A compound fertilizer production process

Abstract

The application discloses a compound fertilizer production process and belongs to the technical field of fertilizers. The compound fertilizer production process comprises the following steps: (1) mixing various raw material components of the compound fertilizer, then adding citric acid, and performing granulation under the condition that water vapor exists to obtain granular substances, and then the granular substances are sent to a drying device; (2) sending the tail gas of a coal-fired boiler into a dryer, mixing and heat exchanging the tail gas of the coal-fired boiler and the granular substances of step (1), and obtaining the compound fertilizer; the various raw material components of the compound fertilizer comprise urea, ammonium dihydrogen phosphate, a potassium salt, brown algal oligosaccharide, chitosan oligosaccharide, a compound acid, sodium alginate, trace elements and corn straw extract; the compound acid comprises alanine and at least one of arginine, glycine and glutamic acid. The compound fertilizer production process not only reduces the treatment cost of the coal combustion tail gas, but also has good fertilizer efficiency and increases the yield of crops.

Description

Technical Field

[0001] This invention belongs to the field of fertilizer technology, specifically relating to a compound fertilizer production process. Background Technology

[0002] In the production of compound fertilizer, the granules need to be dried to minimize their moisture content, preventing granule pulverization during storage and improving granule strength. The primary heat source for drying compound fertilizer is coal combustion. Coal contains sulfur and nitrogen, which react with oxygen in the air during combustion to generate air pollutants, mainly sulfur dioxide, hydrogen sulfide, and nitric oxide. Sulfur oxides in the exhaust gas corrode metal structural components, posing challenges to the selection of dust collectors. Common desulfurization and denitrification technologies involve neutralizing the exhaust gas from coal combustion by contacting it with sprayed acidic or alkaline solutions. However, this process requires significant investment in equipment and recovery ponds, wasting the heat from the coal combustion exhaust gas and greatly increasing exhaust gas treatment costs.

[0003] Sulfur is an important component of cystine, cysteine, and methionine, and participates in chlorophyll formation; it plays an important role in the formation and activation of certain enzymes in plants; sulfur can increase the cold and drought resistance of some crops. Whether crops are deficient in sulfur or nitrogen, their normal growth will be affected, leading to a decline in both yield and quality.

[0004] Therefore, there is an urgent need to provide a new method for producing compound fertilizers that not only reduces the cost of treating coal combustion exhaust gas, but also has good fertilizer efficiency and increases crop yields. Summary of the Invention

[0005] This invention aims to solve at least one of the technical problems existing in the prior art. To this end, this invention proposes a compound fertilizer production process. The compound fertilizer production process of this invention not only reduces the cost of treating coal combustion exhaust gas, but also has good fertilizer efficiency and increases crop yield.

[0006] To address the air pollutants generated during coal-fired drying while ensuring heat supply and reducing unnecessary economic input, this invention presents a compound fertilizer production process that not only improves the fertilizer efficiency of compound fertilizers but also saves energy, reduces emissions, and eliminates pollution.

[0007] A compound fertilizer production process includes the following steps:

[0008] (1) Mix the raw materials of the compound fertilizer, then add citric acid, and granulate in the presence of water vapor to obtain granules, which are then sent to a drying device;

[0009] (2) The tail gas from the coal-fired boiler is sent into a dryer, where it is mixed with the particulate matter from step (1) and heat exchanged to obtain compound fertilizer.

[0010] The raw material components of the compound fertilizer include urea, ammonium dihydrogen phosphate, potassium salt, fucoidan, chitosan oligosaccharide, compound acid, sodium alginate, trace elements and corn stalk extract.

[0011] The preparation method of the corn stalk extract includes: drying, slicing and crushing corn stalks and matsutake mushrooms respectively, then mixing them, adding water and cellulase, stirring and enzymatically hydrolyzing them, then extracting them in a boiling water bath, then extracting them with ultrasound, filtering them, collecting the filtrate, concentrating it under reduced pressure, drying it, and crushing it to obtain the corn stalk extract.

[0012] The complex acid includes alanine, and at least one of arginine, glycine, and glutamic acid.

[0013] Preferably, in the complex acid, the weight ratio of alanine to at least one of arginine, glycine, and glutamic acid is 1:(0.5-1.2), and more preferably 1:(0.8-1).

