A biological silicon fertilizer and a preparation method and use method thereof

Abstract

The application discloses a kind of biological silicon fertilizer and its preparation method and use method, the preparation method of the biological silicon fertilizer is by pyrolysis carbonization silicon accumulation type plant rich in phytolith, effectively release plant available silicon, solve the problem of low silicon availability of highly weathered soil, the method uses agricultural waste as raw material, low cost, avoid heavy metal pollution, comply with green agricultural concept.The pore structure and large specific surface area of biochar can improve the physical structure of soil, enhance the water and fertilizer retention capacity, and increase the soil organic carbon content, building a healthy soil ecosystem. By optimizing the pyrolysis process and raw material selection, a biological silicon fertilizer suitable for different soil types can be designed, especially in highly weathered and desilicated soil. The method provides a basis for studying the use of biological silicon fertilizer to improve crop drought resistance and helps to clarify the mechanism of enhancing the drought resistance of crops.

Description

Technical Field

[0001] This invention belongs to the field of agricultural soil improvement and silicon fertilizer application technology, and relates to a bio-silicon fertilizer and its preparation and application methods. Background Technology

[0002] In agricultural soil environments, highly weathered soils (such as strongly leached soils and ferruginous soils) suffer significant silicon loss due to long-term natural weathering, resulting in a substantial reduction in the availability of silicon in the soil. This situation has a severe negative impact on crop yield and stress resistance. Under highly intensive agricultural production models, high crop yields lead to the absorption and removal of large amounts of plant-available silicon (Si) from the soil by crops. Coupled with the dual effects of natural weathering and leaching, the problem of severe soil desilcation is becoming increasingly prominent. Although silicon is not an essential element for plant growth, it plays a significant and undeniable beneficial role in improving crop photosynthetic efficiency and enhancing crop resistance to abiotic stresses such as drought and biotic stresses such as pests and diseases.

[0003] Traditional silicon fertilizers, such as wollastonite and slag, have revealed many drawbacks in practical applications. They have poor solubility, making them difficult for crops to fully absorb and utilize; they are costly, increasing the economic burden on agricultural production; some traditional silicon fertilizers may also contain heavy metals, posing a potential threat to the soil environment and crop safety; more importantly, they cannot effectively improve soil structure or increase soil organic carbon content. These problems greatly limit the widespread application of traditional silicon fertilizers.

[0004] Against this backdrop, biochar, as a promising soil conditioner, has demonstrated significant application potential. Biochar is produced through the pyrolysis of plant straw, where the abundant phytoliths effectively release available silicon from the plants, making it particularly suitable for addressing the low silicon availability in highly weathered soils. During plant growth, silicon is absorbed and stored in phytoliths within the plant tissues. The pyrolysis process for preparing biochar further enriches these phytoliths and significantly improves the release efficiency of available silicon.

[0005] However, the effectiveness of biochar as a silicon fertilizer is not unlimited, but is significantly affected by soil properties, among which soil pH, buffering capacity, and degree of weathering are particularly critical. In highly weathered and desilicationated soil environments, designing efficient biochar silicon fertilizers becomes a key issue in improving soil silicon availability and promoting crop growth. Furthermore, elucidating the mechanism by which biochar silicon fertilizers improve crop drought resistance not only helps to deepen the understanding of their functional characteristics but also provides a solid theoretical basis for their scientific application in agricultural production. Therefore, designing efficient biochar silicon fertilizers for highly weathered and desilicationated soils and studying their drought resistance mechanisms is an important starting point and core objective of this invention. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention provides a bio-silicon fertilizer and its preparation and application methods, in order to solve the problems of low silicon availability in highly weathered soils, the drawbacks of traditional silicon fertilizers such as poor solubility, high cost, heavy metal content, inability to improve soil structure and increase organic carbon content, and the fact that the effectiveness of biochar as a silicon fertilizer is significantly affected by soil properties. Designing efficient biochar silicon fertilizer and studying its drought resistance mechanism in highly weathered and desiliconized soils has become a challenge.

[0007] This invention is achieved through the following technical solution: A method for preparing bio-silicon fertilizer involves pyrolysis and carbonization of silicon-accumulating plants rich in phytosilicone.

[0008] Preferably, the silica-accumulating plants rich in phytoliths include one or more of rice straw, miscanthus, sugarcane bagasse, wheat straw, and corn straw.

[0009] Preferably, the enriched silica is carbonized by pyrolysis under oxygen-limited conditions; Preferably, the pyrolysis process is carried out at a temperature of 400~600℃ for 60~120 min, with a heating rate of 17℃ / min. 1 .

[0010] A bio-silicon fertilizer is prepared by the above method.

[0011] Preferably, the silicon content of the bio-silicon fertilizer is higher than 30g / kg.

[0012] Preferably, the bio-silicon fertilizer is evenly applied to the weathered soil and mixed with the soil into the soil layer.

[0013] Preferably, the bio-silicon fertilizer is applied evenly to the weathered soil at a rate not exceeding 3 tons per hectare.

[0014] Preferably, the bio-silicon fertilizer is applied evenly to the weathered soil at a rate of 1-3 tons per hectare.

[0015] Preferably, the bio-silicon fertilizer is mixed with the soil to a depth of 0-20cm by tilling or rotary tillage.

