FIELD OF THE INVENTION

[0001] Priority is claimed of European patent application no. 20209124.5, filed on November 23, 2020

[0002] The invention relates to a composition comprising (i) a specific pyrazole or an agriculturally acceptable salt thereof; (ii) a phosphonic acid or an agriculturally acceptable salt thereof; (iii) optionally, one or more carboxylic acids, agriculturally acceptable salts or anhydrides thereof; and (iv) optionally, one or more glycols. Compared to conventional compositions, the compositions according to the invention provide improved solubility of salts of pyrazoles such as 3,4 DMPP in aqueous solution. The solutions are stabilized against crystallization by lowering the crystallization point.

BACKGROUND ART

[0003] Nitrification is an aerobic process performed by small groups of autotrophic bacteria and archaea. It is an important step in the nitrogen cycle in soil, wherein ammonia is biologically oxidized to nitrite, followed by the oxidation of the nitrite to nitrate. Nitrification of nitrogen containing fertilizers reduces their efficiency, as the contained nitrogen is oxidized and no longer available for take up by crops. Therefore, nitrogen containing fertilizers commonly comprise nitrification inhibitors to reduce nitrification, when the fertilizer is applied to the soil.

[0004] Negative side effects of nitrogen-containing fertilizers, such as the production of nitrate ions to be washed out into the subterranean water and/or the production of nitrous fumes, in particular N _Z O which is/are further identified to enhance the climate change, are of growing public concern. Both effects are based on metabolic activities of soil bacteria, which - in several steps - turn urea and other nitrogencontaining fertilizers into N ₂ O and/or nitrate ions.

[0005] The key enzymes involved in nitrification can effectively be inhibited by nitrification inhibitors. The use of nitrification inhibitors to reduce negative side effects of nitrogen containing fertilizers, such as the production of nitrate ions and nitrous gases, has significantly grown in recent years. The enzymes involved in this step can be inhibited by known nitrification inhibitors such as pyrazole derivatives. 3,4- dimethylpyrazole (3,4 DMP) and its phosphate salt 3,4-dimethylpyrazole-phosphate (3,4 DMPP) are the most widely discussed and used ones. [0006] Commercially available fertilizer additives have relatively low concentrations of the active substance and suffer from low stability, especially at lower temperatures. If a nitrification inhibitor comprises 3,4 DMPP, crystallization of the active substance hurdles the usability and shortens the storage life. Users often lack appropriate equipment for stirring or heating to re-dissolve the crystals.

[0007] RU 2248329 relates to a method for treatment of industrial sewage or water-return systems containing ammonium nitrogen and acid-resistant form of bacteria (microorganisms) causing acid microbiological corrosion. RU 2248329 relates to monomethylpyrazole having a molecular weight of 82.1 g/mol but not dimethylpyrazole, let alone dimethylpyrazole phosphates.

[0008] US 2020 0223764 discloses a process for preparing 2-(N-3,4-dimethylpyrazole)succinic acid by chemical reaction of 3,4-dimethylpyrazole with maleic acid and/or maleic acid anhydride in the absence of organic solvents or diluents at pH values greater than 7, and subsequent crystallization from the reaction product obtained in the absence of organic solvents or diluents.

[0009] US 2020 0288712 discloses mixtures including as active components at least one specific nitrification inhibitor (compound I) and at least one urease inhibitor (compound II). Also described are a method for improving the nitrification-inhibiting effect, or for increasing the health of a plant using mixtures of at least one compound I and at least one compound II and a method of using the mixtures comprising compounds I and compounds II for increasing the health of a plant. Also described are agrochemical compositions including these mixtures. Also described is plant propagation material including these mixtures or these agrochemical compositions.

[0010] US 2020 0165173 relates to a process for preparing a formulation F for reducing nitrification. The document also relates to a formulation F obtainable by said process. Furthermore, the document relates to a process of preparing a fertilizer-nitrification inhibitor mixture, and to a fertilizer-nitrification inhibitor mixture obtainable by this process. Moreover, the document relates to a method of fertilizing agricultural soil.

[0011] US 2020 0102255 discloses a method for fertilizing agricultural soil by applying at least one fertilizer N to the soil, wherein the at least one fertilizer N is applied in combination with a formulation F. The formulation F comprises at least one nitrification inhibitor I and at least one organic solvent S, and the at least one solvent S is selected from ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, diglyme, fatty acid dialkylamides, benzyl alcohol, butyrolactone, propylene carbonate, ethyl hexyl lactate, 2-butoxy ethanol, dimethylsulfoxide, or mixtures thereof. The formulation F is essentially free from 3,4-dimethylpyrazolphosphate. [0012] US 2019 0048260 relates to a nitrogen stabilizing composition. The composition includes 22 to 26% w/w N-(n -butyl) thiophosphoric triamide (NBPT), 4 to 8% w/w of 3,4-dimethyl pyrazole phosphate (3,4 DMPP) and/or nitrapyrin, a solvent including N-methyl -2 -pyrrolidone (NMP) and propylene glycol, 0.1 to 5% w/w vegetable oil, and 0.1 to 5% w/w lecithin.

[0013] US 2018 0016199 discloses pyrazole derivatives as nitrification inhibitors.

[0014] US 2017 0362140 relates to a composition comprises a nonaqeuous, liquid carrier, an inhibitor compound, and a colorant composition comprising an azo colorant. A method for making the composition is also provided. A method for making a fertilizer composition using the disclosed composition is also provided.

[0015] US 2016 0176769 discloses particulate compositions of reverted superphosphate substantially free of free acid containing at least one nitrification inhibitor and their methods of preparation and use .

[0016] US 2016 0168042 relates to a method for producing a liquid compound and to the compound used to improve the results of the application of ammoniacal nitrogenated fertilizers to crops requiring same and the ammonium present in the ground, said compound being a mixture consisting mainly of 3,5 DMPP as a nitrification inhibitor, phosphorus, the main function of which is to participate in all of the processes and energetic reactions of the crop, and amino acids winch are synthesized by the plants in enzymatic reactions generated by means of the animation, where absorbed ammonium salts and organic acids are produced. 3,5 DMPP is otherwise known as a plasticizer for polymer compositions.

[0017] US2012157317 discloses a composition in concentrated form (“the concentrate”) for dilution with water in the preparation of an agricultural composition for application to crops, soil or animals, comprising a carbohydrate -based pH modifying agent and a pH indicator and a process for preparing the agricultural composition by mixing the concentrate with water, and adding the agricultural chemical to the composition, if it is not already present in the concentrate. The agricultural composition comprises an agricultural chemical whose agricultural activity varies with the pH of the water. The proportions of the pH indicator and the pH modifying agent in the concentrate are selected so that when the concentrate is diluted with an appropriate amount of water, the pH indicator indicates visually by coloration of the composition, whether or not the pH of the water is suitable for acceptable agricultural activity of the chemical.