[0014] Preferably, the weight ratio of corn stalks to matsutake mushrooms is 100:(1-5), more preferably 100:(2-4).

[0015] Preferably, the particle size is less than 1 cm, and more preferably 2 mm-8 mm.

[0016] Preferably, the enzymatic hydrolysis temperature is 35-45℃ and the enzymatic hydrolysis time is 3-6 hours.

[0017] Preferably, the amount of cellulase added is 2% to 7% of the weight of the crushed corn stalks, more preferably 3% to 6%.

[0018] Preferably, the cellulase has a unit enzyme activity of 90-100 U / mg, for example, 100 U / mg.

[0019] Preferably, the weight of the water is 50% to 100% of the weight of the crushed corn stalks, and more preferably 80% to 100%.

[0020] Preferably, the extraction time in the boiling water bath is 20-40 minutes, for example, 30 minutes or 40 minutes.

[0021] Preferably, the ultrasonic extraction temperature is 70-75℃ and the time is 30-60 minutes; more preferably, the ultrasonic extraction temperature is 70-72℃ and the time is 45-50 minutes.

[0022] Preferably, the frequency of the ultrasonic wave is 60-80kHz and the power is 100-200W.

[0023] Preferably, the process of vacuum concentration, drying, and pulverization involves concentrating the water at 45-55°C and -0.1 to -0.2 MPa to 1 / 6–1 / 10 of the original water volume to obtain a concentrate. The concentrate is then vacuum dried at 60-80°C and -0.1 to -0.2 MPa and pulverized to obtain a corn stalk extract.

[0024] Preferably, the potassium salt includes at least one of potassium sulfate or potassium nitrate.

[0025] Preferably, the trace elements include at least one of zinc, iron, manganese, and copper. These trace elements can participate in the synthesis of plant enzymes and proteins, promote plant photosynthesis, and thus increase plant fruit yield.

[0026] Preferably, the trace elements are provided by at least one of the nitrates and sulfates of zinc, iron, manganese, and copper.

[0027] Preferably, the raw material components of the compound fertilizer, by weight, include 40 parts urea, 5-10 parts ammonium dihydrogen phosphate, 5-10 parts potassium salt, 1-4 parts fucoidan, 2-6 parts chitosan oligosaccharide, 1-5 parts compound acid, 2-8 parts sodium alginate, 0.5-3 parts trace elements, and 0.5-3 parts corn stalk extract; more preferably, the raw material components of the compound fertilizer, by weight, include 40 parts urea, 6-8 parts ammonium dihydrogen phosphate, 5-8 parts potassium salt, 2-4 parts fucoidan, 3-5 parts chitosan oligosaccharide, 2-5 parts compound acid, 3-8 parts sodium alginate, 1-2 parts trace elements, and 1-3 parts corn stalk extract.

[0028] Preferably, the citric acid accounts for 0.1% to 1% of the total weight of the raw material components of the compound fertilizer, and more preferably 0.5% to 0.8%.

[0029] Preferably, the exhaust gas after absorption undergoes cyclone dust removal, sedimentation dust removal, water washing dust removal, and water film dewatering before finally meeting emission standards.

[0030] Preferably, the compound acid also includes humic acid. Humic acid, combined with alanine and at least one of arginine, glycine, and glutamic acid, can not only significantly improve the plant's disease resistance but also help increase plant yield.

[0031] Preferably, the compound fertilizer has a particle diameter of 1-3 mm and a density of 1.1-1.2 g / m³. 3 Specific surface area is 65,000-70,000 m² 2 .

[0032] The drying process consumes approximately 15.0-16.5 kg of coal per ton of compound fertilizer, with an equipment capacity of 18-20 t / h. During the drying process, the drying furnace burns 300-330 kg of coal per hour, and approximately 15-16 kg of sulfur dioxide is generated after burning 1 ton of coal. The drying equipment generates 4-5.28 kg of sulfur dioxide per hour.

[0033] Citric acid is added to each raw material component of compound fertilizer, and after mixing and stirring, it is fed into a granulator and granulated in the presence of steam. At this time, citric acid participates in the granulation of compound fertilizer under the action of steam and is adsorbed on the surface of the particles. The moist particles are sent to a dryer.

