HK1234027A1 - Composition containing n-(n-butyl) thiophosphoric triamide adducts and reaction products - Google Patents

Abstract

A composition containing N-(n-butyl) thiophosphoric triamide adducts and reaction products is provided, particularly reaction products and methods for making and using the reaction products are provided. For example, a reaction product comprising an adduct formed from urea, formaldehyde, and a urease inhibitor is described, which can be provided in various forms. For example, such a reaction product can be in the form of a solid or solution. Such a reaction product can also be combined with one or more additional components including but not limited to additional urease inhibitor and/or a nitrogen-based fertilizer composition.

Description

Compositions containing N- (N-butyl) thiophosphoric triamide adducts and reaction products

Cross reference to related applications

Priority of U.S. provisional application No. 62/196,781 filed on 24/7/2015, which is incorporated herein by reference in its entirety, is claimed.

Technical Field

The present subject matter relates generally to compositions comprising urease inhibitors and methods of making and using the same.

Background

For some time, fertilizers have been used to provide nitrogen to soil. The most widely used and agriculturally important nitrogen fertilizers are urea, CO (NH)₂)₂. Most of the urea produced today is used as fertilizer in its granular (or pelletized) form. After application of urea to soil, it readily hydrolyzes to give ammonia and carbon dioxide. This process is catalyzed by the enzyme urease, which is produced by some bacteria and fungi that may be present in the soil. The gaseous products formed by the hydrolysis reaction (i.e., ammonia and carbon dioxide) may evaporate into the air andand thus a large loss may occur from the total amount of nitrogen applied to the soil.

Attempts to reduce the loss of applied nitrogen have used urease inhibitors and/or nitrification inhibitors as additives to fertilizers. Urease inhibitors are compounds that can inhibit the catalytic activity of urease on urea in soil. Nitrification inhibitors are compounds that inhibit the oxidation of ammonium bacteria in soil to nitrate. Urease inhibitors and nitrification inhibitors can be associated with fertilizers in a variety of ways. For example, they may be coated on fertilizer granules or mixed into a fertilizer matrix. Many granulation processes are known, including falling curtain (tumbling) granulation, spheronization (spherulization) -agglomeration drum granulation, spheronization and fluid bed granulation techniques.

An example of a urease inhibitor is the thiophosphoryl triamide compound disclosed in U.S. patent No. 4,530,714 to Kolc et al, which is incorporated herein by reference. The disclosed thiophosphoric triamide compounds include N- (N-butyl) thiophosphoric triamide (NBPT), which is representative of the most extensively developed of such compounds. When incorporated into urea-containing fertilizers, NBPT reduces the rate at which urea is hydrolyzed to ammonia in the soil. The benefits achieved as a result of delayed urea hydrolysis include the following: (1) the nutrient nitrogen can be obtained by the plants for a long time; (2) excessive accumulation of ammonia in the soil after the urea-containing fertilizer is applied is avoided; (3) reducing the potential for nitrogen loss through ammonia volatilization; (4) reducing the possibility of damage to seedlings and young plants from high levels of ammonia; (5) increasing plant uptake of nitrogen; and (6) obtaining an increase in crop yield. NBPT is commercially available for use in agriculture, and asProducts of the nitrogen stabilizer product line are sold.

Technical grade NBPT is a solid, waxy compound and is decomposed by the action of water, acid and/or elevated temperature. In particular, it is believed that NBPT degrades at elevated temperatures to compounds that do not provide the desired inhibitory effect on urease. Thus, it can be challenging to provide materials that can inhibit urease in combination with other solid materials, particularly by pelletizing with urea (which typically uses heat). Thus, there is a need for urease inhibitor-containing compositions that can be combined with urea, ideally using current urea manufacturing practices, to produce fertilizer compositions that provide effective urease inhibition.

Disclosure of Invention

As disclosed herein, compositions comprising urease inhibitors and methods of making the same are provided. Such compositions typically comprise the reaction product between a urease inhibitor (e.g., N- (N-butyl) thiophosphoric triamide, NBPT), urea, and formaldehyde. Such reaction products may be characterized as adducts in that the product resulting from the reaction retains at least a portion of the two or more reactants (i.e., urease inhibitor, urea, and/or formaldehyde). The compositions resulting from such reactions (including the disclosed reaction products) may be provided separately and, in certain embodiments, may be combined with other ingredients. For example, such adduct-containing compositions may be combined with a fertilizer material comprising a nitrogen source including, but not limited to, urea, ammonia, ammonium nitrate, and combinations thereof. Advantageously, the adduct-containing compositions disclosed herein, alone or in combination with one or more nitrogen sources, can provide fertilizers that exhibit substantial urease-inhibiting effects and thus can be characterized by low ammonia volatilization loss in use (i.e., upon application to soil).

In one aspect, the present disclosure provides a composition comprising an adduct of NBPT, urea and formaldehyde. In another aspect, the present disclosure provides a composition comprising an adduct of NBPT, urea and formaldehyde, and one or more materials selected from the group consisting of: free NBPT, free formaldehyde, Urea Formaldehyde Polymer (UFP), water, and combinations thereof. In a further aspect, the present disclosure provides a composition comprising an adduct of NBPT, urea and formaldehyde, wherein the composition comprises substantially no dicyandiamide. In a further aspect, the present disclosure provides a composition comprising one or more adducts of NBPT, urea and formaldehyde, wherein the one or more adducts are represented by the following structure:

in some embodiments, the compositions provided herein can be in the form of a solution of the adduct (e.g., using an organic solvent, such as those disclosed below). In certain embodiments, the composition is a synergistic mixture of free NBPT and the adduct. The disclosed compositions, in some embodiments, may be substantially free of dicyandiamide (DCD). In some compositions, at least a portion (including all) of the urea and formaldehyde are in the form of a urea-formaldehyde reaction product comprising dimethylol urea.

In another aspect, the present disclosure provides a fertilizer composition comprising urea and an adduct of NBPT, urea and formaldehyde. Any of the compositions of adducts of NBPT, urea and formaldehyde as disclosed herein may be used in such fertilizer compositions. In certain embodiments, the fertilizer composition may comprise a significant amount of urea, for example, at least about 90% by weight urea, at least about 95% by weight urea, at least about 98% by weight urea, at least about 99% by weight urea, or at least about 99.5% by weight urea.

In a further aspect, the present disclosure provides a method of forming a fertilizer composition, the method comprising combining a composition comprising an adduct of NBPT, urea and formaldehyde as disclosed herein with a fertilizer material. The method, in certain embodiments, may include mixing the adduct-containing composition with solid particles of the fertilizer material, and in other embodiments, may include mixing the adduct-containing composition with a molten stream of the fertilizer material. In some embodiments, the method may further comprise combining free NBPT with one or both of the fertilizer material and the adduct-containing composition.

In another aspect, the present disclosure provides a method of preparing a urease inhibiting fertilizer comprising combining urea, formaldehyde and NBPT such that there is an excess of urea to form adducts of NBPT, urea and formaldehyde that remain bound in the remaining urea. In some embodiments, the urea and formaldehyde are in the form of a urea formaldehyde reaction product comprising dimethylol urea.

In a further aspect, the present disclosure provides a method of reducing the hydrolysis of urea to ammonia in soil, the method comprising applying to soil a composition comprising an adduct of NBPT, urea and formaldehyde. Such methods may include combining the nitrogen source with the composition prior to the applying, applying the composition to the soil after applying the nitrogen source to the soil, or applying the composition to the soil before applying the nitrogen source to the soil.

