , including accumulated temperature H, light intensity L, precipitation M and crop density PD; (X x ) 0 represents the standard value under one of the environmental conditions in the nth growth cycle suitable for plant growth, (X x ) n is the actual value of one of the environmental conditions in the nth growth cycle; P 0 It means that the environmental conditions are all standard values ​​(X x ) 0 The standard value of the amount of phosphorus fertilizer required to maintain plant growth in the nth growth cycle, T 0 Refers to the coefficient of the standard soil type suitable for plant growth, T n is the coefficient of soil type in the nth growth period;

[0029] Soil types are arranged in order from fertile to poor as follows: black soil, loam, brown soil, loess, red soil, white soil, sandy soil, saline-alkali soil, peat soil and clay. The soil type coefficient increases gradually in the order from fertile to poor. The difference between the coefficients of two adjacent soil types is 0.1. Loam is the standard soil type with a coefficient of 1.

[0030] The amount of potassium fertilizer required for the nth growth cycle P n The calculation formula of (K) is,

[0031]

[0032] In the formula, X represents the environmental conditions, X is 1 , ..., or X x , including accumulated temperature H, light intensity L, precipitation M and crop density PD; (X x ) 0 represents the standard value under one of the environmental conditions in the nth growth cycle suitable for plant growth, (X x ) n is the actual value of one of the environmental conditions in the nth growth cycle; K 0 It means that the environmental conditions are all standard values ​​(X x ) 0 The standard value of potassium fertilizer required to maintain plant growth in the nth growth cycle, T 0 Refers to the coefficient of the standard soil type suitable for plant growth, T n is the coefficient of soil type in the nth growth period;

[0033] Soil types are arranged in order from fertile to poor as follows: black soil, loam, brown soil, loess, red soil, white soil, sandy soil, saline-alkali soil, peat soil and clay. The soil type coefficient increases gradually in the order from fertile to poor. The difference between the coefficients of two adjacent soil types is 0.1. Loam is the standard soil type with a coefficient of 1.

[0034] The amount of calcium fertilizer required for the nth growth cycle P n The calculation formula of (Ca) is,

[0035]

[0036] (Ca) 0 It refers to the standard amount of calcium fertilizer required to maintain plant growth in the nth growth cycle.

[0037] The amount of magnesium fertilizer required for the nth growth cycle P n The calculation formula of (Mg) is,

[0038]

[0039] (Mg) 0 It refers to the standard amount of magnesium fertilizer required to maintain plant growth during the nth growth cycle.

[0040] The amount of sulfur fertilizer required for the nth growth cycle P n The calculation formula of (S) is,

[0041]

[0042] S 0 It refers to the standard amount of sulfur fertilizer required to maintain plant growth in the nth growth cycle.

[0043] The amount of trace elements required for the nth growth cycle is calculated by separately calculating the amounts of trace elements iron, manganese, copper, zinc, boron and molybdenum, and the calculation can be performed according to the above method.

[0044] The method for calculating the amount of coating material added in step S4 is as follows: under the conditions of S2, the thickness d of the coating material consumed per day is measured by experiment. 0 , calculate the required envelope thickness for each cycle, assuming the envelope thickness of the nth cycle is d n ,but

[0045] d n =d 0 ×D n

[0046] D n is the number of days in the nth cycle;

[0047] The following calculation method is used to further calculate the weight of the coating material required for each layer of fertilizer:

[0048] T1. First, the amount of fertilizer applied according to the innermost layer, which corresponds to the last growth cycle, is To calculate the average radius of the innermost layer, the nth fertilizer layer,

[0049] T2. Then calculate the weight of the innermost layer, which corresponds to the last growth cycle. Where R n =r n +d n ;

[0050] T3. Then according to the amount of fertilizer applied in the n-1th layer Calculate the average radius of the n-1th fertilizer layer,

[0051] T4. Weight of coating material for the n-1th cycle

[0052] T5. Repeat steps T3 and T4 until the weight m of the outermost film material is calculated. 1 ;

[0053] In the formula, ρ 肥 is the density of the fertilizer, ρ 膜 is the density of the coating material, r n is the average distance between the outer surface of the fertilizer layer and the geometric center of the fertilizer particle in the nth period, R n is the average distance between the outer surface of the coating layer and the geometric center of the fertilizer particle in the nth period, R n =r n +d n , d nis the coating thickness of the nth cycle, and Q is the number of coated particles, which is determined by adjusting the parameters of the granulator.

[0054] The step S5 comprises the following steps:

[0055] A1. Prepare the innermost layer, i.e., the nth layer of fertilizer raw materials, the nth layer of coating materials, and the nth layer of liquid film-forming materials in proportion to the coating materials;

[0056] A2. In the disc granulator, the nth layer of fertilizer raw materials is mixed with a certain proportion of binder to prepare a disc with a radius of r. n The nth layer of fertilizer raw material particles;

[0057] A3. The nth layer of fertilizer raw material particles and 50% of the nth layer of liquid film-forming material are mixed evenly, and then 50% of the nth layer of coating material is added, and the disc granulator is started until no less than 85% of the coating material is tightly adhered to the surface of the fertilizer raw material, and then the remaining liquid film-forming material is added and mixed evenly, and finally the remaining coating material is added until the coating material is completely coated on the surface of the nth layer of fertilizer raw material particles, to obtain the nth layer of coated fertilizer;

