WO2024058685A1 - Biomineral fertilizer composition and method for producing same - Google Patents

Abstract

The invention relates to agricultural biotechnology and agrochemistry and can be used for producing biomineral fertilizers for crop production. Proposed for this purpose are a method for immobilizing agronomically beneficial microorganisms on the surface of granules of mineral fertilizers using cationic dextrin, as well as biomineral fertilizers produced using the proposed method. The proposed method makes it possible to reliably affix agronomically beneficial microorganisms to a mineral fertilizer, which reduces dust formation and better preserves the integrity of fertilizers during storage, shipping and application to the soil, allows more even distribution of biomineral fertilizers during application to the soil, enables crops to make more efficient use of soil-applied biomineral fertilizers, and increases crop yield.

Description

COMPOSITION OF BIOMINERAL FERTILIZER AND METHOD OF ITS OBTAINING

The invention relates to agricultural biotechnology and agrochemistry, and can be used for the production of biomineral fertilizers for crop production.

State of the art

It is known that in agricultural production, plants use only part of the nutrients entering the soil with mineral fertilizers to form a crop, while most of the nutrients from mineral fertilizers are washed into groundwater, evaporate into the atmosphere (nitrogen fertilizers) or become a form inaccessible to plants (phosphorus fertilizers). Biomineral fertilizers, the surface and structure of which are populated with microorganisms that increase the absorption of nutrients from fertilizers by plants, are more effective and environmentally superior forms of mineral fertilizers. According to numerous studies, their use can increase the biological activity of the soil, as well as the productivity of agricultural crops.

Today, the most commonly used methods for producing biomineral fertilizers are applying a biomodifier (carrier) to mineral fertilizer granules, on the surface of which bacterial spores are deposited, and direct spraying of bacterial spores onto mineral fertilizer granules. Biomodifiers (dry modifiers) can be made using peat, coal, clay, inorganic soil components, organic materials (composts, soybean meal, wheat bran, sawdust, etc.) or inert materials (for example, vermiculite, perlite, kaolin, bentonite, silicates) (Smith R.S. Legume inoculant formulation and application // Canadian Journal of Microbiology. 1992;38(6):485-492).

Examples of the use of carriers include the use of diatomaceous earth and colloidal silica for bacteria of the genus Rhizobium (BE521850), the use of aluminosilicates (for example, bentonite) for soil bacteria of the genus Azospirillum, Azotobacter, Pseudomonas, Bacillus, Micrococcus, etc. (WO2012093374, published 12.07 .2012). Another example is a method for the biological modification of mineral fertilizers, which includes, at the first stage, obtaining a microbial preparation in the form of a carrier, on the surface of which bacterial spores are deposited by mixing a suspension of a culture of microorganisms with a carrier, where a strain of rhizosphere spore-forming bacteria of the species Bacillus subtilis is used as a culture of microorganisms , preferably the Bacillus subtilis strain 4-13, with a titer of at least 1*10 ⁹ CFU/ml, and their metabolites, and a natural sorbent based on silicon-containing rocks (diatomite, opoka, tripoli, zeolite or kaolin) is used as a carrier. On In the second stage, the resulting microbial preparation is applied in doses to granular mineral fertilizers with short-term mixing (at a ratio of 2-5 kg of microbial preparation per 1 ton of fertilizers) (RU2694570, published 07/16/2019).

The effectiveness of using such carriers depends on the adsorption of microorganisms by the substance/matrix of the carrier. In addition, this method of incorporating microorganisms has a number of limitations related to the survival of microorganisms and the need to protect them during transportation, storage and handling.

As an example of direct spraying of bacterial spores onto mineral fertilizer granules, we can cite a method for producing biofertilizers based on the Bacillus subtilis 4-13 strain by applying dry fine Bacillus subtilis 4-13 powder with a titer of at least 10 ⁶ cells/g to the surface of mineral fertilizer granules at the rate 4-15 kg/t or applying the liquid fraction of Bacillus subtilis 4-13 with a titer of at least 10 ⁸ cells/ml onto the surface of mineral fertilizer granules at the rate of 1-2 l/t by finely spraying them (RU2241692, publ. 07.20.2004) .

A limitation of the use of the direct spraying method is the low efficiency of the resulting modified (biomineral) fertilizers, due to the reduced survival of living microorganism cells on the surface of mineral fertilizer granules, as well as the uneven application of bacteria to mineral fertilizer granules.

In order to improve the stability and increase the shelf life of biomineral fertilizers, organic biopolymers are used as carriers for rhizosphere microorganisms. These are compounds (for example, polysaccharides) that, in the presence of ions or when chemical conditions change (for example, when the pH of the environment changes), form cross-links that create a complex structure. Polymers “immobilize” microorganisms and spores in the matrix and gradually release them through the process of degradation. Polymer formulations ensure long shelf life of biomineral fertilizers even at ambient temperatures, as they provide environmental protection and consistent quality of the biofertilizer through standardized production. The resulting inoculants can be added or mixed with nutrients to enhance bacterial survival after inoculation. Alginate, a natural polymer of D-mannuronic acid and L-glucuronic acid, is most often used as a carrier for rhizosphere microorganisms (see, for example, Yabur R. Alginate from the macroalgae Sargassum sinicola as a novel source for microbial immobilization material in wastewater treatment and plant growth promotion // Journal of Applied Phycology. 2007;19(1):43- 53; Young C. et al. Encapsulation of plant growth-promoting bacteria in alginate beads enriched with humic acid // Biotechnology and Bioengineering. 2006 Sep 5; 95(1):76-83); relatively less commonly used for immobilization of microorganisms other biopolymers, such as for example carrageenan, hydroxyethylcellulose, starch, chitin, lignin or combinations thereof (see, for example, US5021350, published 06/04/1991;

Ivanova E. et al. Alginate based macrocapsules as inoculants carriers for production of nitrogen biofertilizers // Proceedings of the Balkan Conference of Biology; 2005; Plovdiv, Bulgaria:90-108).

