Bagasse biochar fertilizer and preparation method and application thereof

Abstract

This invention discloses a bagasse biochar fertilizer, its preparation method, and its application. It relates to the field of fertilizer technology. The bagasse biochar fertilizer comprises the following components in parts by weight: bagasse biochar, 0.5-1.5 parts; compound fertilizer, 3-5 parts; wherein the compound fertilizer contains nitrogen, phosphorus, and potassium at mass fractions of 15-16%, 15-16%, and 15-16%, respectively; and functional microbial inoculant, 0.1-0.3 parts. This invention constructs an optimal ratio range that achieves deep synergy between the carbon skeleton, microorganisms, and nutrients by precisely defining the mass fraction ranges of bagasse biochar (0.5-1.5 parts), compound fertilizer (3-5 parts) with nitrogen, phosphorus, and potassium mass fractions of 15-16%, 15-16%, and 15-16%, respectively.

Description

Technical Field

[0001] This invention relates to the field of fertilizer technology, and in particular to a bagasse biochar fertilizer, its preparation method, and its application. Background Technology

[0002] Currently, agricultural production is facing unprecedented challenges, with soil degradation becoming a key factor restricting sustainable agricultural development. With the long-term development of intensive agriculture, soil acidification has intensified, soil structure has been damaged, nutrient loss is severe, and soil carbon storage capacity continues to decline. The combined effects of these problems not only directly impact crop yield and quality but also threaten the long-term sustainable use of soil resources. Against this backdrop, how to improve soil, enhance soil fertility, and strengthen soil carbon sequestration capacity through scientific methods has become an urgent technical challenge to be solved in the agricultural sector.

[0003] In current technology, traditional chemical fertilizers are widely used due to their high nutrient content and rapid effects, effectively supplementing the nutrients needed for crop growth and ensuring crop yields in the short term. However, the negative impacts of long-term reliance on traditional chemical fertilizers are becoming increasingly prominent. On the one hand, excessive and improper use of traditional chemical fertilizers can exacerbate soil acidification, leading to soil compaction, damaging soil aggregate structure, reducing soil porosity and permeability, and thus affecting crop root growth and development. On the other hand, long-term use of traditional chemical fertilizers can inhibit the activity of soil microorganisms, reduce the number and diversity of beneficial microorganisms in the soil, and weaken the self-regulating capacity of the soil ecosystem. In addition, the production and application of traditional chemical fertilizers also generate a large amount of greenhouse gas emissions, posing a potential threat to the ecological environment. Therefore, finding alternatives or supplements to traditional chemical fertilizers and developing environmentally friendly fertilizers has become an important direction for the green development of agriculture.

[0004] Biochar-based fertilizers, as a new type of environmentally friendly fertilizer, have received widespread attention in recent years. In existing technologies, biochar-based fertilizers typically use biochar as a carrier or main component, leveraging its porous structure, high specific surface area, and abundant functional groups to improve soil, sequester carbon, reduce emissions, and slowly release nutrients. Some studies have attempted to combine biochar with chemical fertilizers to prepare biochar-based compound fertilizers, aiming to achieve the dual goals of soil improvement and carbon sequestration while providing nutrients. Some existing technologies also attempt to add functional microorganisms, attempting to promote nutrient conversion and inhibit pathogen growth through their action. However, existing biochar-based fertilizers still have many shortcomings in practical applications, especially in terms of formulation design, synergistic nutrient release mechanisms, pH adjustment effects, and precise improvement for different types of acidic soils, where systematic research and optimization are still lacking. Specifically, existing carbon-based fertilizers generally exhibit poor adaptability to soils of varying origins and degrees of acidification, with unstable pH regulation effects, making precise soil improvement difficult. Simultaneously, existing fertilizers have limited effectiveness in increasing soil organic carbon content, failing to significantly increase the content of key carbon pool components such as organic carbon and active organic carbon, resulting in a lack of significant improvement in soil carbon storage capacity. Furthermore, after the application of traditional fertilizers, the soil carbon mineralization rate is often too rapid, leading to substantial organic carbon decomposition and loss, making it difficult to maintain the long-term stability of the soil carbon pool. More critically, current technologies have not yet established an effective synergistic mechanism of "carbon sequestration-nutrient activation," failing to simultaneously optimize the activity of key soil enzymes, such as sucrase and urease, while enhancing soil carbon sequestration capacity, thus affecting soil carbon cycling processes and crop nutrient utilization efficiency. Due to the lack of fertilizer formulations and supporting application schemes that balance short-term carbon sequestration effects with long-term soil fertility enhancement, existing fertilizers generally suffer from insufficient sustainability in carbon sequestration.

[0005] Meanwhile, sugarcane cultivation generates a large amount of agricultural waste such as bagasse every year. Traditionally, this waste is mostly incinerated or discarded, resulting in low resource utilization rates. This not only causes a huge waste of biomass resources but also imposes a serious environmental burden. How to efficiently utilize abundant agricultural waste like bagasse and transform it into high-value agricultural production materials is not only a research hotspot in the field of agricultural waste resource utilization but also an important path to achieving agricultural circular economy and carbon emission reduction goals. However, existing fertilizer technologies mostly focus on the simple function of nutrient supply, paying insufficient attention to the synergistic effect of combining "agricultural waste resource utilization" with "soil carbon sequestration," especially failing to organically combine waste-derived materials with microbial-enhanced carbon sequestration. This makes it difficult for existing technological solutions to simultaneously meet the multiple demands of improved carbon storage capacity, continuous nutrient supply, and waste resource utilization.

[0006] Therefore, developing a new type of fertilizer that can fully utilize bagasse resources, has good pH regulation capabilities, effectively increase the content of soil carbon pool components, slow down the rate of carbon mineralization, form a synergistic effect of carbon fixation and nutrient activation, and has both short-term effects and long-term sustainability, is of great practical significance and application value for solving the current soil degradation problem in agricultural production, improving the resource utilization level of agricultural waste, and promoting the green and sustainable development of agriculture. Summary of the Invention

[0007] The technical solution adopted according to the first aspect of the present invention is as follows:

[0008] A bagasse biochar fertilizer comprises the following components in parts by weight:

[0009] Sugarcane bagasse biochar, 0.5-1.5 parts;

[0010] Compound fertilizer, 3-5 parts; the mass fractions of nitrogen, phosphorus, and potassium in the compound fertilizer are 15-16%, 15-16%, and 15-16%, respectively.

