Iron-aluminum modified carbon-based coated organic-inorganic slow-release microbial compound fertilizer and preparation thereof

Abstract

The invention discloses an iron-aluminum modified carbon-based coated organic-inorganic slow-release microbial compound fertilizer and a preparation method thereof. The iron-aluminum modified carbon-based coated organic-inorganic slow-release microbial compound fertilizer comprises a compound fertilizer master batch and a tobacco straw carbon coating layer wrapping the compound fertilizer master batch, bacteria are planted in the tobacco straw carbon coating; through mutual cooperation of the compound fertilizer master batch, the tobacco stalk carbon coating and the bacteria, the effects of improving the utilization rate of fertilizer nutrients and reducing the application amount of the fertilizer are achieved, on one hand, the tobacco stalk carbon coating can improve the water-holding capacity of soil, and the porosity of the soil can be improved due to the characteristics of high porosity and high specific surface area of the tobacco stalk carbon coating; on the one hand, the tobacco stalk charcoal coating layer is used as a coating layer, the slow release effect is achieved, coordinated and lasting release of nutrient elements is facilitated, the utilization efficiency of fertilizer nutrients is high, and repeated topdressing is avoided, and on the other hand, the tobacco stalk charcoal coating layer is used as a field planting carrier, so that the effect of improving the soil structure and the acid soil is achieved. And colonization of bacteria is facilitated.

Description

Technical Field

[0001] The invention relates to the technical field of agricultural waste utilization, and in particular to an iron-aluminum modified carbon-based coated organic-inorganic slow-release microbial compound fertilizer and a preparation method thereof. Background Art

[0002] In the process of planting and processing tobacco, the waste generated (fireworks branches, rhizomes, unsuitable tobacco leaves, low-grade tobacco leaves after baking) can reach more than 40% of the total tobacco production. If it is not handled properly, it will not only waste resources, but also pollute the atmosphere, soil and groundwater, causing harm to the environment. At present, the tobacco industry still mostly treats tobacco field waste by randomly discarding or centrally burning it. Therefore, exploring how to use tobacco field waste more efficiently and reasonably is one of the problems that need to be solved in ecological and environmental research. In addition, due to some unreasonable factors in the use of chemical fertilizers, not only the nutrient utilization rate of fertilizers is reduced, but also the ecological environment, including the soil environment, has been seriously damaged.

[0003] At present, chemical fertilizers are mainly fully soluble, quick-soluble and quick-dispersing types, which aggravate the waste of fertilizers and the loss of nutrients. In production, multiple topdressings must be carried out to meet the nutrient needs of crops throughout the entire development period. This is not only labor-intensive and increases the cost of fertilization, but also the nutrient loss of topdressing and surface fertilizers is large, which significantly reduces the fertilizer efficiency and makes it difficult to exert the yield-increasing effect of the fertilizer.

[0004] Therefore, providing a fertilizer with coordinated and long-lasting nutrient element release, high nutrient utilization efficiency and obvious slow-release effect has become a technical problem that needs to be solved at present. Summary of the invention

[0005] In view of this, the present application provides an iron-aluminum modified carbon-based coated organic-inorganic slow-release microbial compound fertilizer and its preparation, which is used to solve the problem of how to improve the slow-release and nutrient utilization rate of fertilizers.

[0006] In order to achieve the above technical objectives, this application adopts the following technical solutions: In a first aspect, the present application provides an iron-aluminum modified carbon-based coated organic-inorganic slow-release microbial compound fertilizer, comprising a compound fertilizer masterbatch and a tobacco straw charcoal coating wrapped in the compound fertilizer masterbatch; the tobacco straw charcoal coating is colonized with bacteria.

