Novel hybrid organic-inorganic fertiliser

Abstract

The invention relates to an organic-inorganic fertiliser comprising phosphorus, nitrogen and carbon obtained by means of a method including the phosphorylation of biodegradable organic materials in the presence of urea, wherein the weight ratio of phosphorylation agent / urea X / Y is such that X is between 1 and 2 moles and Y is between 1 and 10 moles per 1 kg of biodegradable organic matter. The invention also relates to a method for manufacturing the organic-inorganic fertiliser as defined above, the method comprising the following consecutive reaction steps: grinding the biodegradable organic materials, mixing, while stirring, the ground biodegradable organic matter with the urea and the phosphorylation agent and water; evaporating followed by phosphorylating by heating the obtained paste at a specifically calibrated temperature, and finally washing and drying. The invention is defined in the claims.

Description

New hybrid organo-mineral fertilizer FIELD OF THE INVENTION The invention relates to the field of fertilizers, more precisely to the production of organo-mineral fertilizers. These fertilizers are designed to provide essential nutrients such as phosphorus and nitrogen to plants, thus promoting their growth and development. PREVIOUS ART Fertilizers commonly used in agricultural production are divided into mineral, organic, and hybrid (organic-inorganic) fertilizers. Mineral fertilizers are readily available, promote plant growth, and improve crop yields, but a large amount of these fertilizers can damage soil structure, cause salinization through leaching, reduce the lifespan of the soil's tillage horizon, and reduce the quality of agricultural products [1,2]. However, they may be less sustainable and can have negative impacts on the environment if used excessively or inappropriately. Organic fertilizers are derived from plant or animal matter, such as compost, manure, dung, or plant remains. They are rich in nutrients, but take longer to become available to plants than inorganic fertilizers [3]. It is possible to combine the two types of fertilizers to produce hybrid fertilizers to obtain the benefits of each. Organo-mineral fertilizers can be used to provide nutrients in a sustainable way. Also, these types of fertilizers can be applied in different ways, such as incorporating them into the soil, spraying them on plants, or using them as granules. They are also available in different forms, such as liquid or solid [4,5]. The production of hybrid fertilizers involves mixing different types of fertilizers to obtain a product that contains a combination of different chemical elements, such as nitrogen, phosphorus, carbon, and potassium, etc. It can be done in different ways, depending on the type of hybrid fertilizer to be produced and its final destination. This can be done through physical mixing where the fertilizer components combine in a precise and homogeneous manner. Also, it can be done using chemical synthesis processes, which allow the production of hybrid fertilizers from basic chemical compounds. Finally, it is also possible to produce hybrid fertilizers from raw materials by chemical functionalization of biodegradable organic materials from food waste, biomass, and other organic waste from the agricultural sector. Organo-mineral fertilizers combine the advantages of organic and mineral fertilizers. They provide an optimal balance of nutrients needed for plant growth and development. Moreover, they can provide nutrients for a longer period of time compared to mineral fertilizers because they degrade slowly and release nutrients gradually. On the other hand, they are resistant to extreme environmental conditions such as drought and high temperatures, making them suitable for use in areas with hot and arid climates. In terms of improving soil quality, organo-mineral fertilizers can improve soil quality by increasing organic matter content and increasing the water-holding capacity of soils. Finally, they can help reduce operating costs for farmers as they can be made from local agricultural or industrial waste. Known technologies do not meet the above requirements, these are synergistic treatments of organic and mineral matter by fermentation or physical mixing processes. For example, document EP2653456A1 describes a method for obtaining organo-mineral fertilizer by post-fermentation of agricultural waste [6]. By the same method, it is known from document EP2653455A1, a new method for obtaining a suspension of organo-mineral fertilizer from post-fermentation waste [7]. It is also known from document EP1644302B1 a process for producing an organo-mineral fertilizer by physical mixing of urea (nitrogen fertilizer) and lignin (organic matter) [8]. BRIEF DESCRIPTION OF THE INVENTION The new technology described in this invention relates to a new type of organo-mineral fertilizer intended to improve the growth and quality of plants and soil. This fertilizer is designed to be more effective and easier to use than conventional fertilizers, thanks to its unique composition that optimally combines different nutrients and organic matter. Thus, nutrients are released from the insoluble part of these materials by biodegradation and factors such as soil moisture, temperature, pH. This invention aims to combine the recycling of agricultural, livestock and agri-food industry waste with the chemical functionalization of organic materials. Thus, it makes it possible to produce green organo-mineral fertilizers, rich in phosphorus and nitrogen, meeting the nutritional needs of plants at different growth phases. The invention covers both the use of this fertilizer and its manufacturing process. Thanks to this simple and ecological process, this invention contributes to a more sustainable use of organic resources and promotes environmentally friendly agriculture. The organo-mineral fertilizers produced improve soil fertility and support healthy plant growth. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1A represents the effect of the amount of urea used in the reaction balance on the rate of P and N nutrients in the organo-mineral fertilizer; Figure 1B represents the effect of reaction temperature on the level of P and N nutrients in the organo-mineral fertilizer; Figure 2 represents the ATG curves of the organo-mineral fertilizers OMF1, OMF2, OMF3 and OMF4 measured by the thermogravimetric method, in comparison with the ATG curve of the raw material SD; Figure 3 represents images recorded by scanning electron microscope respectively of the products resulting from the study of the effect of the temperature (100 to 140 °C) of the reaction on their structural morphology, (a) sawdust, (b) 100 °C, (c) 110 °C, (d) 120 °C, (e) 130 °C and (f) 140 °C; Figures 4A and 4B show the soil phosphorus and nitrogen release profile of organo-mineral fertilizers OMF1, OMF2, OMF3 and OMF4 measured by column leaching. DETAILED DESCRIPTION OF THE INVENTION The invention relates to a new type of organo-mineral fertilizer comprising phosphorus, nitrogen and carbon. The organo-mineral fertilizer according to the invention is obtained by phosphorylation of biodegradable organic materials from different sources. The invention also relates to a method for manufacturing organo-mineral fertilizer. This process is developed in five stages: Stage A (grinding): Coarse grinding of the organic matter to obtain particles with an average diameter of around 200 - 600 pm; Step B (mixing): Stirring the mixture of organic matter with phosphorylation agent / urea and water, the molar ratios of which are shown in Table 1. The mixture is used