[0058] A4. Prepare the n-1th layer of fertilizer raw materials and a certain proportion of binder;

[0059] A5. Start the disc granulator, first mix the nth layer of coated fertilizer and the binder evenly, then add the n-1th layer of fertilizer raw materials, so that the n-1th layer of fertilizer raw materials adheres to the surface of the nth layer of coated fertilizer through the binder, and prepares a disc granulator with a radius of r. n-1 The n-1th layer of fertilizer raw material particles;

[0060] A6. Prepare the n-1th layer of liquid film-forming material and the n-1th layer of coating material;

[0061] A7. Based on A5 and A6, repeat step A3 to obtain the n-1th layer of coated fertilizer;

[0062] A8. Repeat the above steps A4-A7 according to the number of layers of the desired slow-release fertilizer until the final coated slow-release fertilizer is obtained.

[0063] The outermost layer of fertilizer raw materials of the coated slow-release fertilizer is the fertilizer raw materials of the first cycle.

[0064] The preparation method of the liquid film-forming material is as follows (by weight): 80 parts of bentonite and 60 parts of sepiolite are respectively immersed in deacrylic acid, mixed evenly after 24 hours, and KOH solution is added dropwise thereto at a neutralization degree of 60% under conditions of electric stirring and cold water bath to carry out neutralization reaction, 20 parts of cellulose and 40 parts of polyhydroxyalkanoate are added, and then transferred to a 35°C constant temperature ultrasonic instrument for ultrasonic treatment for 30 minutes, and 20 parts of urea-formaldehyde resin crosslinking agent are added to obtain the liquid film-forming material under anaerobic conditions.

[0065] The preparation method of the coating material is as follows: an epoxy resin with a mass concentration of 8% and a polyvinyl alcohol with a mass concentration of 3% react at 60°C for 2 hours to generate etherified modified polyvinyl alcohol, which reduces the number of hydroxyl groups in the molecule and reduces the water absorption of the film. After the modified polyvinyl alcohol film is immersed in deionized water at 200°C for 24 hours, it is filtered, washed and dried to obtain a coating material with significantly reduced water absorption, showing good sustained-release performance.

[0066] The beneficial effects of the present invention are:

[0067] 1. The present invention calculates the amount of fertilizer required for each growth cycle of the plant and the thickness of the coating material required for each cycle of the plant through a manufacturing method, thereby providing data support for the production of slow-release fertilizers, avoiding the problem of inappropriate coating thickness and large fertilizer penetration capacity, which causes the release period of the slow-release fertilizer to be too short; and through calculation, an appropriate amount of fertilizer can be provided in each growth cycle of the plant to avoid excessive topdressing and ensure normal growth of the plant.

[0068] 2. The slow-release fertilizer of the present invention is prepared into a slow-release fertilizer that can cover all growth cycles of the plant according to the amount of fertilizer required for each growth cycle and the thickness of the coating material. That is, from the planting of the plant to the harvesting, the coated slow-release fertilizer only needs to be applied once at the time of sowing to meet the needs of all growth cycles of the plant, thereby improving work efficiency and reducing the consumption of manpower and material resources. DETAILED DESCRIPTION

[0069] The embodiments of the present invention are described in detail below.

[0070] The method for producing the coated slow-release fertilizer of the present invention comprises the following steps:

[0071] S1. Obtain the growth cycle of the plant and mark the growth cycle of the plant as P 1 , P 2 , ..., P n , the number of growth cycles is 3-5;

[0072] S2. Obtaining the environmental conditions of the plant growth area refers to obtaining the environmental parameters corresponding to each cycle of the plant: soil type T, accumulated temperature H, light intensity L, precipitation M and crop density PD;

[0073] S3. Analyze the amount of fertilizer required for plants in each growth cycle in combination with the growth environment; under the conditions of S2, analyze the amount of fertilizer required for plants in each growth cycle per unit area, the amount of fertilizer includes N, P, K, Ca, Mg, S and trace elements required by plants in each growth cycle, and the calculation formula for the amount of fertilizer is:

[0074] P n (Amount of fertilizer applied) = P n (N)+P n (P)+P n (K)+P n (Ca)+P n (Mg)+P n (S)+P n (Trace Elements)

[0075] Where P n (fertilizer amount) refers to the amount of fertilizer required for the nth growth cycle, P n (N) refers to the amount of nitrogen fertilizer required for the nth growth cycle, P n (P) refers to the amount of phosphorus fertilizer required for the nth growth cycle, P n (K) refers to the amount of potassium fertilizer required for the nth growth cycle, P n (Ca) refers to the amount of calcium fertilizer required for the nth growth cycle, P n (Mg) refers to the amount of magnesium fertilizer required for the nth growth cycle, P n (S) refers to the amount of sulfur fertilizer required for the nth growth cycle, P n (Trace elements) refers to the amount of trace elements required for the nth growth cycle.