[0007] Preferably, the compound fertilizer masterbatch includes the following components in mass proportions: 6-10 parts of white phosphate fertilizer, 24-25 parts of ammonium nitrate phosphate, 16-17 parts of monoammonium phosphate, 3-5 parts of potassium sulfate, 7-8 parts of potassium chloride, 26-27 parts of potassium sulfate, 4-5 parts of magnesium sulfate heptahydrate, 3-4 parts of ammonium sulfate, 2-3 parts of magnesium sulfate monohydrate, 1-2 parts of borax pentahydrate, 1-2 parts of zinc sulfate monohydrate, and 4-5 parts of corn starch; the chemical composition of the tobacco straw charcoal coating is tobacco straw charcoal powder.

[0008] Preferably, the bacteria include one or more of phosphate-solubilizing bacteria and potassium-solubilizing bacteria.

[0009] Preferably, in the compound fertilizer masterbatch, the sum of the masses of the three elements N, P and K is 40-60% of the total mass of the compound fertilizer masterbatch.

[0010] In a second aspect, the present application provides a method for preparing an iron-aluminum modified carbon-based coated organic-inorganic slow-release microbial compound fertilizer, comprising the following steps: S1. The raw material components of the compound fertilizer masterbatch are crushed and mixed by mass, and steam is introduced for granulation to obtain a compound fertilizer masterbatch; S2. After mixing the compound fertilizer masterbatch with tobacco straw charcoal powder, coating the masterbatch to obtain a first coated compound fertilizer particle; S3. Spraying the polyvinyl alcohol aqueous solution on the coated compound fertilizer particles for reinforcement coating to obtain a second coated compound fertilizer particles; S4. The second coated compound fertilizer particles, mushroom bran, and tobacco waste fermentation residue are mixed and composted, and aerobic fermentation is performed to obtain the iron-aluminum modified carbon-based coated organic-inorganic slow-release microbial compound fertilizer.

[0011] Preferably, the preparation method of tobacco straw charcoal powder is: pyrolyzing tobacco straw at 550-600° C. in a nitrogen atmosphere, and passing through a 100-200 mesh sieve to obtain the tobacco straw charcoal powder.

[0012] Preferably, the preparation method of the tobacco waste fermentation residue is: mixing tobacco waste and a biogas fermentation agent solution in a mass ratio of 4:1, and performing anaerobically fermentation at a pH value of 6.5-7 to obtain the tobacco waste fermentation residue; the concentration of the biogas fermentation agent solution is 10-15wt%.

[0013] Preferably, in step S4, the pH value of aerobic fermentation is 7-8.

[0014] Preferably, the mass ratio of compound fertilizer masterbatch to tobacco straw charcoal powder is 1.5-2.5:1.

[0015] In a third aspect, the present application provides an application of an iron-aluminum modified carbon-based coated organic-inorganic slow-release microbial compound fertilizer in the field of tobacco cultivation.

[0016] The beneficial effects of the present application are as follows: the present application achieves the effect of improving the fertilizer nutrient utilization rate and reducing the fertilizer application amount through the mutual coordination and synergy of compound fertilizer masterbatch, tobacco straw charcoal coating and bacteria. Among them, the tobacco straw charcoal coating itself can increase the soil water holding capacity on the one hand, and its high porosity and high specific surface area characteristics can increase the soil porosity, improve the soil structure and improve the acidic soil, and reduce the loss of soil nutrients. On the other hand, the tobacco straw charcoal coating acts as a coating layer, which plays a slow-release role, which is beneficial to the coordinated and long-lasting release of nutrients, high fertilizer nutrient utilization efficiency, and avoidance of multiple topdressing. Furthermore, the tobacco straw charcoal coating acts as a colonization carrier, which is beneficial to the colonization of bacteria. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0018] The present application provides an iron-aluminum modified carbon-based coated organic-inorganic slow-release microbial compound fertilizer, comprising a compound fertilizer masterbatch and a tobacco straw charcoal coating wrapped in the compound fertilizer masterbatch; the tobacco straw charcoal coating is colonized with bacteria.