In a still further aspect, the present disclosure provides a method of incorporating an adduct of NBPT, urea and formaldehyde into molten urea, the method comprising combining such adduct (e.g., including, but not limited to, an adduct in the form of an adduct-containing composition) with molten urea. Further, the present disclosure provides a method of forming an adduct of NBPT, urea and formaldehyde, the method comprising contacting NBPT with a molten urea stream comprising formaldehyde and/or a reaction product of urea and formaldehyde.

In one aspect, the present disclosure specifically provides a composition comprising a mixture of: adducts of N- (N-butyl) thiophosphoric triamide (NBPT), urea and formaldehyde; and free NBPT. The present disclosure also provides fertilizer compositions comprising urea and such compositions. It additionally provides a method of forming a fertilizer composition comprising contacting a fertilizer material with such a composition, and also provides a method of reducing the hydrolysis of urea to ammonia in soil comprising applying such a composition to soil.

Drawings

For the purpose of providing an understanding of embodiments of the invention, reference is made to the accompanying drawings. These drawings are exemplary only, and should not be construed as limiting the invention.

FIG. 1 is a graph of the effect of various urease inhibitors on ammonia volatilization (measured in ppm); and is

Figure 2 is a graph of cumulative N loss (measured in%) from urea and urease inhibitor treated urea.

Detailed Description

It is noted herein that, as used in the specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. All percentages, parts and ratios are based on the total weight of the compositions of the present invention, unless otherwise indicated. All such weights as they pertain to listed ingredients are based on the active level and, therefore, do not include solvents or by-products that may be included in commercially available materials, unless otherwise specified. The term "weight percent" may be expressed herein as "% by weight". All molecular weights used herein are weight average molecular weights expressed as grams/mole unless otherwise indicated.

In accordance with the present disclosure, compositions exhibiting effective urease inhibition and methods of producing such compositions are provided. It has been surprisingly found that when higher amounts of urease inhibitor are added to the mixture of urea and formaldehyde, the amount of free urease inhibitor present in the final product mixture does not increase proportionally accordingly. Next, it was determined that at least a portion of the urease inhibitor to which urea and formaldehyde were added reacted under the conditions under which it was carried out to form an adduct containing the urease inhibitor (thus reducing the concentration of free urease inhibitor in the final product mixture). Such reaction products and compositions derived therefrom are described in more detail herein.

In particular, reaction products are provided that include adducts formed from one or more urease inhibitors and urea and/or formaldehyde. Such reaction products may be provided as formed, may be purified to isolate one or more components therefrom, or may be provided in combination with one or more other components, such as additional urease inhibitors or fertilizer compositions, for example, in the form of a nitrogen source (including, but not limited to, a urea source). In some embodiments, the compositions disclosed herein may exhibit a novel, slow release of one or more urease inhibitors.

As used herein, the term "urease inhibitor" refers to a compound that reduces, inhibits, or otherwise slows the conversion of urea to ammonium (NH) in soil₄ ⁺) Any compound of (a). Exemplary urease inhibitors include thiophosphoric triamides and phosphoric triamides of the general formula (I):

X＝P(NH₂)₂NR¹R²(I)

wherein X is oxygen or sulfur, and R¹And R²Independently selected from hydrogen, C₁-C₁₂Alkyl radical, C₃-C₁₂Cycloalkyl radical, C₆-C₁₄Aryl radical, C₂-C₁₂Alkenyl radical, C₂-C₁₂Alkynyl, C₅-C₁₄Heteroaryl group, C₁-C₁₄Heteroalkyl group, C₂-C₁₄Heteroalkenyl radical, C₂-C₁₄Heteroalkynyl, or C₃-C₁₂A cycloheteroalkyl group.

In certain embodiments, the urease inhibitor is an N- (alkyl) thiophosphoric triamide urease inhibitor described in U.S. patent No. 4,530,714 to Kolc et al, which is incorporated herein by reference. Specifically illustrated urease inhibitors may include, but are not limited to, N- (N-butyl) thiophosphoric triamide, N- (N-butyl) phosphoric triamide, thiophosphoric triamide, phenyl phosphorodiamidite, cyclohexyl phosphoric triamide, cyclohexyl thiophosphoric triamide, phosphoric triamide, hydroquinone, p-benzoquinone, hexamidocyclotriphosphazene, thiopyridine, thiopyrimidine, thiopyridine-N-oxide, N-dihalo-2-imidazolidinone, N-halo-2-oxazolinone, derivatives thereof, or any combination thereof. Other examples of Urease inhibitors include phenylphosphoric acid diamine (PPD/PPDA), hydroquinone, N- (2-nitrophenyl) phosphotriamide (2-NPT), Ammonium Thiosulfate (ATS) and organophosphate analogues of Urea, which are potent inhibitors of Urease activity (see, e.g., Kiss and Simiaan, Impropenization effectiveness, resource effectiveness, KluwerAcadematic Publishers, Dode Raehter, the Netherlands, 2002; Watson, Ulease Inhibition, IFAIInternal Workshop on Enhanced-Efficiency fetilizers, Frankfurt International Fertilizer industries, society, resource 2005).

In particular embodiments, the urease inhibitor may be or may include N- (N-butyl) thiophosphoric triamide (NBPT). The preparation of phosphoramide urease inhibitors, such as NBPT, can be accomplished, for example, by a process starting from thiophosphoryl chloride, a primary or secondary amine, and ammonia, as described, for example, in U.S. patent No. 5,770,771, which is incorporated herein by reference. In the first step, thiophosphoryl chloride is reacted with one equivalent of a primary or secondary amine in the presence of a base, and the product is then reacted with excess ammonia to give the final product. Other methods include those described in U.S. Pat. No. 8,075,659, incorporated herein by reference, in which thiophosphoryl chloride is reacted with a primary and/or secondary amine followed by reaction with ammonia. However, this process may result in a mixture. Thus, when N- (N-butyl) thiophosphoric triamide (NBPT) or other urease inhibitor is used, it is understood that this refers not only to the urease inhibitor in pure form, but also to various commercial/industrial grade compounds which may contain up to 50% (or less), preferably no more than 20%, of impurities, depending on the method of synthesis and purification scheme (if any) used in their production. Combinations of urease inhibitors are known, for example using mixtures of NBPT and other alkyl substituted thiophosphoric triamides.

Representative grades of urease inhibitors may contain up to about 50 wt%, about 40%, about 30%, about 20%, about 19 wt%, about 18 wt%, about 17 wt%, about 16 wt%, about 15 wt%, about 14 wt%, about 13 wt%, about 12 wt%, about 11 wt%, 10 wt%, about 9 wt%, about 8 wt%, about 7 wt%, about 6 wt%, about 5 wt%, about 4 wt%, about 3 wt%, about 2 wt%, or about 1 wt% of urease inhibitorImpurities depending on the method of synthesis and purification scheme used in the production of the urease inhibitor (if any). A typical impurity in NBPT is PO (NH)₂)₃It can catalyze the decomposition of NBPT under aqueous conditions. Thus, in some embodiments, the urease inhibitor used is about 80%, about 81%, about 82%, about 83%, about 84%, about 85%, about 86%, about 87%, about 88%, about 89%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, about 99%, about 99.1%, about 99.2%, about 99.3%, about 99.4%, about 99.5%, about 99.6%, about 99.7%, about 99.8%, or about 99.9% pure.

For simplicity, the invention may be described in relation to embodiments in which NBPT is a urease inhibitor. The description of the invention with respect to the NBPT being a urease inhibitor should not be construed as necessarily excluding the use of other urease inhibitors, or combinations of urease inhibitors, unless explicitly stated.