[0011] Functional microbial inoculant, 0.1-0.3 parts.

[0012] According to embodiments of the present invention, one of the technical solutions has at least one of the following advantages or beneficial effects:

[0013] This invention constructs a differentiated functional regulation system that can achieve multi-dimensional synergy between "carbon skeleton-microorganism-nutrients" by precisely limiting the mass fraction range of compound fertilizer (3-5 parts) with mass fractions of 15-16% for bagasse biochar, 15-16% for nitrogen, phosphorus and potassium, and 15-16% for functional microbial agents (0.1-0.3 parts).

[0014] Specifically, 0.5-1.5 parts of bagasse biochar provide a sufficient amount of carrier to form a continuous and stable organic carbon skeleton and to exert physical adsorption protection, but excessive amounts should be avoided to prevent soil nitrogen biological fixation; 3-5 parts of compound fertilizer provide sufficient fast-acting nutrients to initiate rapid microbial proliferation and meet the needs of early crop growth, but excessive amounts should be avoided to prevent salt stress or nutrient loss; 0.1-0.3 parts of functional microbial inoculants ensure that there are a sufficient number of functional strains colonizing in the unit soil and exerting their role in activating the carbon and nitrogen cycle, but excessively high bacterial counts should be avoided to prevent competition for nutrients with crop roots.

[0015] Within the aforementioned ratio range, this invention can achieve targeted control of two types of core functions:

[0016] One type is the carbon sequestration and stabilization formula, which can transform active organic carbon in the soil into more stable inert organic carbon components through physical protection of the carbon skeleton and directional transformation by microorganisms, significantly reducing the loss of organic carbon mineralization, achieving long-term stable improvement of the soil carbon pool, and is suitable for application scenarios such as carbon sequestration and emission reduction in arable land and long-term improvement of degraded soil.

[0017] Another type is the nutrient-efficient formula, which can simultaneously achieve rapid improvement of acidic soil and nutrient supply throughout the entire growth period of crops through the slow-release effect of biochar and the nutrient activation effect of microorganisms, making it suitable for application scenarios of improving the quality and yield of crops in intensive farmland.

[0018] In addition, the functional microbial agent of this application can, on the one hand, convert easily decomposed unstable organic carbon in the soil into microbial biomass carbon (MBC) through its own metabolism, thereby achieving short-term live carbon fixation. At the same time, it continuously secretes extracellular enzymes such as sucrase and urease, which accelerates the decomposition of soil organic matter and the conversion of nitrogen and phosphorus nutrients, activates inert nutrients into forms that can be absorbed by crops, and simultaneously improves soil carbon cycle activity and nutrient utilization efficiency.

[0019] On the other hand, the polysaccharides and polyphenols produced by the functional microbial agents of this application can combine with the organic carbon adsorbed by bagasse biochar. Through the microbial mineralization-humification process, the easily lost active organic carbon in the soil is transformed into more stable inert organic carbon components such as humic carbon and microbial residue carbon, which greatly reduces the rate of mineralization and decomposition of organic carbon and achieves long-term stable fixation of the soil carbon pool.

[0020] According to one embodiment of the present invention, the bagasse biochar fertilizer has the following components in parts by weight: 0.5 parts bagasse biochar: 3 parts compound fertilizer: 0.1 parts functional microbial agent; or 0.5 parts bagasse biochar: 4 parts compound fertilizer: 0.2 parts functional microbial agent; or 0.5 parts bagasse biochar: 5 parts compound fertilizer: 0.3 parts functional microbial agent; or 1 part bagasse biochar: 3 parts compound fertilizer: 0.1 parts functional microbial agent; or 1 part bagasse biochar: 4 parts compound fertilizer: 0.2 parts functional microbial agent; or 1 part bagasse biochar: 5 parts compound fertilizer: 0.3 parts functional microbial agent; or 1.5 parts bagasse biochar: 3 parts compound fertilizer: 0.1 parts functional microbial agent; or 1.5 parts bagasse biochar: 4 parts compound fertilizer: 0.2 parts functional microbial agent; or 1.5 parts bagasse biochar: 5 parts compound fertilizer: 0.3 parts functional microbial agent.

[0021] According to one embodiment of the present invention, the method for preparing bagasse biochar includes the following steps: pretreating bagasse, followed by pyrolysis and carbonization at 450-550°C under an inert atmosphere; the heating rate of the pyrolysis and carbonization is 5-10°C / min. The present invention employs a specific bagasse pyrolysis temperature, which maximizes the carbon fixation efficiency and pore development of the biochar, providing the optimal physical structure for carbon adsorption and microbial habitation; preferably, slow heating is beneficial for uniform carbonization.

[0022] According to one embodiment of the present invention, the method for preparing bagasse biochar includes a heat preservation step after reaching a set temperature during pyrolysis carbonization, wherein the heat preservation time is 2.0-2.5 hours. Appropriate pyrolysis carbonization temperature and heat preservation time ensure complete carbonization and a well-developed pore structure.

[0023] According to one embodiment of the present invention, the bagasse undergoes pretreatment, comprising the following steps: rinsing the bagasse to remove soluble impurities, drying it to a moisture content of less than 10%, and then pulverizing it. This invention employs a pretreatment step, which solves the problem of raw material impurities affecting carbonization quality and product purity.

[0024] According to one embodiment of the present invention, the method for preparing bagasse biochar further includes a post-treatment step: washing the crude biochar after pyrolysis and carbonization until neutral, drying, and grinding and sieving. This post-treatment step solves the problems of high pH and uneven particle size in the biochar.

[0025] According to one embodiment of the present invention, the nitrogen source of the compound fertilizer is a nitrogen source selected from at least one of urea, ammonium sulfate, ammonium chloride, ammonium nitrate, calcium nitrate, and monoammonium phosphate.

