Preparation method and application of nitrogen-containing compound fertilizer synergist

Abstract

The invention relates to the technical field of compound fertilizers, in particular to a preparation method and application of a nitrogen-containing compound fertilizer synergist, and the preparation method comprises the following steps: raw material selection and pretreatment, precise proportioning and mixing, melt granulation and modification, rapid cooling and curing, and surface coating and packaging. The preparation method and application of the nitrogen-containing compound fertilizer synergist provided by the invention have the beneficial effects that by adding the nano silicon dioxide, the humic acid and other active ingredients, the synergist can obviously improve the utilization rate of nitrogen, phosphorus, potassium and other nutrients in a chemical fertilizer and reduce the loss and waste of the nutrients. The porosity and air permeability of the soil can be improved by adding the biochar, and the physical structure of the soil is improved.

Description

Technical Field

[0001] The invention relates to the technical field of compound fertilizers, and in particular to a preparation method and application of a nitrogen-containing compound fertilizer synergist. Background Art

[0002] With the growth of global population and the continuous improvement of agricultural demand, agricultural production is increasingly dependent on chemical fertilizers. However, the excessive use of traditional chemical fertilizers has not only led to the decline of soil quality, such as soil acidification, nutrient imbalance and destruction of soil microbial community structure, but also caused serious environmental pollution problems, including eutrophication of water bodies, air quality and groundwater pollution. Therefore, the development of efficient and environmentally friendly compound fertilizer enhancers to improve the utilization rate of chemical fertilizers and reduce their environmental risks has become an urgent need for the current sustainable development of agriculture.

[0003] Compound fertilizer synergists are additives designed to enhance the effect of chemical fertilizers. They improve the solubility of chemical fertilizers, the rate of nutrient release, and the interaction with the soil environment, thereby increasing the absorption and utilization efficiency of nutrients by crops. Although traditional synergists such as humic acid, amino acids, and trace elements can improve the effect of chemical fertilizers to a certain extent, they have limitations such as uncontrollable nutrient release and unclear interaction mechanisms with soil and crops.

[0004] In recent years, the rapid development of nanotechnology and biotechnology has provided new ideas for the research and development of compound fertilizer enhancers. Nanomaterials, such as nano-silicon dioxide, are widely used to improve the dispersibility and bioavailability of fertilizer nutrients due to their unique physical and chemical properties, such as high specific surface area, good dispersibility and stability. At the same time, biochar, as a carbonaceous material obtained by pyrolysis of agricultural waste (such as crop straw, lignin, etc.) at high temperature, has become an important material for improving soil structure, increasing soil fertility and promoting microbial activity due to its rich pore structure, good adsorption performance and stable chemical properties.

[0005] In addition, with the continuous advancement of information technology and Internet of Things technology, precision agriculture technology has gradually been applied to agricultural production. Through modern technical means such as drones, remote sensing equipment, and soil sensors, the soil nutrient status, crop growth, and environmental conditions of farmland can be monitored in real time, providing a scientific basis for the precise application of fertilizers and enhancers. Precision fertilization can not only improve the utilization rate of fertilizers and enhancers and reduce resource waste, but also reduce the risk of environmental pollution and achieve sustainable development of agricultural production.

[0006] However, although the application of nanotechnology and biotechnology in compound fertilizer enhancers has achieved initial results, how to combine these technologies with precision agriculture technology to develop efficient, environmentally friendly and easy-to-promote compound fertilizer enhancers is still an important topic in the current agricultural science research field.

[0007] In summary, the present invention aims to propose an innovative nitrogen-containing compound fertilizer synergist and its preparation method and application, which combines nanotechnology, biotechnology and precision agriculture technology to improve fertilizer utilization, improve soil structure, promote crop growth, reduce environmental pollution and achieve precision fertilization, thereby providing strong technical support for the sustainable development of agriculture. Summary of the invention

[0008] The purpose of the present invention is to provide a preparation method and application of a nitrogen-containing compound fertilizer synergist to solve the problems raised in the above background technology.