[0034] The exhaust gas from a coal-fired boiler is fed into a dryer. The moist particles are thoroughly mixed and exchange heat with the exhaust gas by the action of the lifting plates. At this time, a citrate solution forms on the surface of the moist particles, which absorbs gases such as sulfur dioxide and nitrogen oxides in the exhaust gas. Sulfur dioxide reacts with water to produce sulfurous acid, which becomes sulfuric acid under heating conditions. The sulfuric acid reacts with citrate to achieve the effect of treating the exhaust gas. Excess citric acid and citrate have a very strong complexing ability and can complex with metal ions to form soluble citrate, which can improve fertilizer efficiency.

[0035] The moist particles form an absorbent curtain under the action of the dryer rotation and the lifting plates, which fully absorbs the exhaust gas of the coal-fired boiler. The absorbed exhaust gas is then subjected to cyclone dust removal, sedimentation dust removal, water washing dust removal and water film dehydration, and finally meets the emission standards. The absorbed particles are then processed through the compound fertilizer post-processing process before entering the finished product packaging.

[0036] A compound fertilizer is prepared by the above-mentioned compound fertilizer production process.

[0037] The application of the above-mentioned compound fertilizer production process in plant cultivation.

[0038] Preferably, the plants include corn, wheat, soybeans, and tomatoes.

[0039] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0040] (1) The raw material components of the compound fertilizer of the present invention include urea, ammonium dihydrogen phosphate, potassium salt, fucoidan, chitosan oligosaccharide, compound acid, sodium alginate, trace elements, and corn stalk extract. Through the fucoidan, chitosan oligosaccharide, compound acid, sodium alginate, trace elements, and corn stalk extract, combined with urea, ammonium dihydrogen phosphate, and potassium salt, the nutritional components during the growth of plants are guaranteed. The preparation process of corn stalk extract introduces a small amount of matsutake mushroom, which is beneficial to stimulating the rapid growth of plants and the increase in fruit weight. The synergistic effect between fucoidan, chitosan oligosaccharide, and compound acid is also beneficial to the growth and yield of plants, such as corn.

[0041] (2) The compound acid also includes humic acid. Humic acid, combined with alanine, and at least one of arginine, glycine, and glutamic acid, can not only greatly improve the plant's disease resistance, but also help increase the plant's yield.

[0042] (3) The compound fertilizer described in this invention can regulate the acidity and alkalinity of the soil, increase the organic matter content of the soil, and protect and improve the soil quality.

[0043] (4) Citric acid is economical and affordable, with ample market supply and demand, and readily available raw materials. It improves the plant growth environment, promotes root development, enhances disease resistance, increases crop yield, and improves product quality.

[0044] (5) The production process of the present invention absorbs sulfur and nitrate in the exhaust gas and transforms them into nutrients in fertilizer, avoiding air pollution and making full use of the heat of the exhaust gas, thus turning waste into treasure.

[0045] (6) The desulfurization and denitrification process of exhaust gas is simple and easy to operate, which reduces the production cost of products and is beneficial to the competitiveness of products in the market. Detailed Implementation

[0046] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention.

[0047] Unless otherwise specified, the raw materials, reagents or devices used in the following examples are available from conventional commercial sources or can be obtained by existing known methods.

[0048] Example 1

[0049] A compound fertilizer production process includes the following steps:

[0050] (1) Mix the raw materials of the compound fertilizer, then add 0.5% of the total weight of the raw materials of the compound fertilizer with citric acid. After mixing and stirring, send the mixture into a granulator and granulate it in the presence of water vapor to obtain granules. Then send the granules to a dryer.

[0051] (2) The tail gas from the coal-fired boiler is sent into the dryer. Under the action of the lifting plate, the tail gas from the coal-fired boiler is mixed with the particulate matter from step (1) and heat exchanged for 2 hours to obtain compound fertilizer.

[0052] The raw material components of the compound fertilizer, by weight, include 40 parts urea, 6 parts ammonium dihydrogen phosphate, 7 parts potassium nitrate, 3 parts brown algae oligosaccharide, 4 parts chitosan oligosaccharide, 4 parts compound acid, 5 parts sodium alginate, 1 part trace element (the trace element is composed of zinc nitrate, ferric nitrate, manganese nitrate, and copper nitrate in a weight ratio of 2:1:1:1), and 2 parts corn stalk extract.

