A humic acid-based water-soluble fertilizer for rapid improvement of albic soil

Abstract

The present invention discloses a humic acid-based water-soluble fertilizer for rapid improvement of albic soil. The raw materials containing humic acid are crushed and impurities are removed to obtain pretreated raw materials. The pretreated raw materials are mixed with water to obtain a mixed solution, an alkali containing sodium is added, heated and stirred for reaction, and after the reaction, solid-liquid separation is carried out to obtain a sodium humate solution; a silane coupling agent is added to the solution containing humic acid, heated and stirred, and then tannic acid and lecithin are respectively added dropwise under insulation. After the addition is completed, the reaction continues to obtain a humic acid solution. The humic acid solution of the present invention can achieve rapid lateral and longitudinal diffusion in albic soil along with water, and can effectively penetrate the soil plough layer and directly act on the underlying albic region. Using the humic acid solution, a humic acid-based water-soluble fertilizer is prepared, which realizes targeted repair of albic soil while providing sufficient nutrients for plant growth, providing strong support for the sustainable development of agricultural production.

Description

Technical Field

[0001] The present invention relates to the technical field of soil improvement, and particularly relates to a humic acid-based water-soluble fertilizer for rapid improvement of albic soil. Background Art

[0002] Albic soil is one of the soil types widely distributed in Northeast China and is a typical low-yield obstacle soil. Its soil profile can be divided into four categories, namely, humus layer, albic layer, illuvial layer, and parent material layer (Dai Lin, 2017). The albic layer with strong albification is characterized by typical silt and flaky structures. Due to its soil compaction, poor permeability, intolerance to drought and waterlogging, low soil organic carbon content, poor crop yield and quality, the average yield reduction is 20% (Yang Song et al., 2020; Zhang Xu, 2021), which seriously affects the sustainable development of agriculture in Northeast China. Soil is a precious non-renewable resource. In order to meet the growing demand of the population for food yield and quality and achieve the sustainable development of agriculture, it is necessary to repair and improve the obstacle albic soil and improve soil quality (Sun Qiang, 2020).

[0003] The main difficulties faced in the repair and improvement of albic soil are as follows: (1) Hard albic layer. The most significant feature of albic soil is that it contains a hard albic layer. This layer of soil has a heavy texture, poor air permeability and water permeability, which hinders the penetration of crop roots and the absorption of deep nutrients. Therefore, how to effectively transform this albic layer is the key to improving albic soil; (2) Low nutrient content. The plough layer of albic soil is shallow, the nutrient content is low, and it contains more toxic substances, such as excessive aluminum and manganese, etc., which will affect the normal growth of crops. Therefore, improving soil fertility and increasing nutrient content are important tasks for improving albic soil; (3) Poor drought and waterlogging tolerance. The water retention and drainage properties of albic soil are both poor, resulting in the soil being easily drought or waterlogged, thus affecting the growth of crops. Therefore, during the improvement process, it is necessary to enhance the water storage and moisture retention function of the soil and improve the physical properties of the soil; (4) Long improvement cycle. The formation of soil is a long process, and improving soil also requires a certain amount of time. For obstacle soils such as albic soil, its improvement is more difficult and significant effects can only be achieved through long-term efforts.

[0004] At present, the main improvement measures for albic soil are: straw returning for improvement, organic fertilizer improvement, and biochar improvement, etc. However, after the straw is applied to the soil, the degradation time is long and it is difficult to quickly provide nutrients; the fertilizer efficiency of organic fertilizer itself is low, and it needs to be applied simultaneously with chemical fertilizer to obtain better effects; biochar is a more suitable improvement material, but its preparation cost is high and it is difficult to recover the cost in actual application. Therefore, it is still necessary to develop measures for rapid improvement of albic soil. Summary of the Invention