[0026] According to one embodiment of the present invention, the phosphorus source of the compound fertilizer is a phosphorus source selected from at least one of diammonium phosphate, monoammonium phosphate, superphosphate, triple superphosphate, and potassium dihydrogen phosphate.

[0027] According to one embodiment of the present invention, the potassium source of the compound fertilizer is a potassium source selected from at least one of potassium sulfate, potassium chloride, potassium nitrate, and potassium dihydrogen phosphate.

[0028] According to one embodiment of the present invention, the mass fractions of nitrogen, phosphorus, and potassium in the compound fertilizer are 15%, 15%, and 15%, respectively. This balanced nutrient ratio of 15%-15%-15% can simultaneously meet the nitrogen, phosphorus, and potassium requirements for crop growth and soil microbial reproduction. It is perfectly matched with the adsorption and slow-release properties of biochar and the nutrient activation properties of microorganisms, thus solving the technical problem of asynchronous nutrient release and carbon fixation processes in existing fertilizers, which prevent the formation of a synergistic effect.

[0029] According to one embodiment of the present invention, the functional microbial agent is selected from at least one of Bacillus, Azotobacter chrysophyte, and arbuscular mycorrhizal fungi; preferably, the functional microbial agent is Bacillus; more preferably, the Bacillus is selected from at least one of Bacillus polymyxa, Bacillus megaterium, Bacillus subtilis, and Bacillus amyloliquefaciens. Bacillus has strong environmental adaptability, can secrete a variety of extracellular enzymes, and promotes soil carbon sequestration and nutrient activation. It is perfectly compatible with the pore structure of bagasse biochar and can stably colonize within the biochar pores.

[0030] According to one embodiment of the present invention, the Bacillus is composed of Bacillus polymyxa, Bacillus megaterium, Bacillus subtilis, and Bacillus amyloliquefaciens in a mass ratio of 1.0:1.0-1.2:1.0-1.2:1.0-1.2.

[0031] According to one embodiment of the present invention, the moisture content of the bagasse biochar fertilizer is less than 10%. Low moisture content ensures fertilizer particle stability and prevents premature microbial activation and product deterioration.

[0032] According to one embodiment of the present invention, the bagasse biochar fertilizer is a granular fertilizer.

[0033] According to one embodiment of the present invention, the bagasse biochar has a particle size ≤0.15mm. Small-particle-size biochar has a larger specific surface area, allowing for more thorough contact with the soil and providing more adsorption sites and microbial habitats.

[0034] According to one embodiment of the present invention, the bagasse biochar coats the compound fertilizer; the functional microbial agent is loaded inside the porous structure of the bagasse biochar.

[0035] Specifically, the technical solution adopted according to the second aspect of the present invention is as follows:

[0036] A method for preparing the bagasse biochar fertilizer includes the following steps:

[0037] Sugarcane bagasse biochar and functional microbial agents are added to a compound fertilizer solution (solid-liquid ratio of 1:2), and then dried to obtain the sugarcane bagasse biochar fertilizer.

[0038] According to one embodiment of the present invention, the pH of the compound fertilizer solution is 7.0-7.5.

[0039] According to one embodiment of the present invention, the solid-liquid ratio of the compound fertilizer solution is 1.0±0.2:2.0±0.2.

[0040] According to one embodiment of the present invention, the solid-liquid ratio of the compound fertilizer solution is 1.0-1.1:2.0-2.2.

[0041] Another aspect of the present invention relates to the application of the bagasse biochar fertilizer in acid soil improvement, soil carbon sequestration and emission reduction, and crop nutrient supply.

[0042] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0043] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0044] Figure 1 The graph shows the SOC test results of the soil after fertilization with bagasse biochar fertilizers from Examples 1-9.

[0045] Figure 2 The graph shows the ROC test results of the soil after fertilization with bagasse biochar fertilizers from Examples 1-9.

[0046] Figure 3 The graph shows the MBC test results of the soil after fertilization with bagasse biochar fertilizers from Examples 1-9.

[0047] Figure 4 The graph shows the soil mineralization rate test results of the soil after fertilization with bagasse biochar fertilizers from Examples 1-9.

[0048] Figure 5 The graph shows the results of sucrase activity testing in the soil after fertilization with bagasse biochar fertilizers from Examples 1-9.

[0049] Figure 6 The graph shows the urease activity test results of the soil after fertilization with bagasse biochar fertilizers from Examples 1-9. Detailed Implementation

[0050] The terms "preferred," "more preferred," etc., used in this invention refer to embodiments of the invention that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this invention.

[0051] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0052] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of the present invention.

[0053] Unless otherwise specified, the reagents, methods and equipment used in this invention are all conventional reagents, methods and equipment in this technical field.

[0054] In the examples, the nitrogen, phosphorus, and potassium elements in the compound fertilizer were derived from urea, diammonium phosphate, and potassium sulfate, respectively; the compound fertilizer was purchased from Stanley Fertilizer Co., Ltd.

[0055] In this embodiment, the Bacillus was composed of the following bacterial agents in a mass ratio of 1:1:1:1:1: Bacillus polymyxa, Bacillus megaterium, Bacillus subtilis, and Bacillus amyloliquefaciens. The Bacillus was purchased from Beihai Qiangxing Biotechnology Co., Ltd.

[0056] Example 1

[0057] A bagasse biochar fertilizer comprises the following components in parts by weight:

[0058] Sugarcane bagasse biochar, 0.5 parts;

[0059] Compound fertilizer, 3 parts; the mass fractions of nitrogen, phosphorus, and potassium in the above compound fertilizer are 15%, 15%, and 15%, respectively.

[0060] Bacillus, 0.1 part.

[0061] The above-mentioned method for preparing bagasse biochar includes the following steps:

[0062] Select dry, mold-free, and sand-free bagasse. Remove foreign objects such as metal and stones. Rinse the bagasse with deionized water to remove residual sugar, dust, and soluble impurities from the surface. Then, place it in an oven and dry it at 105°C to constant weight, reducing the moisture content to below 10%. Use a pulverizer to pulverize the dried bagasse to a particle size of 0.15 mm.

