Acid soil conditioner containing microalgae

Abstract

The invention discloses an acid soil conditioner containing microalgae, and belongs to the technical field of agriculture and environmental restoration. The acid soil conditioner containing the microalgae is prepared from the following components in parts by weight: 100 to 130 parts of biomass charcoal, 30 to 40 parts of vermiculite, 1 to 2 parts of brachyristichum brachyristichum, 0.1 to 0.5 part of a bacillus mucilaginosus microbial agent, 0.1 to 0.5 part of a bacillus subtilis microbial agent and 0.1 to 0.5 part of a bacillus megatherium microbial agent. According to the method disclosed by the invention, the brachyristichum brachyristichum which can be planted under an acidic condition and can generate alkaline metabolites to increase the pH value of acidic soil is selected as a main functional component, and is matched with other components with functions of loosening soil, helping the brachyristichum brachyristichum to proliferate, providing organic matters, helping the soil to release nutrients and the like; and compounding to obtain the soil conditioner capable of effectively improving acid soil.

Description

Technical Field

[0001] This invention belongs to the field of agricultural and environmental remediation technology, and specifically relates to an acidic soil conditioner containing microalgae. Background Technology

[0002] Acidic soil usually refers to soil with a pH value below 7.0. When the pH value is below 5.5, it is usually considered to be strongly acidic soil. Its formation is a natural and slow process, mainly affected by the following factors: (1) Climate factors: In areas with high temperature and heavy rainfall, a large amount of rainfall will leach alkaline base ions such as calcium, magnesium, potassium and sodium in the soil, while hydrogen ions and aluminum ions will replace them, leading to soil acidification; (2) Parent material: Soils formed by the weathering of primary minerals such as granite and sandstone have low base content and are prone to acidification; (3) Biological factors: Plant root respiration, organic matter decomposition and litter of some specific plants (such as tea trees and pine trees) will produce organic and inorganic acids, thus acidifying the soil; (4) Human activities: including excessive application of chemical fertilizers, industrial pollution and improper irrigation, which are the main reasons for the current accelerated soil acidification.

[0003] Currently, there are no remediation solutions for acidic soils that use microalgae as the main functional component for adjusting the pH value of acidic soils. Summary of the Invention

[0004] The purpose of this invention is to provide an acidic soil conditioner containing microalgae. By selecting *Pterygota shortribi*, which can colonize under acidic conditions and produce alkaline metabolites to raise the pH of acidic soil, as the main functional component, and combining it with other components that have functions such as loosening the soil, promoting the proliferation of *Pterygota shortribi*, providing organic matter, and helping the soil release nutrients, a soil conditioner that can effectively improve acidic soil is obtained.

[0005] To achieve the above objectives, the present invention provides the following technical solution: One of the technical solutions of this invention: provides an acidic soil conditioner containing microalgae, comprising, by weight: 100-130 parts biochar, 30-40 parts vermiculite, 1-2 parts short-ribbed feather algae, 0.1-0.5 parts Bacillus mucilaginosus inoculant, 0.1-0.5 parts Bacillus subtilis inoculant and 0.1-0.5 parts Bacillus megaterium inoculant.

[0006] The inventors discovered that *Pterygota shortribi* (a species of *Pterygota*) Pinnularia brebissoniiThe ability to colonize acidic soils while producing alkaline metabolites provides a feasible basis for its application in acidic soil improvement. Furthermore, the inventors, through compounding the soil conditioner formulation, obtained an acidic soil conditioner containing microalgae. Besides *Pterygodium brevichorum*, another key component of this acidic soil conditioner is *Bacillus mucilaginosus* inoculant. The silicates metabolized by *Bacillus mucilaginosus* inoculant can provide nutrients for *Pterygodium brevichorum*, promoting its proliferation and improving the soil improvement effect of the microalgae-containing acidic soil conditioner of this invention.

[0007] Preferably, the biochar particle size is 40-60 mesh.