The urea used to produce the adducts disclosed herein can be in various forms. For example, the urea may be in the form of a solid in the form of small particles, flakes, granules, and the like, and/or in the form of a solution, such as an aqueous solution, and/or molten urea. At least a portion of the urea may be in the form of animal waste. Urea and combined urea-formaldehyde products may be used according to the present disclosure. Illustrative urea-formaldehyde products can include, but are not limited to, urea-formaldehyde concentrates ("UFCs") and urea-formaldehyde polymers ("UFPs"). These types of products can be as discussed and described in U.S. Pat. nos. 5,362,842 and 5,389,716 to Graves et al, which are incorporated herein by reference, for example. Any form of urea or urea in combination with formaldehyde can be used to make UFPs. Examples of solid UFPs include PERGOPAK2 available from Albemarle corporation, and NITAMIN 36S, available from Koch agnomo services, LLC. Any of these urea sources can be used alone or in any combination to produce the reaction products disclosed herein.

As referenced above, in some embodiments, formaldehyde used as a reagent to produce the reaction products disclosed herein can be provided in combination with urea (e.g., in the form of a mixture or polymer with urea). In such embodiments, it is not necessary to add additional formaldehyde to form the desired adduct, although the disclosure is not limited thereto and additional formaldehyde may be added to the urea-formaldehyde product.

In some embodiments, formaldehyde is intentionally added as a formulation to prepare the reaction products disclosed herein, and formaldehyde can be in various forms. For example, polyoxymethylene (solid, polymerized formaldehyde) and/or formalin solutions (aqueous solutions of formaldehyde, sometimes with about 10 wt.%, about 20 wt.%, about 37 wt.%, about 40 wt.%, or about 50 wt.% methanol based on the weight of the formalin solution) are the commonly used forms of formaldehyde. In some embodiments, the formaldehyde may be an aqueous solution having a formaldehyde concentration of from about 10 wt% to about 50 wt%, based on the total weight of the aqueous solution. Formaldehyde gas may also be used. Formaldehyde partially or fully substituted with substituted aldehydes such as acetaldehyde and/or propionaldehyde can also be used as the formaldehyde source. Any of these forms of formaldehyde sources may be used alone or in any combination to produce the reaction products described herein.

The method of making the reaction products disclosed herein may vary. Typically, NBPT is combined with, mixed with, or otherwise contacted with urea and formaldehyde. Thus, in some embodiments, the present disclosure provides a method of preparing an adduct comprising combining urea, formaldehyde, and NBPT to form at least one adduct. For example, at least a portion of the NBPT can react with at least a portion of the urea and/or at least a portion of the formaldehyde to form one or more structurally different adducts, as will be further described below.

The reactants (i.e., urea, formaldehyde, and NBPT) can be combined with one another in any order or sequence. For example, in one embodiment, urea and formaldehyde are first combined and NBPT is added thereto. In another embodiment, urea and urea formaldehyde products (e.g., urea formaldehyde concentrate or urea-formaldehyde polymer) are combined and NBPT is added thereto. In a further embodiment, the urea formaldehyde product and formaldehyde are combined and NBPT is added thereto. In a still further embodiment, urea and NBPT are combined and formaldehyde or a urea formaldehyde product is added thereto. Further, in certain embodiments, other components may be included in any of these stages, alone or in combination with urea, formaldehyde, or NBPT. For example, in some embodiments, nitrification inhibitors (such as those disclosed hereinafter) may be combined with one or more of the components, for example, including, but not limited to, embodiments in which nitrification inhibitors are combined with NBPT and the mixture is combined with other components.

In these various embodiments, the form of NBPT added may vary. For example, NBPT can be used in the form of a molten liquid, in the form of a solution, or in the form of a suspension/dispersion. Similarly, the form of the material (i.e., urea/formaldehyde mixture, urea/urea formaldehyde product mixture, or urea formaldehyde product/formaldehyde mixture) combined with NBPT can vary. For example, in some embodiments, the material combined with NBPT may be in the form of a solution, may be in the form of a dispersion/suspension, or may be in the form of a molten urea liquid. In either case, the form of NBPT, urea and formaldehyde should allow a high degree of contact between the reagents to promote the reaction and formation of the adduct. The most preferred form of NBPT is a solution or suspension/dispersion. The most preferred form of urea/formaldehyde mixture, urea/urea formaldehyde product mixture, urea formaldehyde product/formaldehyde mixture is a solution or molten urea liquid containing formaldehyde. In another embodiment where the reaction is promoted using a MAP, DAP or AMS catalyst, the urea/formaldehyde mixture, the urea/urea formaldehyde product mixture, and the urea formaldehyde product/formaldehyde mixture may be in the form of a solid (i.e., urea particles) and a NBPT solution.

Where a solvent is used at any stage of the combination process, the solvents used are typically those that dissolve one or more of NBPT, urea, and/or formaldehyde. Suitable solvents may include, for example, water (including aqueous buffers), N-alkyl 2-pyrrolidones (e.g., N-methylpyrrolidone), glycols and glycol derivatives, ethyl acetate, propylene glycol, benzyl alcohol, and combinations thereof. Representative solvents known to dissolve NBPT include, but are not limited to, those described in U.S. patent nos. 5,352,265 and 5,364,438 to Weston, Omilinsky et al 5,698,003, Whitehurst et al 8,048,189 and 8,888,886, oriz-Suarez et al WO2014/100561, McNight et al WO2014/055132, Gabrielson et al WO2014/028775 and WO2014/028767, and Cigler EP2032589, which are incorporated herein by reference. In certain embodiments, the solvent or mixture of solvents used to combine the components may be selected from the group consisting of: water (including buffers, e.g., phosphate buffers), glycols (e.g., propylene glycol), glycol derivatives and protected glycols (e.g., glycerol, including protected glycerols such as isopropylidene glycerol, glycol ethers such as monoalkylglycol ethers, dialkyl glycol ethers), acetonitrile, DMSO, alkanolamines (e.g., triethanolamine, diethanolamine, monoethanolamine, alkyldiethanolamine, dialkyl monoethanolamine, where the alkyl group may consist of methyl, ethyl, propyl, or any branched or unbranched alkyl chain), alkyl sulfones (e.g., sulfolane), alkyl amides (e.g., N-methylpyrrolidone, N-ethylpyrrolidone, dimethylformamide, or any acyclic amide), monoalcohols (e.g., methanol, ethanol, propanol, isopropanol, benzyl alcohol), dibasic esters and derivatives thereof, alkylene carbonates (e.g., ethylene carbonate, propylene carbonate), monoesters (e.g., ethyl lactate, ethyl acetate), carboxylic acids (e.g., maleic acid, oleic acid, itaconic acid, acrylic acid, methacrylic acid), ethylene glycol esters, and/or surfactants (e.g., alkyl benzene sulfonates, lignosulfonates, alkylphenyl ethoxylates, polyalkoxylated amines), and combinations thereof. Further co-solvents may be used in certain embodiments, including, but not limited to, liquid amides, 2-pyrrolidone, N-alkyl 2-pyrrolidone, and nonionic surfactants (e.g., alkylaryl polyether alcohols).

Various other additives that do not adversely affect the formation of the adducts disclosed herein can be included in the reaction mixture (i.e., urease, one or more inhibitors, urea, formaldehyde, and optionally one or more solvents). For example, components (e.g., impurities) typically present in urea and/or formaldehyde are typically incorporated into the reaction mixture. In some embodiments, components that are desirably included in the final product can be incorporated into the reaction mixture (e.g., a dye, as described in more detail below).