[0063] The bagasse was placed in a crucible and put into a muffle furnace. Under an inert atmosphere, it was heated to 500°C at a heating rate of 10°C / min and held for 2 hours. After cooling to room temperature, crude biochar was obtained.

[0064] The crude biochar was repeatedly washed with deionized water until the filtrate was neutral. It was then dried at 105°C to constant weight, ground to a particle size of 0.15 mm, and stored in a sealed container away from light to obtain bagasse biochar.

[0065] A method for preparing the above-mentioned bagasse biochar fertilizer includes the following steps:

[0066] Compound fertilizer was dissolved in water (solid-liquid ratio 1:2) to obtain a compound fertilizer solution. 1 mol / L NaOH was added dropwise to adjust the pH of the compound fertilizer solution to 7.0. Then, bagasse biochar and Bacillus were added to the compound fertilizer solution. After adsorption for 4 hours, the solution was dried at 35°C to obtain the above-mentioned bagasse biochar fertilizer with a moisture content of less than 10%, named BF1.

[0067] Example 2

[0068] The difference between Example 2 and Example 1 is that the composition ratio of the bagasse biochar fertilizer is different.

[0069] Specifically:

[0070] A bagasse biochar fertilizer comprises the following components in parts by weight:

[0071] Sugarcane bagasse biochar, 0.5 parts;

[0072] Compound fertilizer, 4 parts; the mass fractions of nitrogen, phosphorus, and potassium in the above compound fertilizer are 15%, 15%, and 15%, respectively.

[0073] Bacillus, 0.2 parts.

[0074] The above-mentioned method for preparing bagasse biochar includes the following steps:

[0075] Select dry, mold-free, and sand-free bagasse. Remove foreign objects such as metal and stones. Rinse the bagasse with deionized water to remove residual sugar, dust, and soluble impurities from the surface. Then, place it in an oven and dry it at 105°C to constant weight, reducing the moisture content to below 10%. Use a pulverizer to pulverize the dried bagasse to a particle size of 0.15 mm.

[0076] The bagasse was placed in a crucible and put into a muffle furnace. Under an inert atmosphere, it was heated to 500°C at a heating rate of 10°C / min and held for 2 hours. After cooling to room temperature, crude biochar was obtained.

[0077] The crude biochar was repeatedly washed with deionized water until the filtrate was neutral. It was then dried at 105°C to constant weight, ground to a particle size of 0.15 mm, and stored in a sealed container away from light to obtain bagasse biochar.

[0078] A method for preparing the above-mentioned bagasse biochar fertilizer includes the following steps:

[0079] Compound fertilizer was dissolved in water (solid-liquid ratio 1:2) to obtain a compound fertilizer solution. 1 mol / L NaOH was added dropwise to adjust the pH of the compound fertilizer solution to 7.0. Then, bagasse biochar and Bacillus were added to the compound fertilizer solution. After adsorption for 4 hours, the solution was dried at 35°C to obtain the above-mentioned bagasse biochar fertilizer with a moisture content of less than 10%, named BF2.

[0080] Example 3

[0081] The difference between Example 3 and Example 1 is that the composition ratio of the bagasse biochar fertilizer is different.

[0082] Specifically:

[0083] A bagasse biochar fertilizer comprises the following components in parts by weight:

[0084] Sugarcane bagasse biochar, 0.5 parts;

[0085] Compound fertilizer, 5 parts; the mass fractions of nitrogen, phosphorus, and potassium in the above compound fertilizer are 15%, 15%, and 15%, respectively.

[0086] Bacillus, 0.3 parts.

[0087] The above-mentioned method for preparing bagasse biochar includes the following steps:

[0088] Select dry, mold-free, and sand-free bagasse. Remove foreign objects such as metal and stones. Rinse the bagasse with deionized water to remove residual sugar, dust, and soluble impurities from the surface. Then, place it in an oven and dry it at 105°C to constant weight, reducing the moisture content to below 10%. Use a pulverizer to pulverize the dried bagasse to a particle size of 0.15 mm.

[0089] The bagasse was placed in a crucible and put into a muffle furnace. Under an inert atmosphere, it was heated to 500°C at a heating rate of 10°C / min and held for 2 hours. After cooling to room temperature, crude biochar was obtained.

[0090] The crude biochar was repeatedly washed with deionized water until the filtrate was neutral. It was then dried at 105°C to constant weight, ground to a particle size of 0.15 mm, and stored in a sealed container away from light to obtain bagasse biochar.

[0091] A method for preparing the above-mentioned bagasse biochar fertilizer includes the following steps:

[0092] Compound fertilizer was dissolved in water (solid-liquid ratio 1:2) to obtain a compound fertilizer solution. 1 mol / L NaOH was added dropwise to adjust the pH of the compound fertilizer solution to 7.0. Then, bagasse biochar and Bacillus were added to the compound fertilizer solution. After adsorption for 4 hours, the solution was dried at 35°C to obtain the above-mentioned bagasse biochar fertilizer with a moisture content of less than 10%, named BF3.

[0093] Example 4

[0094] The difference between Example 4 and Example 1 is that the composition ratio of the bagasse biochar fertilizer is different.

[0095] Specifically:

[0096] A bagasse biochar fertilizer comprises the following components in parts by weight:

[0097] Sugarcane bagasse biochar, 1 part;

[0098] Compound fertilizer, 3 parts; the mass fractions of nitrogen, phosphorus, and potassium in the above compound fertilizer are 15%, 15%, and 15%, respectively.

[0099] Bacillus, 0.1 part.

[0100] The above-mentioned method for preparing bagasse biochar includes the following steps:

[0101] Select dry, mold-free, and sand-free bagasse. Remove foreign objects such as metal and stones. Rinse the bagasse with deionized water to remove residual sugar, dust, and soluble impurities from the surface. Then, place it in an oven and dry it at 105°C to constant weight, reducing the moisture content to below 10%. Use a pulverizer to pulverize the dried bagasse to a particle size of 0.15 mm.