[0016] Compared with the prior art, the present invention has the following beneficial technical effects: This invention proposes a method for preparing bio-silicon fertilizer. By pyrolyzing and carbonizing silicon-accumulating plants rich in phytoliths (such as rice straw and miscanthus), the method effectively releases available silicon from the plants, solving the problem of low silicon availability in highly weathered soils. During pyrolysis, phytoliths are further enriched, improving silicon release efficiency and making the silicon in the bio-silicon fertilizer more easily absorbed and utilized by crops. Compared to traditional silicon fertilizers (such as wollastonite and slag), this method uses agricultural waste as raw material, resulting in low cost and avoiding heavy metal pollution, aligning with the concept of green agriculture. Biochar has a good pore structure and a large specific surface area, which can improve soil physical structure, enhance water and fertilizer retention capacity, and increase soil organic carbon content, contributing to the construction of a healthy soil ecosystem. Although the effectiveness of biochar silicon fertilizer is affected by soil properties, by optimizing the pyrolysis process and raw material selection, bio-silicon fertilizers suitable for different soil types can be designed. Especially in highly weathered and desilicationated soils, highly efficient biochar silicon fertilizers can be prepared by adjusting the pyrolysis conditions. This method also provides a foundation for studying how bio-silicon fertilizers improve crop drought resistance and helps to elucidate the mechanism by which they enhance crop drought resistance.

[0017] Furthermore, the silicon-accumulating plants rich in phytoliths include one or more of rice straw, miscanthus, sugarcane bagasse, wheat straw, and corn straw, thus clarifying the specific types of silicon-accumulating plants rich in phytoliths, including rice straw, miscanthus, sugarcane bagasse, wheat straw, and corn straw. These plants are widely available and have large annual yields, providing ample raw material guarantees for the large-scale production of bio-silicon fertilizer.

[0018] Furthermore, the phytoliths were pyrolyzed and carbonized under oxygen-limited conditions. This limited the pyrolysis and carbonization process to oxygen-limited conditions, which helps maintain the stability of the phytoliths and prevents them from being oxidized and destroyed during pyrolysis, thereby improving the availability of silicon in the bio-silicon fertilizer.

[0019] Furthermore, the pyrolysis process is carried out at a temperature of 400~600℃ for a time of 60~120 min, with a heating rate of 17℃ / min. 1 The study specifies in detail the temperature, time, and heating rate of the pyrolysis process. Optimizing these parameters helps ensure sufficient enrichment of phytoliths and effective release of silicon. By precisely controlling the pyrolysis conditions, stable bio-silicon fertilizers can be prepared.

[0020] A bio-silicon fertilizer is prepared by the above-described method. The bio-silicon fertilizer has a silicon content higher than 30 g / kg, which ensures the fertilizer efficiency of the product and gives it a significant advantage in supplementing available silicon in the soil.

[0021] Furthermore, the bio-silicon fertilizer is evenly applied to the weathered soil and mixed with the soil layer. The application rate of the bio-silicon fertilizer in the weathered soil does not exceed 3 tons / hectare. The application rate of the bio-silicon fertilizer in the weathered soil is 1-3 tons / hectare. The bio-silicon fertilizer is mixed with the soil to a depth of 0-20 cm through tilling or rotary tillage. The application method of the bio-silicon fertilizer is detailed, including the method of application to the weathered soil, the application rate, and the depth of mixing with the soil. These specific usage guidelines help farmers apply bio-silicon fertilizer scientifically and rationally, thereby improving its utilization efficiency and crop yield. At the same time, limiting the application rate to no more than 3 tons / hectare and recommending an application rate of 1-3 tons / hectare ensures fertilizer efficiency while avoiding waste and environmental pollution. Mixing the bio-silicon fertilizer with the soil to a depth of 0-20 cm through tilling or rotary tillage helps to evenly distribute silicon in the soil and ensure full absorption by crops. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced 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 on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 The images shown are (a) scanning electron microscope (SEM) images and (b) energy dispersive X-ray spectra of the phytolithic Miscanthus biochar in Example 1 of the present invention. Figure 2 The images shown are scanning electron microscope (SEM) images (a) and energy dispersive X-ray spectra (b) of the phytolith-enriched rice straw biochar in Example 2 of the present invention. Figure 3 The curves showing the change of extractable silicon content (CaCl2-Si) of different biochars over time are shown. (a) Si-, Si+ and Wo treatment groups; (b) CA, CA:Si-, CA:Si+ and CA:Wo treatment groups; (c) NI, NI:Si-, NI:Si+ and NI:Wo treatment groups. Figure 4 This is a comparison chart showing the growth status of crops treated with the bio-silicon fertilizer prepared in Example 1 of this invention and control crops under drought stress. Detailed Implementation

[0024] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0025] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0026] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0027] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0028] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0029] This invention provides a method for preparing bio-silicon fertilizer, which is produced by pyrolysis and carbonization of silicon-accumulating plants rich in phytosilicone.

[0030] Specifically, it is produced by pyrolysis and carbonization of phytosilicone under oxygen-limited conditions; In this invention, the oxygen-limiting condition is achieved by introducing an inert gas (such as nitrogen or argon) to expel oxygen, and the flow rate of the inert gas is 100~200 mL / min. The silicon-accumulating plants rich in phytoliths include one or more of rice straw, miscanthus, sugarcane bagasse, wheat straw, and corn straw; The pyrolysis process is carried out at a temperature of 400~600℃ for a time of 60~120min, with a preferred temperature of 500℃ and a preferred time of 60min. The heating rate of the pyrolysis process is 17℃ / min, which is fast and has a short pyrolysis time.