[0076] The amount of fertilizer P of any element required for the nth growth cycle n The calculation formula of (R) is,

[0077]

[0078] In the formula, X represents the environmental conditions, X is 1 , ..., or X x , including accumulated temperature H, light intensity L, precipitation M and crop density PD; (X x ) 0 represents the standard value under one of the environmental conditions in the nth growth cycle suitable for plant growth, (X x ) n is the actual value of one of the environmental conditions in the nth growth cycle; R0 It means that the environmental conditions are all standard values ​​(X x ) 0 The standard value of the fertilizer amount of this element required to maintain plant growth in the nth growth cycle, T 0 Refers to the coefficient of the standard soil type suitable for plant growth, T n is the coefficient of soil type in the nth growth period, P n (R) means P n (N) or P n (P) or P n (K) or P n (Ca) or P n (Mg) or P n (S) or P n (trace elements);

[0079] Soil types are arranged in order from fertile to poor as follows: black soil, loam, brown soil, loess, red soil, white soil, sandy soil, saline-alkali soil, peat soil and clay. The soil type coefficient increases gradually in the order from fertile to poor. The difference between the coefficients of two adjacent soil types is 0.1. Loam is the standard soil type with a coefficient of 1.

[0080] Specifically, the amount of nitrogen fertilizer required for the nth growth cycle P n The calculation formula for (N) is,

[0081]

[0082] The amount of phosphorus fertilizer required for the nth growth cycle P n The calculation formula of (P) is,

[0083]

[0084] The amount of potassium fertilizer required for the nth growth cycle P n The calculation formula of (K) is,

[0085]

[0086] The amount of calcium fertilizer required for the nth growth cycle P n The calculation formula of (Ca) is,

[0087]

[0088] (Ca) 0 It refers to the standard amount of calcium fertilizer required to maintain plant growth in the nth growth cycle.

[0089] The amount of magnesium fertilizer required for the nth growth cycle P n The calculation formula of (Mg) is,

[0090]

[0091] (Mg) 0 It refers to the standard amount of magnesium fertilizer required to maintain plant growth during the nth growth cycle.

[0092] The amount of sulfur fertilizer required for the nth growth cycle P n The calculation formula of (S) is,

[0093]

[0094] S 0 It refers to the standard amount of sulfur fertilizer required to maintain plant growth in the nth growth cycle.

[0095] The amount of trace elements required for the nth growth cycle is calculated by separately calculating the amounts of trace elements iron, manganese, copper, zinc, boron and molybdenum, and the calculation can be performed according to the above method.

[0096] S4. Determine the amount of coating material added during each growth cycle of the plant; Under the conditions of S2, the thickness of the coating material lost per day is measured according to the test. 0 , calculate the required envelope thickness for each cycle, assuming the envelope thickness of the nth cycle is d n ,but

[0097] d n =d 0 ×D n

[0098] D n is the number of days in the nth cycle;

[0099] The following calculation method is used to further calculate the weight of the coating material required for each layer of fertilizer:

[0100] T1. First, the amount of fertilizer applied according to the innermost layer, which corresponds to the last growth cycle, is To calculate the average radius of the innermost layer, the nth fertilizer layer,

[0101] T2. Then calculate the weight of the innermost layer, which corresponds to the last growth cycle. Where R n =r n +d n ;

[0102] T3. Then according to the amount of fertilizer applied in the n-1th layer Calculate the average radius of the n-1th fertilizer layer,

[0103] T4. Weight of coating material for the n-1th cycle

[0104] T5. Repeat steps T3 and T4 until the weight m of the outermost film material is calculated. 1 ;

[0105] In the formula, ρ 肥 is the density of the fertilizer, ρ 膜 is the density of the coating material, r n is the average distance between the outer surface of the fertilizer layer and the geometric center of the fertilizer particle in the nth period, R n is the average distance between the outer surface of the coating layer and the geometric center of the fertilizer particle in the nth period, R n =r n +d n , d n is the coating thickness of the nth cycle, and Q is the number of coated particles, which is determined by adjusting the parameters of the granulator.

[0106] S5. Making slow-release fertilizer. It includes the following steps:

[0107] A1. Prepare the innermost layer, the nth layer of fertilizer raw materials P n (fertilizer amount), the nth layer of coating material m n And an nth layer of liquid film-forming material that matches the coating material in proportion; the weight ratio of the liquid film-forming material to the coating material is 1:2-1:4.

[0108] A2. In the disc granulator, the nth layer of fertilizer raw materials is mixed with a certain proportion of binder to prepare a disc with a radius of r. n The nth layer of fertilizer raw material particles;

[0109] A3. First, the nth layer of fertilizer raw material particles and 50% of the nth layer of liquid film-forming material are mixed evenly, then 50% of the nth layer of coating material is added, and the disc granulator is started until no less than 85% of the coating material is tightly adhered to the surface of the fertilizer raw material, and then the remaining liquid film-forming material is added and mixed evenly, and finally the remaining coating material is added until the coating material is completely coated on the surface of the nth layer of fertilizer raw material particles to obtain the nth layer of coated fertilizer;

[0110] A4. Prepare the n-1th layer of fertilizer raw materials P n-1 (fertilizer amount) and a certain proportion of binder; the amount of binder used is 2%-6% of the weight of the fertilizer raw material in the n-1 layer.