[0009] To achieve the above object, the present invention provides the following technical solution: a method for preparing a nitrogen-containing compound fertilizer synergist, the method comprising the following steps:

[0010] (a) Raw material selection and pretreatment:

[0011] Urea N ≥ 46% was selected as the nitrogen source;

[0012] Humic acid HA ≥ 50% was selected as the organic matter source and was crushed to a particle size of ≤ 0.5 mm in advance;

[0013] Trace element additives are selected, including zinc sulfate ZnSO4·7H2O, Zn≥22%, borax Na2B4O7·10H2O, B≥11% and manganese chloride tetrahydrate MnCl2·4H2O, Mn≥23%, to ensure the effective content of each trace element;

[0014] Nano-silicon dioxide SiO2 with a particle size of ≤50nm is introduced as an anti-caking agent, accounting for 0.3% of the total mass;

[0015] (b) Accurate proportioning and mixing:

[0016] The mixture is prepared according to the mass ratio of urea: humic acid: trace element additive: nano silicon dioxide = 58:30:11:1;

[0017] Mix in a high-speed mixer at 1200 rpm for 20 minutes to ensure that the raw materials are fully and evenly dispersed;

[0018] (c) Melt granulation and modification:

[0019] The mixture obtained in step (b) is fed into a melt granulator with a set temperature of 135°C ± 5°C, and after melting, is passed through a specially designed granulation die to form particles with a particle size of 3 mm ± 0.5 mm;

[0020] During the melting process, 0.2% of the total weight of polyethylene glycol PEG-4000 was added as a lubricant to reduce the friction between particles and improve fluidity;

[0021] (d) Rapid cooling and solidification:

[0022] The molten particles are immediately sent to the forced air cooling device, with the wind speed set at 2.5m / s±0.5m / s, and cooled to room temperature 25℃±5℃ to complete solidification;

[0023] (e) Surface coating and packaging:

[0024] Using a liquid coating agent containing a microbial agent such as Bacillus, with a viable count of ≥ 500 million CFU / g, the particles obtained in step (d) are coated on the surface, and the coating thickness is controlled to be 50 μm ± 10 μm;

[0025] The coated particles are screened to remove unqualified particles, sealed in double-layer moisture-proof packaging bags, and stored in a cool and dry place.

[0026] Preferably, in step (a), the trace element additives are specifically zinc sulfate, borax and manganese chloride tetrahydrate, and their mass ratio is 2:1:1.

[0027] Preferably, in step (b), 0.5% of the total mass of bentonite is added as a binder during the mixing process to improve the strength and stability of the particles.

[0028] Preferably, in step (c), the outlet temperature of the melt granulator is controlled at 140°C ± 5°C to ensure the uniformity and surface smoothness of the particles.

[0029] Preferably, in step (d), a fan is provided in the cooling device to assist in heat dissipation, and the wind speed is controlled at 2 m / s to 3 m / s to accelerate the cooling process and prevent particles from sticking.

[0030] An innovative application of a nitrogen-containing compound fertilizer synergist is to add the prepared synergist to a conventional compound fertilizer N-P2O5-K2O=16-16-16 at a mass ratio of 8% to 10%, so as to improve crop nitrogen utilization, soil organic matter content and soil microbial diversity.

[0031] Preferably, the application of compound fertilizer with synergist added to wheat, rice and corn can increase crop yield by at least 10%, reduce nitrogen fertilizer loss rate by at least 20%, and increase soil organic matter content by at least 15%, compared with compound fertilizer without synergist added.

[0032] Preferably, the microbial agent in the synergist can effectively promote root growth in the soil, improve crop resistance, and reduce the occurrence of diseases and insect pests, which is specifically manifested in that the chlorophyll content of crop leaves increases by at least 15%, the root length increases by at least 20%, and the adaptability of crops to drought and saline-alkali adversity is enhanced.

[0033] Preferably, the synergist can be mixed with water at a ratio of 1:80 to 1:120 to form a suspension before application, and applied by drip irrigation, sprinkler irrigation or foliar spraying to improve fertilizer utilization and crop absorption efficiency while reducing nutrient loss and environmental pollution.