[0031] The bio-silicon fertilizer contains silicon content higher than 30g / kg, and more preferably higher than 50g / kg. The bio-silicon fertilizer exhibits a significantly higher content of readily extractable silicon (easily extracted by 0.01 MCaCl2) than traditional silicon fertilizers (such as wollastonite), demonstrating its stronger silicon supply capacity and greater ease of absorption and utilization by crops. Based on this, the application of this type of biochar in highly weathered, desilication-prone soil environments is supported, encompassing typical types such as strongly leached soils and ferruginous soils. These soils suffer severe silicon loss due to long-term weathering, and the application of biochar-silicon fertilizer not only directly replenishes available silicon in the soil but also enhances soil fertility by promoting the biological cycle of silicon (such as the decomposition and reuse of phytoliths), thereby improving crop resistance and yield. This strategy provides a low-cost, environmentally friendly solution for the sustainable improvement of highly weathered soils, combining resource recycling with agricultural ecological benefits.

[0032] In addition, the present invention also discloses a method for using the above-mentioned bio-silicon fertilizer, wherein the bio-silicon fertilizer is evenly applied into weathered soil and the bio-silicon fertilizer is mixed with the soil into the soil layer.

[0033] Specifically, the application rate of bio-silicon fertilizer can be adjusted according to the initial silicon content of the soil and the needs of crops, with a maximum of 3 tons / hectare, a preferred application rate of 1 to 3 tons / hectare, and a more preferred application rate of 1.2 to 2.4 tons. Bio-silicon fertilizer can be mixed with the soil to a depth of 0-20cm by tilling or rotary tilling.

[0034] The weathered soil is one of the following: strongly leached soil, ferroaluminous soil, leached soil, dark soil, or soil with weak water retention capacity.

[0035] Strongly leached soils are soils formed under humid climatic conditions through intense leaching. They are characterized by the significant loss of basic substances (such as calcium, magnesium, potassium, and sodium) from the soil, resulting in an acidic to strongly acidic soil solution. Clay particles migrate significantly downwards in the soil profile, accumulating in layer B (subsoil) to form a clayey layer.

[0036] Ferroalloy soils are soils formed under tropical and subtropical hot and humid climates through intense chemical weathering, leaching, and bioaccumulation. These soils exhibit strong decomposition of silicate minerals, high leaching of bases, and relative enrichment of iron and aluminum oxides, resulting in acidic to strongly acidic soil conditions.

[0037] Leached soils are soils formed through significant leaching, resulting in the loss of large amounts of soluble salts, including some calcium, magnesium, and potassium bases. These soils typically have a clay layer, with clay particles accumulating in the B layer.

[0038] Dark soils typically refer to soils with high organic matter content and a darker color. These soils generally have good granular structure and excellent water and fertilizer retention properties.

[0039] Soils with poor water retention capacity include sandy soil and stony soil. Sandy soil has coarse particles and large, numerous pores, allowing water to infiltrate rapidly through these pores. However, the intergranular water-holding capacity is poor, leading to easy evaporation and thus poor water retention. For example, in some sandy coastal soils in coastal areas, the high sand content causes rapid water loss after rainfall, making the soil prone to drought. Stony soil is mostly distributed in mountainous areas or areas with exposed rocks. It has a thin soil layer and contains many rock fragments. Its large pores make it difficult to retain water, resulting in poor water retention capacity. For example, in some mountainous and hilly areas, the soil layer formed by rock weathering is thin, leading to rapid water loss after rainfall and a pronounced problem of soil drought.

[0040] Furthermore, preferably, during the use of the bio-silicon fertilizer of the present invention, wollastonite or other nitrogen fertilizers can be used in conjunction to further improve silicon availability.

[0041] In the above-mentioned method of using bio-silicon fertilizer, after the bio-silicon fertilizer is mixed with the soil, silicon-accumulating crops can be planted, and the soil silicon availability, moisture content and crop growth can be monitored regularly.

[0042] Here, before planting silicon-accumulating crops, the soil can be irrigated with water and balanced for a week at a field water holding capacity of 70%, and then the silicon-accumulating crops can be planted.

[0043] Meanwhile, after planting silicon-accumulating crops, the crops were dried at 55°C for 7 days without any nutrients except water throughout their entire growth cycle. The biomass of the harvested crops was then weighed to assess their performance.

[0044] The biochar-silicon fertilizer involved in this invention exhibits many significant advantages. The silicon in this fertilizer is more easily soluble and can exert a variety of positive effects when applied to the soil.

[0045] In terms of soil improvement, it can significantly increase soil pH, cation exchange capacity (CEC), and organic carbon content. In particular, it greatly increases the available silicon pool in the soil, with a very significant effect on the extractable silicon index using CaCl2. In highly weathered soils with low buffer capacity, its effect on increasing soil pH and silicon bioavailability is even more pronounced.

[0046] For crop growth, this silicon fertilizer can effectively promote the absorption and accumulation of silicon by crops, increasing the amount of silicon minerals in the plant. By enhancing the silicon nutrition of crops, it can not only significantly promote plant growth, but also strengthen the silicon biological cycle.

[0047] From a practical application perspective, it is an ideal silicon fertilizer alternative for highly weathered and desilicationized soils. Economically, it offers a cost advantage; environmentally, it aligns with the principles of green development. It not only efficiently replenishes available silicon in plants, meeting the silicon requirements for crop growth, but also increases soil organic carbon content, soil moisture content, and improves the soil's physical and chemical properties. These improvements work synergistically to enhance crop growth, ultimately increasing crop yield and drought resistance, providing an effective solution for soil improvement and crop yield enhancement in agricultural production.