Despite the advantages of using immobilized microorganisms, their large-scale production and application in the field are still limited. Therefore, an important area of research is the search for new effective carriers for the immobilization of microorganisms on mineral fertilizers.

Disclosure of the Invention

The objective of the present invention is to develop a method for immobilizing agronomically useful microorganisms on the surface of mineral fertilizer granules, which helps to increase the efficiency of using biomineral fertilizers due to the preservation of microorganisms, and obtaining biomineral fertilizers using the developed method.

To solve this problem, a method for producing biomineral fertilizer has been developed, which includes the following successive steps:

(1) obtaining a culture liquid of agronomically useful microorganisms,

(2) adding gelatinized cationic dextrin to the culture liquid,

(3) spraying a cultural liquid containing agronomically useful microorganisms and gelatinized cationic dextrin (i.e., immobilization of agronomically useful microorganisms contained in the cultural liquid) onto a mineral fertilizer, followed by drying.

Alternatively, after adding gelatinized cationic dextrin to the cultural liquid, the agronomically useful microorganisms contained in the cultural liquid are first immobilized with gelatinized cationic dextrin on an adsorbent carrier, and then, after drying the resulting biomodifier, it is applied to a mineral fertilizer.

In some embodiments, the agronomically beneficial microorganisms are plant growth promoting bacteria in vegetative and/or spore form. In some particular embodiments of the invention, the plant growth promoting bacteria are nitrogen-fixing bacteria and/or phosphorus- and/or potassium-transforming bacteria. In some embodiments, the plant growth promoting bacteria are rhizosphere spore-forming bacteria in vegetative and/or spore form. In some embodiments, the plant growth promoting bacteria are bacteria of the genus Agrobacterium, Azoarcus, Azospirillum, Rhizobium, Azotobacter, Arthrobacter, Bacillus, Clostridium, Enterobacter, Gluconoacetobacter, Paenibacillus Pseudomonas and/or Serratia.

In some other embodiments of the invention, the agronomically beneficial microorganisms are fungi that stimulate plant growth in vegetative and/or spore form. In some particular embodiments of the invention, the plant growth promoting fungi are fungi of the genus Trichoderma, Sebacinales, Mycorrhiza, Penicillium, Debarayomyces and/or Saccharomyces.

In some other embodiments, both plant growth promoting bacteria and plant growth promoting fungi are used for immobilization.

In some embodiments of the invention, the content of agronomically useful microorganisms in the culture liquid is at least 10 ⁹ CFU/ml, in some embodiments - at least 10 ¹⁰ CFU/ml, in some private embodiments - at least 10 ¹¹ CFU/ml.

In some embodiments of the invention, the gelatinized cationic dextrin is pre-sterilized.

In some embodiments of the invention, cationic potato dextrin and/or cationic corn dextrin are used as cationic dextrin.

In some embodiments of the invention, the amount of added cationic gelatinized dextrin is 1.0-1.2 wt.%.

According to the invention, the adsorbent carrier is any mineral or organic natural or synthetic adsorbent that is not prohibited for use in agriculture.

In some embodiments of the invention, the adsorbent carrier is a natural sorbent based on silicon-containing rocks in the form of one of the elements of the series: diatomite, zeolite, opoka, tripoli, kaolin.

In some embodiments of the invention, the biomodifier is mixed with mineral fertilizer in a ratio of up to 4 kg/t.

In some embodiments of the invention, the mineral fertilizer is a nitrogen, phosphorus, potassium, complex (for example, nitrogen-potassium, phosphorus-potassium, nitrogen-phosphorus-potassium), complex mixed or microfertilizer. In particular embodiments of the invention, the mineral fertilizer is urea, ammonium sulfate, calcium sulfur, sodium nitrate, diammonium phosphate, phosphate rock, potassium sulfate, potassium salt, ammophos, diammophos, azofoska, nitrophos or nitrophoska, ammophos, or nitroammophoska, but not limited to them. This problem is also solved by developing a biomineral fertilizer, the composition of which includes agronomically useful microorganisms and gelatinized cationic dextrin applied to the mineral fertilizer.

In some embodiments of the invention, the biomineral fertilizer composition additionally includes an adsorbent carrier, wherein agronomically beneficial microorganisms and gelatinized cationic dextrin are applied to the mineral fertilizer in a composition with an adsorbent carrier.

In addition, this problem is also solved by using gelatinized cationic dextrin to produce biomineral fertilizers.

In addition, the invention also relates to the use of biomineral fertilizers according to the invention to improve growth, increase the productivity of plants, such as, but not limited to, agricultural (cereals, vegetables, fruits, etc.) plants, plants used in forestry, for landscaping areas, in floriculture (indoor, greenhouse, decorative, etc.).

When implementing the invention, the following technical results are achieved:

- the developed method for producing biomineral fertilizers makes it possible to reliably attach agronomically useful microorganisms to the mineral fertilizer. This reduces dust and increases the safety of fertilizers during storage, transportation and application to the soil, and contributes to a more uniform distribution of biomineral fertilizer when applied to the soil;

- the resulting biomineral fertilizers do not cake during storage;

- the use of cationic dextrin in the biomineral fertilizer makes it possible to increase the efficiency of the use of biomineral fertilizers applied to the soil by agricultural and other plants, as a result of which improve their growth, increase their resistance to pests, and increase their productivity;

- thanks to the reliable attachment of microorganisms to the mineral fertilizer, microorganisms do not fall off the surface of the granules;

- due to good flowability, the resulting biomineral fertilizers are evenly distributed on the surface of the sown areas;

- when added to the soil, cationic dextrin, which is part of biomineral fertilizers, promotes the effective germination of spores and the growth of agronomically useful microorganisms, being the initial source of carbon;

- the developed protective composition based on cationic dextrin increases the efficiency of application, survival rate and preservation of effective titers of microorganisms on mineral fertilizers. Detailed Description of the Invention

According to the invention, it is proposed to use a biopolymer for the immobilization of agronomically useful microorganisms on the surface of mineral fertilizers. Cationic dextrin is used as a biopolymer, the positive charge of which ensures electrostatic interaction with microorganisms and the surface of mineral fertilizers. At the same time, it is proposed to immobilize microorganisms on the surface of mineral fertilizers both by directly applying a cultural liquid containing agronomically useful microorganisms and cationic dextrin, and by applying a previously obtained biomodifier of mineral fertilizers, which, in fact, is an adsorbent on the surface of which agronomically useful microorganisms with using cationic dextrin. The biomodifier obtained using cationic dextrin acquires a positive charge, which contributes to its electrostatic fixation on the surface of mineral fertilizers. The effect of fixing agronomically useful microorganisms on the surface of mineral fertilizers and biomodifiers is facilitated by the adhesive properties of cationic dextrin, which causes encapsulation of microorganisms on the biomodifier and mineral fertilizer. These factors contribute to the safety of agronomically useful microorganisms during transportation, storage and application of biomineral fertilizers to the soil.