[0005] In view of the above prior art, the object of the present invention is to provide a humic acid-based water-soluble fertilizer for rapid improvement of albic soil. The present invention first prepares a humic acid solution, which can rapidly diffuse horizontally and vertically in the albic soil along with water, can effectively penetrate the plough layer of the soil and directly act on the underlying albic area, realizing the targeted repair of the albic soil. The present invention also prepares a humic acid-based water-soluble fertilizer for rapid improvement of albic soil by using this humic acid solution, providing sufficient nutrients for plant growth while realizing the targeted repair of the albic soil. Using the humic acid-based water-soluble fertilizer to improve albic soil not only simplifies and saves the investment in large machinery, but also can solve the problem of albic soil from the source, providing strong support for the sustainable development of agricultural production.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] In the first aspect of the present invention, a humic acid solution is provided, and the preparation method of the humic acid solution is as follows:

[0008] Add a silane coupling agent to the solution containing humic acid, heat and stir, and then dropwise add tannic acid and lecithin respectively under insulation. After the dropping is completed, continue the reaction to obtain a humic acid solution.

[0009] Preferably, the solution containing humic acid is a sodium humate solution, and its preparation method is as follows:

[0010] Crush the raw material containing humic acid and remove impurities to obtain a pretreated raw material. Mix the pretreated raw material with water to obtain a mixed solution, add an alkali containing sodium, heat and stir to react, and perform solid-liquid separation after the reaction to obtain a sodium humate solution.

[0011] Preferably, the mass ratio of the pretreated raw material to water is 1:1.4; the alkali containing sodium is a NaOH solution or a Na2CO3 solution, and the mass concentration of the NaOH solution or the Na2CO3 solution > 95%; the mass ratio of the alkali containing sodium to the mixed solution is 1:5.

[0012] Preferably, the raw material containing humic acid is weathered coal or lignite; the heating temperature is 30 - 35 °C; the stirring reaction time is 30 - 40 min.

[0013] Preferably, the heating and stirring temperature is 50 - 70 °C, the time is 10 - 30 min; the continued reaction time is 10 - 30 min.

[0014] Preferably, the mass ratio of the solution containing humic acid, the silane coupling agent, tannic acid and lecithin is 100:5 - 10:2 - 4:2 - 4.

[0015] Preferably, the silane coupling agent is KH560; the dropping rate is 1-3 mL / min.

[0016] In the second aspect of the present invention, there is provided an application of a humic acid solution in quickly infiltrating albic soil or preparing a humic acid-based water-soluble fertilizer.

[0017] In the third aspect of the present invention, there is provided a humic acid-based water-soluble fertilizer for quickly improving albic soil, and the humic acid-based water-soluble fertilizer contains the above-mentioned humic acid solution.

[0018] Preferably, the humic acid-based water-soluble fertilizer further contains the following raw materials:

[0019] 145-170 g / L of urea, 115-155 g / L of monoammonium phosphate, 95-115 g / L of potassium chloride, 0.5-1.5 g / L of zinc sulfate, 0.5-1.5 g / L of ferrous sulfate, 0.5-1.5 g / L of manganese sulfate, 0.5-1.5 g / L of copper sulfate, 0.5-2 g / L of rare earth elements, 0.5-1.5 g / L of defoaming agent, 1.0-6.5 g / L of thickener.

[0020] Advantages of the present invention:

[0021] (1) In the present invention, tannic acid and lecithin are used to improve the horizontal and vertical diffusion of the sodium humate solution in the soil quickly, and the tannic acid and lecithin are coupled with the sodium humate solution through a silane coupling agent, further improving the infiltration rate of the sodium humate solution in albic soil.

[0022] (2) The present invention uses the humic acid solution to prepare a humic acid-based water-soluble fertilizer for quickly improving albic soil, realizing the targeted repair of albic soil; at the same time, providing sufficient nutrients for plant growth. This method of improving albic soil not only simplifies and saves the investment in large machinery, but also can solve the problem of albic soil from the source, providing strong support for the sustainable development of agricultural production. Description of the drawings

[0023] Figure 1 : Schematic diagram of one-dimensional vertical infiltration test;

[0024] Figure 2 : Schematic diagram of one-dimensional horizontal suction infiltration test;

[0025] Figure 3 : Influence of each group of humic acid solutions on the wetting front in the vertical direction;

[0026] Figure 4 : Influence of each group of humic acid solutions on the wetting front in the horizontal direction;

[0027] Figure 5 : Comparison of soil porosity of each group of humic acid-based water-soluble fertilizers

[0028] Figure 6 : Comparison of soil bulk density of each group of humic acid water-soluble fertilizers;

[0029] Figure 7 : Comparison of soil organic matter of each group of humic acid water-soluble fertilizers. Detailed implementation manners

[0030] It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs.