[0048] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0049] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0050] Example 1 The invention utilizes Miscanthus biochar to improve different weathered soils, and a cotton pot experiment was conducted to verify its beneficial effects. Specifically: Miscanthus biochar (Mi) is an effective silicon fertilizer alternative, especially suitable for highly weathered soils with low available silicon content in plants (such as Nitisol (NI)). Miscanthus biochar can significantly increase soil plant available silicon content, cotton biomass, and silicon uptake, while also improving soil fertility (e.g., increasing CEC, pH, and nutrient availability). Cork biochar (SW), due to its low silicon content, has a limited impact on silicon cycling and plant growth.

[0051] (1) Material preparation Two types of soil with different degrees of weathering: Cambisol (CA): Young soil with a low degree of weathering.

[0052] Nitisol (NI): Highly weathered soil.

[0053] Three types of silicon fertilizer improvers: Miscanthus biochar with high silicon content (Mi): Silicon content (34.6 g / kg).

[0054] Low-silicon cork biochar (SW): Silicon content (0.9 g / kg).

[0055] In this embodiment, the preparation processes of Miscanthus biochar (Mi) and cork biochar (SW) are the same: straw is heated in a reactor at 17°C for min. 1 The heating rate was further pyrolyzed to 500°C, the reactor was kept at 500°C for 60 minutes, and then gradually cooled naturally.

[0056] Wollastonite (CaSiO3): a traditional silicon fertilizer, used as a control.

[0057] Mixing ratio: Soil and amendment are mixed at a ratio of 97:3 (w / w).

[0058] (2) Soil-amendant mixing and pretreatment After mixing the soil and the amendment, adjust the water content to 70% of the field capacity with deionized water and allow it to equilibrate for one week.

[0059] Field holding capacity refers to the soil moisture content when capillary suspended water reaches its maximum value. That is, after the soil is drained and gravity water has been removed, the soil moisture content reaches its maximum when capillary water reaches its maximum. It is the maximum amount of suspended water that the soil can hold and is one of the soil moisture constants, representing the upper limit of the effective water that the soil can provide to plants.

[0060] Here, the water content is adjusted to 70% of the field capacity. This means mixing the soil and the soil amendment with deionized water to bring the soil moisture content to 70% of its field capacity. For example, if the field capacity of a certain soil is measured to be 30%, adjusting it to 70% will result in a soil moisture content of 21% (30% × 70% = 21%). This provides a suitable humidity environment for soil microorganisms and the soil amendment, promoting their interaction; on the other hand, it avoids excessive moisture leading to poor soil aeration, which could affect the results of subsequent experiments or treatments.

[0061] (3) Cotton pot experiment Plant: Cotton.

[0062] Design: Each treatment has 3 replicates, for a total of 6 treatments, namely CA-Mi, CA-SW, CA-Wo, NI-Mi, NI-SW, and NI-Wo.

[0063] Growth conditions: Grow in an artificial climate chamber for 5 months at a temperature of 28°C and a relative humidity of 80%.

[0064] Watering: For the first two months, water each pot with 33mL of deionized water every three days, and for the last three months, water with 100mL. Do not apply any fertilizer.

[0065] Harvesting: The above-ground parts are harvested after 5 months, dried, weighed, and their elemental content is analyzed.

[0066] (4) Analyze the project Soil and amendment properties: pH value, CEC, exchangeable cations, total carbon and nitrogen content.

[0067] pH value measures the acidity or alkalinity of soil and soil amendments. Soil pH value affects the availability of nutrients in the soil, microbial activity, and plant growth. Different plants have different tolerance ranges for soil pH, and soil amendments can also alter the soil's acid-base environment.

[0068] CEC (Cation Exchange Capacity): refers to the ability of soil or soil amendment to adsorb and exchange cations, commonly measured in cmol. + / kg. CEC reflects the soil's ability to retain nutrients. The higher the CEC, the stronger the soil's ability to retain nutrients, and the more cationic nutrients it can adsorb, such as ammonium ions and potassium ions, thus preventing nutrient loss.

[0069] Exchangeable cations: This involves analyzing the types and amounts of exchangeable cations in soil and soil amendments, such as calcium, magnesium, sodium, and potassium. These cations are essential nutrients for plant growth, and understanding their content helps assess soil fertility and the impact of soil amendments on nutrient supply.

[0070] Total carbon and nitrogen content: This measures the total amount of carbon and nitrogen in soil and soil amendments. Carbon is an important component of soil organic matter and is closely related to soil structure, water retention, and fertilizer retention capacity; nitrogen is a key nutrient element for plant growth, and total nitrogen content reflects the soil's nitrogen supply potential.

[0071] CaCl2 Extraction of Silicon: Assessing Silicon Bioavailability. Silicon in soil is extracted using CaCl2 solution to assess its bioavailability. Bioavailability refers to the extent to which silicon in soil can be absorbed and utilized by plants. CaCl2 extraction is a commonly used method for assessing available silicon in soil. By measuring the silicon content in the extract, the amount of silicon in the soil that can be directly absorbed and utilized by plants can be determined.

[0072] Total elemental content: Determined by Li-metabort fusion + ICP-AES (Inductively Coupled Plasma Atomic Emission Spectroscopy). Li-metabort fusion converts elements in the sample into a soluble state, facilitating subsequent instrumental analysis. ICP-AES can accurately determine the content of multiple elements, providing a comprehensive understanding of the elemental composition of soil, amendment, or plant samples.