Biomineral fertilizers according to the invention can be used in a wide variety of areas that require plant nutrition, such as, for example, agricultural production, horticulture, forestry, floriculture, etc.

Terms and Definitions

Unless otherwise specified, all technical and scientific terms used in this application have the same meaning as understood by those skilled in the art. References to techniques used in the description of this invention refer to well known techniques, including modifications of these techniques and replacement thereof with equivalent techniques known to those skilled in the art.

As used herein, the terms “includes,” “including,” and the like, as well as “comprises,” “comprising,” and the like are used herein. are interpreted to mean “includes, but is not limited to” (or “contains, among other things”). These terms are not intended to be construed as “consisting only of.”

The term “and/or” means one, more, or all of the above.

By “agronomically beneficial microorganisms” in the present invention we mean any so-called “beneficial soil microorganisms” (BSM from English, “beneficial soil microorganisms”), combining groups of microorganisms promoting plant growth. Such microorganisms include, for example, PGPB (Plant Growth Promoting Bacteria) - bacteria that promote plant growth, represented by endophytic bacteria (inhabiting plant tissues and seeds), PGPR (Plant Growth Promoting Rhizobacteria) - rhizobacteria that promote plant growth), phyllosphere bacteria ( inhabiting the above-ground parts of plants), PGPF (Plant Growth Promoting Fungi) - fungi that promote plant growth; representatives of which can be used in the production of biological preparations for plant protection and fertilizers. Agronomically useful microorganisms can solve several important problems in crop production: their use promotes soil self-purification, inhibits the development of phytopathogenic microorganisms, reduces oxidative and toxic stress, improves nitrogen and phosphorus nutrition, which is reflected in stimulating plant growth and productivity. Rhizosphere bacteria with these properties are, in particular, represented by the genera Agrobacterium, Azoarcus, Azospirillum, Rhizobium, Azotobacter, Arthrobacter, Bacillus, Clostridium, Enterobacter, Gluconoacetobacter, Pseudomonas, Serratia and other bacteria isolated from the surface of the rhizosphere of plants. Plant growth promoting fungi (PGPF) are a variety of genera of non-pathogenic fungi, particularly Trichoderma, Sebacinales, Mycorrhiza, Penicillium, Debarayomyces, Saccharomyces and other fungi. Endophytic bacteria are represented, for example, by the genera Achromobacter, Pseudomonas, Alcaligenes, Enterobacter, Acinetobacter, Bacillus, Stenotrophomonas, Stenotrophomonas, etc. In some particular embodiments, bacterial strains such as, for example, Bacillus subtilis CT2, Bacillus can be used to obtain biomineral fertilizers according to the invention endophticus RCAM02785 (122), Bacillus sp. PRTZ (K-1), Bacillus subtilis CicerEndo, Bacillus subtilis RCAM00711 (124), Bacillus subtilis RCAM00759 (119), Pseudomonas brenneri 14B, Bacillus spp. SL04, Bacillus spp. KUK2A, Paenibacillus castaneae RCAM02202 (580), Paenibacillus mucilaginosus 567, Paenibacillus mucilaginosus 569, but not limited to. According to the invention, agronomically useful microorganisms in the culture liquid can be present in both vegetative and spore forms (both individually and as a mixture of these forms). Since fungi in the vegetative form are characterized by adsorption on the surface of solid nutrient substrates, which ensures their vital activity, additional fixation of the fungal mycelium with any substances that ensure adhesion of the mycelium to the substrate is, as a rule, not required. Therefore, the present invention is more directed to the use of fungi in spore form, as well as bacteria in vegetative and spore form. However, the use of mushrooms in vegetative form is also not excluded.

An “adsorbent carrier” (“carrier”) according to the invention is any adsorbent that is not prohibited for use in agriculture. It could be not limited to, both mineral and organic adsorbent, both natural and synthetic. The main requirements for adsorbent carriers according to the invention are a large specific surface area acceptable for the immobilization of agronomically useful microorganisms according to the invention, and safety for use in crop production, in particular in agriculture. First of all, such adsorbent carriers should not contain cations of heavy metals and radioactive substances. In some non-limiting embodiments of the invention, the adsorbent carrier is a natural sorbent based on silicon-containing rocks in the form of one of the elements of the series: diatomite, zeolite, opoka, tripoli, kaolin.

By “culture liquid” according to the invention is meant a complex mixture obtained by cultivating agronomically useful microorganisms according to the invention in vitro and containing the cultivated microorganisms, residual nutrients and metabolic products of these microorganisms. The cultural liquid is obtained as a result of fermentation - a set of sequential operations from the introduction of agronomically useful microorganisms into a nutrient medium prepared in advance and heated to the required temperature until the completion of the cell growth process. The composition of the nutrient medium for cultivation (the content of easily digestible substances necessary to satisfy physiological needs), its temperature, cultivation time and other necessary conditions (including, for example, pH, the presence of growth factors, vitamins, buffering, etc.) are selected optimal depending on the specific strain of cultivated agronomically useful microorganisms.

“Cationic dextrin” is a substituted dextrin containing cationic groups (for example, amino, ammonium, sulfonium, phosphonium, etc.). According to the invention, cationic dextrin can be used, obtained by any method, the degree of substitution of which with cationic groups is at least 0.065 mol.%. Cationic dextrin according to the invention has complete solubility during heat treatment with subsequent adsorption of microorganisms and the formation of a film on the surface of carriers and mineral fertilizers.