[0018] WO 2019 012383 relates to mixtures comprising as active components a first nitrification inhibitor (compound I) and a second nitrification inhibitor (compound II); to a method for improving the nitrification-inhibiting effect, or for increasing the health of a plant using mixtures of one compound I and one compound II; to the use of mixtures comprising compounds I and compounds II for increasing the health of a plant; to agrochemical compositions comprising these mixtures; and to plant propagation material, comprising these mixtures or these agrochemical compositions.

[0019] WO 2016 097318 discloses novel nitrification inhibitors.

[0020] However, the compositions of nitrification inhibitors of the prior art are not satisfactory in every respect. There is a demand for improved compositions of nitrification inhibitors with a higher concentration of the active substance and longer stability.

[0021] It is an object of the invention to provide compositions of nitrification inhibitors having advantages compared to the compositions of the prior art. The compositions should have higher weight contents of the active substance and improved stability even at low temperatures. In particular, it would be desirable to provide a solution of agriculturally acceptable salts of pyrazoles such as 3,4 DMPP in water which contain approximately 30 wt.-% and which are stable for a reasonable time period under cold („wmterly“) conditions, such as 2 degrees centigrade.

[0022] This object has been achieved by the subject-matter of the patent claims.

[0023] It has been surprisingly found that the solubility of salts of pyrazoles such as 3,4 DMPP in aqueous solutions can be improved by the addition of acids and the resulting reduction of the pH value.

[0024] Further, it has been surprisingly found that the addition of organic acids, such as maleic acid, improves the solubility of salts of pyrazoles such as 3,4 DMPP in aqueous solutions and stabilizes the solution by lowering the crystallization point to about 10 °C.

[0025] Still further, it has been surprisingly found that the addition of phosphonic acids or salts thereof, especially bisphosphonic acids or salts thereof, further stabilizes aqueous solutions of salts of pyrazoles such as 3,4 DMPP by reducing the crystallization point to about 2 °C.

[0026] Yet further, it has been surprisingly found that the addition of one or more glycols to an aqueous solution of salts of pyrazoles such as 3,4 DMPP facilitates the re-dissolution, thereby making solutions easier to handle even at low temperatures.

[0027] Furthermore, it has been surprisingly found that the addition of a phosphonic acid or salt thereof and optionally of one or more carboxylic acids and/or one or more glycols improves the solubility of salts of pyrazoles such as 3,4 DMPP in an aqueous solution compared to conventional compositions. This enables providing compositions with a higher concentration of the active compound and an improved stability, even at low temperatures. The compositions provided are easier to handle and have a relatively long storage life.

[0028] Moreover, it has been surprisingly found that aqueous solutions of salts of pyrazoles such as 3,4 DMPP comprising a phosphonic acid or salt thereof and optionally one or more carboxylic acids and/or one or more glycols can be used as nitrification inhibitors.

SUMMARY OF THE INVENTION

[0029] A first aspect of the invention relates to a composition comprising

(i) a pyrazole of general formula (A) wherein

R1 means -H, or -Ci-6 -alkyl, or -C i-s-alkyl-OH; preferably -H;

R2 means -H, -Ci-s -alkyl, -C i-<, -alkyl -OH. -NH2, -F, -Cl, or -Br; preferably -H; and

R3 and R4 independently of one another mean -H, -Ci-6-alkyl, -C i-s-alkyl-OH, -NHz, -F, -Cl, or -Br; preferably -CH3; or an agriculturally acceptable salt thereof;

(ii) a phosphonic acid or an agriculturally acceptable salt thereof;

(iii) optionally, one or more carboxylic acids, agriculturally acceptable salts or anhydrides thereof; and

(iv) optionally, one or more glycols.

[0030] For the purpose of the specification, a fertilizer is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply one or more plant nutrients essential to the growth of plants . Many sources of fertilizer exist, both natural and industrially produced. They typically provide the three main macronutrients nitrogen, phosphorus, and potassium in varying proportions. The mainly used nitrogen containing fertilizers compose ammonium compounds or derivatives thereof. [0031] For the purpose of the specification, a fertilizer additive is a composition that can be advantageously added to (conventional) fertilizers in order to improve their properties. Typically, the fertilizer additive is no fertilizer as such.

[0032] The composition according to the invention may contain various ingredients that are capable of forming salts with various acids or that are employed in form of acid addition salts. For example, 3,4 DMPP may be regarded as the acid addition salt of 3,4-dimethylpyrazole (3,4 DMP) with phosphoric acid, whereas at a stochiometric ratio of 1:1 the phosphoric acid is present as dihydrogen phosphate anion and the 3,4 DMP is protonated thereby forming a pyrazolium cation. The composition according to the invention may further contain various acids such as one or more phosphonic acids, one or more carboxylic acids, one or more inorganic aids, and the like. A skilled person recognized that in solution is certain solvents such as water, the various anions (conjugate bases of the acids) which exchange with one another by metathesis reactions such that in the solution it can be difficult to clearly specify the various ion pairs that may be involved and that are attracted to one another by electrostatic forces.

[0033] Certain ingredients can be added or may be present in the composition according to the invention in form of carboxylic acid anhydrides. The composition according to the invention is preferably aqueous and as carboxylic acid anhydrides tend to spontaneously hydrolyze in aqueous environment. Unless expressly stated otherwise, irrespective of whether the composition according to the invention is aqueous or non-aqueous, all percentages and weights with regard to the one or more carboxylic acids, agriculturally acceptable salts of anhydrides thereof refer to the corresponding weight of the carboxylic acid anhydride, even if it actually employed in form of the (hydrolyzed) carboxylic acid or a salt thereof. Thus, all percentages and weights with regard to e g. maleic acid (diacid) and its agriculturally acceptable salts refer to maleic acid anhydride (anhydride cyclic), whereas all percentages and weights with regard to e.g. maleic acid and its agriculturally acceptable salts with regard to e.g. acetic acid (monoacid) and its agriculturally acceptable salts refer to acetic anhydride (anhydride dimeric).

[0034] Likewise, certain ingredients can be added or may be present in the composition according to the invention in form of agriculturally acceptable salts of carboxylic acids, phosphonic acids, pyrazoles, and the like. The composition according to the invention is preferably aqueous and as mixtures of salts in aqueous solution readily undergo metathesis reaction. Unless expressly stated otherwise, when the composition according to the invention is aqueous, all percentages and weights refer to the corresponding weight of the non-salt forms, i.e. the free acids and the free pyrazole, i.e. the weight contribution of the salt component is not taken into account. When the composition according to the invention is nonaqueous, however, said percentages and weights refer to the salts as such. [0035] Preferably, the composition according to the invention is aqueous, preferably an aqueous liquid selected from solutions, emulsions and suspensions, more preferably an aqueous solution.

[0036] Preferably, the composition according to the invention is a supersaturated solution of the pyra- zole or agriculturally acceptable salt thereof.