[0111] A5. Start the disc granulator, first mix the nth layer of coated fertilizer and the binder evenly, then add the n-1th layer of fertilizer raw materials, so that the n-1th layer of fertilizer raw materials adheres to the surface of the nth layer of coated fertilizer through the binder, and prepares a disc granulator with a radius of r. n-1 The n-1th layer of fertilizer raw material particles;

[0112] A6. Prepare the n-1th layer of liquid film-forming material and the n-1th layer of coating material m n-1 ;

[0113] A7. Based on A5 and A6, repeat step A3 to obtain the n-1th layer of coated fertilizer;

[0114] A8. Repeat the above steps A4-A7 according to the number of layers of the desired slow-release fertilizer until the final coated slow-release fertilizer is obtained.

[0115] The preparation method of the liquid film-forming material is as follows (by weight): 80 parts of bentonite and 60 parts of sepiolite are respectively immersed in deacrylic acid, mixed evenly after 24 hours, and KOH solution is added dropwise thereto at a neutralization degree of 60% under conditions of electric stirring and cold water bath to carry out neutralization reaction, 20 parts of cellulose and 40 parts of polyhydroxyalkanoate are added, and then transferred to a 35°C constant temperature ultrasonic instrument for ultrasonic treatment for 30 minutes, and 20 parts of urea-formaldehyde resin crosslinking agent are added to obtain the liquid film-forming material under anaerobic conditions.

[0116] The preparation method of the coating material is as follows: an epoxy resin with a mass concentration of 8% and a polyvinyl alcohol with a mass concentration of 3% react at 60°C for 2 hours to generate etherified modified polyvinyl alcohol, which reduces the number of hydroxyl groups in the molecule and reduces the water absorption of the film. After the modified polyvinyl alcohol film is immersed in deionized water at 200°C for 24 hours, it is filtered, washed and dried to obtain a coating material with significantly reduced water absorption, showing good sustained-release performance.

[0117] Example 1

[0118] Taking wheat as an example, the growth cycle of wheat can be divided into seedling stage, green stage, jointing stage, heading stage and filling stage according to the key period of fertilization. The growth cycle of wheat is marked as P 1 , P 2 , P 3 , P 4 and P 5 . Calculate the amount of fertilizer for each cycle according to the following method.

[0119] In the growth environment of the plant in the nth growth cycle, the accumulated temperature, light intensity, precipitation and crop density are all non-standard environmental conditions, and the soil is also poorer than the standard soil type. Then the amount of nitrogen fertilizer required by the plant in the nth growth cycle is P n The calculation formula for (N) is,

[0120]

[0121] Where N 0 It refers to the standard amount of nitrogen fertilizer required to maintain plant growth in the nth growth cycle. 0is the standard value of the accumulated temperature in the nth growth cycle; H n is the actual value of the accumulated temperature in the nth growth period; L 0 is the standard value of light intensity in the nth growth cycle; L n is the actual value of the light intensity in the nth growth cycle; M 0 is the standard value of precipitation in the nth growth cycle; M n is the actual value of precipitation in the nth growth period; (PD) 0 is the standard value of crop density in the nth growth cycle; (PD) n is the actual value of the crop density in the nth growth cycle; T 0 Refers to the coefficient of standard soil types suitable for the growth of various plants, T n is the coefficient of soil type in the nth growth period, T n ﹥T 0 .

[0122] The amount of phosphorus fertilizer P required by the plant in the nth growth cycle n The calculation formula of (P) is,

[0123]

[0124] P 0 It refers to the standard amount of phosphorus fertilizer required to maintain plant growth in the nth growth cycle.

[0125] The amount of potassium fertilizer P required by the plant in the nth growth cycle n The calculation formula of (K) is,

[0126]

[0127] K 0 It refers to the standard amount of potassium fertilizer required to maintain plant growth in the nth growth cycle.

[0128] The amount of calcium fertilizer P required by the plant in the nth growth cycle n The calculation formula of (Ca) is,

[0129]

[0130] (Ca) 0 It refers to the standard amount of calcium fertilizer required to maintain plant growth in the nth growth cycle.

[0131] The amount of magnesium fertilizer P required by the plant in the nth growth cycle n The calculation formula of (Mg) is,

[0132]

[0133] (Mg)0 It refers to the standard amount of magnesium fertilizer required to maintain plant growth during the nth growth cycle.

[0134] The amount of sulfur fertilizer P required by the plant in the nth growth cycle n The calculation formula of (S) is,

[0135]

[0136] S 0 It refers to the standard amount of sulfur fertilizer required to maintain plant growth in the nth growth cycle.

[0137] The amount of trace elements required for the nth growth cycle is calculated by calculating the amount of trace elements iron, manganese, copper, zinc, boron and molybdenum respectively, and the calculation can be performed according to the above method. The standard amount of all elements can be measured experimentally.

[0138] Adding up the above calculation results can calculate the amount of fertilizer required for the plant in each growth cycle.

[0139] You can also only calculate the amount of one type of fertilizer to make a slow-release fertilizer of that type of fertilizer, such as only calculating the amount of nitrogen fertilizer to make a slow-release nitrogen fertilizer; or only calculating the amount of phosphorus fertilizer to make a slow-release phosphorus fertilizer.