[0073] X-ray diffraction (XRD) and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDX): These methods analyze mineral composition and phytolith morphology, allowing observation of the sample's surface structure, such as the shape, size, and surface features of phytoliths. Simultaneously, EDX can perform qualitative and semi-quantitative analysis of the elemental composition of the sample surface, helping to determine the elemental composition of structures such as phytoliths.

[0074] Plant analysis: Biomass (dry weight), measured after harvest, reflects the plant's growth status and productivity. Increased biomass usually indicates good plant growth and directly demonstrates the promoting effect of soil and amendments on plant growth.

[0075] Elemental content (Ca, Mg, Na, K, Si): Analyzing the content of various elements in plants helps understand how plants absorb different nutrients. For example, silicon plays an important role in plant growth, such as enhancing plant stress resistance. By measuring the silicon content in plants, the effect of plant amendments on improving silicon nutrition can be evaluated.

[0076] Mineral mass = element content × biomass. This formula is used to calculate the mass of elements in the plant in mineral form, and to further understand how plants accumulate and utilize elements.

[0077] (5) Data processing One-way ANOVA and Least Significant Difference (LSD) multiple comparisons were performed using Statistical Product and Service Solutions (SPSS) software (p<0.05). Using SPSS for one-way ANOVA and LSD multiple comparisons is a classic method in statistics used to explore the significance and specific location of differences between multiple groups of data.

[0078] Figure 1 The images show scanning electron microscope (SEM) image (a) and energy dispersive X-ray spectrum (b) of the phytolith-rich Miscanthus biochar in Example 1 of this invention. The images clearly show the dominant distribution of carbon (C), oxygen (O) and silicon (Si), confirming the presence of phytoliths (SiO2·nH2O).

[0079] (6) Summary This study, through rigorous pot experiments and multiple physicochemical analyses, demonstrated the following conclusions: In highly weathered soils, the silicon release efficiency of Mi biochar (1.4%) is higher than that of wollastonite (0.7%); the phytoliths in Mi biochar remain intact after pyrolysis at 550°C, and can slowly release soluble silicon into the soil; it increases cotton biomass in both types of soil (CA and NI), especially in NI where the increase is greater (4.7 times), while providing nutrients such as K, Ca, and Mg, improving soil fertility, significantly promoting plant growth, and enhancing the biological cycle of silicon; taking cotton as an example, the increase is particularly significant in Nitisol (5.9 times), indicating that the improvement effect is more significant in silicon-deficient soils; after the phytoliths dissolve, they replenish the soil's available silicon pool and promote plant absorption.

[0080] Miscanthus biochar, rich in phytoliths, has the potential to significantly improve silicon availability, promote plant growth, and enhance silicon absorption in highly weathered soils, making it an environmentally friendly and sustainable alternative to silicon fertilizers. Mi biochar is an effective silicon fertilizer substitute.

[0081] Figure 4 This image shows a comparison of the growth status of crops treated with the bio-silicon fertilizer prepared in Example 1 of this invention and a control crop under drought stress. It visually demonstrates the significant improvement in growth of the crop treated with the bio-silicon fertilizer compared to the untreated control crop under drought conditions, reflecting the positive effect of bio-silicon fertilizer in improving crop drought resistance.

[0082] Example 2 Biochar obtained from the pyrolysis of rice straw with high phytolith content was used to improve soils with different weathering conditions, and wheat planting experiments were conducted to verify the beneficial effects of the invention. Specifically: (1) Material preparation Two types of soil: Cambisol (CA): Moderately weathered, rich in organic matter and weatherable silicate minerals, with strong buffering capacity (31 cmol). c kg 1 Primitive soil is a type of soil in the World Soil Resource Reference Base Classification, referring to moderately weathered soils with high organic matter and weatherable silicate mineral content. Nitisol (NI): Highly weathered, poor in organic matter, rich in iron and aluminum oxides, with extremely weak buffering capacity (0.2 cmol). c kg 1 ), where cmol c kg 1 Centimoles (positive charge) per kilogram is the unit of soil cation exchange capacity, representing the total amount of cations adsorbed per kilogram of soil.

[0083] Three silicon sources: Phytosilica-Biochar (Si+): Biochar prepared by pyrolysis of rice straw with high phytosilica content, with high silicon content (51.3 g / kg). Low-phytosilica biochar (Si-): Biochar prepared by pyrolysis of low-phytosilica rice straw with extremely low silicon content (0.3 g / kg). Wollastonite (CaSiO3): Inorganic silicon reference source; The preparation processes of phytosilica-rich biochar (Si+) and phytosilica-poor biochar (Si-) involve heating straw in a reactor at 65°C for 1 minute. The heating rate of 1 was further pyrolyzed to 550°C, and the reactor was maintained at 550°C for 12 minutes, and then gradually cooled naturally. Si+ biochar was produced by adding silicon nutrients to rice during the hydroponic stage to accumulate phytoliths, followed by slow pyrolysis at 500°C; Si- biochar, on the other hand, was produced by cultivating rice under silicon-free conditions and contained almost no phytoliths after pyrolysis.

[0084] (2) Experimental design Apply the silicon source to the soil at an equal amount of silicon (810 mg Si / kg).

[0085] Wheat was grown using a soil-solution-plant system, and its biomass, silicon uptake, and other parameters were measured.