In the present invention, a “biomodifier” (microbiological modifier) refers to a complex of an adsorbent carrier with agronomically useful microorganisms immobilized on it using gelatinized cationic dextrin.

According to the invention, “mineral fertilizer” refers to compounds of inorganic nature that contain essential plant nutrients, i.e. a fertilizer of industrial or fossil origin containing nutrients in mineral form. According to the invention, there can be used, without limitation, any mineral fertilizers in solid (dry) form (for example, in the form of granules, powder, tablet form, etc.), including nitrogen, phosphorus, potassium, complex (for example, nitrogen-potassium, nitrogen- phosphorus-potassium), complex mixed, microfertilizers (containing microelements in a form accessible to plants). In some particular embodiments, to obtain biomineral fertilizers according to the invention, urea, ammonium sulfate, calcium sulfur, ammophos, sodium nitrate, diammonium phosphate, nitroammophos, phosphate (phosphorite) flour, potassium sulfate, potassium salt, ammophos, diammofos, azofoska, nitrophos, and nitrophoska.

Unless otherwise defined, technical and scientific terms in this application have their standard meanings commonly accepted in the scientific and technical literature.

Methods for producing biomineral fertilizer according to the invention

A) a method using agronomically useful microorganisms immobilized on an adsorbent carrier, followed by application of the resulting biomodifier to mineral fertilizers:

At the first stage, agronomically useful microorganisms are immobilized on a carrier using cationic dextrin.

Microorganisms are pre-cultured until the required concentration is achieved. Since the content of CFU of microorganisms in the culture liquid affects the number of CFU of microorganisms ultimately deposited on the adsorbent carriers and mineral fertilizer, their concentration is selected based on the amount that is the target for content in the biomineral fertilizer. The more CFU in the culture liquid, the greater the number of agronomically useful microorganisms deposited on the adsorbent carrier and mineral fertilizer. For example, in some non-limiting embodiments of the invention, microorganisms are cultivated until the content in the culture liquid is at least 10 ⁹ CFU/ml, or at least 10 ⁷ CFU/ml, or, conversely, at least 10 ¹¹ CFU/ml. Spore-forming bacteria and fungi can be cultivated until spore formation, and optionally, the signal for completion of cultivation is the completion of sporogenesis (formation of endospores in bacteria or formation of conidia (mitospores) in fungi) of all cultivated microorganisms. Depletion of the nutrient medium, the creation of temperature and pH unfavorable for the growth of microorganisms, a high CFU value (a significant population of microorganisms in the bioreactor) and other unfavorable conditions cause sporulation as a way to preserve the population of microorganisms.

Next, cationic dextrin, pre-gelatinized, is added to the culture liquid. Microorganisms, having a negative charge, interact with positively charged cationic dextrin. Optimal amount of application dextrin is usually from 1.0 to 1.2 wt.%. With a smaller amount of cationic dextrin, the persistence of microorganisms on the adsorbent carrier and biomodified fertilizer decreases. An increase in the content of cationic dextrin leads to the adhesion of the adsorbent carrier and the fertilizer, which complicates its application to the soil.

The cultural liquid containing agronomically useful microorganisms, added with cationic gelatinized dextrin, is mixed with the adsorbent carrier. The amount of adsorbent carrier is selected so as to fix the maximum number of CFU of microorganisms on the surface and depends, among other things, on the selected strain and adsorbent carrier. So, for example, in some embodiments of the invention, such a prepared culture liquid is mixed with an adsorbent carrier in a ratio of 1 l/t; in other embodiments, the ratio may differ either up or down.

Colloidal particles, including microorganisms and cationic dextrin, formed after adding cationic dextrin to the culture liquid, have a positive charge, which facilitates their fixation on the surface of a negatively charged adsorbent carrier. The effect of fixing colloidal particles on the surface of the adsorbent carrier is further enhanced by the adhesive properties of cationic dextrin, which by nature is a biopolymer obtained from starch. Adhesive properties are imparted to cationic dextrin by gelatinization.

The positive charge of cationic dextrin exceeds the total negative charge of microorganisms and the adsorbent carrier. This makes it possible to impart a positive charge to a highly dispersed adsorbent carrier with immobilized microorganisms (biomodifier).

Drying the adsorbent carrier leads to dehydration of cationic dextrin (biopolymer), which promotes the fixation of microorganisms on the surface of the carrier.

At the second stage, a highly dispersed adsorbent carrier with agronomically useful microorganisms immobilized on its surface (dried state) is applied to mineral fertilizer granules. To do this, the biomodifier and mineral fertilizer in solid form (for example, granulated) are mixed with vigorous stirring. The fixation of the carrier on the surface of mineral fertilizer granules is facilitated by electrostatic forces. The negatively charged surface of mineral fertilizer granules interacts with the positively charged surface of the carrier. The sizes of granules of mineral fertilizers are many times larger than the sizes of particles of a highly dispersed carrier, which enhances the electrostatic interaction of bodies. The ratio of the resulting biomodifier and mineral fertilizer is selected depending on the desired the final amount of presence of agronomically useful microorganisms in a biomineral fertilizer. In this case, it is necessary to take into account ensuring maximum retention of the biomodifier on the surface of the fertilizer, reducing the loss of agronomically useful microorganisms in the composition of the biomodifier during transportation of the biomineral fertilizer. An excessive increase in the amount of adsorbent carrier leads to a weakening of the electrostatic effect of the interaction of particles of the adsorbent carrier with the surface of fertilizer granules, as a result of which carrier losses increase. In this regard, applying more than 4 kg of carrier per 1 ton of mineral fertilizer is usually not advisable. For example, in some embodiments of the invention, the biomodifier is mixed with mineral fertilizer in a ratio of up to 3-4 kg/t. Since the use of cationic dextrin significantly increases the safety of microorganisms on the surface of mineral fertilizers, a lower ratio of biomodifier and mineral fertilizer is sufficient, compared to obtaining biomineral fertilizers containing the same number of microorganisms by other methods.