[0053] The complex acid includes alanine, as well as arginine and glycine, with a weight ratio of 1:0.4:0.4.

[0054] The preparation method of corn stalk extract includes: drying corn stalks and matsutake mushrooms at 90℃ for 3 hours, slicing and pulverizing them to a particle size of less than 1 cm, then mixing them for 30 minutes, with a weight ratio of corn stalks to matsutake mushrooms of 100:2; adding water and cellulase, with the weight of water being 80% of the weight of the pulverized corn stalks and the amount of cellulase added being 3% of the weight of the pulverized corn stalks, and the unit enzyme activity of cellulase being 100 U / mg; stirring and enzymatic hydrolysis at 40℃ for 5 hours; then extraction in a boiling water bath for 30 minutes; followed by ultrasonic extraction at 70℃ for 40 minutes, with an ultrasonic frequency of 60 kHz and a power of 100 W; filtering; collecting the filtrate; concentrating it under reduced pressure at 50℃ and -0.1 MPa to 1 / 10 of the original volume to obtain a concentrate; then vacuum drying the concentrate at 80℃ and -0.1 MPa; and pulverizing it to obtain the corn stalk extract.

[0055] The exhaust gas after absorption undergoes cyclone dust removal, sedimentation dust removal, water washing dust removal, and water film dehydration before finally meeting emission standards.

[0056] Example 2

[0057] A compound fertilizer production process includes the following steps:

[0058] (1) Mix the raw materials of the compound fertilizer, then add 0.6% of citric acid by weight of the total raw materials of the compound fertilizer, and after mixing and stirring, send it into the granulator. Under the condition of water vapor, the granules are granulated in a rotary drum to obtain granules, and then sent to the dryer.

[0059] (2) The tail gas from the coal-fired boiler is sent into the dryer. Under the action of the lifting plate, the tail gas from the coal-fired boiler is mixed with the particulate matter from step (1) and heat exchanged for 1.5 hours to obtain compound fertilizer.

[0060] The raw material components of the compound fertilizer, by weight, include 40 parts urea, 5 parts ammonium dihydrogen phosphate, 5 parts potassium nitrate, 4 parts brown alginic oligosaccharide, 5 parts chitosan oligosaccharide, 3 parts compound acid, 4 parts sodium alginate, 1 part trace element (the trace element is composed of zinc nitrate, ferric nitrate, manganese nitrate, and copper nitrate in a weight ratio of 2.5:0.5:1:1), and 2.5 parts corn stalk extract;

[0061] The complex acid includes alanine, as well as arginine, glycine, and glutamic acid, with a weight ratio of 1:0.3:0.4:0.3.

[0062] The preparation method of corn stalk extract includes: drying corn stalks and matsutake mushrooms at 90℃ for 3 hours, slicing and pulverizing them to a particle size of less than 1 cm, then mixing them for 30 minutes, with a weight ratio of corn stalks to matsutake mushrooms of 100:1; adding water and cellulase, with the weight of water being 70% of the weight of the pulverized corn stalks and the amount of cellulase added being 4% of the weight of the pulverized corn stalks, and the unit enzyme activity of cellulase being 100 U / mg; stirring and enzymatic hydrolysis at 45℃ for 5 hours; then extracting in a boiling water bath for 30 minutes; followed by ultrasonic extraction at 70℃ for 40 minutes, with an ultrasonic frequency of 60 kHz and a power of 100 W; filtering; collecting the filtrate; concentrating under reduced pressure at 50℃ and -0.1 MPa to 1 / 10 of the original volume to obtain a concentrate; then drying the concentrate under vacuum at 80℃ and -0.1 MPa; and pulverizing to obtain the corn stalk extract.

[0063] The exhaust gas after absorption undergoes cyclone dust removal, sedimentation dust removal, water washing dust removal, and water film dehydration before finally meeting emission standards.

[0064] Example 3

[0065] A compound fertilizer production process includes the following steps:

[0066] (1) Mix the raw materials of the compound fertilizer, then add 0.5% of the total weight of the raw materials of the compound fertilizer with citric acid. After mixing and stirring, send the mixture into a granulator and granulate it in the presence of water vapor to obtain granules. Then send the granules to a dryer.