[0086] The plant availability of silicon was assessed using CaCl2 kinetic extraction (128 days).

[0087] The content of biogenic silica (BSi) was assessed using the DeMaster sodium carbonate alkali dissolution method.

[0088] (3) CaCl2 extraction method CaCl2 extraction principle: Using a 0.01M CaCl2 solution to simulate the ionic strength in soil solution, soluble silicon (H4SiO4) that can be directly absorbed by plants in the soil is extracted, which is bioavailable silicon.

[0089] Objective: To assess the capacity of bioavailable silicon in soil and its dynamic changes after the addition of amendments (biochar, wollastonite).

[0090] Extraction process (kinetic extraction) The solid-liquid ratio is: 5g soil : 50mL 0.01M CaCl2.

[0091] Extraction time points: This is an innovative kinetic extraction method that samples at 10 time points: 6h, 12h, 1 day, 2 days, 4 days, 8 days, 16 days, 32 days, 64 days, and 128 days.

[0092] Procedure: Centrifuge the suspension at each time point (3000g, 20 minutes); filter the supernatant and divide it into two portions: measure the pH of one portion (CaCl2-pH), and acidify the other portion for ICP-AES determination of silicon concentration.

[0093] Data processing: Cumulative release: Calculates the cumulative amount of silicon extracted at each time point.

[0094] Silicon release efficiency (RSi): This formula is used to assess what percentage of the total silicon added by the modifier is released as usable silicon.

[0095] Main results and related conclusions Silicon release follows a "parabolic → plateau" pattern.

[0096] Most of the release occurs in the first two days, then the rate slows down, and reaches equilibrium after 32 days.

[0097] The release rates of Si+ biochar and wollastonite are much higher than those of Si- biochar.

[0098] Relationship between extraction volume in 16 hours and 128 days The study found a strong positive correlation between the amount extracted in 16 hours and the final cumulative amount after 128 days (r=0.96).

[0099] Key conclusion: This confirms that short-term (e.g., 16 hours or 5 hours) CaCl2 extraction methods can effectively predict the long-term potential storage capacity of bioavailable silicon in soil, making them suitable as a routine detection method.

[0100] Dynamic changes in pH During extraction, the pH of the CaCl2 extract initially increases and then slowly decreases. This trend is consistent across different amendments and soils, but the final equilibrium pH is determined and controlled by the soil's inherent properties. In Nitisol, which has a weak buffering capacity, the pH of the extract after applying biochar is significantly higher than that in Cambisol, which has a strong buffering capacity.

[0101] The enormous impact of soil type In Nitisol, the silicon release efficiency of Si+ biochar (RSi=20%) was much higher than that in Cambisol (RSi=5%). This is mainly attributed to the significant pH increase caused by biochar in Nitisol, which greatly promoted the dissolution of phytoliths.

[0102] Key conclusions regarding the CaCl2 extraction method The effectiveness of short-term extraction was verified: the CaCl2-Si content at 128 days quantified the library capacity of bioavailable silicon, while the extraction value at 16 hours could predict it. This confirms the effectiveness of using 0.01 MCaCl2 at 16 hours as a routine procedure for extracting bioavailable silicon from plants. This method is not a simple "snapshot," but rather reflects a continuous release process. Short-term withdrawals are a reliable indicator of long-term potential storage capacity.

[0103] This highlights the crucial role of soil pH: the amount of silicon extracted by CaCl2 is positively correlated with the pH of the extract. This indicates that soil pH and buffering capacity are the core factors controlling silicon availability, and thus determine the extraction efficiency of the CaCl2 method.

[0104] Contribution of CaCl2 extraction method Long-term kinetic experiments validated the short-term (16-hour) CaCl2 extraction method as a reliable and convenient routine method for assessing soil bioavailable silica. It was clarified that the extraction results of this method are highly dependent on soil properties (especially pH and buffering capacity), therefore soil type must be considered when interpreting the results.

[0105] This method clearly demonstrates that phytolith-rich biochar, especially in acidic, low-buffered, highly weathered soils, is a highly efficient silicon fertilizer. Phytolith biochar, as an environmentally friendly and efficient silicon fertilizer, has the potential to improve highly weathered soils and promote crop growth. Soil properties (especially pH and buffering capacity) play a central role in the effectiveness of silicon fertilizer. The results of the 0.01M CaCl2 extraction method at 16 hours and 128 days are highly correlated, supporting its effectiveness as a routine method for assessing plant-available silicon. The effectiveness of silicon fertilizer is soil-dependent; therefore, appropriate silicon sources and application rates should be selected based on soil type.

[0106] (4) Cultivation Experiment Wheat was grown in a soil-solution-plant system and harvested after 32 days of cultivation.

[0107] (5) Main results The experimental results are shown in Table 2.

[0108] Table 2. Effects of Si+ biochar on some indicators in two soil types.

[0109] This study, through rigorous soil-plant system experiments, revealed the potential of phytolith biochar as a silicon fertilizer and the dependence of its effects on soil type, particularly emphasizing the crucial roles of soil buffering capacity and pH in regulating silicon bioavailability. The results demonstrate that applying Si+ biochar significantly increases wheat biomass, silicon content, and silicon mineral content. This provides a scientific basis for the rational application of biochar in highly weathered soils.

[0110] in addition, Figure 2 The images show scanning electron microscope (SEM) image (a) and energy dispersive X-ray spectrum (b) of the phytolith-enriched rice straw biochar of this invention. The images clearly show the dominant distribution of carbon (C), oxygen (O) and silicon (Si), confirming the presence of phytoliths (SiO2·nH2O).

