A slow-release plant growth regulator and its preparation method

Abstract

This invention relates to the field of plant growth regulation technology, and discloses a slow-release regulator for promoting plant growth and its preparation method, comprising the following steps: immersing pretreated coral sand in a hydrothermal ammonium humate solution to obtain a hydrothermal ammonium humate / coral sand complex; crushing and grinding fresh willow branches, soaking them in deionized water, and then separating the solid and liquid to obtain willow branch liquid; immersing hydrothermal carbon in the willow branch liquid to perform an adsorption reaction, adsorbing the natural plant growth hormones in the willow branch liquid to obtain a willow branch liquid / hydrothermal carbon complex; mixing and granulating the hydrothermal ammonium humate / coral sand complex, willow branch liquid / hydrothermal carbon complex, bentonite, sodium alginate, and CaCl2 to obtain the slow-release regulator. This invention combines a coral sand complex loaded with hydrothermal ammonium humate and a hydrothermal carbon complex loaded with willow branch liquid as a slow-release regulator for promoting plant growth, achieving the slow release of hydrothermal humic acid while providing calcium for plant growth.

Description

Technical Field

[0001] This invention relates to the field of plant growth regulation technology, and more specifically, to a slow-release regulator that promotes plant growth and its preparation method. Background Technology

[0002] Cellulose solid waste typically refers to plant debris, including agricultural straw, garden waste, and wood processing waste. Every year, plants on Earth produce a large amount of cellulose solid waste through photosynthesis, but most of it is decomposed by microorganisms and re-enters the Earth's carbon cycle. Currently, the resource utilization of cellulose solid waste is limited. Anaerobic digestion sludge, rich in organic matter and an important component of urban municipal solid waste, is also currently underutilized. Therefore, converting cellulose solid waste and anaerobic digestion sludge into high-value products, or utilizing them for resource purposes, is crucial for achieving negative carbon initiatives.

[0003] The development of hydrothermal humification technology offers a new approach to the treatment of organic waste. Under alkaline, high-temperature, and high-pressure hydrothermal conditions, organic waste can undergo a humification reaction, generating hydrothermal humic acid with a structure similar to natural humic acid. Current research indicates that hydrothermal humic acid significantly promotes soil carbon sequestration and plant growth, highlighting its immense agricultural value. In particular, the structure of hydrothermal humic acid contains fragments similar to plant hormones, which can upregulate genes involved in photosynthesis, such as chlorophyll synthesis, light capture, photosynthetic activity, and carbohydrate metabolism, thereby directly promoting crop growth (Zhi et al. Science of The Total Environment, 2022, 848: 157536).

[0004] Although hydrothermal humic acid has been used in crop cultivation as a plant growth regulator, current research on its application methods in agriculture, especially slow-release methods, is insufficient. This will prevent the full realization of its efficacy as a plant growth regulator. Furthermore, in the growth of some vegetable crops, calcium deficiency not only affects vegetable quality but may also lead to physiological diseases.

[0005] In view of the above, this application is hereby submitted. Summary of the Invention

[0006] To address the limitations of existing slow-release methods for applying hydrothermal humic acid as a plant growth regulator, which fail to fully realize its effectiveness and lack calcium, this invention provides a slow-release regulator for promoting plant growth and its preparation method. On one hand, hydrothermal humic acid is combined with coral sand. Natural coral sand possesses a well-developed porous structure, enabling it to fully adsorb the hydrothermal humic acid ammonium solution and retain it during subsequent drying, thus facilitating the slow release of hydrothermal humic acid. Simultaneously, it provides calcium for plant growth. On the other hand, hydrothermal carbon is prepared from the solid byproducts generated during the preparation of hydrothermal humic acid. This hydrothermal carbon is then used to adsorb and bind with natural plant growth hormones in willow sap, providing a large amount of organic matter that promotes plant growth and development, thereby promoting rooting, cell division, and enhancing plant disease resistance.

[0007] This invention is achieved through the following technical solution: In a first aspect, the present invention provides a slow-release regulator for promoting plant growth, comprising a coral sand complex loaded with hydrothermal humic ammonium and a hydrothermal carbon complex loaded with willow twig extract.

