Aug. 11, 2016  3  US 2016/0228594 Al  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 