B) a method of directly applying agronomically useful microorganisms to mineral fertilizers:

Agronomically useful microorganisms are pre-cultivated (see more details in the description of option A), cationic dextrin, pre-gelatinized, is added to the cultural liquid. Microorganisms, having a negative charge, interact with positively charged gelatinized dextrin. The positive charge of cationic dextrin exceeds the total negative charge of microorganisms.

Colloidal particles, including agronomically useful microorganisms and cationic dextrin, formed after adding cationic dextrin to the culture liquid, are applied to the surface of mineral fertilizer granules by spraying. Such colloidal particles have a positive charge, which facilitates their fixation on the surface of mineral fertilizer granules. The effect of fixing colloidal particles on the surface of the mineral fertilizer is further enhanced by the adhesive properties of cationic dextrin, which by nature is a biopolymer obtained from starch. Adhesive properties are imparted to cationic dextrin by gelatinization. The amount of mineral fertilizer in relation to the prepared cultural liquid containing agronomically useful microorganisms and gelatinized cationic dextrin may also depend on the desired final amount of presence of agronomically useful microorganisms in the biomineral fertilizer, but the upper limit is selected so as to ensure maximum retention of CFU of microorganisms on the surface fertilizers For example, in some non-limiting embodiments of the invention, the ratio is 1 liter per 1 ton of mineral fertilizer.

Granules of mineral fertilizer coated with agronomically useful microorganisms and cationic dextrin are mixed and dried. Dehydration of cationic dextrin (biopolymer) promotes the fixation of microorganisms on the surface of mineral fertilizer granules.

The possibility of objective manifestation of a technical result when using the invention is confirmed by reliable data given in examples containing experimental information obtained in the process of conducting research using methods accepted in this field.

It should be understood that the examples given in the application materials are not limiting and are provided only to illustrate the present invention.

In the presented experiments, the spore-forming culture Bacillus subtilis AM6 was used, the cultivation of which was carried out on a nutrient medium of the following composition: potato flakes - 0.1875 g, peptone - 0.0625 g; K2HPO4 - 0.025 g; MgSC - 0.0125 g; NaCI - 0.0125 g; CaCL - 0.005 g. Cultivation was carried out for 3.5 days at a temperature of 30±1°C and a stirring speed of 54 rpm. The culture fluid contained 5.8*10 ⁹ CFU/ml.

To increase the effect of immobilization of microorganisms on the surface of mineral fertilizer modifiers (adsorbent carriers) and directly on the surface of mineral fertilizers, cationic potato and corn dextrin were used.

The culture liquid with cationic dextrin was sprayed onto adsorbent carriers at the rate of 1 l/t:

- diatomite (Inza, Ulyanovsk). Composition: SiOs - about 75%, Al2O3 + TiO - about 4%, MgO - 1%, EerOs, FeO, CaO, KrO, NagO, etc. - the rest. The structure of diatomite is characterized by the presence of fine pores and, therefore, has a low density, not exceeding 0.25-1.00 g/cm ³ . Diatomite has a negative surface charge. Used in agriculture, applied to the soil;

- zeolite. Composition: Siug - 65.88%, Tiug - 0.35%, AI2O3 - 6.19%, EerOz - 2.65%, MnO - <0.01%, CaO - 17.16%, MdO - 1.45 %, Na ₂ O - 0.16%, K ₂ O - 1.43%, P ₂ O ₅ - 0.13%, porosity: 37.25 - 55.72%, density: 2.03 - 2.37 g/cm ³ . Zeolite has a negative surface charge. Used in agriculture, applied to the soil.

The cultural liquid with cationic dextrin was sprayed onto mineral fertilizers at the rate of 1 l/t of urea, ammophos and nitroammophos.

The number of viable microorganisms (CFU/ml) in the culture liquid in experiments on applying a bacterial culture to adsorbent carriers and granules of mineral fertilizers was determined by methods accepted in microbiology. Preparation of cationic dextrin

According to the invention, for the immobilization of microorganisms on mineral fertilizers, cationic dextrin can be used, the degree of substitution of which by cationic groups is at least 0.065 mol.%, obtained by any method.

Currently, various methods for producing cationic dextrin are known. For example, there is a known method for producing cationic dextrin by carrying out a cationization reaction by adding a cationizing agent to dextrin (US9309328, published 04/12/2016). There is also a known method for producing cationic dextrin by cationization reaction at ultra-high pressure (Cho A. et al. Characterization of cationic dextrin prepared by ultra high pressure (UHP)-assisted cationization reaction // Carbohydrate Polymers 2013 Aug 14;97(1):130-7 Epub 2013 Apr 24). In the above methods, dextrin, previously obtained from native starch, is subjected to cationization. Cationation of dextrin is carried out in an aqueous medium. This method is economically expensive and increases the anthropogenic load on the environment.

Within the framework of the present invention, a method has been developed for producing cationic dextrin from cationic starch (for example, potato or corn) by extrusion.

To obtain cationic dextrin, we used cationic starch obtained by the dry method using M-(3-chloro-2-hydroxypropyl)-M,M,M-trimethylammonium chloride as a cationizing agent. The reaction of the cationic agent with starch takes place in an alkaline medium. Alkali also provides a change in the internal structure, primarily the amorphous regions of starch granules, affecting amylose and hydrolysis of amylopectin molecules. The cationic starch obtained in this way can be subjected to heat treatment in an extruder without catalysts to obtain cationic dextrin.

Extrusion of cationic starch was carried out in a single-screw extruder, into which cationic starch with a moisture content of 22-25% was supplied, at a flow rate of 2.7 kg/h, which made it possible to maintain the degree of substitution of cationic dextrin at 0.065 mol.%. The temperature during extrusion is 120-125°C, the pressure is 10 MPa, the total residence time of the raw material in the screw area is 1.5-2 minutes. The resulting cationic dextrin was dried to a moisture content of 8-10%, ground in a hammer mill and sifted on a sieve with a mesh size of 0.05 mm.