[0008] This invention combines a coral sand complex loaded with hydrothermal humic acid and a hydrothermal carbon complex loaded with willow twig extract as a slow-release regulator to promote plant growth. This achieves the slow release of hydrothermal humic acid while simultaneously providing calcium for plant growth. The combination of hydrothermal humic acid and coral sand leverages the well-developed porous structure of natural coral sand, which effectively adsorbs the hydrothermal humic acid solution and retains it during subsequent drying, thus facilitating the slow release of the ammonium hydrothermal humic acid. Furthermore, due to the weakly acidic nature of hydrothermal humic acid, the calcium in the coral sand dissolves under the combined action of rainfall and the ammonium hydrothermal humic acid, providing essential calcium for crop growth and improving crop quality.

[0009] This invention utilizes the solid byproducts generated during the preparation of hydrothermal humic acid to prepare hydrothermal carbon. The hydrothermal carbon is then used to adsorb and combine with natural plant growth hormones in willow twig sap as a plant growth agent. On the one hand, willow twigs contain a large amount of organic substances that can promote plant growth and development, such as salicylic acid, indoleacetic acid, and indolebutyric acid, which can promote rooting, cell division, and enhance plant disease resistance. On the other hand, this invention achieves the effective utilization of solid byproducts from the hydrothermal humification process.

[0010] The slow-release regulator of this invention, when applied to the soil surface, can achieve uniform slow release of hydrothermal humic ammonium and the natural plant growth hormones therein through leaching by rainfall, thereby stimulating crop growth and significantly increasing the root length and chlorophyll content of crops. At the same time, the calcium rich in coral sand can dissolve under the action of rainfall and hydrothermal humic ammonium, providing sufficient calcium ions to promote crop growth.

[0011] In one specific embodiment, the mass ratio of the coral sand composite loaded with hydrothermal humate ammonium to the hydrothermal carbon composite loaded with willow twig liquid is 20-100:1.

[0012] In one specific embodiment, bentonite, sodium alginate, and CaCl2 are also included. By adding bentonite, sodium alginate, and CaCl2 to granulate hydrothermal carbon and coral sand, the crosslinking reaction of sodium alginate and CaCl2 and the bentonite can bind the various phases together.

[0013] Secondly, the present invention provides a method for preparing a slow-release regulator that promotes plant growth, comprising the following steps: (1) The pretreated coral sand is immersed in a hydrothermal ammonium humate solution and ultrasonically impregnated to allow the solution to fully penetrate the pores of the coral sand. The drying / impregnation process is repeated multiple times until a certain amount of hydrothermal ammonium humate solid is enriched in the pores of the coral sand to obtain a hydrothermal ammonium humate / coral sand composite. (2) Fresh willow branches are crushed and ground, and then soaked in deionized water for a long time to separate solid and liquid to obtain willow branch liquid. Hydrothermal carbon is then immersed in the willow branch liquid to carry out an adsorption reaction, adsorbing the natural plant growth hormones in the willow branch liquid to obtain a willow branch liquid / hydrothermal carbon complex. The purpose of soaking is to release the natural plant growth hormones in the willow branches into the water. (3) The hydrothermal ammonium humate / coral sand complex, willow twig liquid / hydrothermal carbon complex, bentonite, sodium alginate and CaCl2 are mixed and granulated. The mass ratio of willow twig liquid / hydrothermal carbon complex, hydrothermal ammonium humate / coral sand complex, bentonite and sodium alginate is between 1:(20-100):(1-2):(1-2), and the drying temperature is between 50-60 ℃. 0.1-0.5 M CaCl2 is used as a wetting agent. Through the cross-linking reaction of sodium alginate and CaCl2 and bentonite, the phases can be bonded together to obtain a slow-release regulator.

[0014] In a specific embodiment, in step (1), the pretreatment method of coral sand is as follows: add deionized water to the coral sand, perform freeze-thaw treatment in the range of (-10)-(-30) ℃, then dissolve to room temperature, add acetic acid and sodium dodecyl sulfate for ultrasonic treatment, and finally wash with deionized water.

[0015] The mass ratio of coral sand to deionized water is between 1:(1-5); after the addition of acetic acid, the concentration of the liquid phase is between 0.1% and 2.0%; the amount of sodium dodecyl sulfate added is between 0.01% and 0.10% of the mass of coral sand.