[0031] As introduced in the background art section, the main difficulties faced in the remediation and improvement of albic soil are as follows: the hard albic layer. The most significant feature of albic soil is that it contains a hard albic layer. This layer of soil has a heavy texture, is airtight and water-impermeable, which hinders the penetration of crop roots and the absorption of deep nutrients. Therefore, the key to improving albic soil lies in the ability of the amendment to achieve rapid lateral and longitudinal diffusion in albic soil. However, the current improvement measures for albic soil mainly include straw returning, organic fertilizer amendment, and biochar amendment, etc., all of which cannot achieve rapid penetration or rapid diffusion.

[0032] Based on this, the object of the present invention is to provide a humic acid-based water-soluble fertilizer for rapid improvement of albic soil. The present invention first prepares a humic acid solution, and uses a sodium humate solution to couple tannic acid and lecithin to obtain a humic acid solution that can rapidly penetrate and diffuse. Although both tannic acid and lecithin have the function of surfactants, which can reduce the surface tension of the liquid, improve the wettability of the liquid and the emulsion stability; not all surfactants that can reduce the surface tension of the liquid, improve the wettability of the liquid and the emulsion stability are suitable for the sodium humate solution of the present application. After many experiments and studies, the commonly used wetting agents and emulsifiers in water-soluble fertilizers are discarded, and it is found that only when tannic acid and lecithin are used together and coupled with the sodium humate solution can a humic acid solution with the fastest penetration and diffusion speed be obtained. The present invention also mixes the humic acid solution with raw materials such as urea to obtain a humic acid-based water-soluble fertilizer, which not only realizes the targeted repair of albic soil but also provides sufficient nutrients for plant growth, thereby achieving the rapid improvement of albic soil.

[0033] In order to enable those skilled in the art to more clearly understand the technical solution of the present application, the technical solution of the present application will be described in detail below with reference to specific embodiments.

[0034] Note: In the present invention, tannic acid (CAS: 1401-55-4) is purchased from Xi'an Zebang Biotechnology Co., Ltd.;

[0035] Lecithin (powdered soy lecithin) is purchased from Guangzhou Tianbao Biotechnology Co., Ltd.;

[0036] The defoamer was a silicone polyether defoamer purchased from Guangdong Shanmei Environmental Technology Co., Ltd.

[0037] Thickener (C-152) was purchased from Guangdong Zhongke Hongtai New Materials Co., Ltd.

[0038] The test materials used in the examples of the present invention are all conventional test materials in the art and can be purchased through commercial channels.

[0039] Example 1: Preparation of humic acid solution

[0040] (1) Take lignite as raw material (humic acid content ≥ 30%), crush the raw material to less than 2 mm by a pulverizer, and then remove impurities by air separation equipment (such as a cyclone dust collector) to improve the purity of the raw material to obtain pretreated lignite. Add the pretreated lignite and water in a mass ratio of 1:1.4 into a reactor to obtain a mixed solution, add NaOH solution (mass concentration > 95%) to the mixed solution in a mass ratio of 1:5, heat to 35°C in the reactor, and stir for 30 minutes to fully dissolve the humic acid in the alkali solution. Use a rotary solid-liquid separator to separate the solid-liquid of the reaction mixture to obtain a sodium humate solution. The temperature is lowered to room temperature for standby use.

[0041] (2) Add 6 g of KH560 to 100 g of sodium humate solution, heat and stir at 60 °C for 20 min, then add 3 g of tannic acid and 3 g of lecithin dropwise at a rate of 2 mL / min while keeping warm. After the addition is complete, continue the reaction for 20 min to obtain a humic acid solution.