[0008] Preferably, the vermiculite particle size is 20-40 mesh.

[0009] Preferably, the effective viable count of the Bacillus mucilaginosus agent is ≥4×10⁻⁶. 8 cfu / g.

[0010] Preferably, the effective viable count of the Bacillus subtilis inoculant is ≥2×10⁻⁶. 9 cfu / g.

[0011] Preferably, the effective viable count of the Bacillus megaterium agent is ≥1×10⁻⁶. 10 cfu / g.

[0012] The second technical solution of the present invention is to provide an application of the above-mentioned acidic soil conditioner containing microalgae in the improvement of acidic soil.

[0013] Preferably, the application rate of the acidic soil conditioner containing microalgae is 50-70 kg / mu.

[0014] The beneficial technical effects of the present invention are as follows: This invention combines biochar, vermiculite, *Pterygota brevicornu*, *Bacillus mucilaginosus* inoculant, *Bacillus subtilis* inoculant, and *Bacillus megaterium* inoculant to prepare an acidic soil conditioner containing microalgae that has the function of improving acidic soil.

[0015] In this invention, an acidic soil conditioner containing microalgae, biochar serves as the matrix component, providing moisture retention and supplying carbon nutrients. Vermiculite loosens the soil and enhances its aeration. *Pterygota brevicornu*, as the main functional component of the acid-conditioning agent, produces alkaline metabolites that raise the pH of acidic soils. *Bacillus mucilaginosus* provides *Pterygota brevicornu* with the necessary silicates for its growth. *Bacillus subtilis* secretes antibacterial substances, inhibits pathogen growth, increases soil porosity, and enhances the organic matter content of the soil. *Bacillus megaterium* hydrolyzes phosphorus, improves nitrogen utilization, releases trace elements (such as calcium, magnesium, and iron) from the soil, and balances soil nutrients.

[0016] As can be seen from the examples, when the acidic soil conditioner containing microalgae provided by the present invention is used to improve acidic soil, it can increase the pH value of the acidic soil, as well as increase the soil bulk density and organic matter content. Detailed Implementation

[0017] Those skilled in the art will understand that soil acidification triggers a series of serious chemical, physical, and biological problems, hindering agricultural production and disrupting ecological balance. For example, under highly acidic conditions, aluminum and manganese fixed in the soil transform into soluble ions, which are toxic to the roots of most plants, inhibiting root growth and affecting water and nutrient absorption. Acidic soil environments lead to the fixation or leaching of nutrients such as phosphorus, calcium, magnesium, and molybdenum, significantly reducing their availability and making them difficult for crops to absorb even when fertilizers are applied. Most beneficial soil microorganisms (such as nitrogen-fixing bacteria and organic matter-decomposing bacteria) thrive in neutral environments; increased acidity inhibits their activity and numbers, affecting soil fertility formation and nutrient cycling. In acidic soils, hydrogen ions replace calcium ions on soil colloids, causing the soil aggregate structure to break down, resulting in compaction and decreased permeability.

[0018] High concentrations of hydrogen ions in acidic soils can directly attack crop roots. + It can damage the integrity of root cell membranes, interfere with the acid-base balance within cells, and affect the root system's ability to absorb water and nutrients, leading to poor root development, manifested as blackening of root tips, root shrinkage, and reduction of lateral roots, ultimately affecting the growth of the entire plant.

[0019] When the soil pH is below 5.5, solid aluminum in the soil (such as Al(OH)3) will dissolve rapidly, releasing soluble aluminum ions (mainly Al) that are toxic to plants. 3+ Aluminum ions strongly inhibit cell division and elongation in the root tip meristem, directly damaging the root structure and causing the roots to become short, thick, and coral-like, losing their normal absorption function. This is the primary cause of "stunted seedlings" and "poor growth" in crops in acidic soils.