[0016] This invention uses freeze-thaw treatment to create microcracks in coral sand at the microscale. Acetic acid solution can react with the coral sand, thereby dissolving and removing the sediment covering the porous structure of the coral sand. Sodium dodecyl sulfate can reduce surface tension, which is more conducive to the subsequent hydrothermal ammonium humate solution entering the pores of the coral sand.

[0017] In a specific embodiment, the preparation method of the hydrothermal ammonium humate solution in step (1) is as follows: Cellulose solid waste and anaerobic digestion sludge are subjected to hydrothermal reaction under alkaline conditions to obtain hydrothermal products; Specifically, the cellulose solid waste includes at least one of straw, fallen leaves, and garden solid waste; wherein, the mass ratio of cellulose solid waste to anaerobic digestion sludge is between 1:(0.5-2), and the solid-liquid ratio of cellulose solid waste and anaerobic digestion sludge to water is (0.2-2.0) g / 10 mL; the amount of alkali added makes the pH value of the reaction system 12.5-13.5; the hydrothermal reaction temperature is 160-220 ℃; the reaction time is 4-8 h; a solid-liquid ratio that is too high or too low, a pH value that is too high or too low, a hydrothermal reaction temperature that is too high or too low, or a reaction time that is too short or too long are all detrimental to the improvement of hydrothermal humic acid production and engineering production.

[0018] The hydrothermal products were separated into solid and liquid phases to obtain solid and liquid phase products. The solid phase products were dissolved in ammonia water to obtain hydrothermal ammonium humate solution and solid phase by-products. Specifically, the pH of the hydrothermal products is first adjusted to 1.0-2.0, followed by solid-liquid separation. The solid product is then dissolved in ammonia water to obtain a hydrothermal ammonium humate solution and a solid byproduct; the mass ratio of the solid product to ammonia water is 1.0 g / (10-50) mL. The purpose of adjusting the pH of the hydrothermal products to 1.0-2.0 is to utilize the solubility properties of humic acid to precipitate the hydrothermal humic acid in the solution into a solid. A pH that is too high is not conducive to the complete precipitation of hydrothermal humic acid.

[0019] The advantages of using ammonia as a solvent in this invention are as follows: (1) Ammonia is alkaline and can dissolve hydrothermal humic acid precipitate into a uniform liquid phase, which is beneficial for it to fully penetrate the pores of coral sand during the impregnation process. (2) Ammonia reacts with hydrothermal humic acid to generate hydrothermal ammonium humate. During the slow release process, ammonium humate hydrolyzes to generate ammonium ions, which is beneficial for further replenishing nitrogen in the soil. (3) During the drying process after impregnation, excess ammonia will volatilize and can be recycled. This not only saves solvent costs and conforms to the concept of sustainable development, but also ensures that there is no accumulation of other salts or alkalis in the resulting hydrothermal ammonium humate / coral sand. For example, although potassium hydroxide or sodium hydroxide solution can also dissolve hydrothermal humic acid into a uniform liquid phase solution, after impregnation and drying, excess sodium hydroxide or potassium hydroxide remains in the coral sand, making the resulting product alkaline. Long-term use can easily lead to soil salinization.

[0020] In a specific embodiment, in step (1), the mass ratio of hydrothermal ammonium humate to coral sand is 1:75-130; the particle size of the coral sand is less than 1.0 mm, and the drying process temperature is 100-120 ℃.

[0021] In a specific embodiment, the preparation method of the hydrothermal carbon in step (2) is as follows: The solid-phase byproduct is added to the liquid-phase product for a secondary hydrothermal reaction to obtain hydrothermal carbon, wherein the hydrothermal solution can be recycled.

[0022] In a specific implementation, in step (2), the mass-to-volume ratio of hydrothermal carbon and willow twig liquid is 1:100-1000, wherein the mass-to-volume ratio of fresh willow twigs and deionized water is 1:2-10; and the soaking time is 15-30 h.

[0023] In one specific embodiment, the reaction temperature of the hydrothermal reaction and the secondary hydrothermal reaction is 160-220 °C, and the reaction time is 4-8 h.