[0102] The bagasse was placed in a crucible and put into a muffle furnace. Under an inert atmosphere, it was heated to 500°C at a heating rate of 10°C / min and held for 2 hours. After cooling to room temperature, crude biochar was obtained.

[0103] The crude biochar was repeatedly washed with deionized water until the filtrate was neutral. It was then dried at 105°C to constant weight, ground to a particle size of 0.15 mm, and stored in a sealed container away from light to obtain bagasse biochar.

[0104] A method for preparing the above-mentioned bagasse biochar fertilizer includes the following steps:

[0105] Compound fertilizer was dissolved in water (solid-liquid ratio 1:2) to obtain a compound fertilizer solution. 1 mol / L NaOH was added dropwise to adjust the pH of the compound fertilizer solution to 7.0. Then, bagasse biochar and Bacillus were added to the compound fertilizer solution. After adsorption for 4 hours, the solution was dried at 35°C to obtain the above-mentioned bagasse biochar fertilizer with a moisture content of less than 10%, named BF4.

[0106] Example 5

[0107] The difference between Example 5 and Example 1 is that the composition ratio of the bagasse biochar fertilizer is different.

[0108] Specifically:

[0109] A bagasse biochar fertilizer comprises the following components in parts by weight:

[0110] Sugarcane bagasse biochar, 1 part;

[0111] Compound fertilizer, 4 parts; the mass fractions of nitrogen, phosphorus, and potassium in the above compound fertilizer are 15%, 15%, and 15%, respectively.

[0112] Bacillus, 0.2 parts.

[0113] The above-mentioned method for preparing bagasse biochar includes the following steps:

[0114] Select dry, mold-free, and sand-free bagasse. Remove foreign objects such as metal and stones. Rinse the bagasse with deionized water to remove residual sugar, dust, and soluble impurities from the surface. Then, place it in an oven and dry it at 105°C to constant weight, reducing the moisture content to below 10%. Use a pulverizer to pulverize the dried bagasse to a particle size of 0.15 mm.

[0115] The bagasse was placed in a crucible and put into a muffle furnace. Under an inert atmosphere, it was heated to 500°C at a heating rate of 10°C / min and held for 2 hours. After cooling to room temperature, crude biochar was obtained.

[0116] The crude biochar was repeatedly washed with deionized water until the filtrate was neutral. It was then dried at 105°C to constant weight, ground to a particle size of 0.15 mm, and stored in a sealed container away from light to obtain bagasse biochar.

[0117] A method for preparing the above-mentioned bagasse biochar fertilizer includes the following steps:

[0118] Compound fertilizer was dissolved in water (solid-liquid ratio 1:2) to obtain a compound fertilizer solution. 1 mol / L NaOH was added dropwise to adjust the pH of the compound fertilizer solution to 7.0. Then, bagasse biochar and Bacillus were added to the compound fertilizer solution. After adsorption for 4 hours, the solution was dried at 35°C to obtain the above-mentioned bagasse biochar fertilizer with a moisture content of less than 10%, named BF5.

[0119] Example 6

[0120] The difference between Example 6 and Example 1 is that the composition ratio of the bagasse biochar fertilizer is different.

[0121] Specifically:

[0122] A bagasse biochar fertilizer comprises the following components in parts by weight:

[0123] Sugarcane bagasse biochar, 1 part;

[0124] Compound fertilizer, 5 parts; the mass fractions of nitrogen, phosphorus, and potassium in the above compound fertilizer are 15%, 15%, and 15%, respectively.

[0125] Bacillus, 0.3 parts.

[0126] The above-mentioned method for preparing bagasse biochar includes the following steps:

[0127] Select dry, mold-free, and sand-free bagasse. Remove foreign objects such as metal and stones. Rinse the bagasse with deionized water to remove residual sugar, dust, and soluble impurities from the surface. Then, place it in an oven and dry it at 105°C to constant weight, reducing the moisture content to below 10%. Use a pulverizer to pulverize the dried bagasse to a particle size of 0.15 mm.

[0128] The bagasse was placed in a crucible and put into a muffle furnace. Under an inert atmosphere, it was heated to 500°C at a heating rate of 10°C / min and held for 2 hours. After cooling to room temperature, crude biochar was obtained.

[0129] The crude biochar was repeatedly washed with deionized water until the filtrate was neutral. It was then dried at 105°C to constant weight, ground to a particle size of 0.15 mm, and stored in a sealed container away from light to obtain bagasse biochar.

[0130] A method for preparing the above-mentioned bagasse biochar fertilizer includes the following steps:

[0131] Compound fertilizer was dissolved in water (solid-liquid ratio 1:2) to obtain a compound fertilizer solution. 1 mol / L NaOH was added dropwise to adjust the pH of the compound fertilizer solution to 7.0. Then, bagasse biochar and Bacillus were added to the compound fertilizer solution. After adsorption for 4 hours, the solution was dried at 35°C to obtain the above-mentioned bagasse biochar fertilizer with a moisture content of less than 10%, named BF6.

[0132] Example 7

[0133] The difference between Example 7 and Example 1 is that the composition ratio of the bagasse biochar fertilizer is different.

[0134] Specifically:

[0135] A bagasse biochar fertilizer comprises the following components in parts by weight:

[0136] Sugarcane bagasse biochar, 1.5 parts;

[0137] Compound fertilizer, 3 parts; the mass fractions of nitrogen, phosphorus, and potassium in the above compound fertilizer are 15%, 15%, and 15%, respectively.

[0138] Bacillus, 0.1 part.

[0139] The above-mentioned method for preparing bagasse biochar includes the following steps:

[0140] Select dry, mold-free, and sand-free bagasse. Remove foreign objects such as metal and stones. Rinse the bagasse with deionized water to remove residual sugar, dust, and soluble impurities from the surface. Then, place it in an oven and dry it at 105°C to constant weight, reducing the moisture content to below 10%. Use a pulverizer to pulverize the dried bagasse to a particle size of 0.15 mm.

[0141] The bagasse was placed in a crucible and put into a muffle furnace. Under an inert atmosphere, it was heated to 500°C at a heating rate of 10°C / min and held for 2 hours. After cooling to room temperature, crude biochar was obtained.