[0020] Under acidic reducing conditions, manganese in the soil will be released in the form of highly toxic Mn. 2+ Excessive manganese is released in large quantities. It is absorbed by crops and accumulates within them, interfering with enzyme activity, damaging chloroplast structure, and causing typical poisoning symptoms such as brown spots on older leaves and scorched leaf margins.

[0021] The availability of elements such as phosphorus (P), calcium (Ca), magnesium (Mg), and molybdenum (Mo) decreases sharply under acidic conditions. Phosphorus is easily fixed by free aluminum and iron ions to form insoluble phosphates, which cannot be absorbed by the roots; while cations such as calcium and magnesium are lost in large quantities through leaching, leading to soil infertility.

[0022] Excessive H in acidic soil+ Al 3+ and Mn 2+ Will with Ca 2+ Mg 2+ K + The competition between cations and root absorption sites further exacerbates the difficulty for crops to absorb these essential elements, thus affecting crop nutrient supply.

[0023] A healthy soil ecosystem depends on abundant microbial activity. Acidic conditions severely inhibit the activity and population size of most beneficial soil microorganisms, such as nitrogen-fixing bacteria that provide biological nitrogen fixation, bacteria that decompose organic matter and release nutrients, and actinomycetes. At the same time, acidic conditions also facilitate the growth of soil-borne fungal diseases, increasing the risk of crop disease.

[0024] Soil acidification is a complex chemical and biological process with systemic and multifaceted harm to crops. Therefore, the improvement of acidic soils is extremely urgent. Currently, a relatively mature technical system for the improvement of acidic soils has been established globally, and new research and exploration continue. The main improvement methods include: applying lime (to neutralize acid), optimizing fertilizer management (using physiologically neutral or alkaline fertilizers and reducing the use of physiologically acidic fertilizers), and optimizing water management (reducing the accumulation and leaching of acidic substances through proper drainage measures).

[0025] Among the current improvement methods, the application of lime is limited in that it can only act on the topsoil layer of 0-20cm and is difficult to correct the acidity of the subsoil; while optimizing fertilization management measures will inevitably limit crop planting and affect crop yield and quality; although optimizing water management has no obvious disadvantages, it has little effect on improving acidic soil and can only be used as an auxiliary means.

[0026] Therefore, this invention provides a novel method for improving acidic soil, which uses a new acidic soil conditioner containing microalgae.

[0027] The components of the acidic soil conditioner containing microalgae provided by the present invention, by weight, include: 100-130 parts of biochar, 30-40 parts of vermiculite, 1-2 parts of *Pterygota brevicornu*, 0.1-0.5 parts of *Bacillus mucilaginosus* inoculant, 0.1-0.5 parts of *Bacillus subtilis* inoculant, and 0.1-0.5 parts of *Bacillus megaterium* inoculant.

[0028] In the aforementioned acidic soil conditioners containing microalgae, biochar, as a matrix component, primarily serves to retain moisture and supply carbon nutrients. The moisture-retaining effect of biochar can provide a more favorable environment for the proliferation of *Pterygota brevicornu*.

[0029] The addition of vermiculite is mainly to loosen the soil and enhance its permeability. Loose soil is more conducive to the proliferation of the short-ribbed feather algae and microbial agents used.

[0030] Short-ribbed feather algae serves as the main functional component for acid soil improvement. The short-ribbed feather algae in this invention is an acid-loving diatom. The inventors discovered that this diatom can not only colonize in the soil, but also produce alkaline metabolites, which lays the foundation for its application in acid soil improvement.

[0031] The use of Bacillus mucilaginosus inoculants mainly takes advantage of its ability to produce silicates.

[0032] Bacillus subtilis and Bacillus megaterium inoculants are commonly used components in soil conditioners. Bacillus subtilis inoculants secrete antimicrobial substances, inhibiting the growth of pathogens, increasing soil porosity, and enhancing soil organic matter content. Bacillus megaterium inoculants solubilize phosphorus, improve nitrogen use efficiency, and release trace elements (such as calcium, magnesium, and iron) from the soil, thus balancing soil nutrients.