[0034] Preferably, the synergist can gradually improve the soil structure, increase the content of soil aggregate structure, and improve the soil permeability and water retention capacity during long-term use, which is specifically manifested in that the soil bulk density is reduced by at least 8% and the soil porosity is increased by at least 15%. At the same time, it promotes the optimization of the soil microbial community structure and improves the stability and sustainability of the soil ecosystem.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] The preparation method and application of the nitrogen-containing compound fertilizer synergist proposed in the present invention can significantly improve the utilization rate of nutrients such as nitrogen, phosphorus, and potassium in fertilizers by adding active ingredients such as nano-silicon dioxide and humic acid, and reduce the loss and waste of nutrients. The addition of biochar can increase the porosity and aeration of the soil and improve the physical structure of the soil; at the same time, humic acid and trace elements can promote the growth and reproduction of soil microorganisms and improve the biological activity of the soil. The active ingredients in the synergist can stimulate the root development and leaf growth of crops, improve the photosynthesis efficiency and stress resistance of crops, and thus significantly increase the yield and quality of crops. By improving the utilization rate of fertilizers and reducing the loss of nutrients, the synergist can significantly reduce the pollution risk of fertilizers to soil, water and air, and protect the ecological environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The figure is a flow chart of the method of the present invention. DETAILED DESCRIPTION

[0038] In order to make the purpose and technical solution of the present invention clearly and completely described, and the advantages more clearly understood, the embodiments of the present invention are further described in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are part of the embodiments of the present invention, rather than all of the embodiments, and are only used to explain the embodiments of the present invention, and are not used to limit the embodiments of the present invention. All other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] Embodiment 1, the present invention provides a technical solution: preparation and application of innovative nitrogen-containing compound fertilizer synergist

[0040] Preparation method:

[0041] Raw material selection and pretreatment:

[0042] 570 kg of high-purity urea (N≥46%) was selected as the nitrogen source.

[0043] 300 kg of humic acid (HA ≥ 50%) was selected and ultrafinely pulverized by a jet mill to a particle size of ≤ 0.2 mm, and a grading screen was used to ensure uniform particle size.

[0044] Trace element additives were selected: 60 kg of high-purity zinc sulfate (ZnSO4·7H2O, Zn≥23%), 30 kg of borax (Na2B4O7·10H2O, B≥10.5%) and 39 kg of manganese chloride tetrahydrate (MnCl2·4H2O, Mn≥22.5%), i.e., the mass ratio was 2:1:1.3, to meet the trace element requirements of specific crops.

[0045] 10 kg of nano silicon dioxide (SiO2, particle size ≤ 30 nm) was introduced as an anti-caking agent and carrier.

[0046] Precise proportioning and efficient mixing:

[0047] The above raw materials are mixed in a mass ratio of urea: humic acid: trace element additive: nano silicon dioxide = 57:30:12:1.

[0048] Mixing was carried out in a high-speed mixer at a speed of 1300 rpm for 25 minutes. The mixing chamber was equipped with dynamic stirring blades, static mixing elements, ultrasonic dispersion devices, temperature and humidity sensors to ensure that the raw materials were fully and evenly dispersed under optimal conditions.

[0049] Melt granulation and surface modification:

[0050] The mixture was fed into a melt granulator with a set temperature of 138°C ± 3°C.

[0051] After melting, the particles with a particle size of 3mm±0.2mm are formed through a specially designed multi-layer concentric ring mold. There is a tiny gap between each layer of the mold and it is equipped with a precise temperature control system.

[0052] Polyethylene glycol (PEG-6000) was added as a lubricant at 0.2% of the total mass.

[0053] Rapid cooling and solidification:

[0054] The molten particles are immediately sent to a forced air cooling device with a set wind speed of 2.7 m / s ± 0.3 m / s, and cooled to room temperature (23°C ± 2°C) to complete solidification.

[0055] The cooling device is equipped with temperature and wind speed sensors to monitor and adjust the cooling conditions in real time.

[0056] Surface coating and moisture-proof packaging:

[0057] The particles are surface coated using a liquid coating agent containing a highly efficient microbial agent (such as Bacillus, with a viable count of ≥ 1 billion CFU / g), and the coating thickness is controlled at 45 μm ± 5 μm.

[0058] The coated particles are precisely screened to remove unqualified particles.

[0059] Use three layers of moisture-proof and UV-proof packaging bags to seal and store in a cool and dry place.

[0060] application:

[0061] The prepared synergist was added into conventional compound fertilizer (N-P2O5-K2O=16-16-16) at a mass ratio of 8%.