[0142] The crude biochar was repeatedly washed with deionized water until the filtrate was neutral. It was then dried at 105°C to constant weight, ground to a particle size of 0.15 mm, and stored in a sealed container away from light to obtain bagasse biochar.

[0143] A method for preparing the above-mentioned bagasse biochar fertilizer includes the following steps:

[0144] Compound fertilizer was dissolved in water (solid-liquid ratio 1:2) to obtain a compound fertilizer solution. 1 mol / L NaOH was added dropwise to adjust the pH of the compound fertilizer solution to 7.0. Then, bagasse biochar and Bacillus were added to the compound fertilizer solution. After adsorption for 4 hours, the solution was dried at 35°C to obtain the above-mentioned bagasse biochar fertilizer with a moisture content of less than 10%, named BF7.

[0145] Example 8

[0146] The difference between Example 8 and Example 1 is that the composition ratio of the bagasse biochar fertilizer is different.

[0147] Specifically:

[0148] A bagasse biochar fertilizer comprises the following components in parts by weight:

[0149] Sugarcane bagasse biochar, 1.5 parts;

[0150] Compound fertilizer, 4 parts; the mass fractions of nitrogen, phosphorus, and potassium in the above compound fertilizer are 15%, 15%, and 15%, respectively.

[0151] Bacillus, 0.2 parts.

[0152] The above-mentioned method for preparing bagasse biochar includes the following steps:

[0153] Select dry, mold-free, and sand-free bagasse. Remove foreign objects such as metal and stones. Rinse the bagasse with deionized water to remove residual sugar, dust, and soluble impurities from the surface. Then, place it in an oven and dry it at 105°C to constant weight, reducing the moisture content to below 10%. Use a pulverizer to pulverize the dried bagasse to a particle size of 0.15 mm.

[0154] The bagasse was placed in a crucible and put into a muffle furnace. Under an inert atmosphere, it was heated to 500°C at a heating rate of 10°C / min and held for 2 hours. After cooling to room temperature, crude biochar was obtained.

[0155] The crude biochar was repeatedly washed with deionized water until the filtrate was neutral. It was then dried at 105°C to constant weight, ground to a particle size of 0.15 mm, and stored in a sealed container away from light to obtain bagasse biochar.

[0156] A method for preparing the above-mentioned bagasse biochar fertilizer includes the following steps:

[0157] Compound fertilizer was dissolved in water (solid-liquid ratio 1:2) to obtain a compound fertilizer solution. 1 mol / L NaOH was added dropwise to adjust the pH of the compound fertilizer solution to 7.0. Then, bagasse biochar and Bacillus were added to the compound fertilizer solution. After adsorption for 4 hours, the solution was dried at 35°C to obtain the above-mentioned bagasse biochar fertilizer with a moisture content of less than 10%, named BF8.

[0158] Example 9

[0159] The difference between Example 9 and Example 1 is that the composition ratio of the bagasse biochar fertilizer is different.

[0160] Specifically:

[0161] A bagasse biochar fertilizer comprises the following components in parts by weight:

[0162] Sugarcane bagasse biochar, 1.5 parts;

[0163] Compound fertilizer, 5 parts; the mass fractions of nitrogen, phosphorus, and potassium in the above compound fertilizer are 15%, 15%, and 15%, respectively.

[0164] Bacillus, 0.3 parts.

[0165] The above-mentioned method for preparing bagasse biochar includes the following steps:

[0166] Select dry, mold-free, and sand-free bagasse. Remove foreign objects such as metal and stones. Rinse the bagasse with deionized water to remove residual sugar, dust, and soluble impurities from the surface. Then, place it in an oven and dry it at 105°C to constant weight, reducing the moisture content to below 10%. Use a pulverizer to pulverize the dried bagasse to a particle size of 0.15 mm.

[0167] The bagasse was placed in a crucible and put into a muffle furnace. Under an inert atmosphere, it was heated to 500°C at a heating rate of 10°C / min and held for 2 hours. After cooling to room temperature, crude biochar was obtained.

[0168] The crude biochar was repeatedly washed with deionized water until the filtrate was neutral. It was then dried at 105°C to constant weight, ground to a particle size of 0.15 mm, and stored in a sealed container away from light to obtain bagasse biochar.

[0169] A method for preparing the above-mentioned bagasse biochar fertilizer includes the following steps:

[0170] Compound fertilizer was dissolved in water (solid-liquid ratio 1:2) to obtain a compound fertilizer solution. 1 mol / L NaOH was added dropwise to adjust the pH of the compound fertilizer solution to 7.0. Then, bagasse biochar and Bacillus were added to the compound fertilizer solution. After adsorption for 4 hours, the solution was dried at 35°C to obtain the above-mentioned bagasse biochar fertilizer with a moisture content of less than 10%, named BF9.

[0171] Performance testing:

[0172] Soil samples from typical farmland at a depth of 20 cm were collected for soil incubation experiments. The initial average soil organic carbon (SOC) was 9.0-10.0 mg / g, and the average oxidizable organic carbon (ROC) was 0.8-1.0 g / kg. After air drying, impurities were removed, and the soil was ground and sieved through 2 mm and 0.25 mm sieves, respectively. The experiment included a no-fertilizer treatment (control group) and a treatment with bagasse biochar fertilizer (experimental group). The experimental group received 1 g / kg of BF1–BF9 bagasse biochar fertilizer (applied as 1 g of bagasse biochar-based fertilizer to 1 kg of farmland soil). The temperature was controlled at approximately 25℃ during the experiment, and natural light was used.

[0173] Soil SOC, ROC content, carbon mineralization rate, and sucrase and urease activities were measured on days 1, 8, 15, 25, 40, and 60 after fertilization. SOC content was determined using the potassium dichromate oxidation-spectrophotometric method, ROC content using the potassium permanganate oxidation method, microbial biomass carbon (MBC) using the chloroform fumigation method, urease activity using the sodium phenolate-sodium hypochlorite colorimetric method, and sucrase activity using the 3,5-dinitrosalicylic acid (DNS) colorimetric method.