In certain embodiments, monoammonium phosphate (MAP), diammonium phosphate (DAP), and/or ammonium sulfate (AMS) may be used to promote adduct formation. While not meant to be limiting, it is believed that MAP, DAP, or AMS may act as a catalyst to promote the formation of the adducts disclosed herein. In some embodiments, it may be possible to reduce the reaction time and/or perform the reaction at a lower temperature than would otherwise be required to form the adduct by including MAP, DAP, and/or AMS (and/or other catalysts). In certain embodiments, mixing particles of NBPT-treated urea with particles of MAP, DAP, or AMS also accelerates the formation of the adducts disclosed herein compared to embodiments in which no catalyst is used. In some embodiments, the use of a particular catalyst may have an effect on the amount and/or type of various adducts formed during the reaction.

Adduct formation can be carried out at various pH values, and in some embodiments, it may be desirable to adjust the pH of the reaction mixture (e.g., by addition of an acid and/or base). Representative acids include, but are not limited to, solutions of inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, and combinations thereof. Exemplary bases include, but are not limited to, solutions of ammonia, amines (e.g., primary, secondary, and tertiary amines, and polyamines), sodium hydroxide, potassium hydroxide, and combinations thereof. In some embodiments, it may be desirable to control the pH of the reaction mixture using a buffer solution. Representative buffers include, but are not limited to, solutions of triethanolamine, sodium borate, sodium bicarbonate, sodium carbonate, and combinations thereof.

The conditions of the NBPT, urea and formaldehyde (and optionally other additives) combination can be varied. For example, the reaction can be carried out at various temperatures, for example, from ambient temperature (about 25 ℃) to elevated temperature (above 25 ℃). In certain embodiments, the reaction is carried out at a temperature of at least about 50 ℃, at least about 60 ℃, at least about 70 ℃, at least about 80 ℃, at least about 90 ℃, or at least about 100 ℃, such as from about 20 ℃ to about 150 ℃.

Advantageously, in some embodiments, the reaction product may be prepared under conditions of conventional urea manufacture (e.g., as described in Jozeef Meesen, Ullman's Encyclopedia of Industrial Chemistry (2012), volume 37, page 657-695, which is incorporated herein by reference). Such urea production conditions typically include a temperature at which the urea is in molten form, e.g., a temperature of about 130 ℃ to about 135 ℃. For example, in such embodiments, NBPT may be added to a molten mixture of urea and formaldehyde (or urea and urea-formaldehyde (i.e., UF, UFC, or UFP)). The mixtures can be combined and subsequently cooled to provide a reaction product comprising the reaction product, i.e., an adduct of NBPT, urea, and formaldehyde. For example, the composition may be cooled by subjecting the reaction mixture to the usual urea pastillation, granulation or pelletization processes (e.g., fluid bed pelletization, drum pelletization, sprouted bed (sprouted bed) pelletization, etc.), which typically include a cooling step after pastillation, granulation and/or granulation. Typically, the drying process provides the reaction product in the form of a solid material (e.g., an ingot, a granular, or a small granular solid).

NBPT, urea and formaldehyde (i.e., the reaction mixture) can be maintained together under the reaction conditions for different periods of time. For example, in some embodiments, the reaction may be carried out over a relatively short period of time (e.g., in minutes, such as from about 30 seconds to about 30 minutes, from about 1 to about 20 minutes, or from about 1 to about 10 minutes. in some embodiments, the reaction may be carried out for about 1 minute or more, about 2 minutes or more, about 5 minutes or more, about 10 minutes or more, about 15 minutes or more, or about 20 minutes or more. in some embodiments, the reaction may be carried out for about 2 hours or less, about 1 hour or less, about 30 minutes or less, about 25 minutes or less, about 20 minutes or less, about 15 minutes or less, or about 10 minutes or less. in some embodiments, the components may be reacted together for a slightly longer period of time, such as, for example, about 2 hours or more, about 4 hours or more, about 6 hours or more, about 8 hours or more, about 10 hours or more, about 12 hours or more, about 14 hours or more, about 16 hours or more, about 18 hours or more, about 20 hours or more, about 22 hours or more, or about 24 hours or more. In some embodiments, the reaction time is from about 2 hours to about 48 hours, such as from about 4 hours to about 36 hours.

In certain embodiments, the reaction may be carried out for an amount of time required to convert a given percentage of NBPT in the reaction mixture to the adduct form. For example, in one embodiment, the reaction mixture is reacted to about 10 wt.% or less free (i.e., unreacted) NBPT based on total NBPT added to the reaction mixture, or to about 5 wt.% or less free NBPT based on total NBPT added to the reaction mixture. In another embodiment, the reaction mixture is reacted to about 40 wt.% or less free (i.e., unreacted) NBPT based on total NBPT added to the reaction mixture, or to about 30 wt.% or less free NBPT based on total NBPT added to the reaction mixture, or to about 20 wt.% or less free NBPT based on total NBPT added to the reaction mixture. In another embodiment, the reaction mixture is reacted to about 2 wt% or less free NBPT based on total NBPT added to the reaction mixture, or to about 1 wt% or less free NBPT based on total NBPT added to the reaction mixture, or to about 0.1 wt% or less free NBPT based on total NBPT added to the reaction mixture. In a further embodiment, the reaction mixture is reacted to about 50 wt.% NBPT (i.e., unreacted) based on the total NBPT added to the reaction mixture to produce a 1: 1 wt.% adduct: free NBPT product (as measured by phosphorus content). In a still further embodiment, the reaction mixture is reacted to produce adducts ranging from about 4: 1 to 1: 4 (as measured by phosphorus content), including 3: 1 to 1: 3, 2: 1 to 1: 2, and 1: weight ratio of free NBPT product. Thus, in some embodiments, the methods of producing the adducts described herein further comprise monitoring the amount of free NBPT remaining through the course of the reaction based on the amount of free NBPT (as compared to the maximum amount of free NBPT desired by weight included in the reaction product) and evaluating the completion of the reaction.

It is noted that the particular reaction components may affect the reaction conditions required to produce the reaction product. For example, the reaction of components in one solvent may be more efficient than the reaction of those components in a different solvent, and it is understood that, therefore, less time and/or lower temperature may be required for adduct formation in the former case. Further, in the case of using a catalyst, less time and/or lower temperature may be required for adduct formation. It is also noted that, in some embodiments, the use of different reaction conditions may have an effect on the amount and/or type of the various adducts formed during the reaction.

The reaction product provided according to the process disclosed hereinabove may comprise one or more structurally different adducts. For example, a given reaction product may comprise at least one adduct, at least two different adducts, at least three different adducts, at least four different adducts, at least five different adducts, at least ten different adducts, at least twenty-five different adducts, at least about fifty different adducts, or at least about one hundred different adducts. The adduct may be in the form of an isolated compound, oligomer, polymer, and combinations thereof. The total amount of adduct formed may vary, and likewise, the amount of each different adduct (where more than one adduct is present in the composition) may vary.