[0042] Example 2: Preparation of humic acid-based water-soluble fertilizer

[0043] The following substances were added to the humic acid solution prepared in Example 1: 155 g / L urea, 135 g / L monoammonium phosphate, 105 g / L potassium chloride, 1.0 g / L zinc sulfate, 1.0 g / L ferrous sulfate, 1.0 g / L manganese sulfate, 1.0 g / L copper sulfate, 1.25 g / L rare earth elements, 1.0 g / L defoamer, and 3.5 g / L thickener, and the mixture was stirred and mixed to obtain a humic acid water-soluble fertilizer product.

[0044] Comparative Example 1

[0045] Using lignite as raw material (humic acid content ≥ 30%), the raw material is crushed to within 2 mm by a crusher, and then impurities are removed through a pneumatic separation device (such as a cyclone dust collector) to improve the purity of the raw material and obtain pretreated lignite. The pretreated lignite and water are added to a reaction kettle according to a mass ratio of 1:1.4 to obtain a mixed solution. According to a mass ratio of 1:5, NaOH with a purity of more than 95% is added to the mixed solution, and it is heated to 35 °C in the reaction kettle while stirring for 30 minutes to fully dissolve humic acid in the lye. A rotary solid-liquid separator is used to separate the solid and liquid of the reacted mixture, and a solution of sodium humate is obtained after the temperature is lowered to room temperature.

[0046] Comparative Example 2

[0047] The difference from Example 1 is that KH560 is not added, and finally a humic acid solution is obtained.

[0048] Comparative Example 3

[0049] The difference from Example 1 is that lecithin is not added, and finally a humic acid solution is obtained.

[0050] Comparative Example 4

[0051] The difference from Example 1 is that tannic acid is not added, and finally a humic acid solution is obtained.

[0052] Comparative Example 5

[0053] The difference from Example 1 is that tannic acid and lecithin are replaced with an equal amount of OPC-8 (purchased from Shandong Shoucheng Chemical Co., Ltd.), and finally a humic acid solution is obtained.

[0054] Comparative Example 6

[0055] The difference from Example 2 is that the humic acid solution prepared in Comparative Example 1 is used to replace the humic acid water-soluble fertilizer product prepared in Example 1.

[0056] Comparative Example 7

[0057] The difference from Example 2 is that the humic acid solution prepared in Comparative Example 5 is used to replace the humic acid water-soluble fertilizer product prepared in Example 1.

[0058] Test Example 1: Horizontal and vertical diffusion tests

[0059] In this experiment, meadow albic soil (profile configuration: Ah-E-Bt-Cg) from Shuguang Farm, Huanan County, Jiamusi City was selected. The albic soil layer 20 - 40 cm below the surface was taken with a soil drill, air-dried naturally, sieved, and then ground in a mortar to 100 - 150 mesh for standby. Referring to the measured bulk density of the local soil and the actual volume of the experimental device, the soil bulk density was set at 1.67 g / cm³. The experiment was divided into 6 groups: Example 1 group, Comparative Examples 1 - 5 groups. Humic acid solutions were poured into each group for vertical and horizontal infiltration tests.

[0060] 1. Using a vertical one-dimensional ponding constant-head infiltration system as Figure 1 shown, to explore the effect of humic acid solution on the vertical infiltration performance of albic soil.

[0061] The ground albic soil was filled into an acrylic column to obtain an albic soil column. The height of the soil column was 40 cm, and filter paper was laid at the top and bottom to ensure the air permeability of the device. The albic soil was filled in layers and the layer interface was roughened to prevent layering. Humic acid solutions of each group were added to a Mariotte bottle of the same specification as the acrylic column, and the soil column was irrigated. During the irrigation process, the water head of the humic acid solution was kept stable at 3 - 4 cm. For the accuracy of experimental data, the method of first densely sampling points and then extending the time interval between sampling points was used to record data. A humidity sensor was used to regularly record the position of the wetting front. At the beginning, due to the fast infiltration rate, it was measured once every minute in the first 5 minutes, once every 5 minutes within 5 - 30 minutes, and once every 10 minutes after 30 minutes. The moving distance of the wetting front within the same time interval was calculated to obtain the effect of the humic acid solution on the vertical wetting front. When the moving distance of the wetting front reached 40 cm, this experiment was stopped to obtain the effect of the humic acid solution on the vertical wetting front (see Figure 3 ). After quickly draining the accumulated water (humic acid solution), soil samples at different depths were taken every 5 cm with an aluminum box, and the water content of each section of soil, the cumulative soil infiltration amount and other relevant data were measured by the drying method.