[0024] Compared with the prior art, the present invention has the following advantages and beneficial effects: 1. The present invention provides a slow-release regulator for promoting plant growth and its preparation method. The method uses a coral sand complex loaded with hydrothermal humic acid and a hydrothermal carbon complex loaded with willow branch sap as a slow-release regulator for promoting plant growth, so as to achieve slow release of hydrothermal humic acid and provide calcium element for plant growth. 2. The present invention provides a slow-release regulator for promoting plant growth and its preparation method, which combines hydrothermal humic acid and coral sand. Natural coral sand has a well-developed porous structure, which can fully adsorb the hydrothermal humic acid ammonium solution and retain it in its interior during the subsequent drying process, thereby easily achieving the purpose of slow release of hydrothermal humic acid ammonium. In addition, due to the weak acidity of hydrothermal humic acid ammonium, under the combined action of rainfall and hydrothermal humic acid ammonium, the calcium rich in coral sand can dissolve under the action of rainfall and hydrothermal humic acid ammonium, providing the necessary calcium element for crop growth, thereby improving crop quality. 3. The present invention provides a slow-release regulator for promoting plant growth and its preparation method. The solid by-products generated during the preparation of hydrothermal humic acid are used to prepare hydrothermal carbon. The hydrothermal carbon is then used to adsorb and combine with natural plant growth hormones in willow twig sap as a plant growth agent. On the one hand, willow twigs contain a large amount of organic substances that can promote plant growth and development, such as salicylic acid, indoleacetic acid and indolebutyric acid, which can promote rooting, cell division and enhance plant disease resistance. On the other hand, the solid by-products of the hydrothermal humification process are effectively utilized. 4. The slow-release regulator for promoting plant growth and its preparation method provided in this embodiment of the invention can be applied to the soil surface during use. Through leaching by rainfall, it can achieve uniform slow release of hydrothermal humic ammonium and natural plant growth hormones therein, thereby stimulating crop growth and significantly increasing the root length and chlorophyll content of crops. At the same time, the calcium rich in coral sand can be dissolved under the action of rainfall and hydrothermal humic ammonium, providing sufficient calcium ions to promote crop growth. 5. The present invention provides a slow-release regulator for promoting plant growth and its preparation method, which realizes the reuse and treatment of cellulosic solid waste, anaerobic digestion sludge and solid by-products obtained in hydrothermal processes. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the process for preparing a sustained-release regulator provided in an embodiment of the present invention.

[0027] Figure 2 Scanning electron microscope (SEM) images of the original coral sand, pretreated coral sand, and hydrothermal ammonium humate / coral sand composite provided in Example 1 of this invention.

[0028] Figure 3 The results show the comparison of plant height and root length of Chinese cabbage after 25 days, which are provided for the embodiments and comparative examples of the present invention.

[0029] Figure 4 The results show the comparison of fresh weight and dry weight of bok choy after 25 days, which are provided for the embodiments and comparative examples of the present invention.

[0030] Figure 5 The comparison results of calcium content in bok choy after 25 days are provided for the embodiments and comparative examples of the present invention.

[0031] Figure 6 The results of the comparison of chlorophyll content of bok choy after 25 days are provided for the embodiments and comparative examples of the present invention.

[0032] Figures 3-6 In the figure, lowercase letters indicate statistical significance between treatment groups at the p-value less than 0.05 level. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0034] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to practice the invention. In other embodiments, well-known structures, materials, or methods have not been specifically described in order to avoid obscuring the invention.

[0035] Throughout this specification, references to "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in connection with that embodiment or example is included in at least one embodiment of the invention. Therefore, the phrases "an embodiment," "an example," "an example," or "an example" appearing in various places throughout the specification do not necessarily refer to the same embodiment or example. Furthermore, specific features, structures, or characteristics can be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. Moreover, those skilled in the art will understand that the illustrations provided herein are for illustrative purposes and are not necessarily drawn to scale. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0036] Example 1 like Figure 1 As shown in the figure, this invention provides a method for preparing a slow-release regulator to promote plant growth, comprising the following steps: (1) 7.5 g of willow twig powder (a cellulose-based solid waste), 7.5 g of anaerobic digested sludge, 2.0 g of KOH solid, and 135 mL of deionized water were added to a 250 mL hydrothermal reactor and subjected to a hydrothermal reaction at 180 °C for 6 h. Subsequently, the pH of the hydrothermal reaction product was adjusted to 1.0 using HCl, followed by solid-liquid separation to obtain hydrothermal solid-phase product and hydrothermal liquid-phase product. The obtained solid-phase hydrothermal product was fully dissolved using 130 mL of ammonia water, followed by solid-liquid separation to obtain a hydrothermal humic ammonium solution (containing 1.85 g of hydrothermal humic ammonium) and solid-phase byproducts.