[0062] When applied in wheat fields, wheat yield increased by 12%, nitrogen fertilizer loss rate decreased by 25%, and soil organic matter content increased by 18% compared with compound fertilizers without synergists.

[0063] Example 2, based on Example 1, proposes the preparation and application of an innovative nitrogen-containing compound fertilizer synergist (adjusting the proportion of trace elements)

[0064] Preparation method:

[0065] Raw material selection and pretreatment:

[0066] 570 kg of high-purity urea (N≥46%) was selected as the nitrogen source.

[0067] 300 kg of humic acid (HA ≥ 50%) was selected and ultrafinely pulverized by a jet mill to a particle size of ≤ 0.2 mm, and a grading screen was used to ensure uniform particle size.

[0068] Trace element additives were selected: 72 kg of high-purity zinc sulfate (ZnSO4·7H2O, Zn≥23%), 31.5 kg of borax (Na2B4O7·10H2O, B≥10.5%), and 36 kg of manganese chloride tetrahydrate (MnCl2·4H2O, Mn≥22.5%).

[0069] 10 kg of nano silicon dioxide (SiO2, particle size ≤ 30 nm) was introduced as an anti-caking agent and carrier.

[0070] Precise proportioning and efficient mixing:

[0071] The above raw materials are mixed in a mass ratio of urea: humic acid: trace element additive: nano silicon dioxide = 57:30:12:1.

[0072] Mixing was carried out in a high-speed mixer at a speed of 1300 rpm for 25 minutes. The mixing chamber was equipped with dynamic stirring blades, static mixing elements, ultrasonic dispersion devices, temperature and humidity sensors to ensure that the raw materials were fully and evenly dispersed under optimal conditions.

[0073] Melt granulation and surface modification:

[0074] The mixture was fed into a melt granulator with a set temperature of 138°C ± 3°C.

[0075] After melting, the particles with a particle size of 3mm±0.2mm are formed through a specially designed multi-layer concentric ring mold. There is a tiny gap between each layer of the mold and it is equipped with a precise temperature control system.

[0076] Polyethylene glycol (PEG-6000) was added as a lubricant at 0.2% of the total mass.

[0077] Rapid cooling and solidification:

[0078] The molten particles are immediately sent to a forced air cooling device with a set wind speed of 2.7 m / s ± 0.3 m / s, and cooled to room temperature (23°C ± 2°C) to complete solidification.

[0079] The cooling device is equipped with temperature and wind speed sensors to monitor and adjust the cooling conditions in real time.

[0080] Surface coating and moisture-proof packaging:

[0081] The particles are surface coated using a liquid coating agent containing a highly efficient microbial agent (such as Bacillus, with a viable count of ≥ 1 billion CFU / g), and the coating thickness is controlled at 45 μm ± 5 μm.

[0082] The coated particles are precisely screened to remove unqualified particles.

[0083] Use three layers of moisture-proof and UV-proof packaging bags to seal and store in a cool and dry place.

[0084] application:

[0085] The prepared synergist is added into conventional compound fertilizer at a mass ratio of 10%.

[0086] When applied in rice fields, compared with compound fertilizers without added enhancers, rice yield increased by 15%, nitrogen fertilizer loss rate decreased by 22%, and soil organic matter content increased by 16%.

[0087] Example 3, based on Example 1, proposes an innovative preparation and application of nitrogen-containing compound fertilizer synergist (introducing ultrasonic dispersion technology)

[0088] Preparation method:

[0089] Raw material selection and pretreatment:

[0090] 570 kg of high-purity urea (N≥46%) was selected as the nitrogen source.

[0091] 300 kg of humic acid (HA ≥ 50%) was selected and ultrafinely pulverized by a jet mill to a particle size of ≤ 0.2 mm, and a grading screen was used to ensure uniform particle size.

[0092] Trace element additives were selected: 60 kg of high-purity zinc sulfate (ZnSO4·7H2O, Zn≥23%), 30 kg of borax (Na2B4O7·10H2O, B≥10.5%) and 39 kg of manganese chloride tetrahydrate (MnCl2·4H2O, Mn≥22.5%), i.e., the mass ratio was 2:1:1.3, to meet the trace element requirements of specific crops.

[0093] 10 kg of nano silicon dioxide (SiO2, particle size ≤ 30 nm) was introduced as an anti-caking agent and carrier.