[0174] (1) The soil organic carbon mineralization rate was determined as follows: 50 g of air-dried soil samples of different soil types were weighed and placed in small culture bottles. Simultaneously, a small bottle containing 10 mL of 0.2 mol / L NaOH absorbent solution was placed in a 500 mL culture bottle along with the soil-containing bottle. The bottles were sealed and incubated at 25℃. The CO2 release from each soil type was determined by BaCl2-HCl titration on days 1, 8, 15, 25, and 40 of the incubation period. The soil organic carbon mineralization amount (expressed as CO2) was:

[0175]

[0176] Where: V0: volume of standard hydrochloric acid consumed during blank titration, mL; V: volume of standard hydrochloric acid consumed during sample titration, mL; c: concentration of standard hydrochloric acid, mol / L; 0.022: molar mass of carbon dioxide (1 / 2 CO2), M(1 / 2 CO2) = 0.022 g / mmol; (22.4 / 44) × 1000: number of milliliters per gram of CO2 under standard conditions; m: soil weight, g.

[0177] Soil organic carbon mineralization rate:

[0178]

[0179] In the formula: △t: incubation interval time, d.

[0180] Cumulative mineralization of organic carbon (mg / kg):

[0181]

[0182] In the formula: n: incubation time, d.

[0183] Soil SOC test results as follows Figure 1 As shown, from Figure 1It can be seen that soil SOC fluctuates significantly over time. Throughout the entire incubation period, the soil SOC of treatments BF1, BF2, BF5, BF6, BF7, and BF8 all reached their peak on day 25, a phenomenon also observed in the CK treatment. Treatment BF4 reached its peak earlier, on day 15, while BF3 and BF9 reached their peak on day 40. The peak values ​​for all treatments ranged from 10.2 to 21.7 g / kg. At the end of the incubation period, except for treatments BF6 and BF8 where the soil SOC content was lower than CK, the other bagasse char-based fertilizer treatments were higher than CK, with increases ranging from 2.42% to 21.75%. Therefore, this invention, through differentiated formulation design, has for the first time achieved precise control of the peak time of soil organic carbon release (reaching peak values ​​at 15, 25, and 40 days respectively), breaking through the limitation of the single carbon release cycle of traditional biochar fertilizers; and after the incubation period, except for two formulations, the other seven formulations significantly increased the total soil organic carbon storage, demonstrating their ability to improve the soil carbon pool over the long term.

[0184] Soil ROC test results are as follows Figure 2 As shown, from Figure 2 It can be seen that the soil ROC exhibits a general trend of first decreasing, then increasing, and finally stabilizing. This phenomenon is due to the fact that bagasse biochar fertilizer releases a significant amount of readily decomposable carbon in the early stages of cultivation, which is then utilized by microorganisms or converted into stable organic carbon in the later stages. On day 60 of cultivation, compared to day 8 (day 1, when the application of biochar fertilizer caused excessive disturbance to soil ROC), all bagasse biochar fertilizer treatments except BF1 increased soil ROC content (compared to the control), with increases ranging from 14.2% to 168.4%, with BF5 showing the largest increase. Therefore, this invention reveals the core mechanism by which bagasse biochar fertilizer regulates soil active organic carbon (rapidly releasing readily decomposable carbon for microbial utilization in the early stages, and gradually converting it into stable organic carbon in the later stages); and on day 60 of cultivation, except for one formulation, the other eight formulations significantly increased soil active organic carbon content (increases of 14.2%-168.4%), with the BF5 formulation showing a particularly outstanding effect, far exceeding the blank control, providing an effective solution for rapidly activating the soil carbon pool.

[0185] Soil MBC test results as follows Figure 3 As shown, from Figure 3It can be seen that soil MBC initially decreased and then tended to stabilize. Overall, the changes in the BF treatments were complex. At the end of the incubation period, the soil MBC content in the BF2, BF3, BF4, BF5, BF6, and BF7 treatment groups was lower than that in the control (CK), with decreases ranging from 24.3% to 70.8%. The initial decrease in MBC was due to the alteration of soil pH by the application of bagasse char-based fertilizer, which temporarily inhibited the growth and reproduction of some microorganisms. The subsequent increase indicates that the microbial community gradually adapted to the new soil environment and utilized the carbon source in the char-based fertilizer to complete community reconstruction. At the end of the incubation period, the MBC content in the BF2–BF7 treatments was lower than that in the CK because the carbon source provided by these bagasse char-based fertilizers was relatively stable and difficult for microorganisms to utilize rapidly, thus limiting the growth of microbial biomass. The soil MBC content in the BF1, BF8, and BF9 treatment groups was higher than that in the CK, with increases ranging from 10.4% to 19.0%. This indicates that the proportion of additives in these bagasse biochar-based fertilizers has a positive effect on increasing microbial biomass and has a relatively long-lasting microbial-promoting effect. Therefore, this invention has discovered the bidirectional regulatory characteristics of bagasse biochar fertilizer on soil microbial biomass, which was not anticipated by existing technologies: by adjusting the proportion of additives, a stable organic carbon-stable formulation (BF2-BF7) can be obtained: the carbon source provided by it is difficult for microorganisms to utilize quickly, limiting the rapid growth of microbial biomass and reducing carbon decomposition and loss; a microbial-promoting formulation (BF1, BF8, BF9) can also be obtained: it can sustainably increase soil microbial biomass (increase of 10.4%-19.0%), realizing functional customization for different agricultural application scenarios.

