Fertilizer particle comprising a polysaccharide as biostimulant

Abstract

The present invention relates to a fertilizer particle comprising one, two or three of from 1.0 to 30 wt.% of nitrogen (N), from 1,0 to 52 wt.% of phosphorus (P) (expressed as P2O5), from 1,0 to 60,0 wt.% of potassium (K) (expressed as K2O), depending on whether the fertilizer particle is a K, a NP or a PK, or a NPK fertilizer, and from 0.0001 to 5.0 weight% of at least one polysaccharide, more in particular chitosan, as a biostimulant, based on the total weight of the fertilizer particle. The present invention furthermore relates to a method to produce such fertilizer particles.

Description

[0001] Fertilizer particle comprising biostimulant

[0002] Field of the disclosure

[0003] The present disclosure is related to the field of fertilizers, in particular fertilizer products comprising nitrogen, potassium and phosphorus.

[0004] Background information

[0005] Nitrogen is one of the most important nutrients required by plants to grow. It is involved in several physiological processes, such as chlorophyll synthesis and protein synthesis, which are crucial for the development of a plant. Nitrogen is mainly applied in four forms: urea, ammonium ions, nitrate ions, and organic sources, such as proteins. Nitrate ions are readily absorbed by plants and represent a fastacting source of nitrogen. Phosphorus and potassium are two macronutrients, which, in addition to nitrogen, are required by plants. Nitrate ions are the preferred source of nitrogen for most agricultural plants, which they can absorb through their roots. Ammonium ions can also be absorbed, although at a slower rate.

[0006] Soils naturally contain a lot of microorganisms, such as bacteria and fungi, and some of them are capable of transforming ammonium into nitrate, whereas others can transform nitrate into other nitrogen forms, such as nitrous oxide.

[0007] Ammonium nitrate-based fertilizers are commonly used today in agriculture and have several advantages: high nitrogen content (usually around 25-27 weight%), and fast release of nitrogen in the soil due to high water solubility.

[0008] Other nitrogen-containing fertilizers include NPK fertilizers, which comprise nitrogen, phosphorus, and potassium. NPK fertilizers often contain nitrogen in the form of ammonium ions and / or nitrate ions.

[0009] Recently, a new type of agricultural inputs has been discovered: biostimulants. Biostimulants are organic compounds that trigger positive physiological changes in plants. Biostimulants can be absorbed by the roots or leaves of a plant, and they interact with enzymes present in the plant and in the soil to modify the plant's behavior. The presence of biostimulants in the particle provides new benefits and / or improves known benefits to the plant receiving the fertilizer effect, such as increasing the nutrient use efficiency. The nutrient use efficiency measures the amount of nutrient absorbed by a plant compared to the amount of nutrient supplied to it as fertilizer. Biostimulants can furthermore have other advantages, such as solubilizing nutrients in soil, and improving resistance to abiotic stresses. So, there is a need to combine biostimulants with nitrogen-containing fertilizers into a single solid product. Summary of the disclosure

[0010] It has been found that it is possible to prepare homogeneous fertilizer particles comprising a biostimulant. The biostimulant is added during the fertilizer production process and is evenly distributed within the fertilizer. This ensures that the biostimulant is released at the same time as the nutrient comprised in the fertilizer.

[0011] The biostimulant can increase one or more parameters of plants, such as shoot dry matter, root dry matter, leaf area, and phosphorus use efficiency.

[0012] In a first aspect, the present disclosure provides a homogeneous fertilizer particle comprising: one, two or three of from 1.0 to 30 wt.% of nitrogen (N), from 1,0 to 52 wt.% of phosphorus (P) (expressed as P2O5), from 1,0 to 60,0 wt.% of potassium (K) (expressed as K2O), depending on whether the fertilizer particle is a K, a NP or a PK, or a NPK fertilizer, from 0.0001 to 5.0 weight% of at least one polysaccharide, more in particular chitosan, as a biostimulant, based on the total weight of the fertilizer particle.