[0094] Precise proportioning and efficient mixing:

[0095] The above raw materials are mixed in a mass ratio of urea: humic acid: trace element additive: nano silicon dioxide = 57:30:12:1.

[0096] Mixing is carried out in a high-speed mixer at a speed of 1300rpm for 25 minutes. The mixing chamber is equipped with dynamic stirring blades, static mixing elements, ultrasonic dispersion devices, temperature and humidity sensors to ensure that the raw materials are fully and evenly dispersed under optimal conditions; special emphasis is placed on the use of ultrasonic dispersion devices to ensure the uniform distribution of nano-silicon dioxide and trace element additives in the mixing system.

[0097] Melt granulation and surface modification:

[0098] The mixture was fed into a melt granulator with a set temperature of 138°C ± 3°C.

[0099] After melting, the particles with a particle size of 3mm±0.2mm are formed through a specially designed multi-layer concentric ring mold. There is a tiny gap between each layer of the mold and it is equipped with a precise temperature control system.

[0100] Polyethylene glycol (PEG-6000) was added as a lubricant at 0.2% of the total mass.

[0101] Rapid cooling and solidification:

[0102] The molten particles are immediately sent to a forced air cooling device with a set wind speed of 2.7 m / s ± 0.3 m / s, and cooled to room temperature (23°C ± 2°C) to complete solidification.

[0103] The cooling device is equipped with temperature and wind speed sensors to monitor and adjust the cooling conditions in real time.

[0104] Surface coating and moisture-proof packaging:

[0105] The particles are surface coated using a liquid coating agent containing a highly efficient microbial agent (such as Bacillus, with a viable count of ≥ 1 billion CFU / g), and the coating thickness is controlled at 45 μm ± 5 μm.

[0106] The coated particles are precisely screened to remove unqualified particles.

[0107] Use three layers of moisture-proof and UV-proof packaging bags to seal and store in a cool and dry place.

[0108] application:

[0109] The prepared synergist is added into conventional compound fertilizer at a mass ratio of 9%.

[0110] When applied in corn fields, corn yield increased by 13% compared to compound fertilizers without synergists, while corn's ability to adapt to drought was enhanced, leaf chlorophyll content increased by 20%, and root length increased by 25%.

[0111] Example 4, based on Example 1, proposes an innovative preparation and application of nitrogen-containing compound fertilizer synergist (optimized cooling and packaging technology)

[0112] Preparation method:

[0113] Raw material selection and pretreatment:

[0114] 570 kg of high-purity urea (N≥46%) was selected as the nitrogen source.

[0115] 300 kg of humic acid (HA ≥ 50%) was selected and ultrafinely pulverized by a jet mill to a particle size of ≤ 0.2 mm, and a grading screen was used to ensure uniform particle size.

[0116] Trace element additives were selected: 60 kg of high-purity zinc sulfate (ZnSO4·7H2O, Zn≥23%), 30 kg of borax (Na2B4O7·10H2O, B≥10.5%) and 39 kg of manganese chloride tetrahydrate (MnCl2·4H2O, Mn≥22.5%), i.e., the mass ratio was 2:1:1.3, to meet the trace element requirements of specific crops.

[0117] 10 kg of nano silicon dioxide (SiO2, particle size ≤ 30 nm) was introduced as an anti-caking agent and carrier.

[0118] Precise proportioning and efficient mixing:

[0119] The above raw materials are mixed in a mass ratio of urea: humic acid: trace element additive: nano silicon dioxide = 57:30:12:1.

[0120] Mixing was carried out in a high-speed mixer at a speed of 1300 rpm for 25 minutes. The mixing chamber was equipped with dynamic stirring blades, static mixing elements, ultrasonic dispersion devices, temperature and humidity sensors to ensure that the raw materials were fully and evenly dispersed under optimal conditions.

[0121] Melt granulation and surface modification:

[0122] The mixture was fed into a melt granulator with a set temperature of 138°C ± 3°C.

[0123] After melting, the particles with a particle size of 3mm±0.2mm are formed through a specially designed multi-layer concentric ring mold. There is a tiny gap between each layer of the mold and it is equipped with a precise temperature control system.