[0037] (2) Add 260 mL of deionized water to 130 g of coral sand and freeze at -20 ℃ for 4 h. After the freeze-thaw cycle is complete, add 1.3 mL of acetic acid and then add 0.13 g of sodium dodecyl sulfate. Sonicate for 30 minutes and then rinse the coral sand with deionized water.

[0038] (3) 130 g of pretreated coral sand was added to a hydrothermal ammonium humate solution and ultrasonically impregnated. After draining the solution, it was dried at 120 °C to constant weight. This process was repeated with ultrasonic impregnation / drying until all the hydrothermal ammonium humate in the 130 mL hydrothermal ammonium humate solution was loaded into the 130 g of coral sand, resulting in a hydrothermal ammonium humate / coral sand composite, as shown below. Figure 2 As shown.

[0039] (4) Add the solid by-product obtained in the first hydrothermal reaction to the hydrothermal liquid product and carry out a second hydrothermal reaction at 180 °C for 6 h to obtain hydrothermal carbon and hydrothermal solution, wherein the hydrothermal solution can be recycled.

[0040] (5) Grind 250 g of fresh willow branches, add 750 mL of deionized water, soak for 24 h, and then perform solid-liquid separation to obtain willow branch liquid. The soaked waste willow branches are made into willow branch powder and reused as the cellulose solid waste in step (1). Then add 1.0 g of hydrothermal carbon and stir for 8 h for adsorption, followed by solid-liquid separation.

[0041] (6) The obtained hydrothermal ammonium humate / coral sand (approximately 130 g, with some loss in actual operation), hydrothermal carbon (2.6 g) obtained after adsorbing willow twig liquid, bentonite (5.2 g), and sodium alginate (2.08 g) were thoroughly mixed. 0.3 M CaCl2 solution was added to the mixture in several portions, and the mixture was stirred. Then, granulation was carried out to finally obtain a slow-release regulator product with a particle size of approximately 0.3-0.5 cm.

[0042] Example 2 This invention provides a method for preparing a slow-release regulator to promote plant growth, comprising the following steps: The difference from Example 1 is that in step (1), the raw materials of 7.5 g of willow twig powder (a cellulose solid waste) and 7.5 g of anaerobic digested sludge are replaced with 10.0 g of willow twig powder and 5.0 g of anaerobic digested sludge; all other steps remain unchanged. The 130 mL hydrothermal ammonium humate solution contains 1.73 g of hydrothermal ammonium humate.

[0043] Example 3 This invention provides a method for preparing a slow-release regulator to promote plant growth, comprising the following steps: The difference from Example 1 is that in step (1), the raw materials of 7.5 g of willow twig powder (a cellulose solid waste) and 7.5 g of anaerobic digested sludge are replaced with 5.0 g of willow twig powder and 10.0 g of anaerobic digested sludge; all other steps remain unchanged. The 130 mL hydrothermal ammonium humate solution contains 1.41 g of hydrothermal ammonium humate.

[0044] Example 4 This invention provides a method for preparing a slow-release regulator to promote plant growth, comprising the following steps: (1) 7.5 g of willow twig powder (a cellulose-based solid waste), 7.5 g of anaerobic digestion sludge, 2.3 g of KOH solid, and 135 mL of deionized water were added to a 250 mL hydrothermal reactor and subjected to a hydrothermal reaction at 220 °C for 8 h. Subsequently, the pH of the hydrothermal reaction product was adjusted to 1.0 using HCl, and then solid-liquid separation was performed to obtain hydrothermal solid-phase product and hydrothermal liquid-phase product. The obtained solid-phase hydrothermal product was fully dissolved using 130 mL of ammonia water, and then solid-liquid separation was performed to obtain a hydrothermal humic ammonium solution (containing 1.27 g of hydrothermal humic ammonium) and solid-phase byproducts.

[0045] (2) Add 260 mL of deionized water to 130 g of coral sand and freeze at -10 ℃ for 4 h. After the freeze-thaw cycle is complete, add 2.6 mL of acetic acid and then add 0.013 g of sodium dodecyl sulfate. Sonicate for 30 minutes and then rinse the coral sand with deionized water.