[0037] Preferably, the composition according to the invention is sprayable; preferably over a granulated fertilizer according to a predefined mass relation, while maintaining the granulated characteristics of the granulated fertilizer.

[0038] In preferred embodiments of the composition according to the invention, the weight content of water is at least 10 w.-%, relative to the total weight of composition; preferably at least 16 wt.-%, more preferably at least 22 wt.-%, still more preferably at least 28 wt.-%, yet more preferably at least 33 wt.- %, even more preferably at least 38 wt.-%, most preferably at least 43 wt.-%, and in particular at least 48 wt.-%.

[0039] In preferred embodiments of the composition according to the invention, the weight content of water is at most 90 w.-%, relative to the total weight of composition; preferably at most 85 wt.-%, more preferably at most 80 wt.-%, still more preferably at most 75 wt.-%, yet more preferably at most 70 wt.- %, even more preferably at most 65 wt.-%, most preferably at most 60 wt.-%, and in particular at most 55 wt.-%.

[0040] In preferred embodiments of the composition according to the invention, the weight content of water is within the range of 50±40 wt.-%, relative to the total weight of composition; preferably 50±30 wt.-%, more preferably 40±20 wt.-%, still more preferably 35±30 wt.-%, yet more preferably 35±26 wt.-%, even more preferably 35±22 wt.-%, most preferably 35±18 wt-%, and in particular 35±14 wt.- 0 //o.

[0041] The composition according to the invention contains a pyrazole of general formula (A) wherein R1 means -H, or -Ci-e-alkyl, or -Ci-s -alkyl -OH; preferably -H;

R2 means -H, -C , -alkyl. -C|_ ₍ , -alkyl -OH. -NH2, -F, -Cl, or -Br; preferably -H; and

R3 and R4 independently of one another mean -H, -Ci-6-alkyl, -Ci-6-alkyl-OH, -NH2, -F, -Cl, or -Br; preferably -CH3; or an agriculturally acceptable salt thereof.

[0042] The composition according to the invention may contain one or more pyrazoles of general formula (A) or agriculturally acceptable salts thereof Preferably, the composition according to the invention contains a single pyrazole of general formula (A) or an agriculturally acceptable salt thereof.

[0043] Preferably, the pyrazole is selected from the group consisting of pyrazole, 3,4-dimethylpyrazole, 3,5-dimethylpyrazole, 4-chloro-3-methylpyrazole, 5-chloro-l,3-dimethylpyrazole, 5-amino-l,3-dime- thylpyrazole, 3,5-dimethylpyrazole-l-methanol, l-allyl-3,5-dimethylpyrazole, 1 -(2 -hydroxyethyl) -pyrazole, l-methyl-lH-pyrazole-4-carboxaldehyde, l//-pyrazolc-3-carbaldchydc, I //-pyrazole -5 -carb aldehyde. l/F-pyrazole-3-carboxylic acid, 2//-pyrazolc-3-carboxylic acid, l .5-dimethyl-l//-pyrazolc-4- carboxylic acid, 4-bromo-l,3-dimethyl-177-pyrazole-5-carboxylic acid, 17/-pyrazole-4, 5 -diamine.

[0044] Preferably, the pyrazole is 3,4-dimethylpyrazole.

[0045] In preferred embodiment of the composition according to the invention, the pyrazole is present in form of an agriculturally acceptable salt.

[0046] Preferably, the pyrazole is present in form of an agriculturally acceptable acid addition salt with an acid selected from the group consisting of hydrochloric acid, hydrobromic acid, hydrofluoric acid, water (anion = hydroxide), sulfuric acid (anion = hydrogen sulfate or sulfate), amidosulfonic acid, phosphoric acid (anion = dihydrogen phosphate, hydrogen phosphate, or phosphate), nitric acid, carbonic acid (anion = bicarbonate or carbonate), perchloric acid (anion = perchlorate), hexafluorosilicic acid (H ₂ SIF ₆ ), and hexafluorophosphoric acid (HPF ₅ ).

[0047] Preferably, the pyrazole is present a agriculturally acceptable acid addition salt with phosphoric acid, whereas the protonated pyrazole forms a cation and the anion is selected from dihydrogen phosphate, hydrogen phosphate and phosphate, preferably dihydrogen phosphate.

[0048] Preferably, the pyrazole or agriculturally acceptable salt thereof is a nitrification inhibitor or a urease inhibitor; preferably a nitrification inhibitor. [0049] In a particularly preferred embodiment of the composition according to the invention, the pyra- zole is present as 3,4-dimethylpyrazole phosphate (3,4 DMPP). 3,4 DMPP is commercially available.

[0050] In preferred embodiments of the composition according to the invention, the pKb value of the pyrazole is at least at least 7.9; preferably at least 8.4, more preferably at least 8.9, still more preferably at least 9.4, yet more preferably at least 9.9, even more preferably at least 10.4, most preferably at least 10.9, and in particular at least 11.4.

[0051] In preferred embodiments of the composition according to the invention, the pKb value of the pyrazole is at most 13.3; preferably at most 12.8, more preferably at most 12.3, still more preferably at most 11.8, yet more preferably at most 11.3, even more preferably at most 10.8, most preferably at most 10.3, and in particular at most 9.8.

[0052] In preferred embodiments of the composition according to the invention, the pKb value of the pyrazole is within the range of 10.5±4.5; preferably 10.5±4.0, more preferably 10.5±3.5, still more preferably 10.5±3.0, yet more preferably 10.5±2.5, even more preferably 10.5±2.0, most preferably 10.5±1.5, and in particular 10.5±1.0.

[0053] In preferred embodiments of the composition according to the invention, the weight content of the pyrazole or agriculturally acceptable salt thereof, preferably 3,4-dimethyl pyrazole or 3,4 DMPP, is at least 4.0 wt.-%, relative to the total weight of the composition; preferably at least 8.0 wt.-%, more preferably at least 10 wt.-%, still more preferably at least 14 wt.-%, yet more preferably at least 18 wt.- %, even more preferably at least 22 wt.-%, most preferably at least 26 wt.-%, and in particular at least 30 wt.-%.

[0054] In preferred embodiments of the composition according to the invention, the weight content of the pyrazole or agriculturally acceptable salt thereof, preferably 3,4-dimethyl pyrazole or 3,4 DMPP, is at most 70 wt .-%, relative to the total weight of the composition; preferably at most 65 wt.-%, more preferably at most 60 wt.-%, still more preferably at most 55 wt.-%, yet more preferably at most 50 wt- %, even more preferably at most 45 wt.-%, most preferably at most 40 wt.-%, and in particular at most 35 wt.-%.

[0055] In preferred embodiments of the composition according to the invention, the weight content of the pyrazole or agriculturally acceptable salt thereof, preferably 3,4-dimethyl pyrazole or 3,4 DMPP, is within the range of 24±20 wt.-%, relative to the total weight of the composition; preferably 24±18 wt.- %, more preferably 24±16 wt.-%, still more preferably 24±14 wt.-%, yet more preferably 24±12 wt.-%, even more preferably 24±10 wt.-%, most preferably 24±8.0 wt.-%, and in particular 24±6.0 wt.-%. [0056] Preferably, the pyrazole or agriculturally acceptable salt thereof is soluble in water.