[0013] In another aspect, the present disclosure provides a method for producing homogeneous fertilizer particles, the method comprises the steps of a. providing a molten, solid or combination thereof of a K starting material comprising from 48.0 to 62.0 wt.% of potassium (K) (expressed as K2O), a molten, solid, or combination thereof (slurry), NP starting material comprising from 1.0 to 30 wt.% of nitrogen (N), from 1.0 to 52.0 wt.% of phosphorus (P) (expressed as P2O5), or a molten, solid or combination thereof (slurry,) PK starting material comprising from 1.0 to 52.0 wt.% of phosphorus (P) (expressed as P2O5), from 1.0 to 60.0 wt.% of potassium (K) (expressed as K2O), or a molten, solid, or a combination thereof (slurry), NPK starting material comprising from 1.0 to 30.0 wt.% of nitrogen (N), from 1,0 to 52 wt.% of phosphorus (P) (expressed as P2O5), from 1.0 to 60.0 wt.% of potassium (K) (expressed as K2O), the weight percentages based on the total weight of the material; b. optionally, modifying the properties of the starting material by mixing, pH-value adjustments, heating, cooling, and / or evaporating; c. processing the material into homogenous fertilizer particles, more in particular with a particle size of from 0.1 to 5.0 mm; d. adding from 0.0001 to 5.0 wt.% of one or more polysaccharides as a biostimulant, based on the total weight of the material, during one or more of the steps a, b and c, e. optionally, modifying the particle surface with coatings and / or other surface-active ingredients, f. optionally, adding one or more fillers, secondary nutrients, micronutrients, and / or other biostimulants, during one or more of the steps a, b, c, d, and e.

[0014] Detailed description of the disclosure

[0015] Unless otherwise defined, all terms used in disclosing the invention, including technical and scientific terms, have the meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. By means of further guidance, term definitions are included to better appreciate the teaching of the present invention.

[0016] All references cited in this description are hereby deemed to be incorporated in their entirety by way of reference.

[0017] As used herein, the following terms have the following meanings:

[0018] "A", "an", and "the" as used herein refers to both singular and plural referents unless the context clearly dictates otherwise. By way of example, "a compartment" refers to one or more than one compartment.

[0019] "About" as used herein referring to a measurable value such as a parameter, an amount, a temporal duration, and the like, is meant to encompass variations of + / -20 % or less, in particular + / -10 % or less, more in particular + / -5 % or less, even more in particular + / -1 % or less, and still more in particular + / - 0.1 % or less of and from the specified value, in so far such variations are appropriate to perform in the disclosed invention. However, it is to be understood that the value to which the modifier "about" refers is itself also specifically disclosed.

[0020] "Comprise", "comprising", and "comprises" and "comprised of" as used herein are synonymous with "include", "including", "includes" or "contain", "containing", "contains" and are inclusive or open- ended terms that specifies the presence of what follows e.g., component and do not exclude or preclude the presence of additional, non-recited components, features, element, members, steps, known in the art or disclosed therein.

[0021] The recitation of numerical ranges by endpoints includes all numbers and fractions subsumed within that range, as well as the recited endpoints.

[0022] The expression "weight percent", "%wt.", "weight%" or "wt.%", here and throughout the description unless otherwise defined, refers to the relative weight of the respective component based on the overall weight of the formulation.

[0023] In a first aspect, the present disclosure provides a homogeneous fertilizer particle, comprising: one, two or three of from 1.0 to 30 wt.% of nitrogen (N), from 1,0 to 52 wt.% of phosphorus (P) (expressed as P2O5), from 1,0 to 60,0 wt.% of potassium (K) (expressed as K2O), depending on whether the fertilizer particle is a K, a NP or a PK, or a NPK fertilizer, and from 0.0001 to 5.0 weight% of at least one polysaccharide, more in particular chitosan, as a biostimulant, based on the total weight of the fertilizer particle.

[0024] As used herein, a homogeneous material relates to a material where the local concentration in different elements is identical in all parts of the material. However, the material may not necessarily be monophasic, i.e., it may contain chemical compounds in different states. For example, a fertilizer particle may comprise a main component, also called a matrix, and solid particles of a different material evenly distributed within the matrix. Such a fertilizer particle would be considered homogeneous for the purpose of this disclosure if the solid particles are equally distributed within the fertilizer particle. N, P, and K are the primary nutrients of the fertilizer particle that are essential for growth.

[0025] In some embodiments, the fertilizer particle comprises one, two or three of between 5.0 and 37.0 wt.% nitrogen, between 1.0 and 36.0 wt.% phosphorus (expressed as P2O5), between 1.0 and 30.0 wt.% potassium (expressed as K2O), based on the total weight of the fertilizer particle, depending on whether the fertilizer particle is a K, a NP or a PK, or a NPK fertilizer. In other words, in case of NPK fertilizer, all three compounds are present, in case of NP fertilizer, only nitrogen and phosphorus are present, in case of PK fertilizer, only phosphorus and potassium are present, and in case of a K fertilizer, only potassium is present.