[0033] The synergistic effect of the various components in the acidic soil conditioner containing microalgae has achieved good soil improvement results.

[0034] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0035] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0036] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0037] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of this invention.

[0038] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0039] In the embodiments and comparative examples of this invention, "parts" refers to "parts by weight".

[0040] In the embodiments and comparative examples of this invention, *Syngonium breviculatum* was obtained through cultivation. The cultivation method was as follows: Culture medium preparation: Take 500 g of fertile garden soil (free of chemical fertilizers and pesticides), add 1 L of tap water, and boil for 1 hour, continuously replenishing the evaporated water during this time. Let it stand and cool, collect the supernatant, and filter it through gauze to obtain the soil leachate stock solution. Each liter of culture medium contains 50 mL of soil leachate stock solution, 0.1 g of potassium nitrate, 0.01 g of potassium dihydrogen phosphate, and 0.05 g of sodium silicate. Adjust the pH of the culture medium to 4.5-5.5 using dilute hydrochloric acid.

[0041] Cultivation conditions: Illumination: 2000~5000 lux, light-dark cycle 12:12 hours.

[0042] Temperature: 18~25℃.

[0043] Inoculate *Pterygota brevicornu* into the prepared culture medium and culture it under the specified conditions. During the culture process, aeration is introduced as needed. After the culture is completed, remove the *Pterygota brevicornu*, drain the water, and it can be used to prepare an acidic soil conditioner containing microalgae.

[0044] All components of this invention, except for *Pterocarya shortribata*, are commercially available.

[0045] Example 1 Preparation of acidic soil conditioner containing microalgae: The formula consists of 100 parts biochar (40-60 mesh), 30 parts vermiculite (20-40 mesh), 1.5 parts *Pterygota brevicornu*, and *Bacillus mucilaginosus* inoculant (effective viable count 4 × 10⁻⁶). 8 0.3 parts of CFU / g and Bacillus subtilis inoculant (effective viable count of 2×10⁻⁶). 9 0.3 parts of CFU / g and Bacillus megaterium inoculum (effective viable count of 1×10⁻⁶) 10 Prepare all raw materials in a ratio of 0.3 parts (cfu / g), mix all raw materials evenly, and you will get an acidic soil conditioner containing microalgae.

[0046] Example 2 Preparation of acidic soil conditioner containing microalgae: The mixture consists of 110 parts biochar (40-60 mesh), 35 parts vermiculite (20-40 mesh), 1 part *Pterygota brevicornu*, and *Bacillus mucilaginosus* inoculant (effective viable count 4 × 10⁻⁶). 8 0.3 parts of CFU / g and Bacillus subtilis inoculant (effective viable count of 2×10⁻⁶).9 0.3 parts of CFU / g and Bacillus megaterium inoculum (effective viable count of 1×10⁻⁶) 10 Prepare all raw materials in a ratio of 0.3 parts (cfu / g), mix all raw materials evenly, and you will get an acidic soil conditioner containing microalgae.

[0047] Example 3 Preparation of acidic soil conditioner containing microalgae: The mixture consists of 120 parts biochar (40-60 mesh), 40 parts vermiculite (20-40 mesh), 2 parts *Pterygota brevicornu*, and *Bacillus mucilaginosus* inoculant (effective viable count 4 × 10⁻⁶). 8 0.3 parts of CFU / g and Bacillus subtilis inoculant (effective viable count of 2×10⁻⁶). 9 0.3 parts of CFU / g and Bacillus megaterium inoculum (effective viable count of 1×10⁻⁶) 10 Prepare all raw materials in a ratio of 0.3 parts (cfu / g), mix all raw materials evenly, and you will get an acidic soil conditioner containing microalgae.