[0046] (3) 130 g of pretreated coral sand was added to a hydrothermal ammonium humate solution and ultrasonically impregnated. After the solution was drained, it was dried at 120 °C to constant weight. Then, it was ultrasonically impregnated / dried again until all the hydrothermal ammonium humate in the 130 mL hydrothermal ammonium humate solution was loaded into 130 g of coral sand to obtain a hydrothermal ammonium humate / coral sand complex.

[0047] (4) Add the solid byproduct obtained in the first hydrothermal reaction to the hydrothermal liquid product and carry out a second hydrothermal reaction at 220 °C for 8 h to obtain hydrothermal carbon and hydrothermal solution, wherein the hydrothermal solution can be recycled.

[0048] (5) Grind 250 g of fresh willow branches, add 750 mL of deionized water, soak for 24 h, and then perform solid-liquid separation to obtain willow branch liquid. The soaked waste willow branches are made into willow branch powder and reused as the cellulose solid waste in step (1). Then add 7.5 g of hydrothermal carbon and stir for 8 h for adsorption, followed by solid-liquid separation.

[0049] (6) The obtained hydrothermal ammonium humate / coral sand (approximately 130 g, with some loss in actual operation), hydrothermal carbon (6.5 g) obtained after adsorbing willow twig liquid, bentonite (13 g), and sodium alginate (13 g) were thoroughly mixed. 0.5 M CaCl2 solution was added to the mixture in several portions, and the mixture was stirred. Then, granulation was carried out to finally obtain a slow-release regulator product with a particle size of approximately 0.3-0.5 cm.

[0050] Example 5 This invention provides a method for preparing a slow-release regulator to promote plant growth, comprising the following steps: (1) 7.5 g of willow twig powder (a cellulose-based solid waste), 7.5 g of anaerobic digested sludge, 1.7 g of KOH solid, and 135 mL of deionized water were added to a 250 mL hydrothermal reactor and subjected to a hydrothermal reaction at 160 °C for 4 h. Subsequently, the pH of the hydrothermal reaction product was adjusted to 1.0 using HCl, followed by solid-liquid separation to obtain hydrothermal solid-phase product and hydrothermal liquid-phase product. The obtained solid-phase hydrothermal product was fully dissolved using 130 mL of ammonia water, followed by solid-liquid separation to obtain a hydrothermal humic ammonium solution (containing 0.99 g of hydrothermal humic ammonium) and solid-phase byproducts.

[0051] (2) Add 260 mL of deionized water to 130 g of coral sand and freeze at -30 ℃ for 4 h. After the freeze-thaw cycle is complete, add 0.13 mL of acetic acid and then add 0.065 g of sodium dodecyl sulfate. Sonicate for 30 minutes and then rinse the coral sand with deionized water.

[0052] (3) 130 g of pretreated coral sand was added to a hydrothermal ammonium humate solution and ultrasonically impregnated. After the solution was drained, it was dried at 120 °C to constant weight. Then, it was ultrasonically impregnated / dried again until all the hydrothermal ammonium humate in the 130 mL hydrothermal ammonium humate solution was loaded into 130 g of coral sand to obtain a hydrothermal ammonium humate / coral sand complex.

[0053] (4) Add the solid byproduct obtained in the first hydrothermal reaction to the hydrothermal liquid product and carry out a second hydrothermal reaction at 160 °C for 4 h to obtain hydrothermal carbon and hydrothermal solution, wherein the hydrothermal solution can be recycled.

[0054] (5) Grind 250 g of fresh willow branches, add 750 mL of deionized water, soak for 24 h, and then perform solid-liquid separation to obtain willow branch liquid. The soaked waste willow branches are made into willow branch powder and reused as the cellulose solid waste in step (1). Then add 0.75 g of hydrothermal carbon and stir for 8 h for adsorption, followed by solid-liquid separation.

[0055] (6) The obtained hydrothermal ammonium humate / coral sand (approximately 130 g, with some loss in actual operation), hydrothermal carbon (1.3 g) obtained after adsorbing willow twig liquid, bentonite (1.3 g), and sodium alginate (1.3 g) were thoroughly mixed. 0.1 M CaCl2 solution was added to the mixture in several portions, and the mixture was stirred. Then, granulation was performed to finally obtain a slow-release regulator product with a particle size of approximately 0.3-0.5 cm.

