Preparation method of modified water chestnut shell biochar-based organic slow-release fertilizer

Abstract

The preparation method of the modified water chestnut shell biochar-based organic slow-release fertilizer comprises the following steps: S1, preparing modified biochar, taking a proper amount of water chestnut shells, washing with distilled water, drying, screening with a mesh screen, adding a potassium ferrate-potassium oxalate composite activator, fully stirring in pure water for 30-60 minutes, and drying in a drying box to obtain the modified biochar; grinding and sieving with a 100-mesh sieve to obtain modified charcoal; s2, preparing a fermented organic fertilizer, namely selecting a manure fermentation inoculant, adding dry cow dung and a microbial inoculant in proportion, then adding a proper amount of water to obtain a mixture, and continuously fermenting the mixture at a certain temperature for a period of time to obtain the fermented organic fertilizer; s3, preparing the biochar-based slow-release fertilizer, namely mixing the modified biochar, the fermented organic fertilizer and montmorillonite, adding the mixture into a disc granulator, granulating, slowly adding tap water into the disc granulator, stopping adding the tap water after obvious particles appear, and running the granulator for a period of time to obtain the granular biochar-based slow-release fertilizer.

Description

Technical Field

[0001] The invention relates to the preparation of organic fertilizer, and in particular to a method for preparing modified water chestnut shell biochar-based organic slow-release fertilizer. Background Art

[0002] Biochar is a high-quality soil conditioner with high nutritional value and large-area pore structure, which can effectively adsorb various substances. Adding biochar to the soil can enhance the activity of soil microorganisms and the exchange capacity of ions, and reduce nutrient loss and water pollution. Biochar plays an important role in improving fertilizer efficiency, reducing nutrient and pesticide loss and residues in the soil, and preventing the accumulation of harmful substances such as heavy metals. When applied to the soil, it can significantly improve the soil environment and increase the capacity of the stable carbon pool in the soil. It is an excellent soil conditioner and fertilizer. The synergistic application of biochar and nitrogen fertilizer has a significant effect on the migration and conversion rules of nitrogen fertilizer in the soil, nitrogen fertilizer utilization rate and crop yield.

[0003] Water chestnut is a common aquatic herbaceous fruit in the waters of northern and southern my country, but its shell is discarded during processing, polluting the environment and wasting resources. The main component of water chestnut shell is carbon-rich organic matter, which is the raw material for producing high-quality biochar.

[0004] Organic fertilizers can increase crop yields, fertilize the soil, improve the quality of crops, and ensure the sustainable and stable development of agricultural production. The organic nitrogen, phosphorus, amino acids, and nucleic acids produced by organic fertilizers in the soil can significantly increase the content of protein, sugar, vitamins, and aromatic substances in food, and increase the dry matter proportion of fresh food, thereby improving food quality, flavor, and storage resistance, and significantly improving color and appearance. Various vegetables, fruits, and grains produced with organic fertilizers are very popular among the public because of their excellent food quality and safety, but because of their high prices, not everyone can enjoy their high quality.

[0005] Organic fertilizers are more expensive than chemical fertilizers, mainly because (i) the raw materials of organic fertilizers are not fully utilized. According to surveys, the utilization rate is about less than 65%; (ii) the composting and harmless treatment technology of organic fertilizers is incomplete, which takes up a lot of land and the investment cost of new technologies is high; (iii) the quality of fertilizers cannot be guaranteed and the economic benefits are not obvious. In addition, during the application process, it is easy to lose, which increases its use cost.

[0006] So how to solve the problem of resource utilization and reduce loss? Biochar-based slow-release fertilizer came into being. It can not only slow down fertilizer waste, but also maintain nutrients for a long time. It can also improve soil aggregate structure through the effect of biochar, thus achieving a win-win measure of resource utilization and high-quality fertilizer preparation. It is of great significance to the modern agricultural ecological cycle.

[0007] Currently, there are patents that disclose the preparation method of biochar-based slow-release fertilizers, but the slow-release effect is not high, the fertilizer effect is generally maintained for a general period of time, and when too much is added, root burn may occur. Summary of the invention

[0008] The invention aims to prepare a modified water chestnut shell biochar-based organic slow-release fertilizer.

[0009] The method for preparing a modified water chestnut shell biochar-based organic slow-release fertilizer of the present invention comprises the following steps:

[0010] S1: Prepare modified biochar, take an appropriate amount of water chestnut shells, wash with distilled water, dry in a drying oven at 60°C to constant weight, grind through a 50-mesh sieve after cooling, add potassium ferrate-potassium oxalate composite activator, stir thoroughly in pure water for 30-60 minutes, and then dry in a drying oven to obtain a mixture, transfer the mixture to a tubular furnace, heat to 673K ​​at a heating rate of 10K / min under a nitrogen atmosphere, keep for 1 hour, cool, take out and wash to neutrality, soak in nitrogen and phosphorus-containing river water for a period of time, put in a drying oven to dry, grind through a 100-mesh sieve to obtain modified biochar;

[0011] S2: preparing fermented organic fertilizer, selecting feces fermentation agent, adding dry cow dung and microbial agent in proportion, adding an appropriate amount of water to obtain a mixture, and fermenting the mixture for a period of time at a certain temperature to obtain fermented organic fertilizer;

[0012] S3: Prepare biochar-based slow-release fertilizer, mix modified biochar, fermented organic fertilizer and montmorillonite, add the mixture into a disc granulator for granulation, and slowly add tap water into the disc granulator at the same time. Stop adding tap water after obvious particles appear, and let the granulator run for a while to obtain granular biochar-based slow-release fertilizer.