Cationic dextrin, like cationic starch, has a positive surface charge. However, gelatinized cationic starch has a high viscosity, and is applied unevenly to the surface of carriers and mineral fertilizers. The consequence of this is the caking of fertilizers and carriers containing cationic starch, in contrast to the developed biomineral fertilizers based on cationic dextrin. As a result of extrusion processing, the amylose and amylopectin present in starch grains are depolymerized, which leads to the formation of cationic dextrin, which has a lower viscosity. The resulting cationic dextrin has a specific surface area of 120-150 m ² /g (determined by the BET (Brunauer-Emmett-Teller) method), is soluble in water and gelatinizes quite quickly.

Gelatinization and sterilization of cationic dextrin

Within the framework of the invention, gelatinization of cationic dextrin was carried out in a water bath at 100±1°C for 10-15 minutes. It is possible to carry out gelatinization starting from 70°C. However, this increases the duration of gelatinization of the cationic dextrin.

Then the gelatinized dextrin was sterilized at a temperature of 120±1°C, which contributed to the inactivation of foreign microflora in cationic dextrin and further fragmentation of positively charged dextrin particles into amylose and amylopectin.

The production of biomineral fertilizers with the determination of colony-forming units of microorganisms (CFU) at the stages of deposition on the adsorbent carrier and mineral fertilizer was carried out using the following method:

1. Preparation of culture liquid in a volume of 25 ml (we determine KOEi).

2. Preparation of cationic dextrin for addition to the culture liquid

In 1.5 ml of physiological solution (0.9% NaCl solution) add 0.3-0.6 g of cationic dextrin (purity is checked for the presence of CFU of foreign microflora).

Mix the suspension and gelatinize it in a water bath at a temperature of 100°C for 10-15 minutes. Then we sterilize the paste. Why place the test tube with the paste in an autoclave and carry out sterilization at a temperature of 120°C for 50-60 minutes. Next, after the autoclave has cooled, place the sterilized test tube with the paste under a UV lamp for 10-15 minutes.

For a more complete quantitative extraction of gelatinized and sterile dextrin from a test tube, add a culture liquid into it. The application is carried out under sterile conditions over an alcohol lamp or in a laminar flow hood and the suspension is intensively mixed with a sterile glass rod. Then the gelatinized dextrin diluted with the culture liquid is added to the flask with the bulk of the culture liquid. Stir the suspension until a homogeneous mass is obtained using a shaker for 15-20 minutes.

3. Preparation of the adsorbent carrier (zeolite or diatomite)

Place 25.5 g of adsorbent carrier in a glass (heat-resistant) or porcelain glass with a volume of 50 ml and sterilize (using an oven or muffle) at a temperature of 250°C. for 3 hours. Cool the sterile adsorbent carrier to 20-25°C. Since some combustion of organic matter occurs during the sterilization of the adsorbent carrier, the mass of the carrier after sterilization is 25 g. It is advisable to cover the glass with foil (lid) during the sterilization process.

In order to analyze the contamination of the adsorbent carrier with phytopathogenic microorganisms, an aqueous extract is prepared from the original and sterilized adsorbents, which is sown on Petri dishes. The presence of phytopathogenic microorganisms is qualitatively determined on the surface of the solid nutrient medium.

катионным (из расчета 1 л/т) 4. Spray 25 µl onto the prepared sterile adsorbent carrier in an amount of 25 g.

cationic (at the rate of 1 l/t)

5. Drying

The resulting carrier substrate + cultural liquid of agronomically useful microorganisms + cationic dextrin is dried at a temperature of 60-70°C. We determine CFUg on an adsorbent carrier with microorganisms.

6. Application of a carrier with agronomically useful microorganisms to mineral

Application is carried out at the rate of 4 kg per 1t, using the following method:

- first weigh a 50 ml polypropylene test tube with a cap on a scale with an accuracy of 0.001,

- then add 5 g of mineral fertilizer granules into the test tube,

- then add an adsorbent carrier with immobilized agronomically useful microorganisms in an amount of 0.02 g,

- determine the total mass of the test tube, granules, carrier with microorganisms - A, determine the total mass of the mineral fertilizer with the carrier and microorganisms - B,

- mix vigorously for 10 minutes on a shaker,

- pour out the mineral fertilizer with the carrier and microorganisms from the test tube and weigh it - Bi,

- the difference between B and Bi (C _in ) is the loss when applying a carrier with microorganisms to a mineral fertilizer,

- weigh the test tube - Ai,

- the difference between Ai and A (C _a ) is the loss when applying a carrier with microorganisms to a mineral fertilizer. The values of C _a and C _b must match.

For control, we determine the CFU4 of the washout from the test tube after removing the mineral fertilizer with applied microorganisms from the test tube.

7. Determination of CFU on mineral fertilizers with precipitated biomodifier (adsorbent carrier with microorganisms). Add 0.5 g of mineral fertilizer granules with an immobilized biomodifier to 4.5 ml of physiological solution (0.9% NaCI solution). Mix vigorously on a shaker and let the prepared suspension settle for 1.5-2 hours. Next, we determine the CFU in the supernatant liquid. CFU counts are carried out on Petri dishes after 2 days.

Comparison of CFU values (KOEi, CFUg and CFU3) allows us to judge the losses of agronomically useful microorganisms at the stages of deposition on adsorbent carriers and mineral fertilizers.

We also determine the loss of biomodifier with microorganisms when applied to mineral fertilizer. Samples of the biomodifier applied to the mineral fertilizer were stored for 3 months at room temperature and humidity.

To obtain biomineral fertilizers without the use of adsorbent carriers, 5 μl of a culture liquid containing bacteria and cationic dextrin (at the rate of 1 l/t) was sprayed onto 5 g of mineral fertilizer. Then air dried.

During the measurement and calculation process, the weighing accuracy was 0.001 g. Losses were expressed as a percentage. When converting losses expressed in grams into losses expressed as percentages, rounding was carried out to hundredths in accordance with accepted rules.

Statistical processing of the experimental results obtained in triplicate was carried out using the standard Microsoft Excel software package, as well as in accordance with the requirements of the standards for the research methods used in the work.