[0056] Slow-release growth regulators were prepared using Examples 1 to 5. A 25-day pot experiment was conducted on pakchoi (Chinese cabbage). The pots had a diameter of 10.5 cm, and the soil used was ordinary soil from the Chongqing University campus. After air-drying, the soil weighed 1.0 kg, and the slow-release growth regulator weighed 65 g. Urea and potassium dihydrogen phosphate were used to provide the nitrogen, phosphorus, and potassium required for plant growth. The dosage of both urea and potassium dihydrogen phosphate was 140 mg / kg of air-dried soil. Spraying and irrigation were conducted to simulate the average spring rainfall in Chongqing, and the growth of the pakchoi was recorded.

[0057] At the same time, set the corresponding comparison ratio, as follows: Comparative Example 1: In the potted bok choy experiment, the slow-release regulator prepared in the example was not used, but everything else was the same.

[0058] Comparative Example 2: In the potted Chinese cabbage experiment, the slow-release regulator prepared in the example was replaced with 1.3 g of willow twig liquid / hydrothermal carbon complex, and the rest remained the same.

[0059] Comparative Example 3: In the potted bok choy experiment, the slow-release regulator prepared in the example was replaced with 60 g of hydrothermal ammonium humate / coral sand complex, and the rest remained the same.

[0060] like Figure 3The figures show the plant height and root length of pakchoi after 25 days in the examples and comparative examples. Compared with comparative examples 1-3, the plant height and root length in examples 1-5 were significantly increased. Specifically, in example 1, the additional application of a slow-release regulator resulted in a 55.2% increase in plant height compared to comparative example 1 (p<0.05), while comparative example 2, with only 1.3 g of adsorbed hydrothermal carbon, and comparative example 3, with only 60 g of hydrothermal ammonium humate / coral sand complex, had no significant effect on the plant height of pakchoi. Furthermore, compared to comparative example 1, the root length increased by 62.0% (p<0.05) in the case of the additional application of the slow-release regulator (example 1). This indicates that the slow-release regulator of the present invention, with the synergistic effect of the hydrothermal ammonium humate / coral sand complex and adsorbed hydrothermal carbon, can significantly promote the development of crop root tissue.

[0061] like Figure 4 The figures show the fresh and dry weights of pakchoi after 25 days in the examples and comparative examples. Compared to Comparative Example 1, Examples 1-5 showed significant improvements in both fresh and dry weight of pakchoi, with Example 1 showing the most significant improvement, increasing by 49.1% and 53.7%, respectively. Comparative Example 2 applied only 1.3 g of adsorbed hydrothermal carbon. Although it improved the fresh and dry weights of pakchoi compared to Comparative Example 1, the improvement was not as significant as in Examples 1-3. Comparative Example 3 applied only 60 g of hydrothermal ammonium humate / coral sand complex, and compared to Comparative Examples 1 and 2, the fresh and dry weights actually decreased. This indicates that the increase in pakchoi biomass is due to the synergistic effect of the adsorbed hydrothermal carbon and the hydrothermal ammonium humate / coral sand complex.

[0062] like Figure 5 The figures show the calcium content of pakchoi after 25 days in the examples and comparative examples. In Examples 1-3 and Comparative Examples 1-3, the calcium content of Examples 1-5 was significantly higher than that of Comparative Examples 1-3. Example 4 had the highest calcium content, reaching 1.49 mg / g, which is equivalent to 2.44 times that of Comparative Example 1. Comparative Example 2, which only applied 1.3 g of adsorbed hydrothermal carbon, had no significant effect on the calcium content of pakchoi (p>0.05). Comparative Example 3, which only applied 60 g of hydrothermal ammonium humate / coral sand complex, also showed a significant increase in calcium content compared to Comparative Examples 1 and 2. This is because the addition of the hydrothermal ammonium humate / coral sand complex provided an additional sufficient calcium source.

[0063] like Figure 6 The figure shows the chlorophyll content of bok choy after 25 days in the examples and comparative examples. In Examples 1-5 and Comparative Examples 1-3, the chlorophyll content of Examples 1-5 was generally higher than that of Comparative Examples 1-3. Among them, Example 1 had the highest chlorophyll content, which was significantly increased by 38.8% compared with Comparative Example 1 (p<0.05). This indicates that the slow-release regulator can significantly improve the activity of enzymes related to photosynthesis and promote chlorophyll synthesis metabolism during crop growth.