in a stirred reactor at room temperature (25°C ± 5°C) for 6 hours; Step C (drying): the mixture is dried by evaporation of the water at a temperature between 40-65°C, so as to obtain a well-dried paste; Stage D (phosphorylation): The paste obtained from stage C undergoes a solid-state phosphorylation reaction to produce an organo-mineral material rich in carbon, phosphorus and nitrogen (organo-mineral hybrid fertilizer). This reaction is carried out by heating the paste from stage C at a temperature ranging from 90°C to 150°C for a period of 50 to 70 minutes. Step E (washing and drying): washing and drying of the organo-mineral material resulting from the reaction, so as to eliminate the excess of reagents which are not grafted. Example: Preparation of organo-mineral fertilizer from sawdust by phosphorylation process In a reactor containing 30 ml of water, we introduced the three components: sawdust (SD), phosphoric acid (PA) and urea (Table 1). To maintain the molar ratio constant and have intimate contact between the different components of the phosphorylation reaction, 1 kg of SD was impregnated into the reaction mixture. After 6 hours of stirring, the water was evaporated at 60°C. Once the water was removed, the remaining solid was heated at a temperature between 90 and 150°C for 1 h in an oven to react the different components (SD, PA, urea). After the reaction, the product obtained was washed with water, followed by drying in an oven or in the open air. Urea acts here as a nitrogen source and as a catalyst. Table 1: Presentation of the codes of each organo-mineral fertilizer and their correspondence in molar ratio, as used in the reaction. Results of analysis of organo-mineral fertilizer obtained In a particular embodiment of the invention, the organo-mineral fertilizer produced has concentrations of phosphorus and nitrogen, with variations between 3 and 24% by mass for phosphorus and between 3.5 and 6.5% by mass for nitrogen (Table 2). These levels were precisely determined through the use of analytical methods such as ICP-OES for phosphorus and the Kjeldahl method for nitrogen. Table 2: Chemical composition of P and N nutrients for each fertilizer; the rate is measured by the ICP-OES method for P and the Kjeldahl method for N. The rate of grafted phosphate groups also varies between 1633 and 6500 mmol / kg depending on the reaction conditions (Table 3). The determination of the rate of grafted phosphate groups was carried out by conductometric titration. First, 0.3 g of the phosphorylated organic matter was mixed with 85 ml of water and 5 ml of 0.01 M NaCl. Then, to adjust the pH to 2.5, hydrochloric acid (0.1 M) was added. Finally, the mixture was titrated by adding a NaOH solution (0.05 M) while monitoring the conductivity of the suspension of phosphorylated organic matter. The rate of phosphate groups was determined using the middle line of the curve representing the electrical conductivity as a function of the volume of NaOH added. This method allows an accurate and reliable determination of the grafted phosphate groups (Table 3) Table 3: Representation of the rate of phosphate groups grafted in sawdust for the different molar ratios used in the reaction. The ability to modulate the grafted phosphate loading rate provides great flexibility in the production of mineral fertilizers and can meet the specific needs of crops and soils. Therefore, this variability offers a customized solution to improve agricultural productivity while minimizing environmental impact. In a variant of the invention, illustrated in Figure 1 A, the percentage of urea in the organic matter / phosphoric acid / urea ratio was studied in order to evaluate its effect on the composition of the product obtained. The results show a phosphorus level of between 15-24% by mass, for a urea level in the organic matter / phosphoric acid / urea ratio of between 4 and 13% by mass. On the other hand, the nitrogen level varies between 3.3% and 11% by mass depending on the urea ratio used. These results make it possible to determine the optimal combination of raw materials to produce an organo-mineral fertilizer with the desired nitrogen and phosphorus levels. In another variant of the invention, the effect of temperature on the phosphorus and nitrogen composition of the product obtained was studied, as shown in Figure 1 B. The results showed that temperature has a significant effect on the composition of the organo-mineral fertilizer. At a temperature of 90°C, the final product contains only 0.5% phosphorus and 2% nitrogen, while at a temperature of 140°C, the phosphorus and nitrogen levels increase to 24% and 6% respectively. However, at a temperature of 150°C, the nitrogen level reaches 10%, which is higher than the other temperatures tested, while the phosphorus level is 21%. These results suggest that the reaction temperature has a direct effect on the composition of the organo-mineral fertilizer and that specific conditions must be selected to obtain a final product with the desired composition. TGA analysis was used to determine the residue level at a temperature of 650 °C to confirm the grafting of phosphate groups onto organic matter. The results were showed that organic material (OM) had a residue rate of 2%, while fertilizers OMF1, OMF2, OMF3 and OMF4 had residue rates of 40%, 42%, 45% and 25% respectively (Figure 2). The effect of temperature on the morphological structural changes of the obtained OMFs can be observed in the images obtained by scanning electron microscopy (Figure 3). The SEM image of the raw biomass showed a rough surface, with the fibers and microparticles all intact. However, in the temperature range of 90 to 150°C, the SEM images showed a deformation of the microstructure and a structural change by the appearance of macropores, with a probable appearance explained by the grafting of phosphate groups. Figure 4 shows the results of phosphorus and nitrogen release into the soil over time for the four types of organo-mineral fertilizers: OMF1, OMF2, OMF3, and OMF4. The experiment was conducted over a period of 120 days. After 30 days, the OMFs began to release phosphorus and nitrogen into the soil. OMF1 showed the highest release rate, at 2% for phosphorus and 3% for nitrogen, while OMF2 showed the lowest rate, at 1.5% for phosphorus and 2% for nitrogen (Figure 4 A and B). After 60 days, all four types of fertilizers showed an increase in phosphorus and nitrogen release, with OMF2 having the highest release rates, at 8% for phosphorus, and OMF4 having the highest release rates for nitrogen (20%).After 90 days, a significant increase in phosphorus release was observed, with OMF4 showing the highest release rates, at 21% for phosphorus and 33% for nitrogen. At the end of the 120-day experimental period, all four fertilizer types showed a substantial increase in phosphorus release, with OMF4 having the highest release rates, at 41% for phosphorus and 49% for nitrogen. Overall, these results suggest that the developed organo-mineral fertilizers can release significant amounts of phosphorus and nitrogen into the soil over time, with release rates varying depending on the type of fertilizer used. These results could have important implications for agricultural practices and the use of fertilizers to improve crop yields. INDUSTRIAL APPLICATION This organo-mineral fertilizer technology could be used in precision agriculture to optimize fertilizer application based on specific crop needs and soil conditions, thereby improving crop productivity and quality. It would also promote a slow release of nutrients, reducing losses and minimizing environmental impact. REFERENCES