[0067] (2) The tail gas from the coal-fired boiler is sent into the dryer. Under the action of the lifting plate, the tail gas from the coal-fired boiler is mixed with the particulate matter from step (1) and heat exchanged for 2 hours to obtain compound fertilizer.

[0068] The raw material components of the compound fertilizer, by weight, include 40 parts urea, 6 parts ammonium dihydrogen phosphate, 7 parts potassium nitrate, 3 parts brown algae oligosaccharide, 4 parts chitosan oligosaccharide, 5 parts compound acid, 5 parts sodium alginate, 1 part trace element (the trace element is composed of zinc nitrate, ferric nitrate, manganese nitrate, and copper nitrate in a weight ratio of 2:1:1:1), and 2 parts corn stalk extract.

[0069] The compound acid includes humic acid, alanine, arginine, and glycine, with a weight ratio of 1:1:0.4:0.4.

[0070] The preparation method of corn stalk extract includes: drying corn stalks and matsutake mushrooms at 90℃ for 3 hours, slicing and pulverizing them to a particle size of less than 1 cm, then mixing them for 30 minutes, with a weight ratio of corn stalks to matsutake mushrooms of 100:2; adding water and cellulase, with the weight of water being 80% of the weight of the pulverized corn stalks and the amount of cellulase added being 3% of the weight of the pulverized corn stalks, and the unit enzyme activity of cellulase being 100 U / mg; stirring and enzymatic hydrolysis at 40℃ for 5 hours; then extraction in a boiling water bath for 30 minutes; followed by ultrasonic extraction at 70℃ for 40 minutes, with an ultrasonic frequency of 60 kHz and a power of 100 W; filtering; collecting the filtrate; concentrating it under reduced pressure at 50℃ and -0.1 MPa to 1 / 10 of the original volume to obtain a concentrate; then vacuum drying the concentrate at 80℃ and -0.1 MPa; and pulverizing it to obtain the corn stalk extract.

[0071] The exhaust gas after absorption undergoes cyclone dust removal, sedimentation dust removal, water washing dust removal, and water film dehydration before finally meeting emission standards.

[0072] Comparative Example 1

[0073] Compared with Example 1, the only difference in Comparative Example 1 is that citric acid is not added, while the other processes are the same as in Example 1.

[0074] Comparative Example 2

[0075] Compared with Example 1, the only difference in Comparative Example 2 is that an equal amount of arginine is used instead of alanine; the other processes are the same as in Example 1.

[0076] Comparative Example 3

[0077] Compared with Example 1, the only difference in Comparative Example 3 is that an equal amount of corn stalks were used instead of matsutake mushrooms; the other processes were the same as in Example 1.

[0078] Product effectiveness test

[0079] 1. Corn planting experiment

[0080] The fertilizer effects of the compound fertilizers prepared in Examples 1-3 and Comparative Examples 1-3 were tested. Corn was selected as the experimental crop, with a row spacing of about 70 cm and a plant spacing of about 30 cm. The same planting area and field management were used. The compound fertilizers prepared in Examples 1-3 and Comparative Examples 1-3 were applied as base fertilizer at a rate of 45 kg / mu. After harvesting the corn, the emergence rate and corn yield (the corn yield was calculated as yield per mu (kg) = number of ears per mu × number of grains per ear / number of grains per kg) are shown in Table 1.

[0081] Table 1

[0082] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Emergence rate (%) 90 88 94 86 85 78 Rice corn yield per mu (kg) 678.2 665.4 698.6 642.7 635.8 563.1

[0083] As shown in Table 1, the compound fertilizers prepared in Examples 1-3 have significantly better fertilizer effects than those in Comparative Examples 1-3. Examples 1 and Comparative Examples 1-3 demonstrate that the addition of citric acid can increase the fertilizer effect of the compound fertilizer. Specific types of compound acids have a significant promoting effect on corn growth. Furthermore, the addition of matsutake mushrooms during the preparation of corn stalk extract can promote corn growth and increase yield. The reason for this may be that matsutake mushroom extract is beneficial in stimulating corn emergence and increasing yield.

