lower the pH of the manure, converting ammonia (NH$_{3}$ ) to ammonium (NH$_{4 }$+). The ammonium will combine with sul› fate (SO$_{4 }$ 2 -) to form ammonium sulfate (NH 4 ) $_{2}$SO$_{4}$ , which is a water-soluble nitrogen fertilizer. 

[0034] Normally, dry alum can require up to two weeks to absorb sufficient water from the air or surrounding litter to initiate the reduction of the pH of litter and thereby reduce ammonia production. Alum can be mixed with water and sprayed onto manure in an effort to accelerate its function, but this may require additional handling and it reduces the flex› ibility of the application timing with respect to the placement of chicks, for example, in an enclosure. The addition of water also can introduce a detrimental effect on the humidity of the house and the litter. 

[0035] In this disclosure, an organic acid or an inorganic acid is added to alum, or another metal salt, and then applied in the animal enclosure (e.g., a chicken house). In some embodiments, the composition comprises, on a dry basis, from about 75 wt% to about 99.9 wt% metal sulfate (based on its non-hydrated form), and from about 0.1 wt% to about 25 wt % organic acid or a combination of organic acids, wherein the organic acid or a combination of organic acids has an average pKa of about 3 or higher. 

[0036] The combination of the composition and water ( or a liquid containing water) results in aqueous solution, which should be selected to maintain a solution pH of greater than 2.0. The aqueous solution may be formed at the time of forming the composition, or at a later time, such as for product transport, product application (e.g. within an animal enclo› sure), or product use. 

[0037] In some embodiments, the acid is an organic acid, or a combination of acids that includes at least one organic acid. In some embodiments, the acid is a "weak acid," which for purposes of this disclosure means an acid with a pKa value of about 3 or higher. In some embodiments, a combination of acids is employed with an average pKa of the acid mixture, on an acid weight basis, of about 3 or higher. Preferably, no single acid (in a combination of acids) is present with a pKa ofless than 2, in some embodiments of the invention. 

[0038] In various embodiments, an organic acid may be selected from the group consisting of acetic acid, acetoacetic acid, citric acid, formic acid, lactic acid, ascorbic acid, ben› zoic acid, propionic acid, 3-hydroxypropanoic acid, carbonic acid, glycolic acid, glyoxylic acid, glyceric acid, acrylic acid, adipic acid, malonic acid, methymalonic acid, succinic acid, malic acid, tartaric acid, itaconic acid, mesaconic acid, glu› taric acid, and combinations or salts thereof. 

[0039] The composition is preferably selected so that the resulting aqueous solution has a solution pH of greater than 2.0. For example, when using 7% acetic acid with aluminum sulfate, the resulting pH is about 2.4. In contrast, a product with 7% sulfuric acid (a strong acid) with aluminum sulfate has a pH of about 1.7 or less. (Note this is a logarithmic scale so this difference is quite significant.) 

[0040] In some embodiments, the composition comprises, on a dry basis, from about 75 wt% to about 99.9 wt% metal sulfate (based on its non-hydrated form), and from about 0.1 wt % to about 25 wt % inorganic acid or a combination of inorganic acids, wherein the inorganic acid or a combination of inorganic acids has an average pKa of about 3 or higher. 

[0041] It is understood that stronger acids can also be used, if a buffer system is designed to keep the solution pH above 2.0. In some embodiments, the cost of the acid, the needs of the farmer, or the target pH may dictate the use ofa strong acid 

along with an appropriate salt, to create a buffer that main› tains the performance of the product while increasing the pH above 2.0. In some embodiments, a strong acid having pKa > 1 is utilized. In some embodiments, one or more strong acids having pKa between about 1 to 3, such as about 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, or 3.0 are utilized. 

[0042] Therefore in some embodiments, the composition comprises, on a dry basis, from about 75 wt% to about 99.9 wt % metal sulfate (based on its non-hydrated form), from about 0.1 wt% to about 25 wt% inorganic acid or a combi› nation of inorganic acids, and an effective buffer to maintain an aqueous solution pH above 2.0. 

[0043] In some embodiments, the acid or combination of acids may include an inorganic acid, such as (but not limited to) phosphoric acid, hydrogen peroxide, nitrous acid, hydra› zoic acid, or combinations or salts thereof. In certain embodi› ments, the acid or combination of acids may include a stron› ger acid (pKa less than 3) in combination with weaker acids, which may be organic or inorganic acids, such that the aver› age pKa of the acid mixture is about 3 or higher on an acid weight basis. In certain embodiments, the acid or combina› tion of acids may include a stronger acid (pKa less than 3) along with a buffer to maintain solution pH above 2.0. 

[0044] A "buffer" or "buffering agent" is a weak acid (with a conjugate base) or weak base (with a conjugate acid) used to maintain the acidity (pH) of a solution near a chosen value after the addition of another acid or base. One function of a buffer is to prevent a rapid change in pH when acids or bases are added to the solution. In this disclosure, a buffer may be utilized to customize the pH of the product for storage or shipping. As one example, using a relatively weak acid like phosphoric acid along with sodium phosphate or other phos› phate counter ions will suppress the dissolution of the acid and allow use of an acid with a relatively low pKa. A buffer may also be employed with acetic acid. 

[0045] A buffer may be employed to reach the target pH while still having the acid capacity (right amount of acidity) to start the desired reaction with metal salt. In some embodi› ments of making a buffer, an organic acid as added to reach a target potential concentration of H+ ions (i.e., acidity). The "potential concentration ofH+ ions" is determined by assum› ing the acid is a strong acid and fully dissociates. Then, based on the desired pH, the salt of the organic acid is added to reach a concentration that forces the equilibrium to the target pH value. 

[0046] As an example for the case of acetic acid (HOAc ), 

so 7% HOAc by weight will give an equal concentration ofH+ ions. But acetic acid ( and generally speaking, organic acids or weak acids) does not fully dissociate. So EQ. 1 equation becomes 

Using the common ion effect, one can add NaOAc (acetate salt that fully disassociates) to change the concentration ofH+ in solution according to EQ. 2. 

[0047] Alternatively, one can make the salt real time by again adding excess acid and then titrating back with a strong base (such as NaOH) to tune the solution to the right pH. In other words, a buffer is constructed by forming a conjugate base from the acid. The desired amount of acidity is selected and then a calculation is made as to how much acid can be used. Then the solution is titrated back to the right pH. This 

EQ.1 

EQ.2 