[0019] In the present application, on the one hand, the tobacco straw charcoal coating itself can increase the water holding capacity of the soil, and its high porosity and high specific surface area characteristics can increase the porosity of the soil, improve the soil structure and improve the acidic soil, and reduce the loss of soil nutrients. On the other hand, the tobacco straw charcoal coating, as a coating layer, plays a slow-release role, which is conducive to the coordinated and lasting release of nutrients, high fertilizer nutrient utilization efficiency, and avoidance of multiple topdressing. Furthermore, the tobacco straw charcoal coating, as a colonization carrier, is conducive to the colonization of bacteria; in the present application, colonizing bacteria in the tobacco straw charcoal coating is conducive to improving the utilization efficiency of fertilizer nutrients, and the compound fertilizer masterbatch also plays a role in nutrient supply for the colonization of bacteria; through the mutual cooperation and synergy of the compound fertilizer masterbatch, the tobacco straw charcoal coating, and the bacteria, the effect of improving the fertilizer nutrient utilization rate and reducing the amount of fertilizer applied is achieved.

[0020] In some embodiments, the compound fertilizer masterbatch includes the following components in mass proportions: 6-10 parts of white phosphate fertilizer, 24-25 parts of ammonium nitrate phosphate, 16-17 parts of monoammonium phosphate, 3-5 parts of potassium sulfate, 7-8 parts of potassium chloride, 26-27 parts of potassium sulfate, 4-5 parts of magnesium sulfate heptahydrate, 3-4 parts of ammonium sulfate, 2-3 parts of magnesium sulfate monohydrate, 1-2 parts of borax pentahydrate, 1-2 parts of zinc sulfate monohydrate, and 4-5 parts of corn starch; the chemical composition of the tobacco straw charcoal coating is tobacco straw charcoal powder.

[0021] In the present application, the compound fertilizer masterbatch provides potassium, phosphorus and nitrogen elements as nutrients for growing tobacco, while corn starch plays a role in providing nutrients for bacterial colonization.

[0022] In some embodiments, the bacteria include one or more of phosphate-solubilizing bacteria and potassium-solubilizing bacteria.

[0023] The bacteria colonized in the carbon coating of tobacco straw in the present application are derived from fermentation of tobacco stalks.

[0024] In some embodiments, in the compound fertilizer masterbatch, the sum of the masses of the three elements N, P, and K is 40-60% of the total mass of the compound fertilizer masterbatch.

[0025] The present application provides a method for preparing an iron-aluminum modified carbon-based coated organic-inorganic slow-release microbial compound fertilizer, comprising the following steps: S1. The raw material components of the compound fertilizer masterbatch are crushed and mixed by mass, and steam is introduced for granulation to obtain a compound fertilizer masterbatch; S2. After mixing the compound fertilizer masterbatch with tobacco straw charcoal powder, coating the masterbatch to obtain a first coated compound fertilizer particle; S3. Spraying the polyvinyl alcohol aqueous solution on the coated compound fertilizer particles for reinforcement coating to obtain a second coated compound fertilizer particles; S4. The second coated compound fertilizer particles, mushroom bran, and tobacco waste fermentation residue are mixed and composted, and aerobic fermentation is performed to obtain the iron-aluminum modified carbon-based coated organic-inorganic slow-release microbial compound fertilizer.

[0026] In the present application, the raw material components of the compound fertilizer masterbatch are first granulated to obtain granular compound fertilizer masterbatch, and then the tobacco straw charcoal powder is wrapped on the surface of the compound fertilizer masterbatch by a coating machine, and then the tobacco straw charcoal powder is further reinforced on the compound fertilizer masterbatch with a polyvinyl alcohol aqueous solution as an adhesive to improve the tightness of the coating, and finally the bacteria are colonized in the tobacco straw charcoal coating through fermentation treatment; it is worth noting that during the aerobic fermentation process, the bacteria produce water to dissolve the corn starch in the compound fertilizer masterbatch, and the dissolved corn starch serves as a nutrient for the bacteria to accelerate the colonization of the bacteria.