The following examples confirm the feasibility of the proposed method of using cationic dextrin for the immobilization of agronomically useful microorganisms on the surface of mineral fertilizers, both with and without the use of adsorbent carriers.

Example 1. Determination of the effectiveness of immobilization of agronomically useful microorganisms on an adsorbent carrier when using cationic potato dextrin

The efficiency of immobilization of microorganisms (using the example of bacterial spores Bacillus subtilis AM6) on adsorbent carriers was determined without the use of cationic potato dextrin and with cationic potato dextrin (Table 1). From the resulting adsorbent carrier, immediately after drying to an air-dry state, an extract was obtained using saline solution, in which the number of CFU was determined. The CFU number reflects the suitability of the adsorbent carrier for the immobilization of microorganisms.

As studies have shown, cationic potato dextrin added to the culture liquid contributes to a significant increase in the number of CFU. This proves that bacterial spores are adsorbed by dextrin when obtaining extracts from biomodifiers and are transferred in greater quantities to a solid nutrient medium when determining the number of CFU.

Table. 1 - Effect of cationic dextrin on the efficiency of immobilization of bacterial spores

The initial CFU value in the culture fluid is 5.0*10 ⁹ /ml. During the study, cationic potato dextrin was used at a dosage of 1.2%. Zeolite or diatomite was used as an adsorbent carrier.

Example 2. Determination of the effect of cationic potato dextrin as part of a microbiological modifier on the deposition of agronomically useful microorganisms on mineral fertilizers

The resulting biomodifier of microbiological fertilizers based on diatomite or zeolite, containing bacterial spores fixed with cationic potato dextrin on the surface of the corresponding adsorbent carrier, was deposited on the mineral fertilizers urea, ammophos or nitroammophos. To do this, the biomodifier and fertilizer were mixed with vigorous stirring in a mixer for 10 minutes.

The results presented in Tables 2-4 show that the use of cationic potato dextrin as part of a biomodifier of fertilizers helps to significantly increase the safety of bacterial spores on the surface of mineral fertilizers and reduce losses of the biomodifier. Table 2 - Effect of cationic potato dextrin as part of a biomodifier on the deposition of bacterial spores on urea and the loss of the biomodifier.

During the study, the biomodifier was applied at the rate of 4 kg per 1 ton of urea. The amount of cationic potato dextrin in the biomodifier was 1.2%.

Table 3 - Effect of cationic potato dextrin as part of a biomodifier on the deposition of bacterial spores on ammophos and the loss of the biomodifier.

During the study, the biomodifier was applied at the rate of 4 kg per 1 ton of ammophos. The amount of cationic potato dextrin in the biomodifier was 1.2%.

Table 4 - Effect of cationic potato dextrin in the composition of the biomodifier on the deposition of bacterial spores on the nitroammophoska and the loss of the biomodifier.

During the study, the biomodifier was applied at the rate of 4 kg per 1 ton of nitroammophosphate. The amount of cationic potato dextrin in the biomodifier was 1.2%.

Example 3. Determination of the effect of cationic corn dextrin as part of a microbiological modifier on the deposition of agronomically useful microorganisms on mineral fertilizers

The resulting biomodifier of microbiological fertilizers based on diatomite or zeolite, containing bacterial spores fixed with cationic corn dextrin on the surface of the corresponding adsorbent carrier, was deposited on the mineral fertilizers urea, ammophos or nitroammophos. To do this, the biomodifier and fertilizer were mixed with vigorous stirring in a mixer for 10 minutes.

The results presented in Tables 5-7 show that, as in the case of cationic potato dextrin, the use of cationic corn dextrin as part of a biomodifier of fertilizers helps to significantly increase the safety of bacterial spores on the surface of mineral fertilizers and reduce biomodifier losses.

Table 5 - Effect of cationic corn dextrin as part of a biomodifier on the deposition of bacterial spores on urea and the loss of the biomodifier.

Таблица 6 - Влияние декстрина катионного кукурузного в составе микробиологического модификатора (биомодификатора) на осаждение спор бактерий на аммофосе и потерю биомодификатора. During the study, the biomodifier was applied at the rate of 4 kg per 1 ton of urea. The amount of cationic corn dextrin in the biomodifier was 1.2%.

Table 6 - Effect of cationic corn dextrin as part of a microbiological modifier (biomodifier) on the deposition of bacterial spores on ammophos and the loss of the biomodifier.

During the study, the biomodifier was applied at the rate of 4 kg per 1 ton of ammophos. The amount of cationic corn dextrin in the biomodifier was 1.2%.

Table 7 - Effect of cationic corn dextrin as part of a microbiological modifier (biomodifier) on the deposition of bacterial spores on nitroammophoska and the loss of the biomodifier.

During the study, the biomodifier was applied at the rate of 4 kg per 1 ton of nitroammophosphate. The amount of cationic corn dextrin in the biomodifier was 1.2%.

Example 4. Assessment of the influence of cationic potato and corn dextrin in the composition of the cultural liquid on the safety of agronomically useful microorganisms applied to the surface of mineral fertilizers without the use of adsorbent carriers

Table 8 below presents the results reflecting the effect of cationic potato and corn dextrin in the composition of the culture liquid on safety of bacterial spores applied to the surface of mineral fertilizers by spraying. Analysis of the results obtained shows that the safety of bacterial spores on the surface of mineral fertilizers when cationic potato or corn dextrin is added to the cultural liquid is an order of magnitude greater than the safety of bacterial spores applied to mineral fertilizers without dextrin.

Table 8 - Effect of the presence of cationic potato and corn dextrin in the culture liquid on the deposition of bacterial spores on mineral fertilizers.

During the study, the dextrin content in the culture fluid was 1.2%. The content of CFU in the culture liquid is 1*10 ⁹ CFU/ml. The consumption of cultural liquid during spraying is 1 l/t of mineral fertilizer.