[0057] Preferably, the pyrazole or agriculturally acceptable salt thereof is soluble, freely soluble or very soluble in water (pure water at 23 °C), whereas 10 to 30 mL volume of water are needed in order to dissolve a soluble pyrazole or agriculturally acceptable salt thereof, 1 to 10 mL volume of water are needed in order to dissolve a freely soluble pyrazole or agriculturally acceptable salt thereof, and less than 1 mL volume of water are needed in order to dissolve a very soluble pyrazole or agriculturally acceptable salt thereof.

[0058] The composition according to the invention contains a phosphonic acid or an agriculturally acceptable salt thereof.

[0059] The composition according to the invention may contain one or more phosphonic acids or agriculturally acceptable salts thereof. Preferably, the composition according to the invention contains a single phosphonic acid or an agriculturally acceptable salt thereof.

[0060] Preferably, the phosphonic acid has general formula (B) wherein

R1 means -H, -OH, -NH ₂ , or -Cl; preferably -OH;

R2 means -H, -Ci-io-alkyl, -Ci-6-alkyl-NH ₂ , -Ci-6-alkyl-N(Ci-6-alkyl)-Ci-io-alkyl, or -Cl; preferably -CH ₃ ; and

R3 means -H, -Ci-io-alkyl, -Ci-e-alkyl-NH ₂ , -Ci-6-alkyl-N(Ci-6-alkyl)-Ci-io-alkyl, -Cl, or -P(=O)(OH) ₂ ; preferably -P(=O)(OH) ₂ .

[0061] Preferably, the phosphonic acid is a bisphosphonic acid or an agriculturally acceptable salt thereof.

[0062] Preferably, the phosphonic acid or the agriculturally acceptable salt thereof improves the solubility of the pyrazole or agriculturally acceptable salt thereof in an aqueous solution, preferably relative to the same composition not containing the phosphonic acid or the agriculturally acceptable salt thereof. [0063] Preferably, the phosphonic acid is selected from the group consisting of etidronic acid, tiludronic acid, pamidronic acid, aledronic acid, ibandronic acid, risedronic acid, and zoledronic acid or an agriculturally acceptable salt thereof.

[0064] In a particularly preferred embodiment of the invention, the phosphonic acid or the agriculturally acceptable salt thereof is etidronic acid

H ₃ C OH TO V OH HO-ip-^^^p' -OH II II

O 0 or an agriculturally acceptable salt thereof. Etidronic acid is commercially available, e.g. as active solution, e.g. 40 % of a 60% active solution (such as Cublen® KT600/with 60% active).

[0065] In preferred embodiments of the composition according to the invention, the weight content of the phosphonic acid, preferably etidronic acid, is at least 6.0 wt.-% relative to the total weight of the composition; preferably at least 8.0 wt.-%, more preferably at least 10 wt.-%, still more preferably at least 12 wt.-%, yet more preferably at least 14 wt.-%, even more preferably at least 16 wt.-%, most preferably at least 18 wt.-%, and in particular at least 20 wt.-%.

[0066] In preferred embodiments of the composition according to the invention, the weight content of the phosphonic acid or agriculturally acceptable salt thereof, preferably etidronic acid, is at most 90 wt.- % relative to the total weight of the composition; preferably at most 80 wt-%, more preferably at most 70 wt.-%, still more preferably at most 60 wt.-%, yet more preferably at most 50 wt.-%, even more preferably at most 40 wt.-%, most preferably at most 30 wt.-%, and in particular at most 22 wt.-%.

[0067] In preferred embodiments of the composition according to the invention, the weight content of the phosphonic acid or agriculturally acceptable salt thereof, preferably etidronic acid, is within the range of 25±23 wt.-%, relative to the total weight of the composition; preferably 20±18 wt.-%, more preferably 16±14 wt.-%, still more preferably 16±12 wt.-%, yet more preferably 16±10 wt.-%, even more preferably 16±8.0 wt.-%, most preferably 16±6.0 wt-%, and in particular 16±4.0 wt.-%.

[0068] In preferred embodiments of the composition according to the invention, the relative weight ratio of the phosphonic acid or agriculturally acceptable salt thereof, preferably etidronic acid, to the pyrazole or agriculturally acceptable salt thereof, preferably 3,4-dimethyl pyrazole or 3,4 DMPP, is at least 1: 10; preferably at least 1:9, more preferably at least 1:8, still more preferably at least 1:7, yet more preferably at least 1:6, even more preferably at least 1:5, most preferably at least 1:4, and in particular at least 1:3. [0069] In preferred embodiments of the composition according to the invention, the relative weight ratio of the phosphonic acid or agriculturally acceptable salt thereof, preferably etidronic acid, to the pyrazole or agriculturally acceptable salt thereof, preferably 3,4-dimethyl pyrazole or 3,4 DMPP, is at most 7: 1; preferably at most 6: 1, more preferably at most 5:1, still more preferably at most 4:1, yet more preferably at most 3: 1, even more preferably at most 2: 1, most preferably at most 1 : 1, and in particular at most 1:2.

[0070] In preferred embodiments of the composition according to the invention, the relative weight ratio of the phosphonic acid or agriculturally acceptable salt thereof, preferably etidronic acid, to the pyrazole or agriculturally acceptable salt thereof, preferably 3,4-dimethyl pyrazole or 3,4 DMPP, is within the range of 1: 10 to 7: 1; preferably 1:9 to 6: 1, more preferably 1:8 to 5:1, still more preferably 1:7 to 4: 1, yet more preferably 1:6 to 3: 1, even more preferably 1:5 to 2: 1, most preferably 1:4 to 1: 1, and in particular 1:3 to 1:2.

[0071] Optionally, the composition according to the invention contains one or more carboxylic acids, agriculturally acceptable salts or anhydrides thereof. Unless expressly stated otherwise, all percentages and weights refer to the total content of all carboxylic acids that are contained in the composition.

[0072] Preferably, the one or more carboxylic acids, agriculturally acceptable salts or anhydrides thereof protonate the pyrazole thereby forming an agriculturally acceptable salt thereof. A skilled person recognizes that anhydrides of carboxylic acids may first interact with water, thereby hydrolyze and then protonate the pyrazole.

[0073] Preferably, the one or more carboxylic acids, agriculturally acceptable salts or anhydrides thereof improves the solubility of the pyrazole or agriculturally acceptable salt thereof in an aqueous solution, preferably relative to the same composition not containing the one or more carboxylic acids, agriculturally acceptable salts or anhydrides thereof.

[0074] Preferably, the one or more carboxylic acids, agriculturally acceptable salts or anhydrides thereof comprise or consist of a diacid or an agriculturally acceptable salt or anhydride thereof.