[0026] In some embodiments, the fertilizer particle more in particular comprises between 7.0 and 27.0 wt.% of nitrogen, between 3.0 and 22.0 wt.% of phosphorus (expressed as P2O5), between 3.0 and 22.0 wt.% of potassium (expressed as K2O), based on the total weight of the fertilizer particle, depending on whether the fertilizer particle is a K, a NP or a PK, or a NPK fertilizer.

[0027] Polysaccharides are compositions that consist of complex carbohydrates that are composed of long chains of monosaccharides. Chitosan is a linear polysaccharide produced by several marine species, such as shrimp, lobster, and crab. It comprises p-l inked D-glucosamine and N-acetyl-D-glucosamine. In some embodiments, the fertilizer particle comprises from 0.0005 to 0.1 weight% of one or more polysaccharides, more in particular from 0.001 to 0.011 wt.%, and most in particular from 0.008 to 0.012 wt.%, based on the total weight of the fertilizer particle. In some embodiments, the fertilizer particle comprises from 0.0005 to 0.1 wt.% of chitosan, more in particular from 0.001 to 0.011 wt.%, and mostt in particular from 0.0008 to 0.012 wt.%, based on the total weight of the fertilizer particle. In some embodiments, the fertilizer particle comprises one or more other biostimulants selected from the group consisting of a humic acid, a fulvic acid, a seaweed extract, a protein hydrolysate including an amino acid or a peptide comprising at least two amino acids, a lignosulfonate compound, and mixtures thereof. It was found that different types of biostimulants were suitable to be added in a fertilizer production process. The total amount of biostimulants is more in particular present in the fertilizer particle in an amount of between 0.0001 and 5.0 weight%, based on the total weight of the fertilizer particle.

[0028] Humic and fulvic acids may be obtained from the process of leonhardite, which is a natural raw material from the decomposition of organic matter. Humic and / or fulvic acids may be present as a salt. Humic and fulvic acids are complex organic molecules comprising carboxylic acid groups, so humic and fulvic salts, also called humate and fulvate, can be prepared by mixing the acid with a base. It has been observed that humic and fulvic acids comprised in fertilizer particles can increase one or more parameters of plants, such as shoot dry matter, root dry matter, leaf area, and phosphorus use efficiency.

[0029] In some embodiments, the humic and / or fulvic acids, more in particular the mixture of humic and fulvic acids, are present in an amount of from 0.005 to 1.5 weight% of a mixture of humic and fulvic acids, more in particular from 0.015 to 0.16 wt.%, most in particular from 0.05 to 0.07 wt.%, based on the total weight of the fertilizer particle.

[0030] A protein hydrolysate is a composition obtained by hydrolysis of proteins. A protein hydrolysate comprises amino-acids and peptides of various length, for example from 2 to 20 amino-acids. A protein hydrolysate may be of vegetable origin, animal origin, or a mixture of both.

[0031] In some embodiments, the fertilizer particle comprises from 0.01 to 1.50 weight%, more in particular from 0.03 to 0.55 wt.%, most in particular from 0.10 to 0.20 wt.%, of one or more protein hydrolysates, based on the total weight of the fertilizer particle.

[0032] Lignosulfonate compounds are by-products of the paper industry. These compounds are polymers and may be highly branched polymers comprising phenyl propane units, which have a broad distribution of size. Lignosulfonates comprise sulfonate groups and can comprise sodium, potassium, or calcium as counter-ions. It has been observed that lignosulfonate compounds comprised in fertilizer particles can increase one or more parameters of plants, such as shoot dry matter, root dry matter, leaf area, and phosphorus use efficiency. In some embodiments, the lignosulfonate compound is a calcium lignosulfonate.

[0033] In some embodiments, the fertilizer particle comprises one or more lignosulfonate compounds in an amount of from 0.01 to 1.50 weight%, more in particular from 0.03 to 0.55 wt.%, most in particular from 0.10 to 0.20 wt.%, based on the total weight of the fertilizer particle.

[0034] In some embodiments, the lignosulfonate compound is calcium lignosulfonate.

[0035] In some embodiments, the fertilizer particle comprises at least one filler selected from the group consisting of dolomite, MgO, lime, calcium sulphate, clay, and mixtures thereof. Dolomite (CaMg(CO3)2) and lime (usually CaO or Ca(OH)z) are calcium-containing fillers, as well as calcium sulphate (CaS04), which is commonly known as gypsum. Clay is a broad term for a variety of aluminosilicates and can comprise calcium, but does not always do. Filler materials are used in some fertilizer production processes.

[0036] In some embodiments, the fertilizer particle comprises from 1.0 to 30 weight%, from 5.0 to 30 weight%, from 10 to 30 weight%, from 1.0 to 25 weight%, from 5.0 to 25 weight%, or from 10 to 30 weight% of at least one filler, based on the total weight of the fertilizer particle.