[0140] After the fertilizer application amount for each cycle is calculated, the thickness of the coating material consumed per day is measured under S2 conditions according to the test. 0 , calculate the required envelope thickness for each cycle, assuming the envelope thickness of the nth cycle is d n ,but

[0141] d n =d 0 ×D n

[0142] D n is the number of days in the nth cycle;

[0143] The following calculation method is used to further calculate the weight of the coating material required for each layer of fertilizer:

[0144] T1. First, the amount of fertilizer applied according to the innermost layer, which corresponds to the last growth cycle, is To calculate the average radius of the innermost layer, the nth fertilizer layer,

[0145] T2. Then calculate the weight of the innermost layer, which corresponds to the last growth cycle. Where R n =r n +d n ;

[0146] T3. Then according to the amount of fertilizer applied in the n-1th layer Calculate the average radius of the n-1th fertilizer layer,

[0147] T4. Weight of coating material for the n-1th cycle

[0148] T5. Repeat steps T3 and T4 until the weight m of the outermost film material is calculated. 1 ;

[0149] In the formula, ρ 肥 is the density of the fertilizer, ρ 膜 is the density of the coating material, r n is the average distance between the outer surface of the fertilizer layer in the nth period and the geometric center of the fertilizer particles, that is, the average radius of the nth fertilizer layer, R n is the average distance between the outer surface of the coating layer and the geometric center of the fertilizer particle in the nth period, R n =r n +d n , d n is the coating thickness of the nth cycle, and Q is the number of coated particles, which is determined by adjusting the parameters of the granulator.

[0150] With the amount of fertilizer applied and the total amount of coating in each cycle, the ratio of liquid film-forming material to coating material is set at 1:4, and the amount of binder is 6% of the fertilizer raw material. Then, the slow-release fertilizer can be made according to the above slow-release fertilizer production method.

[0151] Example 2

[0152] Taking corn as an example, the growth cycle of corn can be divided into seedling stage, jointing stage, heading stage, flowering and grain stage and filling stage according to the key period of fertilization. 1 , P 2 , P 3 , P 4 and P 5 . Calculate the amount of fertilizer for each cycle according to the following method.

[0153] In the growth environment of the plant in the nth growth cycle, the accumulated temperature, light intensity, precipitation and crop density are all non-standard environmental conditions, and the soil is standard soil, T n =T 0 , then the amount of nitrogen fertilizer P required by the plant in the nth growth cycle n The calculation formula for (N) is,

[0154]

[0155] Where N 0It refers to the standard amount of nitrogen fertilizer required to maintain plant growth in the nth growth cycle. 0 is the standard value of the accumulated temperature in the nth growth cycle; H n is the actual value of the accumulated temperature in the nth growth period; L 0 is the standard value of light intensity in the nth growth cycle; L n is the actual value of the light intensity in the nth growth cycle; M 0 is the standard value of precipitation in the nth growth cycle; M n is the actual value of precipitation in the nth growth period; (PD) 0 is the standard value of crop density in the nth growth cycle; (PD) n is the actual value of the crop density in the nth growth cycle.

[0156] The amount of phosphorus fertilizer P required by the plant in the nth growth cycle n The calculation formula of (P) is,

[0157]

[0158] P 0 It refers to the standard amount of phosphorus fertilizer required to maintain plant growth in the nth growth cycle.

[0159] The amount of potassium fertilizer P required by the plant in the nth growth cycle n The calculation formula of (K) is,

[0160]

[0161] K 0 It refers to the standard amount of potassium fertilizer required to maintain plant growth in the nth growth cycle.

[0162] The amount of calcium fertilizer P required by the plant in the nth growth cycle n The calculation formula of (Ca) is,

[0163]

[0164] (Ca) 0 It refers to the standard amount of calcium fertilizer required to maintain plant growth in the nth growth cycle.

[0165] The amount of magnesium fertilizer P required by the plant in the nth growth cycle n The calculation formula of (Mg) is,

[0166]

[0167] (Mg) 0 It refers to the standard amount of magnesium fertilizer required to maintain plant growth during the nth growth cycle.

[0168] The amount of sulfur fertilizer P required by the plant in the nth growth cycle n The calculation formula of (S) is,

[0169]

[0170] S 0 It refers to the standard amount of sulfur fertilizer required to maintain plant growth in the nth growth cycle.

[0171] Adding up the above calculation results can calculate the amount of fertilizer required for the plant in each growth cycle.

[0172] With the amount of fertilizer applied and the total amount of coating in each cycle, the ratio of liquid film-forming material to coating material is set at 1:3, and the amount of binder is 4% of the fertilizer raw material. Then, the slow-release fertilizer can be made according to the above slow-release fertilizer production method.

[0173] Example 3

[0174] In the growth environment of the plant in the nth growth cycle, the accumulated temperature, light intensity and precipitation are all non-standard environmental conditions, the crop density is the standard environmental condition, and the soil is also a type that is poorer than the standard soil type. Then the amount of nitrogen fertilizer required by the plant in the nth growth cycle is P n The calculation formula for (N) is,

[0175]

[0176] Where N 0 It refers to the standard amount of nitrogen fertilizer required to maintain plant growth in the nth growth cycle. 0 is the standard value of the accumulated temperature in the nth growth cycle; H n is the actual value of the accumulated temperature in the nth growth period; L 0 is the standard value of light intensity in the nth growth cycle; L n is the actual value of the light intensity in the nth growth cycle; M 0 is the standard value of precipitation in the nth growth cycle; M n is the actual value of precipitation in the nth growth period; T 0 Refers to the coefficient of standard soil types suitable for the growth of various plants, T n is the coefficient of soil type in the nth growth period, T n ﹥T 0 .