[0013] In a specific embodiment, in step S1, the nitrogen and phosphorus contents of the river water are 3.10-4.20 mg / L and 0.44-0.56 mg / L respectively, the soaking time is 24 hours, the drying temperature is 55-65 degrees, and the sieving is 60-80 mesh.

[0014] In a specific embodiment, in step S2, the ratio of dry cow dung to microbial agent is 1:1-2, the moisture content is 63-67%, the fermentation temperature is above 25 degrees, and the fermentation days are 4-6 days.

[0015] In a specific embodiment, the content of modified biochar is 15-25%, the content of dry cow dung is 70-60%, the content of montmorillonite is 15%, the granulator runs for 4-6 minutes, and the number of repetitions is 8-9 times.

[0016] Beneficial effects:

[0017] 1. The biochar-based slow-release fertilizer of the present invention adopts multiple wrapping during granulation, which can effectively prevent the release of nutrients, and pre-absorb nitrogen and phosphorus on the modified water chestnut shell biochar, which can increase its nutritional content, and can also remove part of the nitrogen and phosphorus in the water, thereby improving the nutrients of the organic fertilizer and reducing the nitrogen and phosphorus content in the water.

[0018] 2. The use of commercially available manure fermentation agents is more conducive to the operation of the fermentation process, increasing the effective fertilizer content in cow dung and increasing soil fertility.

[0019] 3. The modified water chestnut shell biochar-based organic slow-release fertilizer prepared by the present invention is environmentally friendly and green, has a long slow-release time, and has a good fertilizer retention effect. It also improves the soil water holding capacity, soil aggregate structure, and the microecological environment of the roots. It is granular, convenient for fertilization, and easy to control. DETAILED DESCRIPTION

[0020] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be understood as limiting the present invention.

[0021] In the description of the present invention, it should be understood that the terms "center", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "counterclockwise", "clockwise", "axial", "radial", "circumferential" and the like indicating positions or positional relationships are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0022] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection, it can be a direct connection, it can be an indirect connection through an intermediate medium, and it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0023] Example 1

[0024] A method for preparing modified water chestnut shell biochar-based organic slow-release fertilizer comprises the following steps:

[0025] ①. Biochar pretreatment: add a certain amount of biochar into nitrogen and phosphorus-rich river water above the surface of the biochar and soak it for 24 hours, dry it at a constant temperature of about 65 degrees, crush it and pass it through a 60-80 mesh sieve for standby use.

[0026] ②. Cow dung fermentation: add cow dung and fermentation agent into a black insulation bag at a ratio of 1:1 (kg:mL), add appropriate amount of water and place it in an ambient temperature above 25 degrees to ensure the fermentation temperature and microbial activity. The fermentation time is 5 days, and stir regularly every day.

[0027] 3. Granulation of slow-release fertilizer: weigh 315g of fermented cow dung, 67.5g of montmorillonite, and 67.5g of modified water chestnut shell biochar, mix them evenly, pour them into the granulator, turn it to gear 6, slowly add a little bit of water, stop adding water when granules appear, continue running for 5 minutes, complete granulation, and bag.

[0028] Example 2

[0029] A method for preparing modified water chestnut shell biochar-based organic slow-release fertilizer comprises the following steps:

[0030] (1) Biochar pretreatment, same as step ① in Example 1.

[0031] (2) Cow dung fermentation, same as step ② in Example 1.

[0032] (3) Granulation of slow-release fertilizer: weigh 292.5 g of fermented cow dung, 67.5 g of montmorillonite, and 90 g of modified water chestnut shell biochar, mix them evenly, pour them into the granulator, turn it to gear 6, slowly add a little bit of water, stop adding water when granules appear, continue running for 5 minutes, complete granulation, and bag.

[0033] Example 3

[0034] ① Biochar pretreatment, same as ① in Example 1.

[0035] ② Cow dung fermentation, same as ② in Example 1.

[0036] ③ Weigh 270g of fermented cow dung, 67.5g of montmorillonite, and 112.5g of modified water chestnut shell biochar, mix them evenly, pour them into the granulator, turn it to gear 6, slowly add a little bit of water, stop adding water when granules appear, continue running for 5 minutes, complete granulation, and bag.

[0037] Example 4

[0038] A method for preparing modified water chestnut shell biochar-based organic slow-release fertilizer comprises the following steps:

[0039] ① Biochar pretreatment, same as ① in Example 1.