[0084] 2. Wheat planting experiment

[0085] One mu (approximately 0.16 acres) of experimental field was divided into six plots. Sunshine 818 wheat was used as the experimental crop. Before sowing, the land was plowed. The compound fertilizers prepared in Examples 1-3 and Comparative Examples 1-3 were applied to each plot, with 4.5 kg of compound fertilizer applied per plot and 1 kg of wheat sown per plot. Another 4 kg of compound fertilizer was applied when the wheat reached the greening stage, and another 8 kg of compound fertilizer was applied when the wheat reached the heading stage. At maturity, the grains were collected, weighed, and the wheat yield and grain morphology of each plot were recorded. The results are shown in Table 2 below.

[0086] Table 2

[0087] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Production (kg) 125.3 116.6 139.7 108.2 101.1 94.6 wheat grain morphology plump kernels plump kernels plump kernels plump kernels plump kernels plump kernels

[0088] As can be seen from Table 2, the compound fertilizer prepared in the embodiments of the present invention has better fertilizer efficiency in wheat cultivation. It also further demonstrates that the addition of citric acid in the compound fertilizer production process of the present invention can increase the fertilizer efficiency, that specific types of compound acids have a significant promoting effect on wheat growth, and that the addition of matsutake mushrooms in the preparation of corn stalk extract can promote increased wheat yield.

[0089] It should be noted that, in this document, terms such as “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0090] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A process for the production of compound fertilizers, characterized in that, The method comprises the following steps: (1) mixing each raw material component of the compound fertilizer, then adding citric acid, and granulating under the condition of water vapor to obtain granules, and then sending the granules to a drying device; (2) sending the tail gas of the coal-fired boiler into the drying machine, mixing and exchanging heat between the tail gas of the coal-fired boiler and the granules of step (1) to obtain the compound fertilizer; each raw material component of the compound fertilizer comprises urea, ammonium dihydrogen phosphate, potassium salt, brown algal oligosaccharide, chitosan oligosaccharide, compound acid, sodium alginate, trace elements and corn straw extract; the preparation method of the corn straw extract comprises the following steps: drying, slicing and crushing the corn straw and tricholoma matsutake respectively, then mixing, adding water and cellulase, stirring, enzyme hydrolysis, extraction in a boiling water bath, ultrasonic extraction, filtration, collection of the filtrate, concentration under reduced pressure, drying, crushing and obtaining the corn straw extract; the compound acid comprises three of alanine, arginine and glycine, or four of alanine, arginine, glycine and glutamic acid, or four of humic acid, alanine, arginine and glycine.

2. A process for the production of compound fertilizers according to claim 1, characterized in that, The weight ratio of the corn straw to the tricholoma matsutake is 100: (1-5).

3. The process for producing compound fertilizer according to claim 1, characterized in that, The temperature of the enzyme hydrolysis is 35-45℃, and the time of the enzyme hydrolysis is 3-6 hours.

4. The process for producing compound fertilizer according to claim 1, characterized in that, The time of the extraction in the boiling water bath is 20-40 minutes; and / or, the temperature of the ultrasonic extraction is 70-75℃, and the time of the ultrasonic extraction is 30-60 minutes.

5. The process for producing compound fertilizer according to claim 1, characterized in that, The potassium salt comprises at least one of potassium sulfate or potassium nitrate.

6. A compound fertilizer production process according to claim 1, characterized in that, The trace elements comprise at least one of zinc, iron, manganese and copper.

7. A process for the production of compound fertilizer as claimed in claim 1, wherein, Each raw material component of the compound fertilizer comprises, by weight, 40 parts of urea, 5-10 parts of ammonium dihydrogen phosphate, 5-10 parts of potassium salt, 1-4 parts of brown algal oligosaccharide, 2-6 parts of chitosan oligosaccharide, 1-5 parts of compound acid, 2-8 parts of sodium alginate, 0.5-3 parts of trace elements and 0.5-3 parts of corn straw extract.

8. A process for the production of compound fertilizers according to any one of claims 1 to 7, characterized in that, The weight of the citric acid is 0.1%-1% of the total weight of each raw material component of the compound fertilizer.

9. A compound fertilizer, characterized by, The compound fertilizer is prepared by the compound fertilizer production process of any one of claims 1-8.

10. The compound fertilizer production process of any one of claims 1-8 is applied to plant cultivation.