[0027] The present application prepares a tobacco-specific carbon-based coated slow-release compound fertilizer according to the fertilizer requirement characteristics of tobacco during its growth process. The compound fertilizer contains abundant nitrogen, phosphorus, potassium and other macroelements necessary for wheat growth, and adds trace nutrients and beneficial elements such as calcium, magnesium, sulfur, zinc, iron, molybdenum and sodium. The compound fertilizer provides tobacco with a large amount of nutrients required for its growth by controlling the addition of tobacco straw charcoal powder as a coating. The porous structure of the tobacco straw charcoal powder has the characteristics of water and fertilizer retention, which can improve the utilization rate of the fertilizer. The biochar has bonding and adsorption properties, forming soil agglomerates, which is beneficial to provide a microenvironment for beneficial bacteria and meet their growth and development needs. The fertilizer in the soil can be kept released slowly and persistently. The fertilizer of the present application can release the nutrients slowly and persistently in combination with the growth characteristics and fertilizer requirements of tobacco, thereby extending the effective release period of the nutrients in the fertilizer, thereby meeting the nutrient needs of tobacco in the middle and late growth stages, making the absorption of nutrients by tobacco more comprehensive and balanced, improving the agronomic traits of tobacco, improving the quality and yield of tobacco, and at the same time improving the physical and chemical properties of the soil, such as pH, water retention, porosity, etc., and improving soil fertility. The fertilizer of the present application can be applied once as a base fertilizer to basically meet the nutrient needs of tobacco during the entire growth period, and has the advantages of saving labor and time and having a high fertilizer utilization rate.

[0028] In some embodiments, tobacco straw is placed in a reactor, the temperature is adjusted to 80°C, the stirring rod is adjusted to 200 rpm, and the sample is washed with water for 1 hour. After washing, the sample is filtered and dried in an oven at 80°C, and then the tobacco straw is pyrolyzed at 550-600°C in a nitrogen atmosphere. After passing through a 100-200 mesh sieve, the tobacco straw charcoal powder is obtained.

[0029] In some embodiments, the preparation method of the tobacco waste fermentation residue is: tobacco waste and biogas fermentation agent solution are mixed in a mass ratio of 4:1, and anaerobically fermented at a pH value of 6.5-7 to obtain the tobacco waste fermentation residue; the concentration of the biogas fermentation agent solution is 10-15wt%. The biogas fermentation agent solution is a commercially available methanogen solution. The bacterial bran contains one or more of phosphate-solubilizing bacteria and potassium-solubilizing bacteria.

[0030] In some embodiments, in step S4, the pH value of aerobic fermentation is 7-8.

[0031] At this pH value, the fermentation temperature rises quickly and the final temperature is high, which is conducive to the accelerated colonization of bacteria.

[0032] In some embodiments, the mass ratio of compound fertilizer masterbatch to tobacco straw charcoal powder is 1.5-2.5:1.

[0033] Under this dosage limit, tobacco straw charcoal powder can completely coat the coated compound fertilizer masterbatch, while excessive use of tobacco straw charcoal powder will cause waste.

[0034] The present application provides an application of an iron-aluminum modified carbon-based coated organic-inorganic slow-release microbial compound fertilizer in the field of tobacco cultivation.

[0035] The present solution is further described below through specific embodiments.

[0036] Raw material preparation The preparation method of tobacco straw charcoal powder is as follows: putting tobacco straw into a reactor, adjusting the temperature to 80°C, adjusting the stirring rod, the rotation speed to 200rpm, washing with water for 1h, filtering the sample after washing, drying it in an oven at 80°C, and then pyrolyzing the tobacco straw at 550°C under a nitrogen atmosphere, and passing it through a 100-mesh sieve to obtain the tobacco straw charcoal powder.

[0037] The preparation method of tobacco waste fermentation residue is: tobacco waste and biogas fermentation agent solution are mixed in a mass ratio of 4:1, and anaerobically fermented for 5 days at a pH value of 6.5 to obtain the tobacco waste fermentation residue; the biogas fermentation agent solution is a commercially available methanogen solution with a concentration of 10wt%.

[0038] The fungus bran contains phosphate-solubilizing bacteria and potassium-solubilizing bacteria in a mass ratio of 1:1.