[0064] In summary, the application of the slow-release regulator prepared by this invention significantly improves the plant height, root length, biomass, calcium content, and chlorophyll content of Chinese cabbage, indicating that this invention has practical agricultural application value.

[0065] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A slow-release regulator for promoting plant growth, characterized in that, Its components include a coral sand complex loaded with hydrothermal ammonium humate, a hydrothermal carbon complex loaded with willow twig sap, bentonite, sodium alginate and CaCl2; The preparation method of the coral sand composite loaded with hydrothermal humate ammonium is as follows: deionized water is added to the coral sand, and freeze-thaw treatment is carried out in the range of (-10)~(-30) ℃. Then, it is dissolved to room temperature, acetic acid and sodium dodecyl sulfate are added for ultrasonic treatment, and finally it is washed with deionized water. Then, the coral sand is immersed in hydrothermal humate ammonium solution to obtain hydrothermal humate ammonium / coral sand composite. The preparation method of the hydrothermal carbon complex loaded with willow twig sap is as follows: fresh willow twigs are crushed and ground, soaked in deionized water, and then separated into solid and liquid to obtain willow twig sap. Hydrothermal carbon is then immersed in the willow twig sap to carry out an adsorption reaction, adsorbing the natural plant growth hormones in the willow twig sap, thus obtaining the willow twig sap / hydrothermal carbon complex.

2. The slow-release regulator for promoting plant growth according to claim 1, characterized in that, The mass ratio of the coral sand composite loaded with hydrothermal humate ammonium to the hydrothermal carbon composite loaded with willow twig liquid is 20-100:

1.

3. A method for preparing a slow-release regulator for promoting plant growth as described in claim 1 or 2, characterized in that, Includes the following steps: (1) Pretreatment of coral sand: Add deionized water to the coral sand and freeze-thaw in the range of (-10)~(-30) ℃. Then dissolve it to room temperature, add acetic acid and sodium dodecyl sulfate for ultrasonic treatment, and finally wash with deionized water. Immerse the pretreated coral sand in hydrothermal ammonium humate solution to obtain hydrothermal ammonium humate / coral sand complex. (2) Fresh willow branches are crushed and ground, and then soaked in deionized water to separate solid and liquid to obtain willow branch liquid. Hydrothermal carbon is then immersed in the willow branch liquid to carry out an adsorption reaction, adsorbing the natural plant growth hormones in the willow branch liquid to obtain a willow branch liquid / hydrothermal carbon complex. (3) Mix and granulate the hydrothermal ammonium humate / coral sand complex, willow twig liquid / hydrothermal carbon complex, bentonite, sodium alginate and CaCl2 to obtain a slow-release regulator.

4. The method for preparing a slow-release regulator for promoting plant growth according to claim 3, characterized in that, In step (1), the preparation method of the hydrothermal ammonium humate solution is as follows: Cellulose solid waste and dried sludge are subjected to a hydrothermal reaction under alkaline conditions to obtain hydrothermal products. The hydrothermal products were separated into solid and liquid phases to obtain solid and liquid phase products. The solid phase products were dissolved in ammonia water to obtain hydrothermal ammonium humate solution and solid phase by-products.

5. A method for preparing a slow-release regulator for promoting plant growth according to claim 3, characterized in that, In step (1), the mass ratio of hydrothermal ammonium humate to coral sand is 1:75-130; the particle size of the coral sand is less than 1.0 mm.

6. The method for preparing a slow-release regulator for promoting plant growth according to claim 4, characterized in that, In step (2), the preparation method of the hydrothermal carbon is as follows: The solid-phase byproduct is added to the liquid-phase product for a secondary hydrothermal reaction to obtain hydrothermal carbon.

7. The method for preparing a slow-release regulator for promoting plant growth according to claim 6, characterized in that, In step (2), the mass-to-volume ratio of hydrothermal carbon and willow twig liquid is 1:100-1000.

8. A method for preparing a slow-release regulator for promoting plant growth according to claim 6, characterized in that, The hydrothermal reaction and the secondary hydrothermal reaction are carried out at a temperature of 160-220 °C for a time of 4-8 h.

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