[0048] Comparative Example 1 Preparation of an acidic soil conditioner containing microalgae (the difference from Example 1 is that the Bacillus mucilaginosus inoculant is replaced with an equal mass of Bacillus megaterium inoculant): The formula consists of 100 parts biochar (40-60 mesh), 30 parts vermiculite (20-40 mesh), 1.5 parts *Pterygota brevicornu*, and *Bacillus subtilis* inoculant (effective viable count 2 × 10⁻⁶). 9 0.3 parts of CFU / g and Bacillus megaterium inoculum (effective viable count of 1×10⁻⁶) 10 Prepare all raw materials in a ratio of 0.6 parts (cfu / g), mix all raw materials evenly, and you will get an acidic soil conditioner containing microalgae.

[0049] Comparative Example 2 Preparation of soil conditioner (the difference from Example 1 is that *Pinus shortribatus* is not added): The formula consists of 100 parts biochar (40-60 mesh), 30 parts vermiculite (20-40 mesh), and Bacillus subtilis inoculant (effective viable count 4×10⁻⁶). 8 0.3 parts of CFU / g and Bacillus subtilis inoculant (effective viable count of 2×10⁻⁶). 9 0.3 parts of CFU / g and Bacillus megaterium inoculum (effective viable count of 1×10⁻⁶) 10 Prepare all raw materials in a ratio of 0.3 parts (cfu / g), mix all raw materials evenly, and the soil conditioner is obtained.

[0050] The soil conditioners prepared in Examples 1-3 and Comparative Examples 1-2 were compared to improve the acidic soil: The parameters of the acidic soil used are shown in Table 1. Soil improvement was carried out in the laboratory. The soil amendments in each group were mixed with the acidic soil at a ratio of 5g of soil amendment per 100g of soil. The control group was not added with soil amendments. The soil was aged at room temperature for 30 days, and then the parameters of the acidic soil were measured. The results are shown in Table 1.

[0051] Table 1. Effects of acid soil improvement Table 1 shows that the acid soil conditioner containing microalgae provided by this invention has a significant effect on improving acid soil, noticeably increasing the pH value. If the component *Bacillus mucilaginosus* (whose metabolic products, besides silicates, share some similarities with *Bacillus megaterium*, and were therefore used as a control) is replaced with *Bacillus megaterium*, the soil improvement effect is significantly worse, mainly reflected in the increase in pH and the increase in soil organic matter. Furthermore, omitting *Pterygodium brevichorum* from the formula has almost no effect on improving acid soil.

[0052] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. An acidic soil conditioner containing microalgae, characterized in that, By weight, the components include: 100-130 parts biochar, 30-40 parts vermiculite, 1-2 parts short-ribbed feather algae, 0.1-0.5 parts Bacillus mucilaginosus inoculant, 0.1-0.5 parts Bacillus subtilis inoculant and 0.1-0.5 parts Bacillus megaterium inoculant.

2. The acidic soil conditioner containing microalgae according to claim 1, characterized in that, The biochar has a particle size of 40-60 mesh.

3. The acidic soil conditioner containing microalgae according to claim 1, characterized in that, The vermiculite has a particle size of 20-40 mesh.

4. The acidic soil conditioner containing microalgae according to claim 1, characterized in that, The effective viable count of the Bacillus subtilis agent is ≥4×10⁻⁶. 8 cfu / g.

5. The acidic soil conditioner containing microalgae according to claim 1, characterized in that, The effective viable count of the Bacillus subtilis inoculant is ≥2×10⁻⁶. 9 cfu / g.

6. The acidic soil conditioner containing microalgae according to claim 1, characterized in that, The effective viable count of the Bacillus megaterium inoculum is ≥1×10⁻⁶. 10 cfu / g.

7. The application of the acidic soil conditioner containing microalgae as described in any one of claims 1 to 6 in the improvement of acidic soil.

8. The application according to claim 7, characterized in that, The application rate of the acidic soil conditioner containing microalgae is 50-70 kg / mu.

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