[0039] The coating machine model is Maibang MB-300.

[0040] Example 1 A method for preparing an iron-aluminum modified carbon-based coated organic-inorganic slow-release microbial compound fertilizer comprises the following steps: S1. 10 parts of white phosphate fertilizer, 25 parts of ammonium nitrate phosphate, 17 parts of monoammonium phosphate, 5 parts of potassium sulfate, 8 parts of potassium chloride, 27 parts of potassium sulfate, 5 parts of magnesium sulfate heptahydrate, 4 parts of ammonium sulfate, 3 parts of magnesium sulfate monohydrate, 2 parts of borax pentahydrate, 2 parts of zinc sulfate monohydrate, 5 parts of corn starch filler are put into a raw material mixer and stirred evenly, and then the mixture is lifted to a crusher by an elevator and crushed, and then the mixture is transported to a granulator by a variable frequency belt conveyor, and mixed evenly at 45°C, the granulator speed is 50r / min, and hot steam is intermittently introduced for 2min / times to obtain a composite fertilizer masterbatch; S2. After the compound fertilizer masterbatch is cooled to 50°C, it is sieved and transported to the wrapped granulator via a variable frequency belt conveyor, and the tobacco straw charcoal powder is fed into the wrapped granulator according to 1 / 2 of the mass of the compound fertilizer masterbatch for coating to obtain the first coated compound fertilizer particles; S3. At the entrance of the coating granulator, a 5wt% aqueous solution of polyvinyl alcohol was sprayed (flow rate of 800ml / min, each spray for 1 second, sprayed twice per minute) on the coated compound fertilizer particles, the coating machine speed was 45r / min, the coating was reinforced at 45°C, and cooled to 30°C to obtain a second coated compound fertilizer granule; S4. The second coated compound fertilizer particles, mushroom bran, and tobacco waste fermentation residue are mixed and composted in a mass ratio of 10:1:10, and the pH is adjusted to 8. The compost is turned and ventilated continuously during the composting period. The compost is composted for 4 days and then dried to obtain an iron-aluminum modified carbon-based coated organic-inorganic slow-release microbial compound fertilizer.

[0041] The iron-aluminum modified carbon-based coated organic-inorganic slow-release microbial compound fertilizer obtained by the preparation method comprises compound fertilizer masterbatch and a tobacco straw charcoal coating wrapped in the compound fertilizer masterbatch; the tobacco straw charcoal coating is colonized with bacteria.

[0042] Example 2 A method for preparing an iron-aluminum modified carbon-based coated organic-inorganic slow-release microbial compound fertilizer comprises the following steps: S1. 6 parts of white phosphate fertilizer, 24 parts of ammonium nitrate phosphate, 16 parts of monoammonium phosphate, 3 parts of potassium sulfate, 7 parts of potassium chloride, 26 parts of potassium sulfate, 4 parts of magnesium sulfate heptahydrate, 3 parts of ammonium sulfate, 2 parts of magnesium sulfate monohydrate, 1 part of borax pentahydrate, 1 part of zinc sulfate monohydrate, 4 parts of corn starch filler are put into a raw material mixer and stirred evenly, and then the mixture is lifted to a crusher by an elevator and crushed, and then the mixture is transported to a granulator by a variable frequency belt conveyor, and mixed evenly at 80°C, the granulator speed is 30r / min, and hot steam is intermittently introduced to obtain a composite fertilizer masterbatch; S2. After the compound fertilizer masterbatch is cooled to 40°C, it is sieved and transported to the wrapped granulator via a variable frequency belt conveyor, and the tobacco straw charcoal powder is fed into the wrapped granulator according to 1 / 2 of the mass of the compound fertilizer masterbatch for coating to obtain the first coated compound fertilizer particles; S3. At the entrance of the coating granulator, a 5wt% aqueous solution of polyvinyl alcohol was sprayed on the coated compound fertilizer particles. The coating speed of the coating machine was 25r / min, and the coating was reinforced at 45°C and cooled to 20°C to obtain a second coated compound fertilizer granule. S4. The second coated compound fertilizer particles, mushroom bran, and tobacco waste fermentation residue are mixed and composted in a mass ratio of 10:1:10, and the pH is adjusted to 7. The compost is turned and ventilated continuously during the composting period. The compost is composted for 3 days and then dried to obtain an iron-aluminum modified carbon-based coated organic-inorganic slow-release microbial compound fertilizer.