[0111] Table 1 Total silicon content, sodium carbonate extractable phytoliths (Si) alk The study measured the content of α-silicon and calcium chloride-extractable plant-available silicon (CaCl2-Si) (after 128 days) and their supply efficiency in amendments, soil, and soil-ammonia mixtures, as well as the silicon content in wheat aboveground parts, wheat aboveground dry matter (DMs), and the accumulation of silicon minerals in soil-ammonia mixtures. (Taking wheat as an example)

[0112] Note: In the "Amendments" and "Soil (SoilCA and SoilNI) and Soil-Amendment Mixtures (Ca:Si-, Ca:Si+, Ca:Wo, NI:Si-, NI:Si+, NI:Wo)" groups, the mean values ​​of the same letter designations indicate no statistically significant difference (p=0.05, Tukey multiple comparison test). The p-values ​​between treatment groups were calculated using one-way ANOVA.

[0113] † indicates the silicon content obtained through a 128-day dynamic extraction experiment; see details below. Figure 3 ; †††R Si The calculated value is negative because the amount of silicon released from the soil:Si-treated group is lower than the amount of silicon released from the untreated soil CA and NI.

[0114] Additionally, in Table 1, Materials represents the materials, TotalSi represents the total silicon, and Si alk This represents basic silicon, CaCl2-Si. † Indicates calcium chloride-extractable silicon, Efficiency of SireleaseR si †† The values ​​represent silicon release efficiency, ShootSicontent represents the silicon content in the aboveground parts, DMs represent dry matter, Simineralomass represents the total amount of silicon minerals, Amendements represent amendments, Cambisol represents Cambisol soil (i.e., one type of soil used in the experiment), Nitisol represents Nitisol soil (i.e., another type of soil used in the experiment), and ANOVAp represents the probability value of the analysis of variance.

[0115] Figure 3 The curves showing the change in extractable silicon content (CaCl2-Si) of different biochars over time (6 hours, 12 hours, 24 hours (1 day), 2, 4, 8, 16, 32, 64 and 128 days) are shown. (a) Treatment groups: Si-, Si+ and Wo; (b) Treatment groups: CA, CA:Si-, CA:Si+ and CA:Wo; (c) Treatment groups: NI, NI:Si-, NI:Si+ and NI:Wo. In (a) the CaCl2-Si unit is g / kg. 1 (bc) The units in the figure are mg / kg 1 The error bars represent ± standard deviation (n=3).

[0116] Example 3 This embodiment systematically studies the silicon (Si) cycle in the soil-plant system, focusing on comparing the contributions of mineral-derived silicon (from weatherable silicate minerals) and plant-derived silicon (from phytoliths) to silicon uptake by rice, and quantifying the distribution of silicon in different pools (soil, plants, leachate).

[0117] (1) Experimental design and materials Soil materials: Initial soil: The main component is quartz, with almost no weatherable silicates and phytoliths.

[0118] Source of weatherable minerals: Fresh basaltic volcanic rock powder is used, which is rich in easily weatherable silicate minerals (such as pyroxene, olivine, leucite, etc.).

[0119] Soil weathering gradient construction: Five Total Reserve of Bases (TRB) levels were constructed by adding different proportions of tephrite to the initial soil: 5, 15, 45, 135, and 405 cmol6 / kg, named T5, T15, T45, T135, and T405, respectively.

[0120] Biochar materials: Phytosilicone-poor biochar (Si–): prepared from low-silica rice straw.

[0121] Phytolith-enriched biochar (Si+): prepared from high-silica rice straw (cultivated by adding silicon to nutrient solution).

[0122] Biochar preparation: slow pyrolysis (500℃, 60 minutes), grinding and sieving (<0.154mm).

[0123] Soil-biochar mixture: Adding 2.5g of biochar per kg of soil is equivalent to a field application rate of 2.8T / ha.

[0124] Si+ treatment provides 121 mg of phytosilicic silicon per kg of soil.

[0125] Experimental treatment: There are 4 types of treatments, with 5 replicates for each treatment: Bare soil (no planting, no biochar added) Rice is grown without the addition of biochar. Rice cultivation with added Si-biochar Rice cultivation with added Si+ biochar (2) Experimental procedures First planting season (13 weeks): Soil pretreatment: 4 weeks of pre-cultivation to maintain field water holding capacity.

[0126] Rice cultivation: IR64 variety, 3 plants per pot.

[0127] Fertilization: Apply NH4NO3 (total N 15mg / kg) in 3 applications.

[0128] Harvesting: Separate the above-ground straw from the grains, dry them, weigh them, and crush them for later use.

[0129] Second planting season (13 weeks): Return the first harvested straw (3g / pot) to the original soil.

[0130] The remaining steps are the same as in Season 1.

[0131] (3) Sample analysis Soil: pH, CEC, mineral composition (XRD), elemental content (ICP-AES), etc.

[0132] Plants: dry weight, elemental content (C, N, Si, etc.), phytolith content.

[0133] Leachate solution: volume, pH, concentration of elements such as Si, Al, and Fe (ICP-AES).

[0134] (4) Main results Si+ biochar: Phytoliths dissolve quickly, directly providing available silicon to plants, especially contributing significantly in low TRB soils.

[0135] Plant phytoliths: accounting for <1%~3.4% of initial silicon input, but silicon from phytoliths makes a significant contribution to plant absorption.