[0186] The test results of soil mineralization rate are as follows: Figure 4 As shown, from Figure 4It can be seen that the soil organic carbon mineralization rate under the nine bagasse biochar fertilizer treatments can be divided into two stages throughout the entire cultivation period: the organic carbon mineralization rate increases from day 1 to day 15, and decreases from day 15 to day 60. On day 15, the soil organic carbon mineralization rate of each treatment reaches its peak, indicating that the bagasse biochar fertilizer of this invention has a short-term stimulating effect on organic carbon mineralization. When each treatment reaches its peak on day 15, the organic carbon mineralization rate of treatments BF3 and BF5 has already begun to fall below the control (CK), and this situation continues until day 40. From day 40 to day 60, the organic carbon mineralization rate of treatments BF3 and BF5 rebounds, slightly exceeding the CK. Although the organic carbon mineralization rate of other bagasse biochar fertilizer treatments begins to decrease after reaching its peak, it remains higher than the CK until the end of the cultivation period. Therefore, this invention solves the technical problems of excessively rapid organic carbon mineralization and poor carbon sequestration in traditional biochar fertilizers: all formulations reach the peak mineralization rate on day 15, and have the common effect of stimulating soil carbon cycling in the short term; among them, the BF3 and BF5 formulations show unique mineralization regulation capabilities, which can significantly inhibit organic carbon mineralization in the medium term (15-40 days), greatly reduce carbon loss, and only slightly rebound in the later stage, achieving the optimal balance between carbon sequestration and mineralization.

[0187] The test results of sucrase activity are as follows: Figure 5 As shown, from Figure 5 It can be seen that soil sucrase activity generally showed a trend of first increasing and then decreasing, with a slight increase at the end of the incubation period. On day 8 of incubation, the soil sucrase content in all nine bagasse biochar fertilizer treatment groups increased to varying degrees. This indicates that the bagasse biochar fertilizer of this invention has a short-term stimulating effect on the activity of carbon cycle-related enzymes. From day 8 to day 40, sucrase activity showed a decreasing trend, with the decrease in all treatment groups, including CK, ranging from 70.0% to 80.0%. From day 40 to day 60 of incubation, the soil sucrase content showed a slight rebound; at this time, the sucrase activities of BF1, BF2, BF3, BF4, BF5, and BF9 treatments were all higher than those of the CK treatment, with increases ranging from 0.5 to 2.2 times. This indicates that the application of bagasse biochar fertilizer can promote the hydrolysis of sugars in the soil, accelerate the soil carbon cycle, thereby activating enzymatic reactions related to sucrase in the soil, and ultimately increasing the activity of sucrase in the soil. Therefore, this invention demonstrates that bagasse biochar fertilizer can not only stimulate the activity of carbon cycle-related enzymes in the short term (all formulations increased sucrase activity on day 8 of cultivation), but also significantly and continuously enhance enzyme activity in the later stages of the cultivation cycle (the activity of 6 formulations was higher than that of the blank control). It can promote the hydrolysis of soil sugars, accelerate the carbon cycle process, and activate related enzymatic reactions in the long term. This long-term enzyme activity regulation effect is something that the prior art did not expect.

[0188] The test results for urease activity are as follows: Figure 6 As shown, from Figure 6 It was observed that soil urease activity fluctuated significantly over time, and throughout the entire culture period, the urease activity of all bagasse char-based fertilizer treatments was lower than that of the control (CK) treatment. In the early stages of culture, the urease activity in the bagasse char-based fertilizer treatment group showed an upward trend. This was attributed to the organic nitrogen substrate introduced by the bagasse char-based fertilizer stimulating urease secretion. Simultaneously, changes in pH also promoted the availability of soil enzymatic reaction substrates, thereby increasing soil urease activity. Although urease may be synthesized in some organisms, its expression is generally regulated by nitrogen, particularly when cells are in an environment with nitrogen content of NH4+. + When grown under conditions where the bagasse charcoal fertilizer is the preferred nitrogen source, enzyme synthesis is inhibited. This explains why the urease activity in all bagasse charcoal-based fertilizer treatment groups was lower than that in the control group at the end of the cultivation period.

[0189] The above are merely embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent modifications made based on the content of the present invention specification, or direct or indirect applications in related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A bagasse biochar fertilizer, characterized in that: The components include the following parts by weight: Sugarcane bagasse biochar, 0.5-1.5 parts; Compound fertilizer, 3-5 parts; the mass fractions of nitrogen, phosphorus, and potassium in the compound fertilizer are 15-16%, 15-16%, and 15-16%, respectively. Functional microbial inoculant, 0.1-0.3 parts.

2. The bagasse biochar fertilizer according to claim 1, characterized in that: The method for preparing bagasse biochar includes the following steps: pretreating the bagasse, and then pyrolyzing and carbonizing it at 450-550°C under an inert atmosphere; preferably, the heating rate of the pyrolyzing and carbonizing is 5-10°C / min.

3. The bagasse biochar fertilizer according to claim 2, characterized in that: The method for preparing bagasse biochar includes a heat preservation step after the set temperature is reached during pyrolysis carbonization, wherein the heat preservation time is 2.0-2.5 hours.

4. The bagasse biochar fertilizer according to claim 2, characterized in that: The bagasse pretreatment includes the following steps: rinsing the bagasse to remove soluble impurities, drying it to a moisture content of less than 10%, and then crushing it.

5. The bagasse biochar fertilizer according to claim 1, characterized in that: The functional microbial agent is selected from at least one of Bacillus, Azotobacter chrysozoans, and arbuscular mycorrhizal fungi; preferably, the functional microbial agent is Bacillus; more preferably, the Bacillus is selected from at least one of Bacillus polymyxa, Bacillus megaterium, Bacillus subtilis, and Bacillus amyloliquefaciens.

6. The bagasse biochar fertilizer according to claim 5, characterized in that: The Bacillus species are composed of Bacillus polymyxa, Bacillus megaterium, Bacillus subtilis, and Bacillus amyloliquefaciens in a mass ratio of 1.0:1.0-1.2:1.0-1.2:1.0-1.

2.

7. The bagasse biochar fertilizer according to claim 1, characterized in that: The moisture content of the bagasse biochar fertilizer is less than 10%.

8. A method for preparing bagasse biochar fertilizer as described in any one of claims 1 to 7, characterized in that: Includes the following steps: Sugarcane bagasse biochar and functional microbial agents are added to a compound fertilizer solution, and then dried to obtain the sugarcane bagasse biochar fertilizer.

9. The method according to claim 8, characterized in that: The pH of the compound fertilizer solution is 7.0-7.

5.

10. The application of bagasse biochar fertilizer as described in any one of claims 1 to 7 in acid soil improvement, soil carbon sequestration and emission reduction, and crop nutrient supply.

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