[0177] The amount of phosphorus fertilizer P required by the plant in the nth growth cycle n The calculation formula of (P) is,

[0178]

[0179] P 0It refers to the standard amount of phosphorus fertilizer required to maintain plant growth in the nth growth cycle.

[0180] The amount of potassium fertilizer P required by the plant in the nth growth cycle n The calculation formula of (K) is,

[0181]

[0182] K 0 It refers to the standard amount of potassium fertilizer required to maintain plant growth in the nth growth cycle.

[0183] The amount of calcium fertilizer P required by the plant in the nth growth cycle n The calculation formula of (Ca) is,

[0184]

[0185] (Ca) 0 It refers to the standard amount of calcium fertilizer required to maintain plant growth in the nth growth cycle.

[0186] The amount of magnesium fertilizer P required by the plant in the nth growth cycle n The calculation formula of (Mg) is,

[0187]

[0188] (Mg) 0 It refers to the standard amount of magnesium fertilizer required to maintain plant growth during the nth growth cycle.

[0189] The amount of sulfur fertilizer P required by the plant in the nth growth cycle n The calculation formula of (S) is,

[0190]

[0191] S 0 It refers to the standard amount of sulfur fertilizer required to maintain plant growth in the nth growth cycle.

[0192] With the amount of fertilizer applied and the total amount of coating in each cycle, the ratio of liquid film-forming material to coating material is set at 1:4, and the amount of binder is 6% of the fertilizer raw material. Then, the slow-release fertilizer can be made according to the above slow-release fertilizer production method.

[0193] Example 4

[0194] In the growth environment of the plant in the nth growth cycle, the accumulated temperature, light intensity and precipitation are all non-standard environmental conditions, the crop density is the standard environmental condition, and the soil is the standard soil, T n =T 0 , then the amount of nitrogen fertilizer P required by the plant in the nth growth cycle nThe calculation formula for (N) is,

[0195]

[0196] Where N 0 It refers to the standard amount of nitrogen fertilizer required to maintain plant growth in the nth growth cycle. 0 is the standard value of the accumulated temperature in the nth growth cycle; H n is the actual value of the accumulated temperature in the nth growth period; L 0 is the standard value of light intensity in the nth growth cycle; L n is the actual value of the light intensity in the nth growth cycle; M 0 is the standard value of precipitation in the nth growth cycle; M n is the actual value of precipitation in the nth growth cycle.

[0197] The amount of phosphorus fertilizer P required by the plant in the nth growth cycle n The calculation formula of (P) is,

[0198]

[0199] P 0 It refers to the standard amount of phosphorus fertilizer required to maintain plant growth in the nth growth cycle.

[0200] The amount of potassium fertilizer P required by the plant in the nth growth cycle n The calculation formula of (K) is,

[0201]

[0202] K 0 It refers to the standard amount of potassium fertilizer required to maintain plant growth in the nth growth cycle.

[0203] The amount of calcium fertilizer P required by the plant in the nth growth cycle n The calculation formula of (Ca) is,

[0204]

[0205] (Ca) 0 It refers to the standard amount of calcium fertilizer required to maintain plant growth in the nth growth cycle.

[0206] The amount of magnesium fertilizer P required by the plant in the nth growth cycle n The calculation formula of (Mg) is,

[0207]

[0208] (Mg) 0 It refers to the standard amount of magnesium fertilizer required to maintain plant growth during the nth growth cycle.

[0209] The amount of sulfur fertilizer P required by the plant in the nth growth cycle n The calculation formula of (S) is,

[0210]

[0211] S 0 It refers to the standard amount of sulfur fertilizer required to maintain plant growth in the nth growth cycle.

[0212] With the amount of fertilizer applied and the total amount of coating in each cycle, the ratio of liquid film-forming material to coating material is set at 1:4, and the amount of binder is 6% of the fertilizer raw material. Then, the slow-release fertilizer can be made according to the above slow-release fertilizer production method.

[0213] Example 5

[0214] In the growth environment of the plant in the nth growth cycle, the precipitation is a non-standard environmental condition, the accumulated temperature, light intensity and crop density are all standard environmental conditions, and the soil is also a poorer type than the standard soil type. Then the amount of nitrogen fertilizer P required by the plant in the nth growth cycle is n The calculation formula for (N) is,

[0215]

[0216] Where N 0 It refers to the standard amount of nitrogen fertilizer required to maintain plant growth in the nth growth cycle, M 0 is the standard value of precipitation in the nth growth cycle; M n is the actual value of precipitation in the nth growth period; T 0 Refers to the coefficient of standard soil types suitable for the growth of various plants, T n is the coefficient of soil type in the nth growth period, T n ﹥T 0 .

[0217] The amount of phosphorus fertilizer P required by the plant in the nth growth cycle n The calculation formula of (P) is,

[0218]

[0219] P 0 It refers to the standard amount of phosphorus fertilizer required to maintain plant growth in the nth growth cycle.