[0037] In some embodiments, the fertilizer particle comprises one or more element(s) selected from the group consisting of calcium, magnesium, sulfur, and sodium, and mixtures thereof, which are secondary nutrients, and boron, manganese, selenium, zinc, and molybdenum, and mixtures thereof, which are micronutrients. It is remarked that one or more other element(s) out of cobalt, copper and iron, which are also micronutrients, can be present in K, NP or PK, or NPK fertilizer particles, this due to impurities present in the raw material.

[0038] In some embodiments, the fertilizer particle further comprises one or more components selected from the group consisting of magnesium sulfate, sodium nitrate, potassium nitrate, magnesium nitrate, aluminum sulfate, struvite, biotite, and mixtures thereof. These components can be used in fertilizers to provide secondary nutrients and micronutrients and to improve the physical properties, such as caking tendency, dusting tendency, particle strength, and water absorption, of the fertilizer particle.

[0039] In some embodiments, the fertilizer particle has a particle size ranging from 0.1 to 5.0 mm.

[0040] In another aspect, the present disclosure provides a method for producing homogeneous fertilizer particles, the method comprising the steps of a. providing a molten, solid or combination thereof (slurry), of a K starting material comprising from 48.0 to 62.0 wt.% of potassium (expressed as KZO), a molten, solid or combination thereof (slurry) of NP starting material comprising from 1.0 to 30.0 wt.% of nitrogen, from 1.0 to 52.0 wt.% of phosphorus (expressed as P2O5), or a molten, solid or combination thereof (slurry) of PK starting material comprising from 1.0 to 52.0 wt.% of phosphorus (expressed as P2O5), from 1.0 to 60.0 wt.% of potassium (expressed as K2O), a molten, solid or a combination thereof (slurry) of NPK starting material comprising from 1.0 to 30.0 wt.% of nitrogen, from 1.0 to 52.0 wt.% of phosphorus (expressed as P2O5), from 1.0 to 60.0 wt.% of potassium (expressed as K2O), the weight percentages based on the total weight of the material; b. optionally, modifying the properties of the starting material by mixing, pH-value adjustments, heating, cooling, and / or evaporating; c. processing the material into homogenous fertilizer particles, more in particular with a particle size of from 0.1 to 5.0 mm; d. adding from 0.0001 to 5.0 wt.% of one or more lignosulfonate compounds as a biostimulant, based on the total weight of the material during one or more of the steps a, b and c, e. optionally, modifying the particle surface with coatings and / or other surface-active ingredients, f. optionally, adding one or more fillers, secondary nutrients, micronutrients, and / or other biostimulants, during one or more of the steps a, b, c, d, and e.

[0041] In order to produce fertilizer particles at a high rate, at several hundreds of kilos a day, production methods using molten materials have been developed. Molten materials can be converted into a solid particulate compositions with a variety of methods and devices, such as prilling tower, pan granulator, fluidized bed granulator, drum granulator, spherodizer, and pugmill. The particles made by these methods have the same chemical composition as the molten material.

[0042] In some embodiments, the molten, solid or combination thereof, K starting material comprising muriate of potash (MOP) (KCI) comprising between 58.0 and 62.0 wt.% of potassium (expressed in KjO), and / or sulphate of potash (SOP) (K2SO4) comprising between 48.0 and 52.0 wt.% of potassium (expressed in K2O), or the molten, solid or combination thereof, of PK starting material comprising between 1.0 and 36.0 wt.% phosphorus (expressed in P2O5), and between 1.0 and 30.0 wt.% potassium (expressed in K2O), or the molten, solid or combination thereof, NP starting material comprising between 5.0 and 37.0 wt.% nitrogen, between 1.0 and 36 wt.% phosphorus (expressed in P2O5), or the molten, solid or combination thereof, NPK starting material comprising between 5.0 and 37.0 wt.% nitrogen, between 1.0 and 36.0 wt.% phosphorus (expressed in P2O5), between 1.0 and 30.0 wt.% potassium (expressed in K2O), based on the total weight of the material, is provided in step a. It is remarked that SOP also comprises between 16 to 18 wt.% of sulphur.