[0062] 2. A one-dimensional horizontal imbibition system as Figure 2As shown in the figure, it consists of two parts: a water supply device and a soil column (the soil column is filled into a plexiglass column). The water supply device uses a Mariotte bottle of the same specifications as the plexiglass column of the soil column, with an inner diameter and a total height of 10 cm and 40 cm respectively, and continuous water supply (humic acid solution) is ensured throughout the experiment. The soil column is made by filling ground albic soil into a columnar transparent container. A 3-cm water storage chamber is provided at the front end of the soil column, equipped with a ventilation hole, a drainage port, and a water inlet pipe for water storage, drainage, and connection to the water supply. The main body of the soil column is a 40-cm long open plexiglass column, with soil sampling holes set every 5 cm in the upper part for measuring soil moisture content after the experiment. The water storage chamber is connected to the soil column through small holes to ensure uniform distribution of accumulated water and eliminate the influence of gravity and capillary action. A humidity sensor is used to regularly record the position of the wetting front. At the beginning, due to the relatively fast infiltration rate, it is measured once every minute in the first 5 minutes, once every 5 minutes within 5 - 30 minutes, and once every 10 minutes after 30 minutes. Calculate the moving distance of the wetting front within the same time interval to obtain the influence of the humic acid solution on the wetting front in the horizontal direction (see Figure 4 ). The moisture content of each section of soil, the cumulative soil infiltration amount, and other relevant data are measured by the drying method.

[0063] 3. Fit the relevant data such as the moisture content and the cumulative soil infiltration amount obtained from the horizontal infiltration and vertical infiltration according to the FPhilip model and the Brooks-Corey model, and calculate the moisture absorption and infiltration rate and the soil water suction. The results are shown in Table 1.

[0064] Table 1 Evaluation of soil water holding capacity under different conditions of adding humic acid solution

[0065]

[0066] From Figure 3 and Figure 4 and Table 1, it can be seen that the humic acid solution prepared in Example 1 has the fastest infiltration rate in the horizontal and vertical directions of the albic soil, can effectively penetrate the soil plough layer and directly act on the underlying albic area, realizing the targeted repair of albic soil. And it simplifies and saves the investment in large machinery, and can solve the problem of albic soil from the source.

[0067] Test Example 2: Application of humic acid-based water-soluble fertilizer in the improvement of albic soil

[0068] Location: Shuguang Farm, Huanan County, Jiamusi City

[0069] The basic physical and chemical properties of the soil are as follows: bulk density 1.33, field water holding capacity 275.36 g / Kg, capillary porosity 39.87%, organic matter content 25.2 g / Kg, pH 5.92, total nitrogen 0.62 g / Kg, ammonium nitrogen content 24.8 mg / kg, available phosphorus content 16.6 mg / kg, and available potassium content 121.4 mg / kg.

[0070] A total of 4 groups of treatments were set up in the experiment: blank control group (CK), Example 2 group, Comparative Example 6 group, and Comparative Example 7 group. Among them, the blank control group was applied with an equal amount of clear water, the Example 2 group was applied with the humic acid water-soluble fertilizer prepared in Example 2, and the Comparative Example 6 - 7 groups were respectively applied with the water-soluble fertilizers prepared in Comparative Example 6 - 7. Each treatment was divided into 3 replicated plots, with a total of 12 plots of equal area, and the area of each plot was 222.22 m 2 .