[0220] The amount of potassium fertilizer P required by the plant in the nth growth cycle n The calculation formula of (K) is,

[0221]

[0222] K 0 It refers to the standard amount of potassium fertilizer required to maintain plant growth in the nth growth cycle.

[0223] The amount of calcium fertilizer P required by the plant in the nth growth cycle n The calculation formula of (Ca) is,

[0224]

[0225] (Ca) 0 It refers to the standard amount of calcium fertilizer required to maintain plant growth in the nth growth cycle.

[0226] The amount of magnesium fertilizer P required by the plant in the nth growth cycle n The calculation formula of (Mg) is,

[0227]

[0228] (Mg) 0 It refers to the standard amount of magnesium fertilizer required to maintain plant growth during the nth growth cycle.

[0229] The amount of sulfur fertilizer P required by the plant in the nth growth cycle n The calculation formula of (S) is,

[0230]

[0231] S 0 It refers to the standard amount of sulfur fertilizer required to maintain plant growth in the nth growth cycle.

[0232] With the amount of fertilizer applied and the total amount of coating in each cycle, the ratio of liquid film-forming material to coating material is set at 1:4, and the amount of binder is 6% of the fertilizer raw material. Then, the slow-release fertilizer can be made according to the above slow-release fertilizer production method.

[0233] Example 6

[0234] In the growth environment of the plant in the nth growth cycle, the precipitation is a non-standard environmental condition, the accumulated temperature, light intensity and crop density are all standard environmental conditions, and the soil is standard soil, T n =T 0 , then the amount of nitrogen fertilizer P required by the plant in the nth growth cycle n The calculation formula for (N) is,

[0235]

[0236] Where N 0 It refers to the standard amount of nitrogen fertilizer required to maintain plant growth in the nth growth cycle, M 0 is the standard value of precipitation in the nth growth cycle; M nis the actual value of precipitation in the nth growth cycle.

[0237] The amount of phosphorus fertilizer P required by the plant in the nth growth cycle n The calculation formula of (P) is,

[0238]

[0239] P 0 It refers to the standard amount of phosphorus fertilizer required to maintain plant growth in the nth growth cycle.

[0240] The amount of potassium fertilizer P required by the plant in the nth growth cycle n The calculation formula of (K) is,

[0241]

[0242] K 0 It refers to the standard amount of potassium fertilizer required to maintain plant growth in the nth growth cycle.

[0243] The amount of calcium fertilizer P required by the plant in the nth growth cycle n The calculation formula of (Ca) is,

[0244]

[0245] (Ca) 0 It refers to the standard amount of calcium fertilizer required to maintain plant growth in the nth growth cycle.

[0246] The amount of magnesium fertilizer P required by the plant in the nth growth cycle n The calculation formula of (Mg) is,

[0247]

[0248] (Mg) 0 It refers to the standard amount of magnesium fertilizer required to maintain plant growth during the nth growth cycle.

[0249] The amount of sulfur fertilizer P required by the plant in the nth growth cycle n The calculation formula of (S) is,

[0250]

[0251] S 0 It refers to the standard amount of sulfur fertilizer required to maintain plant growth in the nth growth cycle.

[0252] With the amount of fertilizer applied and the total amount of coating in each cycle, the ratio of liquid film-forming material to coating material is set at 1:4, and the amount of binder is 6% of the fertilizer raw material. Then, the slow-release fertilizer can be made according to the above slow-release fertilizer production method.

[0253] Although the above embodiments have been shown and described, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. Changes, modifications, substitutions and variations of the above embodiments by those of ordinary skill in the art are all within the scope of protection of the present invention.

Claims

1. A coated slow-release fertilizer, characterized in that: It comprises multiple layers of fertilizer raw materials and coating materials which are alternately arranged from the inside to the outside, wherein the innermost layer is the fertilizer raw materials and the outermost layer is the coating material.

2. A method for producing a coated slow-release fertilizer as claimed in claim 1, characterized in that: The following steps are involved: S1. Obtain the growth cycle of the plant; S2. Obtain the environmental conditions of the plant growth area; S3. Analyze the amount of fertilizer required for the plant in each growth cycle based on the growth environment; S4. Determine the amount of coating material added during each growth cycle of the plant; S5. Make slow-release fertilizer.

3. The method for producing a coated slow-release fertilizer according to claim 2, characterized in that: The growth periods of the plants in step S1 are marked as P1, P2, ..., P n , the number of growth cycles is 3-5.

4. The method for producing a coated slow-release fertilizer according to claim 2, characterized in that: The step S2 of obtaining the environmental conditions of the plant growth area refers to obtaining the environmental conditions corresponding to each cycle of the plant: soil type T, accumulated temperature H, light intensity L, precipitation M and crop density PD.