Some representative adducts that have been identified in the reaction products based on the reaction between urea, formaldehyde and NBPT are as follows (wherein these adducts are referred to as "adduct 1", "adduct 2" and "adduct 3" are temporary names chosen to distinguish them from each other and from other adducts that may be present in the various reaction products):

in addition to the one or more adducts, the reaction product may comprise various other components. It is to be understood that other components that may be present in the reaction product may be the result of the particular process used to produce the reaction product, and in particular, the amount of each reactant included in the reaction mixture. For example, where the reaction conditions are such that an excess of one or both reactants is present, the reaction product may comprise free reactant (i.e., reactant not incorporated into the adduct). In various embodiments, the reaction product may comprise at least some weight percent of one or more components selected from the group consisting of: free NBPT, free formaldehyde, free urea-formaldehyde product (e.g., UFP), catalyst (e.g., MAP, DAP, or MAS), impurities (e.g., resulting from the grade of reactants used), solvent, water, and combinations thereof. The relative amounts of such components may vary, with exemplary amounts and ratios disclosed below.

The reaction products disclosed herein may include a wide range of varying mole percentages of urea, formaldehyde, and NBPT (including both complexed and free forms of the respective components, e.g., as determined by elemental analysis). Similarly, the reaction products disclosed herein can have widely varying molar ratios, particularly because the process of producing the adduct-containing composition can vary. In some embodiments, the reaction product may have a molar ratio of NBPT: urea (including both the individual components in complexed and free form, e.g., as determined by elemental analysis) of about 1: 0.5 to about 1: 2. In certain embodiments, urea is used in a large excess with respect to NBPT; subsequently, in this embodiment, the molar ratio of NBPT: urea is significantly lower. In some embodiments, the reaction product may have a molar ratio of NBPT: formaldehyde (including both complexed and free forms of the individual components, e.g., as determined by elemental analysis) of from about 1: 0.5 to about 1: 2. Furthermore, in some embodiments, formaldehyde is present in a significant excess with respect to NBPT, in this embodiment, the molar ratio of NBPT: formaldehyde is significantly lower.

The reaction products disclosed herein may advantageously exhibit effective urease inhibition and, in preferred embodiments, may exhibit a slow release of NBPT, providing prolonged urease inhibiting properties. Thus, these reaction products may exhibit urease inhibition for a longer period of time than comparative compositions comprising only free (i.e., unreacted) NBPT. Surprisingly, the reaction product, in some embodiments, may exhibit effective urease inhibition even at NBPT levels that are considered ineffective. In other words, a reaction product prepared using a given amount of NBPT, in some embodiments, can exhibit effective urease inhibition without a comparative composition comprising the same amount of NBPT in free (i.e., unreacted) form exhibiting significant urease inhibition.

The reaction product obtained according to the methods disclosed herein can be used or stored for later use in a form that provides it, can be processed in some manner before use or storage for later use (e.g., by providing it in a different form or separating one or more components therefrom), and/or can be combined with other components before use or storage for later use. Various compositions comprising at least a portion of the reaction products disclosed herein are disclosed below.

For example, in one embodiment, the reaction product is maintained substantially in a form that provides it after reaction (e.g., in undiluted liquid or solid form, in solution form, in suspension/dispersion form, in the form of urea-based particles comprising adduct, etc.). As noted above, such forms, in some embodiments, may comprise other components, for example, residual reactants and/or solvents. The particular form of these initially formed reaction products, in certain embodiments, may be further modified prior to use and/or storage, for example, by concentrating the solution or suspension/dispersion form by removing solvent therefrom, by diluting any form by adding one or more solvents thereto, by dissolving the solid form, or by contacting the solid, undiluted liquid, solution, or suspension/dispersion form with a contacting solid support, to provide a solid form of the reaction product. In a particular embodiment, the reaction product is provided in the form of a homogeneous solution.

In another embodiment, the reaction product is treated to isolate one or more adducts therefrom. For example, the reaction product may be treated to remove any or all components other than the adduct from the reaction product to obtain a mixture comprising all of the adducts, a mixture comprising some of the adducts, or one or more individual, isolated adducts. Such an isolated mixture or individual adduct may be provided in its native form (e.g., solid or liquid, substantially pure form), or may be treated as described with respect to the initially formed reaction product modified prior to use or storage (e.g., by adding one or more solvents thereto to provide a solution or suspension/dispersion of the one or more adducts, or by contacting the adduct or adduct mixture in solid, undiluted liquid, solution or suspension/dispersion form with a solid support to provide the adduct or adduct mixture in solid form).

In a further embodiment, the reaction product (initially formed, or modified as described above) or one or more isolated adducts (initially provided, or modified as described above) may be combined with one or more other components. For example, certain compositions are provided that comprise a reaction product in admixture with one or more other components, e.g., one or more nitrogen sources (e.g., urea or urea formaldehyde products) or free NBPT. Certain compositions are provided that comprise one or more isolated adducts in admixture with one or more other components, e.g., one or more nitrogen sources (e.g., urea or urea formaldehyde products) or free NBPT. In addition, any of these combinations may be in altered forms (e.g., solid form, undiluted liquid form, solution form, dispersion/suspension form, etc.).

Initially formed reaction product

As described in detail above, the reaction products provided herein may comprise varying amounts of one or more adducts, and may also comprise varying amounts of other components. The particular configuration of the reaction product may determine the particularly suitable method of use of the reaction product.

For example, where a reaction product comprising a significant free urea content and/or a significant urea-formaldehyde product content is provided, the reaction product (in an altered physical form, e.g., as described above) may be used as a fertilizer composition. For example, although not intended to be limiting, reaction products comprising at least about 90% urea, at least about 95% urea, at least about 98% urea, or at least about 99% urea may be used as fertilizer compositions. Because the reaction product may contain varying amounts of urea and/or urea-formaldehyde products, the amount of reaction product applied as a fertilizer composition may vary. In some embodiments, the rate at which the composition is applied to the soil may thus be the same as or may be proportional to the rate at which urea is currently used for a given application (e.g., based on the weight percentage of urea contained within the reaction product).

Reaction products containing high concentrations of urea can be widely used in all agricultural applications where urea is currently used. These applications include a very wide range of crop and turf species, farming systems, and fertilizer placement methods. The compositions disclosed herein can be used to fertilize a variety of seeds and plants, including seeds for human consumption, for silage, or for other agricultural uses. In fact, any seed or plant may be treated according to the invention with the composition of the invention, such as cereals, vegetables, ornamentals, conifers, coffee, turf grass, feed and fruits, including citrus. Plants which may be treated include cereals such as barley, oats and maize, sunflower, sugar beet, rape, safflower, flax, canarygrass (canary grass), tomato, cottonseed, peanut, soybean, wheat, rice, alfalfa, sorghum, beans, sugar cane, cauliflower, cabbage and carrot. Applying reaction products containing substantial urea concentrations to soil and/or plants can increase nitrogen uptake by the plants, enhance crop yield, and minimize nitrogen loss from the soil.

Such reaction products can be used for fertilizing and inhibiting urease in various types of soil. Although not limited thereto, such compositions are particularly useful in certain embodiments for very acidic soils. It is generally understood that acid soils degrade NBPT; however, the reaction products of the present disclosure were shown to perform well in acidic soils (e.g., better than urea-based fertilizers combined with equivalent amounts of free NBPT).

In some embodiments, the reaction product is used in combination (in modified form, e.g., as described above, including in isolated adduct form) with one or more fertilizer compositions. The process can be used for reaction products containing substantial urea concentrations and reaction products containing lower urea concentrations (including reaction products containing little to no free urea). For example, the reaction product may be applied to the soil before, simultaneously with, or after the application of the nitrogen-based fertilizer composition. The reaction product may be combined with the fertilizer composition, for example, within the soil, on or near the surface of the soil, or a combination thereof. The urea may comprise any of the types of urea disclosed hereinabove, such as free urea, urea-formaldehyde products, and the like and may additionally comprise various substituted ureas. Other suitable urea sources may be or include animal waste such as urine and/or manure from one or more animals, for example, cattle, sheep, chickens, buffalos, turkeys, goats, pigs, horses, and the like.