[0124] Polyethylene glycol (PEG-6000) was added as a lubricant at 0.2% of the total mass.

[0125] Rapid cooling and solidification:

[0126] The molten particles are immediately sent to a forced air cooling device with a set wind speed of 2.7 m / s ± 0.3 m / s, and cooled to room temperature (23°C ± 2°C) to complete solidification.

[0127] The cooling device is equipped with temperature and wind speed sensors to monitor and adjust the cooling conditions in real time.

[0128] Surface coating and moisture-proof packaging:

[0129] The particles are surface coated using a liquid coating agent containing a highly efficient microbial agent (such as Bacillus, with a viable count of ≥ 1 billion CFU / g), and the coating thickness is controlled at 45 μm ± 5 μm.

[0130] The coated particles are precisely screened to remove unqualified particles.

[0131] Use three layers of moisture-proof and UV-proof packaging bags to seal and store in a cool and dry place.

[0132] Among them, a humidity control system is added to the forced air cooling device to adjust the air humidity during the cooling process; four-layer packaging bags with higher moisture-proof performance are used for sealed packaging.

[0133] application:

[0134] The prepared synergist is added into conventional compound fertilizer at a mass ratio of 8.5%.

[0135] It was applied to a variety of crops and the soil changes were tracked over a long period of time. It was found that the soil bulk density decreased by 10%, the soil porosity increased by 20%, the soil microbial diversity increased significantly, and the stability and sustainability of the soil ecosystem were improved. At the same time, the crop yield and stress resistance were significantly improved.

[0136] Example 5: Preparation and application of innovative nitrogen-containing compound fertilizer synergist (adding biochar)

[0137] Preparation method:

[0138] Raw material selection and pretreatment:

[0139] On the basis of Example 1, 50 kg of biochar (derived from agricultural waste, such as lignin, crop straw, etc., obtained by high-temperature pyrolysis) was additionally added to increase the water retention capacity and carbon storage of the soil.

[0140] Other raw materials and pretreatment steps are the same as those in Example 1.

[0141] Precise proportioning and efficient mixing:

[0142] Mix biochar with other raw materials in a new ratio: urea: humic acid: trace element additives: nano-silica: biochar = 57:30:12:1:5.

[0143] The mixing steps are the same as in Example 1 to ensure that all raw materials are evenly dispersed.

[0144] Next steps:

[0145] The steps of melt granulation, rapid cooling and solidification, surface coating and moisture-proof packaging are the same as those in the first embodiment.

[0146] application:

[0147] The prepared synergist is added into conventional compound fertilizer at a mass ratio of 9%.

[0148] When applied in vegetable greenhouses, the vegetable growth cycle is shortened by 10% and the yield is increased by 18% compared to compound fertilizers without added enhancers. At the same time, the soil's water retention capacity is enhanced, reducing the number of irrigation times.

[0149] Example 6: Preparation and application of innovative nitrogen-containing compound fertilizer synergist (adjusting coating agent composition)

[0150] Preparation method:

[0151] The steps from raw material selection and pretreatment to rapid cooling and solidification are the same as those in Example 1.

[0152] Surface coating and moisture-proof packaging:

[0153] Add 5% of natural polymer materials (such as chitosan) to the coating agent to enhance the sustained release effect and biodegradability of the coating.

[0154] The other film coating and packaging steps are the same as those in Example 1.

[0155] application:

[0156] The prepared synergist is added into conventional compound fertilizer at a mass ratio of 8%.

[0157] When applied in fruit tree planting areas, compared with compound fertilizers without added enhancers, the leaves of fruit trees are greener, the quality of fruit is improved, and the yield is increased by 12%, while the pollution of fertilizer loss to the environment is reduced.

[0158] Example 7: Preparation and application of innovative nitrogen-containing compound fertilizer synergist (combined with precision agriculture technology)

[0159] Preparation method:

[0160] Raw material selection and pretreatment:

[0161] 570 kg of high-purity urea (N≥46%) was selected as the nitrogen source.

[0162] 300 kg of humic acid (HA ≥ 50%) was selected and ultrafinely pulverized by a jet mill to a particle size of ≤ 0.2 mm, and a grading screen was used to ensure uniform particle size.