[0001] Akanza, PK and N'Da, AH, 2018. Effects of fertilizer on fertility, nutrition and yield of maize: impact on the diagnosis of soil deficiencies. Journal of the West African Chemical Society, 45, pp.54-66. [2] Knittel, Fabien. "Agronomy of fertilizers in France in the 19th century: Saltpeter, urban waste, chemical fertilizers: three examples of agricultural valorization." Histoire & Sociétés Rurales (2017): 177-200. [3]Wu, Linnan, et al. "Increased organic fertilizer application and reduced chemical fertilizer application affect the soil properties and bacterial communities of grape rhizosphere soil." Scientific Reports 10.1 (2020): 1-10. [4]Devkota, K. P., et al. "Fertilizers, hybrids, and the sustainable intensification of maize systems in the rainfed mid-hills of Nepal." European Journal of Agronomy 80 (2016): 154-167. [4]Hammad, Hafiz Mohkum, et al. "Comparative effects of organic and inorganic fertilizers on soil organic carbon and wheat productivity under arid region." Communications in Soil Science and Plant Analysis 51.10 (2020): 1406-1422. [5] Bisson, Thomas Karl, et al. "Organic liquid fertilizer and process of making." U.S. Patent No. 10,023,501. 17 Jul. 2018. [6]Shirley, Bruce Lamar, William D. li Peterson, and Larry Connell. "Method of manufacturing sterilized organic fertilizer and apparatus therefor." [7]Wojciech Jozef KedziaRobert Merta. “Fertilizer and method of obtaining a suspension of mineral-organic fertilizer from waste post-fermentation.” [8] Maurice Aloysius Antonius EversAnton Terlouw.” Process for the production of a fertilizer and fertilizer”. DESCRIPTION ABRIDGED The invention relates to a new type of organo-mineral hybrid fertilizer (organophosphate), comprising phosphorus, nitrogen and carbon, obtained by means of a process including solid-state phosphorylation of biodegradable organic materials 5 in the presence of urea. The invention also describes a method for manufacturing this type of organo-mineral fertilizer.