[0136] In highly weathered soils (low TRB), phytoliths can contribute up to 80% to plant silicon uptake.

[0137] In low-weathered soils (high TRB), mineral silica remains the primary source, while the contribution of phytoliths decreases to 26%.

[0138] (5) Summary This study systematically investigated the silicon cycle in the soil-plant system, focusing on comparing the contributions of mineral-derived silicon and plant-derived silicon (phytoliths) to silicon absorption by rice, and quantifying the distribution of silicon in different pools. Five weathering gradients were constructed by adding different proportions of tephrite to quartz-containing initial soil. Two types of biochar were prepared using low-silicon and high-silicon rice straw, and four treatments (five replicates per treatment) were implemented in a two-season rice planting experiment. Sample analysis covered multiple indicators of soil, plants, and leachate. The results showed that phytoliths in Si+ biochar dissolved rapidly and made a significant contribution in low-weathered soils. While plant phytoliths accounted for a low proportion of the initial silicon input, they made a large contribution to absorption, reaching up to 80% in highly weathered soils and decreasing to 26% in low-weathered soils. Therefore, mineral silicon and phytoliths are competing sources, with soil weathering determining the dominant source. Returning straw to the field or applying Si+ biochar can enhance plant silicon absorption.

[0139] Example 4 Field trials and demonstrations The experiment was conducted in highly intensively cultivated farmland (soil with desilication and low moisture content). The treatment group was treated with the straw-biosilicon fertilizer of this invention (2 tons / hectare), while the control group was not treated with silicon fertilizer. The results showed that the wheat stalk strength of the treatment group increased, the incidence of diseases and pests decreased, and it exhibited better water retention and yield stability during the dry season, ultimately increasing wheat yield by more than 15%, and also improving wheat yield.

[0140] The phytosilica-enriched biochar silicon fertilizer proposed in this invention significantly improves the bioavailability of soil silicon and enables the resource utilization of agricultural waste, providing a sustainable solution for highly intensive farmland. This technology uses agricultural waste (such as straw) as raw material, preparing phytosilica-enriched biochar through pyrolysis. This not only transforms waste into high-value fertilizer, aligning with the concept of circular agriculture, but also possesses economic feasibility due to the wide availability and low cost of raw materials. Compared to traditional mineral silicon fertilizers, the silicon in phytosilica-enriched biochar exists in the form of phytosilica, which is more easily extracted by weak acids after pyrolysis activation, resulting in higher release efficiency. It is particularly suitable for soils with poor buffering capacity, low water retention, high weathering, and easy desilication, where its silicon supply effect is significantly superior to traditional silicon fertilizers under these extreme conditions. After application, the biochar not only directly replenishes the available silicon in the soil but also comprehensively improves soil fertility and water retention capacity by increasing soil organic matter content, adjusting pH, and enhancing cation exchange capacity (CEC), forming a synergistic effect of "silicon supply-improvement." At the crop level, silicon absorption enhances cell wall mechanical strength, reduces water transpiration, and improves water use efficiency, thereby significantly enhancing crop tolerance to drought stress and ultimately increasing yield and optimizing quality. In terms of environmental benefits, biochar's carbon sequestration helps achieve carbon neutrality while avoiding the heavy metal pollution risks that traditional silicon fertilizers may introduce, truly achieving "green yield increase." In summary, this invention, through the development of phytosilicic biochar silicon fertilizer, effectively solves the problems of soil desilication leading to fertility decline and unstable yields under drought stress in highly intensive farmland, achieving the dual goals of increasing crop yield and quality and improving soil health. Its low cost, high efficiency, and environmentally friendly characteristics provide an innovative path for sustainable agricultural development and have broad prospects for widespread application.

[0141] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a bio-silicon fertilizer, characterized in that, It is produced by pyrolysis and carbonization of silicon-accumulating plants rich in phytoliths.

2. The method for preparing a bio-silicon fertilizer according to claim 1, characterized in that, The silica-accumulating plants rich in phytoliths include one or more of rice straw, miscanthus, sugarcane bagasse, wheat straw, and corn straw.

3. The method for preparing a bio-silicon fertilizer according to claim 1, characterized in that, The enriched silica is carbonized by pyrolysis under oxygen-limited conditions.

4. The method for preparing a bio-silicon fertilizer according to claim 1, characterized in that, The pyrolysis process is carried out at a temperature of 400~600℃ for a time of 60~120 min, with a heating rate of 17℃ / min. 1 .

5. A bio-silicon fertilizer, characterized in that, It is prepared by the manner described in any one of claims 1 to 4.

6. The bio-silicon fertilizer according to claim 1, characterized in that, The silicon content of the bio-silicon fertilizer is higher than 30g / kg.

7. A method of using a bio-silicon fertilizer according to any one of claims 5 to 6, characterized in that, The bio-silicon fertilizer is evenly applied to the weathered soil and mixed with the soil into the soil layer.

8. The method of using a bio-silicon fertilizer according to claim 7, characterized in that, The bio-silicon fertilizer is applied evenly to the weathered soil, and the application rate does not exceed 3 tons / hectare.

9. The method of using a bio-silicon fertilizer according to claim 7, characterized in that, The bio-silicon fertilizer is applied evenly to the weathered soil at a rate of 1-3 tons per hectare.

10. The method of using a bio-silicon fertilizer according to claim 7, characterized in that, The bio-silicon fertilizer is mixed with the soil to a depth of 0-20cm by tilling or rotary tilling.

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