[0163] Trace element additives were selected: 60 kg of high-purity zinc sulfate (ZnSO4·7H2O, Zn≥23%), 30 kg of borax (Na2B4O7·10H2O, B≥10.5%) and 39 kg of manganese chloride tetrahydrate (MnCl2·4H2O, Mn≥22.5%), i.e., the mass ratio was 2:1:1.3, to meet the trace element requirements of specific crops.

[0164] 10 kg of nano silicon dioxide (SiO2, particle size ≤ 30 nm) was introduced as an anti-caking agent and carrier.

[0165] Precise proportioning and efficient mixing:

[0166] The above raw materials are mixed in a mass ratio of urea: humic acid: trace element additive: nano silicon dioxide = 57:30:12:1.

[0167] Mixing was carried out in a high-speed mixer at a speed of 1300 rpm for 25 minutes. The mixing chamber was equipped with dynamic stirring blades, static mixing elements, ultrasonic dispersion devices, temperature and humidity sensors to ensure that the raw materials were fully and evenly dispersed under optimal conditions.

[0168] Melt granulation and surface modification:

[0169] The mixture was fed into a melt granulator with a set temperature of 138°C ± 3°C.

[0170] After melting, the particles with a particle size of 3mm±0.2mm are formed through a specially designed multi-layer concentric ring mold. There is a tiny gap between each layer of the mold and it is equipped with a precise temperature control system.

[0171] Polyethylene glycol (PEG-6000) was added as a lubricant at 0.2% of the total mass.

[0172] Rapid cooling and solidification:

[0173] The molten particles are immediately sent to a forced air cooling device with a set wind speed of 2.7 m / s ± 0.3 m / s, and cooled to room temperature (23°C ± 2°C) to complete solidification.

[0174] The cooling device is equipped with temperature and wind speed sensors to monitor and adjust the cooling conditions in real time.

[0175] Surface coating and moisture-proof packaging:

[0176] The particles are surface coated using a liquid coating agent containing a highly efficient microbial agent (such as Bacillus, with a viable count of ≥ 1 billion CFU / g), and the coating thickness is controlled at 45 μm ± 5 μm.

[0177] The coated particles are precisely screened to remove unqualified particles.

[0178] Use three layers of moisture-proof and UV-proof packaging bags to seal and store in a cool and dry place.

[0179] application:

[0180] The prepared synergist is added into conventional compound fertilizer (N-P2O5-K2O=16-16-16) at a mass ratio of 8%.

[0181] When applied in wheat fields, wheat yield increased by 12%, nitrogen fertilizer loss rate decreased by 25%, and soil organic matter content increased by 18% compared with compound fertilizers without synergists.

[0182] application:

[0183] Combined with precision agriculture technology:

[0184] Before application, use drones or ground remote sensing equipment to accurately monitor soil nutrients and crop growth conditions in farmland.

[0185] According to the monitoring results, the mixing ratio of the synergist and conventional compound fertilizer, as well as the application location and depth are adjusted to achieve precise fertilization.

[0186] The synergist application method can be drip irrigation, sprinkler irrigation or foliar spraying, which is the same as Example 9. However, after combining with precision agriculture technology, the amount of fertilizer and the timing of fertilization are more accurate.

[0187] Long-term follow-up and evaluation:

[0188] Long-term monitoring points are set up in the farmland where the synergist is applied, and soil and crop samples are collected regularly for analysis.

[0189] Evaluate the effects of synergists on crop yield, soil nutrient content, soil structure and microbial diversity.

[0190] Based on the evaluation results, the formulation and application strategy of the enhancer are continuously optimized.

[0191] Application effect:

[0192] Under the guidance of precision agriculture technology, the combined application of enhancers and conventional compound fertilizers has significantly increased crop yield and quality, while reducing fertilizer use and environmental pollution.

[0193] Soil structure and microbial diversity are improved, and the soil ecosystem is more stable and sustainable.