[0043] In some embodiments, more in particular, the K starting material comprising molten, solid or combination thereof, MOP comprising between 60.0 and 62.0 wt.% of potassium (expressed in K2O), and / or SOP comprising between 50.0 and 52.0 wt.% of potassium (expressed in K2O), or the NP starting material comprising between 7.0 and 27.0 wt.% of nitrogen, between 3.0 and 22.0 wt.% of phosphorus, or the PK starting material comprising between 3.0 and 22.0 wt.% of phosphorus, and between 3.0 and 22.0 wt.% of potassium, or the NPK starting material comprising between 7.0 and 27.0 wt.% of nitrogen, between 3.0 and 22.0 wt.% of phosphorus, between 3.0 and 22.0 wt.% of potassium, based on the total weight of the material, is provided in step a.

[0044] In some embodiments, in step d, the one or more polysaccharides, and more in particular chitosan, is added in an amount of from 0.0005 to 0.1 weight%, more in particular from 0.001 to 0.011 wt.%, most in particular from 0.008 to 0.012 wt.%, in steps a, b and / or c. In some embodiments, the at least one polysaccharide is added as a dry composition, for example, a dry powder. In some embodiments, the at least one polysaccharide is added as a liquid composition, for example, an aqueous solution or an aqueous suspension.

[0045] Furthermore, in some embodiments, in step f, one or more fillers, more in particular in an amount of from 1.0 to 30.0 wt.% based on the total weight of the material, selected from the group consisting of dolomite, MgO, lime, calcium sulfate, and / or clay, and mixtures thereof, are added during one or more of the steps a, b, c, d, and e.

[0046] Also, in some embodiments, in step f, one or more secondary nutrients selected from the group consisting of calcium, magnesium, sulphur, sodium, and mixtures thereof, and / or one or more micronutrients selected from the group consisting of boron, manganese, selenium, zinc, molybdenum are added during one or more of steps a, b, c, d, and / or e. It is remarked that one or more other element(s) out of cobalt, copper and iron, can be present in K, NP or PK, or NPK fertilizer particles, this due to impurities present in the raw material.

[0047] Depending on the type of process, the other biostimulants, the one or more fillers, the second nutrients and / or the micronutrients, can be added in a different step of the process. More specifically, when the method is a prilling or a spherodizing process, the one or more fillers, the secondary nutrients, the micronutrients, and / or the other biostimulants, are added in steps a, b, and / or e, and when the method is a drum granulation or a blunger process, the one or more fillers, the secondary nutrients, the micronutrients, and / or the other biostimulants are added in steps a, b, c, and / or e.

[0048] In an optional step b, the properties of the starting material may be modified by mixing, adjusting the pH-value, heating, cooling and / or evaporating. The starting material from step a may optionally be mixed in step b to become homogeneous, meaning that the one or more polysaccharides, more in particular chitosan, that are added in step d during steps a, b, and / or c, and optionally, when added in step a, b, c, and / or d, the other biostimulants, the one or more fillers, the second nutrients, and the micronutrients, are evenly distributed within the molten material.

[0049] Once the desired material is obtained in step b, the material is processed in step c into homogeneous fertilizer particles, for example using a prilling tower, a granulator, a spherodizer, or a pugmill, whichever is applicable. Some production techniques, such as prilling and spherodizing, require a homogeneous material to produce homogenous particles. Other techniques do not require a homogeneous material to produce homogenous particles, because the production technique homogenizes the composition during its production for example, in the drum or pugmill granulation process, by direct combination of solids with the molten material in the granulator.

[0050] In some embodiments, the homogeneous fertilizer particles obtained in the method of the present disclosure have a particle size ranging from 0.1 to 5.0 mm. Modern agriculture machinery, in particular fertilizer spreaders, is often configured to manipulate fertilizer particles having a size of a few millimeters.

[0051] In some embodiments, the processing of the material as performed in step c comprises producing homogeneous particles using a device selected from the group consisting of a prilling tower, a pan granulator, a fluidized bed granulator, a drum granulator, a spherodizer, and a pugmill, whichever is applicable.

[0052] In some embodiments, in an optional step e, the homogeneous fertilizer particles obtained from the processing of material as performed in step c, are coated with a coating composition which can comprise one or more fillers, secondary nutrients, micronutrients, and / or other biostimulants as mentioned above. These coating compositions may be applied to the fertilizer particles to modify their chemical composition and / or to improve their physical properties, such as particle strength, caking property, dusting property, and swelling property.

[0053] In some embodiments, the homogeneous fertilizer particles obtained from the processing are fertilizer particles according to the present disclosure.

[0054] Example 1

[0055] A molten material §= melt) comprising 16 weight% of nitrogen, 16 weight% of phosphorus (expressed as P2O), and 16 weight% of potassium (expressed as K2O) was prepared. As can be seen in Table 1, to this molten material, different amounts of chitosan, which is a type of polysaccharide, were added as a biostimulant in this NPK melt, which was then stirred for 5 min, before being cooled on a plate and broken down in small pieces with a size below 5.0 mm.