[0043] The iron-aluminum modified carbon-based coated organic-inorganic slow-release microbial compound fertilizer obtained by the preparation method comprises compound fertilizer masterbatch and a tobacco straw charcoal coating wrapped in the compound fertilizer masterbatch; the tobacco straw charcoal coating is colonized with bacteria.

[0044] Comparative Example 1 A method for preparing fertilizer, the other contents of which are the same as those of Example 1, except that the method does not include coating the tobacco straw with a charcoal coating, that is, does not include step S2.

[0045] Comparative Example 2 A method for preparing a fertilizer, the other contents of which are the same as those of Example 1, except that spraying of a polyvinyl alcohol aqueous solution is not included, that is, step S3 is not included.

[0046] Comparative Example 3 A method for preparing a fertilizer, the other contents of which are the same as those of Example 1, except that the method does not include a bacterial colonization step, that is, does not include step S4.

[0047] Comparative Example 4 A method for preparing fertilizer, the other contents are the same as those of Example 1, except that corn starch is not added in step S1.

[0048] Test and Evaluation The fertilizers obtained in Example 1 and Comparative Examples 1-4 were applied before tobacco sowing. The fertilization method was: one-time furrow application of 4.2 kg / row, 20 plants / row, ploughing and covering with soil, mixing evenly, filling with water, covering with mulch film, and punching holes to transplant Yunyan 87.

[0049] The effects of different fertilizers on agronomic traits of field tobacco were tested, and the results are shown in Table 1.

[0050] Table 1 Effects of different fertilizer treatments on agronomic traits of field tobacco

[0051] It can be seen from Table 1 that for 87 types of tobacco tested in Yunyan, the average plant height, leaf length, leaf width and stem girth of the tobacco increased significantly after the fertilizer of the present application was applied.

[0052] The fertilizers obtained in Example 1 and Comparative Examples 1-4 were tested for slow-release lysozyme effect, and the test process was as follows: A 1L empty plastic bottle with a height of 23.2cm and an inner diameter of 8.4cm was selected as the elution device. To prevent the soil in the column from flowing out into the filtrate during the elution process, a 200-mesh gauze was wrapped around the mouth of the empty plastic bottle, and a conical bottle was used to receive the elution. No fertilizer was added to the control group CK, and 10 grams of slow-release fertilizer and 5 grams of tobacco-specific fertilizer were added to the others to ensure that the nitrogen, phosphorus and potassium contents were roughly the same. 80g of quartz sand (2cm thick) and 500g of air-dried and sieved soil were added to each soil column in turn. To prevent the soil layer from being disturbed, 80g of quartz sand was added on top to cover it.

[0053] After the soil column was made, distilled water was added to saturate the soil water content. The soil in the column was left for 24 hours to balance and stabilize. After 1, 3, 5, and 7 days, 200 mL of deionized water was added to each soil column for leaching. The leached solution was transferred to a 250 ml volumetric flask, water was added to the volume, and the total nitrogen, total phosphorus, total potassium and other indicators were tested by flow analyzer and flame photometer. The results are shown in Table 2-4. The more balanced the single nutrient leaching rate of nitrogen, potassium and phosphorus is, the better the slow-release effect is. The lower the single nutrient leaching rate of nitrogen, potassium and phosphorus is, the better the slow-release effect is.

[0054] Table 2 Nitrogen cumulative leaching rate (%)

[0055] Table 3 Cumulative leaching rate of potassium and nitrogen (%)

[0056] Table 4 Cumulative leaching rate of phosphorus and nitrogen (%)

[0057] It can be seen from Tables 2-4 that the fertilizer of the present application has the most balanced single nutrient leaching rates of nitrogen, potassium and phosphorus, and the lowest single nutrient leaching rates of nitrogen, potassium and phosphorus, indicating that the slow-release effect is the best.