[0194] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a nitrogen-containing compound fertilizer synergist, characterized in that: The method comprises the following steps: (a) Raw material selection and pretreatment: Urea N ≥ 46% was selected as the nitrogen source; Humic acid HA ≥ 50% was selected as the organic matter source and was crushed to a particle size of ≤ 0.5 mm in advance; Trace element additives are selected, including zinc sulfate ZnSO4·7H2O, Zn≥22%, borax Na2B4O7·10H2O, B≥11% and manganese chloride tetrahydrate MnCl2·4H2O, Mn≥23%, to ensure the effective content of each trace element; Nano-silicon dioxide SiO2 with a particle size of ≤50nm is introduced as an anti-caking agent, accounting for 0.3% of the total mass; (b) Accurate proportioning and mixing: The mixture is prepared according to the mass ratio of urea: humic acid: trace element additive: nano silicon dioxide = 58:30:11:1; Mix in a high-speed mixer at 1200 rpm for 20 minutes to ensure that the raw materials are fully and evenly dispersed; (c) Melt granulation and modification: The mixture obtained in step (b) is fed into a melt granulator with a set temperature of 135°C ± 5°C, and after melting, is passed through a specially designed granulation die to form particles with a particle size of 3 mm ± 0.5 mm; During the melting process, 0.2% of the total weight of polyethylene glycol PEG-4000 was added as a lubricant to reduce the friction between particles and improve fluidity; (d) Rapid cooling and solidification: The molten particles are immediately sent to the forced air cooling device, with the wind speed set at 2.5m / s±0.5m / s, and cooled to room temperature 25℃±5℃ to complete solidification; (e) Surface coating and packaging: Using a liquid coating agent containing a microbial agent such as Bacillus, with a viable count of ≥ 500 million CFU / g, the particles obtained in step (d) are coated on the surface, and the coating thickness is controlled to be 50 μm ± 10 μm; The coated particles are screened to remove unqualified particles, sealed in double-layer moisture-proof packaging bags, and stored in a cool and dry place.

2. The method for preparing a nitrogen-containing compound fertilizer synergist according to claim 1, characterized in that: In step (a), the trace element additives are specifically zinc sulfate, borax and manganese chloride tetrahydrate, and their mass ratio is 2:1:

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3. The method for preparing a nitrogen-containing compound fertilizer synergist according to claim 1, characterized in that: In step (b), 0.5% of the total mass of bentonite is added as a binder during the mixing process to improve the strength and stability of the particles.

4. The method for preparing a nitrogen-containing compound fertilizer synergist according to claim 1, characterized in that: In step (c), the outlet temperature of the melt granulator is controlled at 140°C ± 5°C to ensure the uniformity and surface smoothness of the particles.

5. The method for preparing a nitrogen-containing compound fertilizer synergist according to claim 1, characterized in that: In step (d), a fan is provided in the cooling device to assist in heat dissipation, and the wind speed is controlled at 2 m / s to 3 m / s to accelerate the cooling process and prevent particles from sticking.

6. An innovative application of nitrogen-containing compound fertilizer synergist, characterized in that: The synergist prepared according to any one of claims 1 to 5 is added to the conventional compound fertilizer N-P2O5-K2O=16-16-16 at a mass ratio of 8% to 10% to improve crop nitrogen utilization, soil organic matter content and soil microbial diversity.

7. The use according to claim 6, characterized in that: The application of compound fertilizers with synergists added to wheat, rice and corn can increase crop yield by at least 10%, reduce nitrogen fertilizer loss rate by at least 20%, and increase soil organic matter content by at least 15%, compared with compound fertilizers without synergists added.

8. The use according to claim 6, characterized in that: The microbial agents in the synergist can effectively promote root growth in the soil, improve crop resistance, and reduce the occurrence of diseases and insect pests. Specifically, the chlorophyll content of crop leaves increases by at least 15%, the root length increases by at least 20%, and the crop's ability to adapt to drought and saline-alkali adversity is enhanced.

9. The use according to claim 6, characterized in that: Before application, the synergist can be mixed with water in a ratio of 1:80 to 1:120 to form a suspension, and applied through drip irrigation, sprinkler irrigation or foliar spraying to improve fertilizer utilization and crop absorption efficiency while reducing nutrient loss and environmental pollution.

10. The use according to claim 6, characterized in that: During long-term use, the synergist can gradually improve the soil structure, increase the content of soil aggregate structure, and improve soil permeability and water retention capacity. Specifically, the soil bulk density is reduced by at least 8%, and the soil porosity is increased by at least 15%. At the same time, it promotes the optimization of the soil microbial community structure and improves the stability and sustainability of the soil ecosystem.

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