the accumulation of gaseous ammonia in areas wherein animals are housed or maintained is controlled by providing to the areas animal litter , bedding , or other absorbent material which contain a low molecular weight , non - volatile organic acid . acids such as citric , malic , fumaric , phosphoric , tartaric , maleic , malonic , succinic , sorbic and mixtures of these acids are used and especially phosphoric and fumaric . these acids can be used in concentrations of about 0 . 0001 to 2 wt % of the dry bedding .