Claims

CLAIMS 1. An organo-mineral fertilizer comprising phosphorus, nitrogen and carbon obtained by means of a process including the phosphorylation of biodegradable organic materials in the presence of urea, wherein the weight ratio of phosphorylation agent / urea X / Y is such that X is between 1 and 2 moles, Y is between 1 and 10 moles, for 1 kg of biodegradable organic matter.

2. Organo-mineral fertilizer according to claim 1, characterized in that it comprises from 4 to 6% by weight of nitrogen and from 3 to 20% by weight of phosphorus.

3. Organo-mineral fertilizer according to at least one of claims 1 and 2, characterized in that the rate of grafted phosphate groups is between 1633 and 6240 mmol per kg of biodegradable organic matter.

4. Organo-mineral fertilizer according to at least one of claims 1 to 3, in which the biodegradable organic materials are selected from co-products and residues from agriculture and livestock farming, natural waste from wood and forestry, as well as biodegradable organic waste from agri-food industries rich in lignocellulosic materials.

5. Process for manufacturing the organo-mineral fertilizer according to claim 1, characterized in that it comprises the following steps: • Crushing of biodegradable organic materials; • Mixing under agitation the crushed biodegradable organic matter with urea and the phosphorylation agent and water; • Evaporation of water at a temperature below approx. 65oC until a dry paste is obtained; • Heating the dry paste resulting from step c to a temperature above approx. 90oC; • Washing with water, filtration and drying of the product resulting from step d.

6. Process for manufacturing the organo-mineral fertilizer, according to claim 5, characterized in that the grinding of the biodegradable organic matter is carried out until particles with an average diameter of between 200 and 600 pm are obtained.

7. Process for manufacturing the organo-mineral fertilizer, according to at least one of claims 5 and 6, characterized in that the mixing of the biodegradable organic materials, the phosphorylation agent, the urea and water is carried out at room temperature for approximately 6 hours.

8. Process for manufacturing the organo-mineral fertilizer according to at least one of claims 5 to 7, characterized in that the phosphorylation agent is selected from phosphoric acid, diammonium phosphate, ammonium phosphate and triple superphosphate.

9. Process for manufacturing organo-mineral fertilizer according to at least one of claims 5 to 8, characterized in that step (d) of solid-state phosphorylation is carried out under atmospheric pressure and at a temperature between 90°C and 150°C.