[0075] Preferably, the one or more carboxylic acids, agriculturally acceptable salts or anhydrides thereof comprise or consist of an unsaturated acid or an agriculturally acceptable salt or anhydride thereof. [0076] Preferably, the one or more carboxylic acids, agriculturally acceptable salts or anhydrides thereof comprise or consist of an unsaturated carboxylic diacid or an agriculturally acceptable salt or anhydride thereof.

[0077] Preferably, the one or more carboxylic acids, agriculturally acceptable salts or anhydrides thereof comprise or consist of formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, undecylic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, stearic acid, nonadecylic acid, ara- chidic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, muconic acid, maleic acid, fumaric acid, glutaconic acid, itaconic acid, citraconic acid, salicylic acid, benzoic acid, salicylic acid, phthalic acid, mixtures thereof, agriculturally acceptable salts or anhydrides thereof.

[0078] Preferably the one or more carboxylic acids, agriculturally acceptable salts or anhydrides thereof comprise or consist of maleic acid, maleic acid anhydride and/or acetic acid.

[0079] Preferably, the one or more carboxylic acids, agriculturally acceptable salts or anhydrides thereof compnse or consist of maleic acid and/or maleic acid anhydride.

[0080] Preferably, the one or more carboxylic acids, agriculturally acceptable salts or anhydrides thereof comprise or consist of two organic acids or agriculturally acceptable salts or anhydrides thereof; preferably (i) maleic acid and/or maleic acid anhydride and (ii) acetic acid.

[0081] In preferred embodiments of the composition according to the invention, the one or more carboxylic acids, agriculturally acceptable salts or anhydrides thereof comprise or consist of

(a) maleic acid alone;

(b) maleic acid anhydride alone;

(c) acetic acid alone;

(d) maleic acid in combination with acetic acid; or

(e) maleic acid anhydride in combination with acetic acid.

[0082] In preferred embodiments of the composition according to the invention, the one or more carboxylic acids, agriculturally acceptable salts or anhydrides thereof (anhydrides in their corresponding hydrolyzed form) independently of one another have a pKa value of at least 0.5; preferably at least 0.7, more preferably at least 0.9, still more preferably at least 1.1, yet more preferably at least 1.3, even more preferably at least 1.5, most preferably at least 1.7, and in particular at least 1.9. [0083] In preferred embodiments of the composition according to the invention, the one or more carboxylic acids, agriculturally acceptable salts or anhydrides thereof (anhydrides in their corresponding hydrolyzed form) independently of one another have a pKa value of at most 6.2; preferably at most 6.0, more preferably at most 5.8, still more preferably at most 5.6, yet more preferably at most 5.4, even more preferably at most 5.2, most preferably at most 5.0, and in particular at most 4.8.

[0084] In preferred embodiments of the composition according to the invention, the one or more carboxylic acids, agriculturally acceptable salts or anhydrides thereof (anhydrides in their corresponding hydrolyzed form) independently of one another have a pKa value of within the range of 3.9±3.5; preferably 3.9±3.0, more preferably 3.9±2.5, still more preferably 3.9±2.0, yet more preferably 3.4±3.0, even more preferably 3.4±2.5, most preferably 3.4±2.0, and in particular 3.4±1.5.

[0085] When a carboxylic acid carries more than a single carboxylic acid functional group, preferably at least one of the carboxylic acid functional group has a pKa value as defined above.

[0086] In preferred embodiments of the composition according to the invention, the total weight content of the one or more carboxylic acids, agriculturally acceptable salts or anhydrides thereof, preferably maleic acid, maleic acid anhydride and/or acetic acid, is at least 1.0 wt.-%, based upon the equivalent weight of the anhydride and relative to the total weight of the composition; preferably at least 3.0 wt.- %, more preferably at least 5.0 wt.-%, still more preferably at least 7.0 wt.-%, yet more preferably at least 9.0 wt.-%, even more preferably at least 11 wt.-%, most preferably at least 13 wt.-%, and in particular at least 15 wt.-%.

[0087] In preferred embodiments of the composition according to the invention, the total weight content of the one or more carboxylic acids, agriculturally acceptable salts or anhydrides thereof, preferably maleic acid, maleic acid anhydride and/or acetic acid, is at most 50 wt.-%, based upon the equivalent weight of the anhydride and relative to the total weight of the composition; preferably at most 45 wt.- %, more preferably at most 40 wt.-%, still more preferably at most 35 wt.-%, yet more preferably at most 30 wt.-%, even more preferably at most 25 wt.-%, most preferably at most 20 wt-%, and in particular at most 16 wt.-%.

[0088] In preferred embodiments of the composition according to the invention, the total weight content of the one or more carboxylic acids, agriculturally acceptable salts or anhydrides thereof, preferably maleic acid, maleic acid anhydride and/or acetic acid, is within the range of 12±10 wt.-%, based upon the equivalent weight of the anhydride and relative to the total weight of the composition; preferably 12±9.0 wt.-%, more preferably 12±8.0 wt.-%, still more preferably 12±7.0 wt.-%, yet more preferably 12±6.0 wt.-%, even more preferably 12±5.0 wt.-%, most preferably 12±4.0 wt.-%, and in particular 12±3.5 wt.-%.

[0089] In preferred embodiments of the composition according to the invention, the relative weight ratio of the one or more carboxylic acids, agriculturally acceptable salts or anhydrides thereof, preferably maleic acid, maleic acid anhydride and/or acetic acid, to the pyrazole or agriculturally acceptable salt thereof, preferably 3,4-dimethyl pyrazole or 3,4 DMPP, is at least 1:9; preferably at least 1:8, more preferably at least 1:7, still more preferably at least 1:6, yet more preferably at least 1:5, even more preferably at least 1 :4, most preferably at least 1 :3, and in particular at least 1 :2, in each case based upon the equivalent weight of the anhydride.

[0090] In preferred embodiments of the composition according to the invention, the relative weight ratio of the one or more carboxylic acids, agriculturally acceptable salts or anhydrides thereof, preferably maleic acid, maleic acid anhydride and/or acetic acid, to the pyrazole or agriculturally acceptable salt thereof, preferably 3,4-dimethyl pyrazole or 3,4 DMPP, is at most 8: 1; preferably at most 7: 1, more preferably at most 6: 1, still more preferably at most 5: 1, yet more preferably at most 4: 1, even more preferably at most 3: 1, most preferably at most 2: 1, and in particular at most 1: 1, in each case based upon the equivalent weight of the anhydride.

[0091] In preferred embodiments of the composition according to the invention, the relative weight ratio of the one or more carboxylic acids, agriculturally acceptable salts or anhydrides thereof, preferably maleic acid, maleic acid anhydride and/or acetic acid, to the pyrazole or agriculturally acceptable salt thereof, preferably 3,4-dimethyl pyrazole or 3,4 DMPP, is within the range of 1:9 to 8: 1; preferably 1:8 to 7: 1, more preferably 1 :7 to 6: 1, still more preferably 1:6 to 5: 1, yet more preferably 1:5 to 4: 1, even more preferably 1:4 to 3:1, most preferably 1:3 to 2: 1, and in particular 1:2 to 1: 1, in each case based upon the equivalent weight of the anhydride.