[0056] Table 1

[0057] The particulated fertilizers, i.e. entries 1 and 2, and a control without the chitosan solution (see entry 0 in Table 2 below), were then tested in a scientific agronomic trial: Maize plants are grown in a controlled greenhouse in 10 L pots filled with 70% sand and 30% low-P soil (wt. / wt.). 50% supply of micronutrients were applied by 100 ml / pot of drenched nutrient solution during soil preparation. Fertilizer modality is applied before sowing, by mixing it in the entire substrate volume. Sowing of 5 seeds / pot, covered with 3 cm of substrate, thinned to 2 plants per pot at 10-15 DAS (days after sowing). There were 10 replicates per treatment arranged in RCBD. At 20 DAS: Supplementary N fertilization was applied to 100% of the plant requirement and accompanied with spot irrigation to drench the nutrients into the soil. The sum of nutrient application rates were: NPK (with or without the chitosan, 150, 15 and 253 mg / kg, N, P and K respectively), and other macro and micronutrients (Mg, Ca, S, Cl, Fe, Mn, Zn, B, Cu, Mo at 12, 200, 70, 83, 7.7, 5.1, 1.1, 1.0, 1.1 and 0.26 mg / kg, respectively). The first set of 5 replicates was harvested at 35 DAS and the remaining set of 5 replicates at 62 DAS, partitioned, dried, and stored for later laboratory analyses.

[0058] In Table 2 below, different parameters, i.e. the leaf area expressed in canopeo index and measured 35 days after sowing, the P-deficiency measured 35 days after sowing, the shoot dry matter expressed in g / plant and measured 62 days after sowing, the root dry matter expressed in g / plant and measured 65 days after sowing, the total root length index as measured with a RhizoVision, and the shoot P content expressed in mg / plant are shown which were measured by maize plants treated with entry 0 without the chitosan as biostimulant (= control), and with the entries as mentioned above in Table 1. RhizoVision is a common method to measure total root length. In this experiment, the method uses an image which is taken with standardized photography. The Canopeo index is a tool which is developed using Matlab and analyses fractional green canopy cover (FGCC) from images and videos. It is based on color ratios of red to green (R / G) and blue to green (B / G) and an excess green index (2G- R-B). In this experiment, it estimates leaf area based on total green pixel area. The P (phosphorus) - deficiency is a visual scoring of P-deficiency induced purple leaf anthocyanin coloration in old plant leaves. The shoot dry matter is measured by drying harvested shoot to constant weight at 60°C. Likewise, the root dry matter is measured by drying harvested root to constant weight at 60°C. The shoot P content is the percentage of phosphorus in shoot sampled multiplied by the total shoot dry matter. To determine the percentage of phopshorus in a shoot sample, a known weight of dried finely milled shoot sample is used for P extraction by microwave digestion with an acid and P is detected and quantified in the extract by ICP-OES (Inductively Coupled Plasma Optical Emission Spectrometry).

[0059] Table 2

[0060] Conclusion

[0061] The stem diameter, the leaf chlorophyll index, the root dry matter, the shoot dry matter, the shoot P content and the phosphate use efficiency (PUE) should be as high as possible, whereas, as already explained above in the conclusion of Table 2, the P deficiency should be as low as possible. In Table 3 above, it can be seen that the NPK-fertilizer comprising the chitosan as the biostimulant has a higher leaf area, shoot dry matter, root dry matter and total root length index than the control without the chitosan, and thus perform better than the control without the chitosan. As can further be seen in Table 3, the P deficiency is lower in case the chitosan is present in view of the control without the chitosan. This indicates that there is an increased nutrient use efficiency of the plant when the chitosan is present.

[0062] Experiment 2

[0063] Likewise experiment 1, a NPK melt comprising 16 weight% of nitrogen, 16 weight% of phosphorus (expressed as P2O), and 16 weight% of potassium (expressed as K2O) was prepared. As can be seen in Table 1 above, a mixture of humic and fulvic acids was added as a biostimulant to this NPK melt, which was then stirred for 5 min, before being cooled on a plate and broken down in small pieces with a size below 5.0 mm.