Thus, the experiments showed that the use of cationic dextrin promotes the immobilization of agronomically useful microorganisms on the surface of mineral fertilizers, both with the use of adsorbent carriers and by direct application of a culture liquid containing cationic dextrin to the surface of mineral fertilizers. The developed protective composition increases the efficiency of application, the survival rate and the preservation of effective titers of agronomically useful microorganisms on mineral fertilizers, making it possible to reliably attach agronomically useful microorganisms to the mineral fertilizer.

Although the invention has been described with reference to the disclosed embodiments, it will be apparent to those skilled in the art that the specific experiments detailed are provided for purposes of illustrating the present invention only and should not be construed as limiting the scope of the invention in any way. It should be understood that various modifications can be made without departing from the spirit of the present invention.

Claims

Claim 1 . A method for producing biomineral fertilizer, the composition of which includes agronomically useful microorganisms and gelatinized cationic dextrin applied to the mineral fertilizer, including the following successive steps: (1) obtaining a culture liquid of agronomically useful microorganisms, (2) adding gelatinized cationic dextrin to the culture liquid, (For) spraying a cultural liquid containing agronomically useful microorganisms and gelatinized cationic dextrin onto a mineral fertilizer in solid form, followed by drying, or (36) immobilization of agronomically useful microorganisms contained in the cultural liquid with gelatinized cationic dextrin on an adsorbent carrier, drying the resulting biomodifier and its application to mineral fertilizer in solid form. 2. The method according to claim 1, in which the agronomically beneficial microorganisms are plant growth-stimulating bacteria and/or plant growth-stimulating fungi in vegetative and/or spore form. 3. The method according to claim 2, in which the agronomically useful microorganisms are rhizosphere spore-forming bacteria. 4. The method according to claim 3, in which rhizosphere spore-forming bacteria are nitrogen-fixing bacteria and/or phosphorus- and/or potassium-transforming bacteria. 5. The method according to claim 2, wherein the plant growth promoting bacteria are bacteria of the genus Azospirillum, Rhizobium, Azotobacter, Bacillus and/or Paenibacillus. 6. The method according to claim 2, wherein the fungi that stimulate plant growth are fungi of the genus Trichoderma, Mycorrhiza and/or Penicillium. 7. The method according to claim 1, in which the content of agronomically useful microorganisms in the culture liquid is at least 10 ⁹ CFU/ml. 8. The method according to claim 1, in which the gelatinized cationic dextrin is pre-sterilized. 9. The method according to claim 1, in which cationic potato dextrin and/or cationic corn dextrin are used as cationic dextrin. 22 10. The method according to claim 1, in which cationic dextrin is used as cationic dextrin, the degree of substitution of which with cationic groups is at least 0.065 mol%. 11. The method according to claim 1, in which the amount of added cationic gelatinized dextrin is 1.0-1.2 wt.%. 12. The method according to claim 1, wherein the adsorbent carrier is a mineral or organic natural or synthetic adsorbent acceptable in agriculture. 13. The method according to claim 1, in which the adsorbent carrier is a natural sorbent based on silicon-containing rocks in the form of one of the elements of the series: diatomite, zeolite, opoka, tripoli, kaolin. 14. The method according to claim 1, in which the biomodifier is mixed with mineral fertilizer in a ratio of up to 4 kg/t. 15. The method according to claim 1, in which the mineral fertilizer is a nitrogen, phosphorus, potassium, complex, complex mixed or microfertilizer. 16. The method according to claim 14, in which the mineral fertilizer is urea, ammonium sulfate, calcium sulfur, ammophos, sodium nitrate, diammonium phosphate, nitroammophoska, phosphate rock, potassium sulfate, potassium salt, ammophos, diammophos, azofoska, nitrophos or nitrophoska. 17. Biomineral fertilizer, the composition of which includes agronomically useful microorganisms and gelatinized cationic dextrin applied to the mineral fertilizer. 18. Biomineral fertilizer according to claim 17, the composition of which additionally includes an adsorbent carrier, wherein bacteria and gelatinized cationic dextrin are applied to the mineral fertilizer in a composition with an adsorbent carrier. 19. Biomineral fertilizer according to claim 17, in which the agronomically useful microorganisms are plant growth-stimulating bacteria and/or plant growth-stimulating fungi in vegetative and/or spore form. 20. Biomineral fertilizer according to claim 19, in which the agronomically useful microorganisms are rhizosphere spore-forming bacteria. 21. Biomineral fertilizer according to claim 20, in which the rhizosphere spore-forming bacteria are nitrogen-fixing bacteria and/or phosphorus- and potassium-transforming bacteria. 22. Biomineral fertilizer according to claim 19, in which the bacteria that stimulate plant growth are bacteria of the genus Azospirillum, Rhizobium, Azotobacter, Bacillus and/or Paenibacillus. 23. Biomineral fertilizer according to claim 19, in which the fungi that stimulate plant growth are fungi of the genus Trichoderma, Mycorrhiza and/or Penicillium. 24. Biomineral fertilizer according to claim 17, in which the cationic dextrin is cationic potato dextrin and/or cationic corn dextrin. 25. Biomineral fertilizer according to claim 17, in which the cationic dextrin is cationic dextrin, the degree of substitution of which by cationic groups is at least 0.065 mol%. 26. Biomineral fertilizer according to claim 18, in which the adsorbent carrier is a mineral or organic natural or synthetic adsorbent acceptable in agriculture. 27. Biomineral fertilizer according to claim 18, in which the adsorbent carrier is a natural sorbent based on silicon-containing rocks in the form of one of the elements of the series: diatomite, zeolite, opoka, tripoli, kaolin. 28. Biomineral fertilizer according to claim 17, in which the mineral fertilizer is a nitrogen, phosphorus, potassium, complex, complex mixed or microfertilizer. 29. Biomineral fertilizer according to claim 28, in which the mineral fertilizer is urea, ammonium sulfate, calcium sulfur, ammophos, sodium nitrate, diammonium phosphate, nitroammophoska, phosphate flour, potassium sulfate, potassium salt, ammophos, diammophos, azofoska, nitrophos or nitrophoska . 30. The use of gelatinized cationic dextrin for the production of biomineral fertilizer according to any of paragraphs 17-29.