[0058] The nutrient release rates of the fertilizers obtained in Example 1 and Comparative Examples 1-4 were tested as follows: Select 5 1000ml conical flasks, add the fertilizers obtained in Example 1 and Comparative Examples 1-4 respectively, and adjust the addition amount to ensure that the total content of nitrogen, phosphorus and potassium in each fertilizer is the same. Stand for 24 hours, sample 1ml respectively, and use flow analyzer and flame photometer to detect total nitrogen, total phosphorus, total potassium and other indicators. After 27 days, sample 1ml again, and use flow analyzer and flame photometer to detect total nitrogen, total phosphorus, total potassium and other indicators. After that, sample 1ml every 5 days and send samples for detection. The results are shown in Table 5.

[0059] Table 5 Nutrient release rate test results

[0060] It can be seen from Table 5 that the fertilizer of the present application meets the requirement that the slow-release fertilizer nutrient release rate is less than 15%. On the 28th day, it meets the requirement that the cumulative nutrient release rate is less than 80%, and on the 38th day, it meets the requirement that the cumulative release rate during the nutrient release period is greater than 80%. The slow-release effect is good, and the nutrient release is sufficient.

[0061] The improvement effect of the fertilizers obtained in Example 1 and Comparative Examples 1-4 on the soil pH value was tested as follows: 5 50 ml conical flasks were selected, 10 g of field soil (pH value was 5.2) was taken respectively, 25 ml of distilled water was added, and the fertilizers obtained in Example 1 and Comparative Examples 1-4 were added respectively, and the nitrogen, phosphorus and potassium contents were ensured to be the same. A magnetic stirrer was used to fully and evenly stir for 2 minutes, and then allowed to stand for 30 minutes, and 5 ml of the supernatant was taken to measure the pH. The results are shown in Table 6.

[0062] Table 6 Effect of different fertilizers on soil pH improvement

[0063] It can be seen from Table 6 that the fertilizer of the present application has a good effect on improving soil pH.

[0064] The present application prepares a tobacco-specific carbon-based coated slow-release compound fertilizer according to the fertilizer requirement characteristics of tobacco during its growth process. The compound fertilizer contains abundant nitrogen, phosphorus, potassium and other macroelements necessary for tobacco growth, with particular emphasis on the addition of potassium, and covers trace nutrients and beneficial elements such as calcium, magnesium, sulfur, zinc, iron, molybdenum and sodium. The compound fertilizer forms a coating structure by controlling the addition of tobacco straw charcoal powder, thereby achieving a slow-release effect of the fertilizer. The tobacco straw charcoal powder not only provides wheat with the nutrients it needs for its growth, but also has the characteristics of water and fertilizer retention due to its porous structure, which can increase the utilization rate of the fertilizer to 35%. About, wherein polyvinyl alcohol is water-soluble, which is conducive to the gradual melting of the coating structure, tobacco straw charcoal powder fully absorbs large, medium and trace elements such as nitrogen, phosphorus and potassium, and can keep the fertilizer in the soil slowly and persistently released, the fertilizer requirement characteristics of tobacco show that coordinating and meeting the demand for nutrients of tobacco is a key measure to promote tobacco production increase, and the yield of tobacco and the content of soil nutrients are extremely significantly positively correlated, the present application can combine the growth characteristics of tobacco and the fertilizer requirement law to release the nutrient elements slowly and persistently, so that the effective release period of nutrients in the fertilizer is extended, thereby meeting the demand for nutrients in the middle and late stages of tobacco growth, making tobacco's absorption of nutrients more comprehensive and balanced, thereby improving the quality and yield of tobacco, and at the same time, tobacco straw charcoal powder improves soil physical and chemical properties, acidity and alkalinity, increases soil organic matter, fertilizes soil fertility, and improves microbial characteristics. The present application is applied as a base fertilizer once and can basically meet the demand for nutrients of tobacco throughout the growth period, with the advantages of saving labor, saving time and high fertilizer utilization rate.