[0064] The particulated fertilizers, i.e. entries 1 and 2 of Table 1 above, as well as entry 0 without chitosan (=control), were then tested in a second scientific agronomic trial: Maize plants are grown in a controlled greenhouse in 11 L pots filled with 70% sand and 30% low-P soil (wt. / wt.). 50% supply of micronutrients were applied by 100 ml / pot of drenched nutrient solution during soil preparation. Fertilizer modality is applied before sowing, by mixing it in the entire substrate volume. Sowing of 4 seeds / pot (maize (Zea mays L.))„ covered with 3 cm of substrate, thinned to 2 plants per pot at 14 DAS (days after sowing). There were 5 replicates per treatment arranged in CRD. At 20 DAS: Supplementary N fertilization was applied to 100% of the plant requirement and accompanied with spot irrigation to drench the nutrients into the soil. The sum of nutrient application rates were: NPK (with or without chitosan, 150, 15 and 253 mg / kg, N, P and K respectively), and other macro and micronutrients (Mg, Ca, S, Cl, Fe, Mn, Zn, B, Cu, Mo at 12, 200, 70, 83, 7.7, 5.1, 1.1, 1.0, 1.1 and 0.26 mg / kg, respectively). All 5 replicates were harvested at 54 DAS, partitioned, dried, and stored for later laboratory analyses. In Table 3 below, different parameters, i.e. the P-deficiency expressed as the purple anthocyanin leaf coloration index, the stem diameter expressed in mm, the leaf chlorophyll index expressed in N-Tester value, the shoot dry matter expressed in g / plant, the shoot P content expressed in mg / pot and the phosphate use efficiency (PUE) expressed in g shoot dry matter (DM) / 100 mg fertilizer-P, are shown which were measured by maize plants treated with the entry 0 without Ca-lignosulfonate (= control), and with the second entry as mentioned above in Table 1. The stem diameter is the diameter of the stem 1 cm above the soil surface using a digital caliper. The leaf chlorophyll index is the average of 4 measurements on the youngest fully developed leaf using an N-tester® of Yara International ASA, which is a handheld leaf nitrogen measurement tool. The phosphate use efficiency (PUE) is the shoot dry matter (DM) produced by the plant for each 100 mg fertilizer phosphorus (P) taken up by the plant.

[0065] Table 3

[0066] Conclusion

[0067] The stem diameter, the leaf chlorophyll index, the shoot dry matter, the shoot P content and the phosphate use efficiency (PUE) should be as high as possible, whereas, as already explained above in the conclusion of Table 2, the P deficiency should be as low as possible. In Table 3 above, it can be seen that the NPK-fertilizer comprising the chitosan as the biostimulant has a higher leaf area, shoot dry matter and total root length index than the control without the chitosan and thus perform better than the control without chitosan. As can further be seen in Table 3, the P deficiency is lower in case the chitosan is present in view of the control without the chitosan. This indicates that there is an increased nutrient use efficiency of the plant when chitosan as a form of polysaccharide is present.

Claims

Claims1. A homogeneous fertilizer particle comprising one, two or three of from 1.0 to 30 wt.% of nitrogen (N), from 1,0 to 52 wt.% of phosphorus (P) (expressed as P2O5), from 1,0 to 60,0 wt.% of potassium (K) (expressed as K2O), depending on whether the fertilizer particle is a K, a NP or a PK, or a NPK fertilizer, and from 0.0001 to 5.0 weight% of at least one polysaccharide, more in particular chitosan, as a biostimulant, based on the total weight of the fertilizer particle.

2. The fertilizer particle according to claim 1, wherein the at least one polysaccharide, more in particular the chitosan, is present in an amount of from 0.0005 to 0.1 weight%, more in particular from 0.001 to 0.011 wt.%, most in particular from 0.008 to 0.012 wt.%, based on the total weight of the fertilizer particle.

3. The homogeneous fertilizer particle according to claim 1 or 2, wherein the fertilizer particle comprises one, two or three from between 5.0 and 37.0 wt.% nitrogen, between 1.0 and 36.0 wt.% phosphorus, between 1.0 and 30.0 wt.% potassium, more in particular between 10.0 and 27.0 wt.% of nitrogen, between 3.0 and 20 wt.% of phosphorus, between 3 and 20 wt.% of potassium, based on the total weight of the fertilizer particle, depending on whether the fertilizer particle is a K, a NP or a PK, or a NPK fertilizer.

4. The homogeneous fertilizer particle according to any one of claims 1 to 4, wherein the fertilizer particle comprises one or more other biostimulants selected from the group consisting of a humic acid, a fulvic acid, a seaweed extract, a protein hydrolysate comprising an amino acid or a peptide comprising at least two amino acids, a lignosulfonate compound, and mixtures thereof.

5. The homogeneous fertilizer particle according to any one of the preceding claims, further comprising at least one filler selected from the group consisting of dolomite, MgO, lime, calcium sulfate, clay, and mixtures thereof.