In some embodiments, the urea source may be or may include animal waste such as urine and/or manure deposited on or in the soil, or the nitrogen source may be or may include a fertilizer product previously applied to the soil. Thus, the reaction product may be applied to soil and mixed with animal waste and/or with one or more fertilizers applied to the animal waste on the surface of and/or within the soil. The reaction products may be applied to the soil before, during and/or after the animal waste and/or one or more fertilizers are deposited onto and/or into the soil. In other examples, the urea source may be or may include animal waste such as urine and/or manure that may be collected and placed in a storage, pond, or the like, and the reaction product may be added to the animal waste to provide a mixture. The resulting mixture may then be deposited adjacent to soil for use therein as a fertilizer.

Reaction product + free NBPT

In certain embodiments, the reaction product (in altered form, e.g., as described above, including in isolated adduct form) may be combined with additional free urease inhibitor (e.g., including, but not limited to, additional free NBPT). The reaction product and free urease inhibitor, in some embodiments, may be combined during use (e.g., the reaction product may be applied to the soil prior to, simultaneously with, or after the application of free NBPT).

In certain embodiments, the reaction product and the free urease inhibitor may be provided in a single composition. The free urease inhibitor combined with the reaction product may be the same urease inhibitor as present in the adduct or a different urease inhibitor or may be a combination of the same urease inhibitor and a different urease inhibitor. In such compositions, the free urease inhibitor (e.g., NBPT) may be present in varying amounts. The adduct and free urease inhibitor may be provided in approximately equivalent amounts, the amount of NBPT may be greater than the amount of adduct, or the amount of NBPT may be less than the amount of adduct. In some embodiments, the molar ratio of NBPT: adduct is from about 1: 1 to about 1: 10, e.g., from about 1: 1 to about 1: 7. In other embodiments, the molar ratio may be from about 10: 1 to about 1: 1, for example, from about 7: 1 to about 1: 1. In other embodiments, the weight ratio of adduct to free NBPT product ranges from about 4: 1 to 1: 4 (as measured by phosphorus content), including 3: 1 to 1: 3, 2: 1 to 1: 2, and 1: 1. This embodiment may include a solution of the adduct and free NBPT, or a fertilizer (solid or molten) comprising the adduct and free NBPT. The solution of adduct and free NBPT may contain about 15 wt% total weight adduct and free NBPT to about 50 wt% total weight adduct and free NBPT, including about 20 wt% total weight adduct and free NBPT to about 40 wt% total weight adduct and free NBPT, and about 25 wt% total weight adduct and free NBPT to about 30 wt% total weight adduct and free NBPT.

As noted above, the reaction product disclosed herein, in some embodiments, may already contain some percentage of free (unreacted) NBPT, which is added to the reaction mixture (but which does not react under the reaction conditions to form an adduct). Thus, in some embodiments, free NBPT may be added to the reaction product to bring the total amount of free NBPT to the desired range. In other embodiments (e.g., where the reaction product is in the form of an isolated adduct), it is understood that little to no NBPT is present in the isolated individual adduct or mixtures thereof; therefore, sufficient free NBPT must be added to bring the free NBPT content of the resulting composition to the above range.

Surprisingly, the adducts disclosed herein, in combination with free NBPT, can, in some embodiments, produce synergistic activity. For example, when the reaction product is combined with free NBPT, the resulting composition may exhibit higher urease inhibition than would be expected based on a comparable amount of NBPT (all in free (unreacted) form), or urease inhibition based on a comparable amount of adduct alone.

In certain embodiments, the reaction product/free NBPT composition can be used directly as a fertilizer composition (i.e., wherein the reaction product comprises a substantial free urea content and/or a substantial urea-formaldehyde product content). More commonly, however, such reaction product/free NBPT compositions are used in combination with a nitrogen source. In this embodiment, the composition comprising the reaction product and free NBPT may be applied to the soil in a modified form (e.g., in liquid, solution, dispersion/suspension, or solid form) prior to, concurrent with, or after application of the nitrogen-based fertilizer composition. The nitrogen-based fertilizer may include, for example, any of the types of urea and urea-formaldehyde products disclosed hereinabove. The composition may be combined with the fertilizer composition, for example, within soil, on or around soil, or a combination thereof. The reaction product/free NBPT composition advantageously provides effective urease inhibition in terms of nitrogen-based fertilizer compositions.

Reaction product + urea

The reaction product, in some embodiments, may be combined with a nitrogen source to provide an adduct-containing fertilizer composition. For example, in some embodiments, the reaction product (in various forms, including as an isolated adduct) may be combined (e.g., mixed, blended, or otherwise combined) with one or more nitrogen sources (e.g., urea or urea-formaldehyde products). The relative amounts of adduct and urea in such fertilizer compositions may vary, and in certain embodiments, the amount of adduct in the fertilizer composition may, for example, be in the range of about 1ppm to about 10,000ppm adduct, including about 20ppm to about 1000ppm, and about 100ppm to about 800 ppm. Further, the amount of adduct in the fertilizer can be measured on a phosphorus basis (i.e., ppmP from the adduct) and includes ranges of about 20ppmP to about 1000ppmP, 50ppmP to about 500ppmP, and 20ppmP to 250 ppmP. Combining the reaction product with urea provides a composition that can provide a fertilizer composition comprising up to about 95 wt.% urea, up to about 98 wt.% urea, up to about 99 wt.% urea, up to about 99.5 wt.% urea, or up to about 99.9 wt.% urea, e.g., about 95% to about 99.9 wt.% urea, about 98% to about 99.9 wt.% urea, or about 99% to about 99.9 wt.% urea, etc.

In certain embodiments, the reaction product may be directly blended with particulate urea or may be used as an additive to liquid (molten) urea. Combining the reaction product with urea may be carried out at ambient or elevated temperatures, e.g., at least about 50 ℃, at least about 60 ℃, at least about 70 ℃, at least about 80 ℃, at least about 90 ℃, or at least about 100 ℃, such as from about 20 ℃ to about 150 ℃. Advantageously, in some embodiments, the reaction product may be combined with urea under conventional urea manufacturing conditions that typically include a temperature at which urea is in molten form, e.g., a temperature of about 130 ℃ to about 135 ℃. In this embodiment, it is advantageous to ensure that sufficient mixing is used in this combination step so that the adduct is substantially uniformly distributed within the molten urea, especially before the urea is melt cooled and solidified in the subsequent granulation step.

The reaction product may be combined with urea in various forms, for example, liquid form, solution or suspension/dispersion, or solid form. The amount of reaction product added to urea according to this embodiment depends on the adduct content of the resulting fertilizer composition as well as the adduct content of the reaction product and can be readily calculated by a person skilled in the art. It is noted that in some embodiments, additional free NBPT may be added to the reaction product, urea, or a combination thereof. Other components may be present in the adduct-containing fertilizer composition, which may be added intentionally or may be inherently present in one or more of the composition components. For example, in addition to urea and reaction product components, the composition may include some moisture, urea synthesis byproducts, one or more solvents, and may optionally contain other additives, such as one or more dyes, one or more NBPT stabilizers, and/or one or more micronutrients, as further described herein.