[0092] Preferably, the molar ratio of the one or more carboxylic acids, agriculturally acceptable salts or anhydrides thereof to the pyrazole or agriculturally acceptable salt thereof is stoichiometric.

[0093] In preferred embodiments of the composition according to the invention, the composition comprises (i) a first carboxylic acid, an agriculturally acceptable salt or anhydride thereof, preferably maleic acid and/or maleic acid anhydride, and (ii) a second carboxylic acid, an agriculturally acceptable salt or anhydride thereof, preferably acetic acid, wherein the relative weight ratio of (i) : (ii) is at least 1:9; preferably at least 1:8, more preferably at least 1:7, still more preferably at least 1 :6, yet more preferably at least 1:5, even more preferably at least 1:4, most preferably at least 1:3, and in particular at least 1:2, in each case based upon the equivalent weight of the anhydrides. [0094] In preferred embodiments of the composition according to the invention, the composition comprises (i) a first carboxylic acid, an agriculturally acceptable salt or anhydride thereof, preferably maleic acid and/or maleic acid anhydride, and (ii) a second carboxylic acid, an agriculturally acceptable salt or anhydride thereof, preferably acetic acid, wherein the relative weight ratio of (i) : (ii) is at most 8: 1; preferably at most 7: 1, more preferably at most 6: 1, still more preferably at most 5: 1, yet more preferably at most 4: 1, even more preferably at most 3 : 1, most preferably at most 2: 1, and in particular at most 1: 1, in each case based upon the equivalent weight of the anhydrides.

[0095] In preferred embodiments of the composition according to the invention, the composition comprises (i) a first carboxylic acid, an agriculturally acceptable salt or anhydride thereof, preferably maleic acid and/or maleic acid anhydride, and (ii) a second carboxylic acid, an agriculturally acceptable salt or anhydride thereof, preferably acetic acid, wherein the relative weight ratio of (i) : (ii) is within the range of 1:9 to 8:1; preferably 1:8 to 7:1, more preferably 1:7 to 6: 1, still more preferably 1:6 to 5: 1, yet more preferably 1:5 to 4: 1, even more preferably 1:4 to 3: 1, most preferably 1:3 to 2: 1, and in particular 1 :2 to 1 : 1, in each case based upon the equivalent weight of the anhydrides.

[0096] Optionally, the composition according to the invention contains one or more glycols. Unless expressly stated otherwise, all percentages and weights refer to the total content of all glycols that are contained in the composition.

[0097] Preferably, the one or more glycols improve the solubility of the pyrazole or agriculturally acceptable salt thereof in an aqueous solution, preferably relative to the same composition not containing the one or more glycols.

[0098] Preferably, the one or more glycols facilitate the re-dissolution of the pyrazole or agriculturally acceptable salt thereof, preferably relative to the same composition not containing the one or more glycols.

[0099] Preferably, the one or more glycols comprises or consists of a single glycol or two glycols

[0100] Preferably, the one or more glycols comprises or consists of an alkyl glycol, a polyalkyl glycol ether, or a mixture thereof.

[0101] Preferably, the one or more glycols comprise or consist of ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol (PEG) 200, PEG 300, PEG 400, PEG 600, PEG 1000, PEG 1500, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol (PPG) 425, PPG 725, PPG 1000, butylene glycol, and mixtures thereof; preferably PEG 200, propylene glycol or a mixture thereof.

[0102] Preferably, the one or more glycols comprise or consist of an alkyl glycol and a polyalkyl glycol ether; preferably propylene glycol and PEG 200.

[0103] In preferred embodiments of the composition according to the invention, the one or more glycols comprise or consist of

(a) an alkyl glycol alone, preferably propylene glycol alone;

(b) a polyalkyl glycol ether alone, preferably PEG 200 alone; or

(c) an alkyl glycol, preferably propylene glycol, in combination with a polyalkyl glycol ether, preferably PEG 200.

[0104] In preferred embodiments of the composition according to the invention, the total weight content of the one or more glycols, preferably alkyl glycol and/or polyalkyl glycol ether, is at least 1.0 wt.-%, relative to the total weight of the composition; preferably at least 2.0 wt.-%, more preferably at least 3.0 wt.-%, still more preferably at least 4.0 wt.-%, yet more preferably at least 6.0 wt.-%, even more preferably at least 8.0 wt.-%, most preferably at least 10 wt.-%, and in particular at least 12 wt.-%.

[0105] In preferred embodiments of the composition according to the invention, the total weight content of the one or more glycols, preferably alkyl glycol and/or polyalkyl glycol ether, is at most 50 wt.-%, relative to the total weight of the composition; preferably at most 45 wt.-%, more preferably at most 40 wt.-%, still more preferably at most 35 wt.-%, yet more preferably at most 30 wt.-%, even more preferably at most 25 wt.-%, most preferably at most 20 wt.-%, and in particular at most 16 wt.-%.

[0106] In preferred embodiments of the composition according to the invention, the total weight content of the one or more glycols, preferably alkyl glycol and/or polyalkyl glycol ether, is within the range of 12±22 wt.-%, relative to the total weight of the composition; preferably 12±18 wt.-%, more preferably 12±14 wt.-%, still more preferably 12±10 wt-%, yet more preferably 12±6.0 wt.-%, even more preferably 12±4.0 wt.-%, most preferably 12±2.0 wt.-%, and in particular 12±1.0 wt.-%.

[0107] In preferred embodiments of the composition according to the invention, the relative weight ratio of the one or more glycols, preferably alkyl glycol and/or polyalkyl glycol ether, to the pyrazole or agriculturally acceptable salt thereof, preferably 3,4-dimethyl pyrazole or 3,4 DMPP, is at least 1: 11; preferably at least 1: 10, more preferably at least 1:9, still more preferably at least 1:8, yet more preferably at least 1:7, even more preferably at least 1:6, most preferably at least 1:5, and in particular at least 2:5. [0108] In preferred embodiments of the composition according to the invention, the relative weight ratio of the one or more glycols, preferably alkyl glycol and/or polyalkyl glycol ether, to the pyrazole or agriculturally acceptable salt thereof, preferably 3,4-dimethyl pyrazole or 3,4 DMPP, is at most 7: 1; preferably at most 6: 1, more preferably at most 5: 1, still more preferably at most 4: 1, yet more preferably at most 3: 1, even more preferably at most 2: 1, most preferably at most 1: 1, and in particular at most 2:3.