[0071] The tested variety was Demeiya, with a growth period of 110 days. Six rows of corn were planted, and the planting density was approximately 85,000 plants per hectare. The corn seeds were buried at a depth of 5 cm. Starting from the 15th day of the corn growth period, the humic acid water-soluble fertilizers of each group were irrigated, once every 20 days. The humic acid water-soluble fertilizer was diluted with water at a volume concentration of 0.05% to make an aqueous solution, and then sprayed at a rate of 750 liters per hectare between 2 pm and 4 pm. After the corn matured, the random sampling method was used to measure the corn yield, and the results are shown in Table 2. When harvesting, soil samples of 20 - 40 cm were collected. The soil bulk density was measured according to the core method, the soil specific gravity was measured by the hydrometer method, and the soil porosity was calculated. The soil organic matter was measured by the potassium dichromate - ferrous sulfate titration method, and the results are shown in Figures 5 - 7 . The water-stable aggregate content of the soil was measured by the wet sieving method, and the results are shown in Table 3.

[0072] Table 2 Corn yield and yield components under different treatments

[0073]

[0074] Table 3 Effects of different treatments on soil water-stable aggregates

[0075]

[0076] Note: Different lowercase letters indicate significant differences (P < 0.05).

[0077] From Tables 2 - 3 and Figures 5 - 7 it can be seen that the humic acid water-soluble fertilizer prepared in Example 2 can not only increase the corn yield, but also reduce the porosity of the albic soil, increase the soil bulk density and organic matter content, achieving targeted repair of the albic soil and providing sufficient nutrients for plant growth, thus realizing the rapid improvement of the albic soil.

[0078] The above are only the preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A humic acid solution, characterized in that, The preparation method of the humic acid solution is as follows: Add a silane coupling agent to the solution containing humic acid, heat and stir, and then dropwise add tannic acid and lecithin respectively under insulation. After the dropping is completed, continue the reaction to obtain the humic acid solution; The solution containing humic acid is a sodium humate solution, and its preparation method is as follows: Crush the raw material containing humic acid and remove impurities to obtain a pretreated raw material. Mix the pretreated raw material with water to obtain a mixed solution, add an alkali containing sodium, heat and stir for reaction, and perform solid-liquid separation after the reaction to obtain the sodium humate solution; The mass ratio of the pretreated raw material to water is 1:1.4; the alkali containing sodium is a NaOH solution or a Na2CO3 solution; the mass ratio of the alkali containing sodium to the mixed solution is 1:

5.

2. The humic acid solution according to claim 1, wherein The raw material containing humic acid is weathered coal or lignite; the heating temperature is 30-35°C; the stirring reaction time is 30-40 min.

3. The humic acid solution according to claim 1, characterized in that, The heating and stirring temperature is 50-70°C, and the time is 10-30 min; the continued reaction time is 10-30 min.

4. The humic acid solution according to claim 1, wherein The mass ratio of the solution containing humic acid, silane coupling agent, tannic acid and lecithin is 100:5-10:2-4:2-4.

5. The humic acid solution according to claim 1, wherein, The silane coupling agent is KH560; the dropping rate is 1-3 mL / min.

6. The application of the humic acid solution according to any one of claims 1-5 in quickly infiltrating albic soil or preparing a humic acid-based water-soluble fertilizer.

7. A humic acid-based water-soluble fertilizer for rapid improvement of albic soil, characterized in that, The humic acid-based water-soluble fertilizer contains the humic acid solution according to any one of claims 1-5.

8. The humic acid-based water-soluble fertilizer according to claim 7, wherein The humic acid-based water-soluble fertilizer further contains the following raw materials: 145-170 g / L urea, 115-155 g / L monoammonium phosphate, 95-115 g / L potassium chloride, 0.5-1.5 g / L zinc sulfate, 0.5-1.5 g / L ferrous sulfate, 0.5-1.5 g / L manganese sulfate, 0.5-1.5 g / L copper sulfate, 0.5-2 g / L rare earth elements, 0.5-1.5 g / L defoamer, 1.0-6.5 g / L thickener.

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