Other optional Components (which may be used in all of the compositions disclosed herein)

Other optional components may be used in the compositions of the present invention. Examples of other such components include, but are not limited to: a nitrification inhibitor; a modulator; xanthan gum; various forms of calcium carbonate (agricultural lime) for increasing weight and/or raising the pH of acidic soils; metal-containing compounds and minerals such as gypsum, metal silicates, and chelates of various micronutrient metals such as iron, zinc, and manganese; talc; elemental sulfur; activated carbon, which can be used as a "safener" to protect soil from potentially harmful chemicals; a plant protectant; a nutrient; a nutrient stabilizer; a superabsorbent polymer; a wicking agent; a humectant; a plant stimulator for stimulating growth; inorganic nitrogen, phosphorus, potassium (N-P-K) type fertilizers; a source of phosphorus; a potassium source; an organic fertilizer; surfactants such as alkylaryl polyether alcohols; an initiator; a stabilizer; a crosslinking agent; an antioxidant; a UV stabilizer; a reducing agent; dyes, such as blue dyes (FD & C blue # 1); an insecticide; a herbicide; a fungicide; and a plasticizer. The amount of the additional one or more components disclosed herein can be from about 1 to about 75 weight percent of the composition and will depend, in part, on the desired function of the additional one or more components and the configuration of the composition in which the additional one or more components are added.

Examples of modifiers include, but are not limited to, tricalcium phosphate, sodium bicarbonate, sodium ferricyanide, potassium ferricyanide, bone phosphate, sodium silicate, silica, calcium silicate, talc, bentonite, calcium aluminum silicate, stearic acid, and polyacrylate powder. Examples of plant protectants and nutrient stabilizers include silica and the like. Examples of nutrients include, but are not limited to, phosphorus and potassium based nutrients. Commercially available fertilizer nutrients may include, for example, K-Fol 0-40-53, which is a solution containing 40 wt% phosphate and 53 wt% potassium, manufactured and distributed by GBS Biosciences, LLC.

Nitrification inhibitors are compounds that inhibit the conversion of ammonium to nitrate and reduce nitrogen loss in soil. Examples of nitrification inhibitors include, but are not limited to, dicyandiamide (DCD) and the like. Although the compositions disclosed herein may include DCD, in certain embodiments, the compositions are substantially free of DCD. "substantially free" means either no DCD is detected in the mixture or, if DCD can be detected, (1) it is present at < 1% w/w (preferably, < 0.85% w/w, < 0.80% w/w, or < 0.75% w/w); and (2) no effect characterized by DCD is produced at higher ratios. For example, a composition that is substantially free of DCD will not have the environmental impact of exposure to concentrated or pure DCD, even though trace amounts of DCD may be detected in the mixture. Certain exemplary compositions may have a DCD content of less than about 0.85 wt%, less than about 0.80 wt%, less than about 0.75 wt%, less than about 0.5 wt%, or less than about 0.25 wt%.

Examples

In order to provide a better understanding of the above discussion, the following non-limiting examples are provided. While all examples may be directed to particular embodiments, they are not to be construed as limiting the invention in any particular manner. All parts, ratios and percentages are by weight unless otherwise indicated.

Example 1: synthetic preparation of adducts

As a representative example, to a solution of NBPT (5.0g, 29.90mmol) in N-methylpyrrolidinone (NMP, 25mL) at room temperature was added ACS-grade urea (1.79g, 29.90mmol, 1 equiv) followed by formalin (50%, 795. mu.L, 29.90mmol, 1 equiv). The reaction mixture was stirred for 24 h. A homogeneous solution was obtained containing-10% unreacted NBPT (assessed by HPLC) and adduct, among other substances.

Table 1: adduct formation observed with different reactants and reaction conditions

^aACS-U is ACS-grade urea, which is identified as formaldehyde-free and/or UF-free.

^bReg-U is a commercial grade urea containing about 0.4 wt% formaldehyde as UF.

Example 2: effect of catalyst

Urea (> 99% purity) was used at 260ppmPRIME solution (i.e., NBPT-containing solution) treatment; note that formaldehyde is already present in urea. One day later, the obtainedThe treated urea (ATU) was blended with monoammonium phosphate (MAP) 50: 50 wt%, diammonium phosphate (DAP) 50: 50 wt%, or ammonium sulfate (AMS) 50: 50 wt%. The blend was retained for 6 months and samples were retrieved for analysis at defined time points. The ATU was separated from the other admixed components, followed by analysis of NBPT content by HPLC and characterization of NBPT and adduct by LC-MS.

Table 2: adduct formation in the presence of MAP

Table 3: adduct formation in the presence of DAP

Table 4: adduct formation in the presence of AMS

Example 3: determination of urease inhibition

The effectiveness of urease inhibition was measured as follows. One scoop of water was used to wet 4 oz (. about.100 g) of Tifton, GA soil, pH 7.7. The wetted soil was placed in an 8 oz plastic cup with a snug lid. About 1 scoop (. about.2 g) of NBPT-and/or adductThe treated urea particles are applied to the soil surface and the container is sealed. Incubating the container at room temperature for three days and by sensitizing ammoniaThe tube was inserted through the lid of the sealed container to analyze ammonia volatilization. In this way, the amount of ammonia present in the headspace of the vessel is quantified to at most 600ppm,the limit of the tube. Generally, more potent urease inhibitors are characterized by having a lower concentration of ammonia in the headspace. All tests were performed in duplicate in the presence of a positive control (i.e., untreated urea), which typically exhibited > 600ppm ammonia after 3 days of application.

Various compositions comprising NBPT and/or the adducts disclosed herein are prepared by combining NBPT and/or the adducts with urea particles; and urease inhibition was determined using the method described above. The adduct used in this example was prepared according to entry 14 in table 1 above.

The data in figure 1 show the effect of various urease inhibitors, i.e., NBPT and/or the adducts disclosed herein, on the volatilization of ammonia from treated urea exposed to soil, according to the methods described above. For comparison, data for various inhibitors used to treat urea are provided in terms of phosphorus content (i.e., ppmP as measured by ICP). These data indicate that increasing the amount of NBPT in the range of 111-196ppmP in terms of urea content had no significant effect on the onset of significant ammonia volatilization. For example, for urea treated with varying amounts of NBPT, the onset of significant ammonia volatilization (provisionally selected to be ≧ 100ppm) was comparable to about day 8 after application, i.e., ATU 111ppm to ATU 128ppm to ATU 196 ppm. However, when some NBPT was replaced with the adducts disclosed herein-with the same phosphorus content-a significant delay in the onset of significant ammonia volatilization was observed, e.g., > 100ppm ammonia no earlier than the 9 th day after application, i.e., 'NBPT/adduct 42/69 ppm' > ATU 111 ppm. Furthermore, when NBPT and the adducts disclosed herein were combined with urea in a ratio of NBPT to adduct 1: 1 based on phosphorus content, no significant onset of ammonia volatilization was observed until after the 10 th day after application, i.e., 'NBPT/adduct 111/85 ppmP' > ATU 196 ppmP. Surprisingly, the adduct alone did not outperform a comparable amount of NBPT, i.e., 'adduct 111 ppmP' ═ ATU 111 ppmP. This confirms the synergistic relationship between NBPT and the adducts disclosed herein, as described above.

Example 4: analysis of volatilization

For NBPT-and/or adduct-treated urea particles applied to soil at pH 5.05, the cumulative N loss during volatilization was determined over a period of 14 days. Generally, more potent urease inhibitors are characterized by having lower N production. All tests were performed in duplicate in the presence of a control (i.e., unfertilized soil).