[0040] ② Cow dung fermentation: Add cow dung and fermentation agent into a black insulation bag at a ratio of 1:1.5 (kg:mL), add appropriate amount of water and place it in an ambient temperature above 25 degrees to ensure the fermentation temperature and microbial activity. The fermentation time is 5 days, and stir regularly every day.

[0041] ③ Granulation of slow-release fertilizer, the steps are the same as those in step ③ of Example 1.

[0042] Example 5

[0043] A method for preparing modified water chestnut shell biochar-based organic slow-release fertilizer comprises the following steps:

[0044] ① Biochar pretreatment, same as ① in Example 1.

[0045] ② Cow dung fermentation: Add cow dung and fermentation agent into a black insulation bag at a ratio of 1:2 (kg:mL), add appropriate amount of water and place it in an ambient temperature above 25 degrees to ensure the fermentation temperature and microbial activity. The fermentation time is 5 days, and stir regularly every day.

[0046] ③ Granulation of slow-release fertilizer, the steps are the same as those in step ③ of Example 1.

[0047] Pot test

[0048] The soil for the potted test was taken from a vegetable field in Tinghu, Yancheng, Jiangsu, where Chinese cabbage was grown. The basic properties of the test soil are shown in Table 1.

[0049] Table 1 Basic properties of the tested soil

[0050] project parameter pH 7.38 Organic matter (g / kg) 20.91 Cation exchange capacity (cmol / kg) 17.86 Available phosphorus (mg / kg 38.66 Total phosphorus (g / kg) 3.24 Potassium (g / kg) 11.4

[0051] Six treatments were set up in the pot experiment. Treatment 1 was applied with cow dung, and treatments 2-6 were applied with the rice straw-based organic slow-release fertilizer of Examples 1-5. Each treatment was repeated 3 times.

[0052] In treatments 1-6, each fertilizer was added at 3% and mixed thoroughly with the soil in the pot.

[0053] When planting Chinese cabbage, 15 seeds were planted in each pot and cultivated for 20 days. The effects on germination rate, plant height, biomass, etc. were compared (see Table 2).

[0054] Table 2 Seedling rate and quality of Chinese cabbage under different treatments

[0055] Seedling rate (%) Plant height (cm) Biomass (dry weight, g) Process 1 75 6.1 7.45 Process 2 93 8.2 10.09 Process 3 83 6.8 8.74 Process 4 85 6.9 8.06 Process 5 84 7.1 8.89 Process 6 100 9.3 14.32

[0056] As shown in Table 2, the germination rate of implementation 1 of the present invention is lower than that of treatments 2-6, and the plant height and biomass are also lower than those of biochar-based organic slow-release fertilizers. Treatment 6 has the best effect, indicating that the granular organic fertilizer with a large amount of fermentation bacteria and fertilizer has a long fertility retention time and a good release effect.

[0057] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a modified water chestnut shell biochar-based organic slow-release fertilizer, comprising the following steps: S1: Prepare modified biochar, take an appropriate amount of water chestnut shells, wash with distilled water, dry in a drying oven at 60°C to constant weight, grind through a 50-mesh sieve after cooling, add potassium ferrate-potassium oxalate composite activator, stir thoroughly in pure water for 30-60 minutes, and then dry in a drying oven to obtain a mixture, transfer the mixture to a tubular furnace, heat to 673K ​​at a heating rate of 10K / min under a nitrogen atmosphere, keep for 1 hour, cool, take out and wash to neutrality, soak in nitrogen and phosphorus-containing river water for a period of time, put in a drying oven to dry, grind through a 100-mesh sieve to obtain modified biochar; S2: preparing fermented organic fertilizer, selecting feces fermentation agent, adding dry cow dung and microbial agent in proportion, adding an appropriate amount of water to obtain a mixture, and fermenting the mixture for a period of time at a certain temperature to obtain fermented organic fertilizer; S3: Prepare biochar-based slow-release fertilizer, mix modified biochar, fermented organic fertilizer and montmorillonite, add the mixture into a disc granulator for granulation, and slowly add tap water into the disc granulator at the same time. Stop adding tap water after obvious particles appear, and let the granulator run for a while to obtain granular biochar-based slow-release fertilizer.

2. The method for preparing a modified water chestnut shell biochar-based organic slow-release fertilizer according to claim 1, characterized in that: In step S1, the nitrogen and phosphorus contents of the river water are 3.10-4.20 mg / L and 0.44-0.56 mg / L respectively, the soaking time is 24 hours, the drying temperature is 55-65 degrees, and the sieving is 60-80 mesh.

3. The method for preparing a modified water chestnut shell biochar-based organic slow-release fertilizer according to claim 1, characterized in that: In step S2, the ratio of dry cow dung to microbial agent is 1:1-2, the moisture content is 63-67%, the fermentation temperature is above 25 degrees, and the fermentation days are 4-6 days.

4. The method for preparing a modified water chestnut shell biochar-based organic slow-release fertilizer according to claim 1, characterized in that: The content of modified biochar is 15-25%, the content of dry cow dung is 70-60%, the content of montmorillonite is 15%, the granulator operation time is 4-6 minutes, and the number of repetitions is 8-9 times.