5. The method for producing a coated slow-release fertilizer according to claim 4, characterized in that: The step S3 specifically refers to analyzing the amount of fertilizer required by the plant in each growth cycle per unit area under the conditions of S2. The amount of fertilizer includes N, P, K, Ca, Mg, S and trace elements required by the plant in each growth cycle. The calculation formula for the amount of fertilizer is: n (Amount of fertilizer applied) = P n (N)+P n (P)+P n (K)+P n (Ca)+P n (Mg)+P n (S)+P n (Trace Elements) Where P n (fertilizer amount) refers to the amount of fertilizer required for the nth growth cycle, P n (N) refers to the amount of nitrogen fertilizer required for the nth growth cycle, P n (P) refers to the amount of phosphorus fertilizer required for the nth growth cycle, P n (K) refers to the amount of potassium fertilizer required for the nth growth cycle, P n (Ca) refers to the amount of calcium fertilizer required for the nth growth cycle, P n (Mg) refers to the amount of magnesium fertilizer required for the nth growth cycle, P n (S) refers to the amount of sulfur fertilizer required for the nth growth cycle, P n (Trace elements) refers to the amount of trace elements required for the nth growth cycle.

6. The method for producing a coated slow-release fertilizer according to claim 5, characterized in that: The amount of fertilizer P of any element required for the nth growth cycle n The calculation formula of (R) is, Wherein, X represents the environmental condition, X is X1, ..., or X x , including accumulated temperature H, light intensity L, precipitation M and crop density PD; (X x )0 represents the standard value under one of the environmental conditions in the nth growth cycle suitable for plant growth, (X x ) n is the actual value of one of the environmental conditions in the nth growth cycle; R0 refers to the value of the standard value (X x )0 is the standard value of the fertilizer amount of the element required to maintain plant growth in the nth growth cycle, T0 refers to the coefficient of the standard soil type suitable for plant growth, T n is the coefficient of soil type in the nth growth period, P n (R) means P n (N) or P n (P) or P n (K) or P n (Ca) or P n (Mg) or P n (S) or P n (trace elements); Soil types are arranged in order from fertile to poor as follows: black soil, loam, brown soil, loess, red soil, white soil, sandy soil, saline-alkali soil, peat soil and clay. The soil type coefficient increases gradually in the order from fertile to poor. The difference between the coefficients of two adjacent soil types is 0.

1. Loam is the standard soil type with a coefficient of 1.

7. The method for producing a coated slow-release fertilizer according to claim 2, characterized in that: The method for calculating the amount of coating material added in step S4 is as follows: under the conditions of S2, the coating material thickness d0 consumed per day is measured experimentally, and the coating thickness required for each cycle is calculated. Suppose the coating thickness of the nth cycle is d n ,but d n =d0×D n D n is the number of days in the nth cycle; The following calculation method is used to further calculate the weight of the coating material required for each layer of fertilizer: T1. First, the amount of fertilizer applied according to the innermost layer, which corresponds to the last growth cycle, is To calculate the average radius of the innermost layer, the nth fertilizer layer, T2. Then calculate the weight of the coating material corresponding to the innermost layer, i.e. the last growth cycle. Where R n =r n +d n ; T3. Then according to the amount of fertilizer applied in the n-1th layer Calculate the average radius of the n-1th fertilizer layer, T4. Calculate the weight of the coating material for the n-1th cycle of coating T5. Repeat steps T3 and T4 until the weight m1 of the outermost film material is calculated; In the formula, ρ 肥 is the density of the fertilizer, ρ 膜 is the density of the coating material, r n is the average distance between the outer surface of the fertilizer layer and the geometric center of the fertilizer particle in the nth period, R n is the average distance between the outer surface of the coating layer and the geometric center of the fertilizer particle in the nth period, R n =r n +d n , d n is the coating thickness of the nth cycle, and Q is the number of coated particles, which is determined by adjusting the parameters of the granulator.

8. The method for producing a coated slow-release fertilizer according to claim 7, characterized in that: The step S5 comprises the following steps: A1. Prepare the innermost layer, i.e., the nth layer of fertilizer raw materials, the nth layer of coating materials, and the nth layer of liquid film-forming materials in proportion to the coating materials; A2. In the disc granulator, the nth layer of fertilizer raw materials is mixed with a certain proportion of binder to prepare a disc with a radius of r. n The nth layer of fertilizer raw material particles; A3. The nth layer of fertilizer raw material particles and 50% of the nth layer of liquid film-forming material are mixed evenly, and then 50% of the nth layer of coating material is added, and the disc granulator is started until no less than 85% of the coating material is tightly adhered to the surface of the fertilizer raw material, and then the remaining liquid film-forming material is added and mixed evenly, and finally the remaining coating material is added until the coating material is completely coated on the surface of the nth layer of fertilizer raw material particles, to obtain the nth layer of coated fertilizer; A4. Prepare the n-1th layer of fertilizer raw materials and a certain proportion of binder; A5. Start the disc granulator, first mix the nth layer of coated fertilizer and the binder evenly, then add the n-1th layer of fertilizer raw materials, so that the n-1th layer of fertilizer raw materials adheres to the surface of the nth layer of coated fertilizer through the binder, and prepares a disc granulator with a radius of r. n-1 The n-1th layer of fertilizer raw material particles; A6. Prepare the n-1th layer of liquid film-forming material and the n-1th layer of coating material; A7. Based on A5 and A6, repeat step A3 to obtain the n-1th layer of coated fertilizer; A8. Repeat the above steps A4-A7 according to the number of layers of the desired slow-release fertilizer until the final coated slow-release fertilizer is obtained.

9. The method for producing a coated slow-release fertilizer according to claim 8, characterized in that: The outermost layer of fertilizer raw materials of the coated slow-release fertilizer is the fertilizer raw materials of the first cycle.

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