Soil (pH 5.05) was obtained (representing 4 inches of soil from the surface of a given location) and the soil was air dried, passed through a 2-mm sieve, and mixed evenly with a cement mixer. Portions of air-dried soil (500 g each) were transferred to individual pots. The soil moisture in each tank was adjusted to 2/3 moisture capacity by adding deionized water and the entire process was mixed to ensure overall consistency of soil moisture within each tank. Once the entire soil was equilibrated to moisture, the pots were placed in a temperature controlled wooden cabinet for 24h to equilibrate the wet soil to 26 ℃. Three N sources were evaluated, including two experimental urease inhibitors-treated urea and untreated urea. In addition, untreated soil was included to assess background ammonia levels. The urea used for all treatments was passed through a 8-mesh screen and retained on a 10-mesh screen to ensure homogeneity. The nitrogen source was applied at an equivalent rate of 120 pounds N/acre based on the surface area of the soil in the tank. Each treatment was repeated 4 times and randomly placed in four separate chambers, each containing four canisters.

Controlling the air flow rate through the soil chamber to be 1.00L min^-1And the temperature was maintained at 26 ℃. An acid separator containing 100mL of 0.02M orthophosphoric acid was used to capture NH volatilized in the air stream flowing over the soil surface₃. 24, 48 after the start of the testThe acid dispenser was changed 72, 96, 120, 144, 168, 216, 264, 312, and 336h (2 weeks). the acid dispenser was weighed and the total volume of the solution was calculated using a density of 0.02M phosphoric acid at 25 ℃. the ammonium N concentration in the acid dispenser was determined colorimetrically using a Lachat QuickChem automatic ion analyzer (Lachat Instruments, Loveland, CO). the assay was designed (grouped) according to four replicates of random groupings analysis using analysis of variance (ANOVA), the individual assays were analyzed separately using Proc Mixed in SAS (SAS Institute, 2009). minimum significant difference (LSD) mean separation was used to determine the treatment difference for the cumulative N captured in the acid dispenser at α -0.05₃The percent loss is calculated by dividing the duration of the sampling interval (hours).

Table 2 below provides the results of the study in which soil source N K1 represents urea treated with vehicle (N-methylpyrrolidone and dye) only, soil source N K2 represents ATU (111ppmP), and soil source N K3 represents adduct-treated urea (adduct/NBPT, 55ppmP/55 ppmP). The adduct-treated urea used in this example was prepared according to entry 14 in table 1 above.

Table 4: cumulative N loss during volatilization

^aMeaning that the same letter or symbol is not significantly different following (P ═ 0.05, LSD)

^bIndicates a comparison made only when AOV treatment (P (F)) is significant at mean comparison OSL

^cUntreated treatments excluded from analysis 4

The data provided in table 5 clearly show that, in this study, adduct-treated urea (K3) produced significantly less volatilized N loss than urea treated with either vehicle (K1) or ATU (K2) alone, starting on day 2 after application to acidic soil. After 2 days, the adduct-treated urea (K3) provided a 98% reduction in N loss compared to the carrier-treated urea alone (K1) and performed 75% better than ATU (K2). After 14 days, the adduct-treated urea (K3) provided a 65% reduction in N loss compared to the carrier-treated urea alone (K1) and performed 25% better than ATU (K2). Furthermore, even in acid soils, the maximum N loss upon volatilization was delayed for 2-3 days with adduct-treated urea (K3) compared to that exhibited by ATU (K2) (according to the curve generated from this data in fig. 2 at days 4-5, K3 at day 7 was compared to the equivalent N loss for K2).

Claims (28)

1. A composition comprising one or more adducts of N- (N-butyl) thiophosphoric triamide (NBPT), urea, and formaldehyde, wherein the one or more adducts are represented by the following structure:

2. the composition of claim 1, wherein the composition comprises substantially no dicyandiamide.

3. The composition of claim 1, further comprising one or more materials selected from the group consisting of: free NBPT, free formaldehyde, Urea Formaldehyde Polymer (UFP), water, and combinations thereof.

4. The composition of claim 1, wherein the urea and formaldehyde are in the form of a urea-formaldehyde reaction product comprising dimethylol urea.

5. The composition of claim 1, wherein the composition is a solution comprising the adduct in an organic solvent.

6. The composition of claim 1, wherein the composition is a synergistic mixture of free NBPT and the adduct.

7. A fertilizer composition, the fertilizer composition comprising:

urea; and

the composition of claim 1.

8. The fertilizer composition of claim 7, wherein the composition comprises greater than about 90% by weight urea.

9. The fertilizer composition of claim 7, wherein the composition comprises greater than about 98% by weight urea.

10. The fertilizer composition of claim 7, wherein the composition of claim 1 is present in an amount between 20ppm p to 1000ppm p based on the total weight of the fertilizer composition.

11. The fertilizer composition of claim 7, further comprising free NBPT, wherein the weight ratio of the composition of claim 1 to free NBPT (as measured by phosphorus content) is in the range of 4: 1 to 1: 4.

12. A method of forming a fertilizer composition, the method comprising combining a fertilizer material with the composition of claim 1.

13. The method of claim 11 wherein the composition of claim 1 is in the form of a solution comprising the adduct in an organic solvent.

14. The method of claim 13, wherein the method comprises mixing the composition of claim 1 with solid particles of the fertilizer material.

15. The method of claim 11, wherein the method comprises mixing the composition of claim 1 with a molten stream of the fertilizer material.

16. The method of claim 15, wherein the molten stream of fertilizer material comprises formaldehyde or a reaction product of urea and formaldehyde.

17. A method of preparing a urease inhibiting fertilizer comprising combining urea, formaldehyde and N- (N-butyl) thiophosphoric triamide (NBPT) such that there is an excess of urea to form an adduct of NBPT, urea and formaldehyde represented by:

the adduct remains bound to the remaining urea.

18. The method of claim 17, wherein the urea and formaldehyde are in the form of a urea-formaldehyde reaction product comprising dimethylol urea.

19. A composition comprising a mixture of:

adducts of N- (N-butyl) thiophosphoric triamide (NBPT), urea and formaldehyde; and

free NBPT.

20. The composition of claim 19, wherein the weight ratio of the adduct to free NBPT (as measured by phosphorus content) is in the range of 4: 1 to 1: 4.

21. The composition of claim 19, wherein the weight ratio of the adduct to free NBPT (as measured by phosphorus content) is in the range of 2: 1 to 1: 2.

22. The composition of claim 19 wherein the weight ratio of the adduct to free NBPT (as measured by phosphorus content) is about 1: 1.

23. The composition of claim 19, wherein the adduct and free NBPT are present in a solution comprising at least one solvent selected from the group consisting of: NMP, glycols, glycol derivatives and protected glycols, acetonitrile, DMSO, alkanolamines, alkyl sulfones, monoalcohols, dibasic esters and derivatives thereof, alkylene carbonates, monobasic esters, carboxylic acids, ethylene glycol esters.

24. A fertilizer composition, the fertilizer composition comprising:

urea; and

the composition of claim 19.

25. The composition of claim 24, wherein the composition of claim 23 is present in an amount of 50 to 1000 ppmP.

26. The composition of claim 24 wherein the weight ratio of the adduct to free NBPT (as measured by phosphorus content) is in the range of 4: 1 to 1: 4.

27. The composition of claim 24 wherein the weight ratio of the adduct to free NBPT (as measured by phosphorus content) is in the range of 2: 1 to 1: 2.

28. The composition of claim 24 wherein the weight ratio of the adduct to free NBPT (as measured by phosphorus content) is about 1: 1.