[0109] In preferred embodiments of the composition according to the invention, the relative weight ratio of the one or more glycols, preferably alkyl glycol and/or polyalkyl glycol ether, to the pyrazole or agriculturally acceptable salt thereof, preferably 3,4-dimethyl pyrazole or 3,4 DMPP, is within the range of 1 : 11 to 7: 1 ; preferably at most 1 : 10 to 6: 1, more preferably at most 1 :9 to 5 : 1, still more preferably at most 1:8 to 4: 1, yet more preferably at most 1:7 to 3: 1, even more preferably at most 1:6 to 2: 1, most preferably at most 1:5 to 1: 1, and in particular at most 2:5 to 2:3.

[0110] In preferred embodiments of the composition according to the invention, the one or more glycols compnse or consist of (i) a polyalkylglycol ether, preferably polyethylene glycol (PEG) 200, and (ii) an alkyl glycol, preferably propylene glycol, wherein the relative weight ratio of (i) : (ii) is at least 1: 12; preferably at least 1: 11, more preferably at least 1:10, still more preferably at least 1:9, yet more preferably at least 1:8, even more preferably at least 1 : 7, most preferably at least 1:6, and in particular at least 1:5.

[0111] In preferred embodiments of the composition according to the invention, the one or more glycols comprise or consist of (i) a polyalkylglycol ether, preferably polyethylene glycol (PEG) 200, and (ii) an alkyl glycol, preferably propylene glycol, wherein the relative weight ratio of (i) : (ii) is at most 5: 1; preferably at most 4: 1, more preferably at most 3: 1, still more preferably at most 2: 1, yet more preferably at most 1: 1, even more preferably at most 1:2, most preferably at most 1:3, and in particular at most 1 :4.

[0112] In preferred embodiments of the composition according to the invention, the one or more glycols comprise or consist of (i) a polyalkylglycol ether, preferably polyethylene glycol (PEG) 200, and (ii) an alkyl glycol, preferably propylene glycol, wherein the relative weight ratio of (i) : (ii) is within the range of 1 : 12 to 5: 1; preferably 1: 11 to 4: 1, more preferably 1: 10 to 3: 1, still more preferably 1:9 to 2: 1, yet more preferably l:8 to 1: 1, even more preferably l:7 to 1:2, most preferably 1:6 to 1:3, and in particular 1:5 to 1:4.

[0113] In preferred embodiments of the composition according to the invention, the pH value of the composition is at least 0.4; preferably at least 0.6, more preferably at least 0.8, still more preferably at least 1 0, yet more preferably at least 1.2, even more preferably at least 1.4, most preferably at least 1.6, and in particular at least 1.8.

[0114] In preferred embodiments of the composition according to the invention, the pH value of the composition is at most 5.0; preferably at most 4.6, more preferably at most 4.2, still more preferably at most 3.8, yet more preferably at most 3.4, even more preferably at most 3.0, most preferably at most 2.6, and in particular at most 2.2.

[0115] In preferred embodiments of the composition according to the invention, the pH value of the composition is within the range of 5.0±4.0; preferably 4.0±3.0, more preferably 4.0±2.5, still more preferably 4.0±2.0, yet more preferably 2.0±1.5, even more preferably 2.0±1.0, most preferably 2.0±0.5, and in particular 2.0±0.2.

[0116] In preferred embodiments of the composition according to the invention, the pyrazole or agriculturally acceptable salt thereof stays in solution and does not crystallize at a temperature of at most 20 °C; preferably at most 15 °C, more preferably at most 10 °C, still more preferably at most 8.0 °C, yet more preferably at most 6.0 °C, even more preferably at most 4.0 °C, most preferably at most 2.0 °C, and in particular at most 1.0 °C.

[0117] In preferred embodiments of the composition according to the invention, the pyrazole or agriculturally acceptable salt thereof stays in solution and does not crystallize at a temperature of at least - 5.0 °C; preferably at least -4.0 °C, more preferably at least -3.0 °C, still more preferably at least -2.0 °C, yet more preferably at least -1.0 °C, even more preferably at least 0 °C, most preferably at least 1.0 °C, and in particular at least 2.0 °C.

[0118] In preferred embodiments of the composition according to the invention, the pyrazole or agriculturally acceptable salt thereof stays in solution and does not crystallize at a temperature within the range of 1.5±7.0 °C; preferably 1 5±6.0 °C, more preferably 1.5±5 0 °C, still more preferably 1.5±4.0 °C, yet more preferably 1.5±3.0 °C, even more preferably 1.5±2.0 °C, most preferably 1.5±1.0 °C, and in particular 1.5±0.5 °C.

[0119] In preferred embodiments of the composition according to the invention, the pyrazole or agriculturally acceptable salt thereof, preferably under the temperature conditions defined above, stays in solution and does not crystallize for at least 1 day; preferably at least 2 days, more preferably at least 3 days, still more preferably at least 4 days, yet more preferably at least 5 days, even more preferably at least 6 days, most preferably at least 7 days, and in particular at least 8 days. [0120] Preferably, the composition according to the invention additionally comprises a tracer, preferably a dye.

[0121] Preferred contents of preferred ingredients of particularly preferred aqueous compositions ac- cording to the invention are compiled as embodiments A ¹ to A ³ in the following tables:

[0122] Preferred contents of preferred ingredients of particularly preferred aqueous compositions ac- cording to the invention are compiled as embodiments B ¹ to B ³ in the following tables:

[0123] Another aspect of the invention relates to a process for preparing of a composition according to the invention as described above, the process comprising the steps of:

(a) providing a pyrazole of general formula (A) or an agriculturally acceptable salt thereof according to the invention as described above;

(b) providing a phosphonic acid or an agriculturally acceptable salt thereof according to the invention as described above;

(c) optionally, providing one or more organic acids, agriculturally acceptable salts or anhydrides thereof according to the invention as described above;

(d) optionally, providing one or more glycols according to the invention as described above;

(e) optionally, providing a tracer, preferably a dye;

(f) optionally, providing water or an aqueous liquid; and

(g) mixing the components provided in steps (a) to (f) with one another to produce a composition.

[0124] Another aspect of the invention relates to a process for preparing of a fertilizer additive comprising a composition according to the invention as described above, the process comprising the process for preparing of a composition according to the invention as described above. [0125] Another aspect of the invention relates to a process for preparing of a fertilizer comprising a fertilizer additive, the process comprising the steps of

(a) providing a composition according to the invention as described above;

(b) providing a fertilizer, preferably a granulated fertilizer; and

(c) applying the composition provided in step (a) to the fertilizer provided in step (b).

[0126] Another aspect of the invention relates to a fertilizer additive comprising or consisting of the composition according to the invention as described above; preferably wherein the fertilizer additive is obtainable by the process for preparing of a fertilizer additive according to the invention as described above.

[0127] Another aspect of the invention relates to a fertilizer comprising a fertilizer additive, wherein the fertilizer additive comprises or consists of the composition according to the invention as described above; preferably wherein the fertilizer is obtainable by the process for preparing of a fertilizer according to the invention as described above.