[0065] The above are only preferred specific implementations of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. An iron-aluminum modified carbon-based coated organic-inorganic slow-release microbial compound fertilizer, characterized in that: The invention comprises a compound fertilizer masterbatch and a tobacco straw charcoal coating wrapped in the compound fertilizer masterbatch; the tobacco straw charcoal coating is colonized with bacteria.

2. The iron-aluminum modified carbon-based coated organic-inorganic slow-release microbial compound fertilizer according to claim 1, characterized in that: The compound fertilizer masterbatch comprises the following components in mass proportions: 6-10 parts of white phosphate fertilizer, 24-25 parts of ammonium nitrate phosphate, 16-17 parts of monoammonium phosphate, 3-5 parts of potassium sulfate, 7-8 parts of potassium chloride, 26-27 parts of potassium sulfate, 4-5 parts of magnesium sulfate heptahydrate, 3-4 parts of ammonium sulfate, 2-3 parts of magnesium sulfate monohydrate, 1-2 parts of borax pentahydrate, 1-2 parts of zinc sulfate monohydrate, and 4-5 parts of corn starch; the chemical composition of the tobacco straw charcoal coating is tobacco straw charcoal powder.

3. The iron-aluminum modified carbon-based coated organic-inorganic slow-release microbial compound fertilizer according to claim 1, characterized in that: The bacteria include one or more of phosphate-solubilizing bacteria and potassium-solubilizing bacteria.

4. The iron-aluminum modified carbon-based coated organic-inorganic slow-release microbial compound fertilizer according to claim 1, characterized in that: In the compound fertilizer masterbatch, the sum of the masses of the three elements N, P and K is 40-60% of the total mass of the compound fertilizer masterbatch.

5. A method for preparing the iron-aluminum modified carbon-based coated organic-inorganic slow-release microbial compound fertilizer according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1. The raw material components of the compound fertilizer masterbatch are crushed and mixed by mass, and steam is passed through the masterbatch to obtain a compound fertilizer masterbatch; S2. After mixing the compound fertilizer masterbatch with tobacco straw charcoal powder, coating the masterbatch to obtain a first coated compound fertilizer particle; S3. Spraying the polyvinyl alcohol aqueous solution on the coated compound fertilizer particles for reinforcement and coating treatment to obtain a second coated compound fertilizer particles; S4. The second coated compound fertilizer particles, mushroom bran, and tobacco waste fermentation residue are mixed and composted, and aerobic fermentation is performed to obtain the iron-aluminum modified carbon-based coated organic-inorganic slow-release microbial compound fertilizer.

6. The preparation method according to claim 5, characterized in that: The preparation method of tobacco straw charcoal powder is as follows: in a nitrogen atmosphere, the tobacco straw is pyrolyzed at 550-600° C., and the charcoal powder is obtained after passing through a 100-200 mesh sieve.

7. The preparation method according to claim 5, characterized in that: The preparation method of the tobacco waste fermentation residue is as follows: tobacco waste and a biogas fermentation agent solution are mixed in a mass ratio of 4:1, and anaerobically fermented at a pH value of 6.5-7 to obtain the tobacco waste fermentation residue; the concentration of the biogas fermentation agent solution is 10-15wt%.

8. The preparation method according to claim 5, characterized in that: In step S4, the pH value of the aerobic fermentation is 7-8; and the bacterial bran contains one or more of phosphate-solubilizing bacteria and potassium-solubilizing bacteria.

9. The preparation method according to claim 5, characterized in that: The mass ratio of the compound fertilizer masterbatch to the tobacco straw charcoal powder is 1.5-2.5:

1.

10. Use of the iron-aluminum modified carbon-based coated organic-inorganic slow-release microbial compound fertilizer obtained by the preparation method according to any one of claims 5 to 9 in the field of tobacco cultivation.

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