6. The homogeneous fertilizer particle according to claim 6, comprising from 1.0 to 30.0 weight% of the at least one filler, based on the total weight of the fertilizer particle.

7. The homogeneous fertilizer particle according to any one of the preceding claims, further comprising one or more second nutrients selected from the group consisting of calcium, sodium, magnesium, sulphur, and mixtures thereof, and / or one or more micronutrients selected from the group consisting of boron, manganese, selenium, zinc, molybdenum, and mixtures thereof.

8. The homogeneous fertilizer particle according to any one of claims 1 to 7, having a particle size ranging from 0.1 to 5.0 mm.

9. A method for producing homogeneous fertilizer particles, the method comprises the steps of a. providing a molten, solid or a combination thereof NPK starting material comprising from 1.0 to 30.0 wt.% of nitrogen, from 1,0 to 52 wt.% of phosphorus (expressed as P2O5), from 1.0 to 60.0 wt.% of potassium (expressed as K2O), a molten, solid or a combination thereof NP starting material comprising from 1.0 to 30.0 wt.% of nitrogen, from 1.0 to 52.0 wt.% of phosphorus (expressed as P2O5), or a molten, solid or a combination thereof PK starting material comprising from 1,0 to 52 wt.% of phosphorus (expressed as P2O5), from 1.0 to 60.0 wt.% of potassium (expressed as K2O), a molten, solid or combination thereof of K starting material comprising from 48.0 to 62.0 wt.% of potassium (expressed as K2O), the weight percentages based on the total weight of the material; b. optionally, modifying the properties of the starting material by mixing, pH-value adjustments, heating, cooling, and / or evaporating; c. processing the material into homogenous fertilizer particles, more in particular with a particle size of from 0.1 to 5.0 mm; d. adding from 0.0001 to 5.0 wt.% of one or more polysaccharides as a biostimulant, based on the total weight of the material, during the steps a, b and / or c, e. optionally, modifying the particle surface with coatings and / or other surface-active ingredients, f. optionally, adding one or more fillers, secondary nutrients, micronutrients, and / or other biostimulants, during the steps a, b, c, d, and / or e.

10. A method according to claim 9, wherein in step d, the one or more polysaccharides, more in particular the chitosan, are added in an amount of from 0.0005 to 0.1 weight% of a mixture of humic and fulvic acids, more in particular from 0.01 to 0.011 wt.%, most in particular from 0.008 to 0.012 wt.%, based on the total weight of the fertilizer particle, in step a, b, and / or c.

11. A method according to claim 9 or 10, wherein the molten, solid, or combination thereof, K starting material comprising muriate of potash (MOP) comprising between 58.0 and 62.0 wt.% of potassium (expressed in K2O), and / or sulphate of potash (SOP) comprising between 48.0 and 52.0 wt.% of potassium (expressed in K2O), the molten, solid, or combination thereof, NP starting material comprising between 5.0 and 37.0 wt.% nitrogen, between 1.0 and 36 wt.% phosphorus (expressed in P2O5), the molten, solid, or combination thereof, PK starting material comprising between 1.0 and 36.0 wt.% phosphorus (expressed in P2O5), and between 1.0 and 3.00 wt.% potassium (expressed in K2O), or the molten, solid, or combination thereof, NPK starting material comprising between 5.0 and 37.0 wt.% nitrogen, between 1.0 and 36.0 wt.% phosphorus (expressed in P2O5), between 1.0 and 30.0 wt.% potassium (expressed in K2O), is provided in step a.

12. A method according to claim 11, wherein the MOP starting material comprising between 60.0 and 62.0 wt.% of potassium (expressed in K2O), and / or SOP starting material comprising between 50.0 and 52.0 wt.% of potassium (expressed in K2O), the NP starting material comprising between 7.0 and 27.0 wt.% of nitrogen, between 3.0 and 22.0 wt.% of phosphorus, the PK starting material comprising between 3.0 and 22.0 wt.% of phosphorus, and between 3.0 and 22.0 wt.% of potassium, based on the total weight of the molten material, or the NPK starting material comprising between 7.0 and 27.0 wt.% of nitrogen, between 3.0 and 22.0 wt.% of phosphorus, between 3.0 and 22.0 wt.% of potassium, is provided in step a.

13. A method according to any one of claims 9 to 12, wherein, when the method isa prilling or a spherodizing process, the one or more fillers, the secondary nutrients, the micronutrients, and / or the other biostimulants, are added in steps a, b, and / or e, a drum granulation or a blunger process, the one or more fillers, the secondary nutrients, the micronutrients, and / or the other biostimulants are added in steps a, b, c, and / or e.

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