[0128] Another aspect of the invention relates to the use of a composition according to the invention as described above as fertilizer additive.

[0129] Another aspect of the invention relates to a method for reducing nitrification comprising the step of applying a fertilizer comprising a composition according to the invention as described above to soil or a plant.

[0130] The following examples further illustrate the invention but are not to be construed as limiting its scope.

Example 1:

[0131] The solubility of 3,4-dimethylpyrazole dihydrogen phosphate salt (3,4 DMPP) in pure water (pH 7.0) at room temperature was investigated. Solubility was rather poor and formation of an oily phase on top of the aqueous layer indicated phase separation already at comparatively low concentrations of 3,4 DMPP.

Example 2:

[0132] Various combinations of 3,4 DMPP with organic or inorganic acids were prepared including fumaric acid, malonic acid, salicylic acid, acetic acid, amidosulfonic acid, and hydrochloric acid. The solubility of these combinations in pure water (pH 7.0) at room temperature was also investigated. It was observed that in comparison to the absence of the above acids, solubility of the pyrazole was significantly enhanced.

[0133] However, it was observed that at considerable concentrations of the pyrazole, such systems tend to crystallization of pyrazole salts around 10-12°C yielding a solid block of hard crystals. Such behavior would compromise the usability in winterly conditions.

Example 3:

[0134] Surprisingly, the use of maleic acid anhydride as acidic component provided a significant decrease of the crystallization temperature and for some time a stable supersaturated solution was formed. In aqueous solution maleic acid anhydride should readily hydrolyze to maleic acid. In view of these preliminary experimental results, maleic acid was chosen as the best available organic acid for the protonation of the pyrazole.

[0135] However, stoichiometric addition of maleic acid (added in form of maleic caid anhydride) after some time still ended up in crystallization of pyrazole salt at around 5°C. The desired concentration of pyrazole in solution of about 30 wt.-% corresponds to an approximately concentration of 1.55 mol/L. An equivalent proportional addition of 1.55 mol/L maleic acid anhydride corresponds to an addition level of 15.2 wt.-%.

Example 4:

[0136] It was investigated whether crystallization of pyrazole salts from aqueous solutions can be inhibited by adding guanidinium chloride, benzyl alcohol, quaternary surfactants or imidazole, e.g. due to complex formation. However, these additives did not show any effect on crystallization behavior.

Example 5: [0137] Aqueous mixtures of 3,4 DMPP, maleic acid (added in form of maleic acid anhydride) and etidronic acid showed a further decrease of the crystallization temperature towards low refrigerator temperature like 1-2°C. It was observed that this effect is proportional to the amount of added etidronic acid until a threshold is reached.

[0138] For solubility reasons, the possible amount of etidronic acid is restricted to 40 wt.-% of a 60 wt.-% active solution (such as Cublen® KT600/with 60% active). Thus, 3,4 DMPP solutions at intermediate concentration, i.e. distant from the inflection point between solution and crystallization, can be stabilized with lower amounts/lower stoichiometric addition levels of etidronic acid.

Example 6:

[0139] It was found that if during exposure to harsh conditions (winter at the farmland or during transport through extreme climate zones) crystallization occurs, the addition of polyethylene glycol (PEG) 200 and propylene glycol significantly facilitates the re-dissolution of the 3,4 DMPP. Therefore, appropriate amounts were added to make the solution easier to handle for final users.

[0140] A solution of 3,4 DMPP having a somewhat lower concentration of about 18 wt.-% active was less difficult to obtain/stabilize. Such solutions can be prepared by half-stoichiometric replacement of the maleic acid by acetic acid and a reduction of the etidronic acid addition down to 12 wt.-%:

Example 7:

[0141] A multitude of identical samples was prepared each containing identical amounts of 3,4 DMPP, propylene glycol and polyethylene glycol (PEG 200) in water. To each sample, a different amount of (ii) a phosphonic acid or an agriculturally acceptable salt thereof and (iii) a carboxylic acids, agriculturally acceptable salts or anhydrides thereof was added in order to investigate the enhancing effect on solubility. All substances used were industrial grade or directly taken out of production stocks. PBTC was bought from Carl Roth. [0142] For sample preparation, compositions of 100 mL aliquots fix in 30 wt.-% 3,4 DMPP, 10 wt.-% propylene glycol, and 2 wt.-% PEG 200 were prepared with various amounts of maleic acid anhydride (MSA), etidronic acid, 2-phosphono-l,2,4-butanetricarboxylic acid (PBTC) and/or acetic acid, respectively. The total amount of each sample was adjusted to 100 wt.-% by addition of demineralized water.

[0143] Those samples that did not provide clear solutions at room temperature, i.e. that remained suspensions, were visually inspected and ranked with regard to the quantity of undissolved material (3,4 DMPP). With respect to solubility, samples with a high amount of undissolved material were ranked as "very poor", whereas samples with a lower amount of undissolved material were ranked as "poor".

[0144] Those samples that provided clear solutions at room temperature were subjected to additional testing in order to reveal temperature dependence of solubility. Samples were placed a climate chamber and slowly cooled down at a rate of one degree centigrade per day (temperature was allowed to equilibrate at least for 24 hours, or over the weekend, respectively). The solubility status was monitored visually every morning. In case of precipitation, the temperature at the first day of precipitation was noted. The temperature noted is the exact temperature measured every morning (taking daily climate changes into account).

[0145] The solubility assessment for samples comprising maleic acid anhydride (MSA) and/or etidronic acid are compiled in the table here below:

[0146] The solubility assessment for samples comprising maleic acid anhydride (MSA) and/or 2-phos- phono-l,2,4-butanetricarboxylic acid (PBTC) are compiled in the table here below: [0147] The solubility assessment for samples comprising maleic acid anhydride (MSA) and/or acetic acid are compiled in the table here below:

[0148] At most of the concentrations monitored, the solubility is very poor and 3,4 DMPP stayed undissolved in suspension. Only at an almost stoichiometrically addition level of maleic acid anhydride (MSA), a solubility at minimum room temperature was observed. However, such co-solution still crys- talized at approximately 12 °C. The same was observed with an addition of acetic acid (industrial grade).

[0149] In contrast, addition of a phosphonic acid (etidronic acid or PBTC) further decreased the crystallization point, i.e. further enhanced solubility. In this regard, etidronic acid was more effective than PBTC.

Example 8:

[0150] During the development of a 3,4 DMPP-MSA/etidromc acid co-solution, an optimal point of freeze stability was identified to be at the 1: 1 stoichiometric addition of maleic acid anhydride (MSA), followed by a subsequent addition of 20 wt.-% etidromc acid.

[0151] 300 kg of such solution were produced, filled into a small IBC (International Bulk Container) of appr. 375 L volume and subjected to a freeze stability experiment under almost real-life conditions in a big scale climate chamber. The solution stayed stable without visible crystal formation for at least six weeks at 0-2 °C.

[0152] Results are shown in Figure 1.