EFFECT OF ADDED MONOCALCIUM PHOSPHATE MONOHYDRATE AND AERATION ON NITROGEN RETENTION BY LIQUID HOG MANURE

Abstract

Retention of nitrogen in manure to be used for crop production and to reduce environmental pollution is an essential management component. The effects of monocalcium phosphate monohydrate (MCPM) and aeration on N retention in liquid hog (Sus scrofa domesticus) manure (LHM) were investigated under laboratory conditions. The manure received 0, 20 or 40 g of MCPM kg−1 of LHM (0, 250 or 500 g MCPM kg−1 manure solids) and was incubated over a 15-d period with and without aeration. Manure pH decreased with added MCPM and then remained constant, but pH increased with time when MCPM was not added. Losses of NH3 from hog manure were significantly reduced by added MCPM, but increased significantly with aeration where MCPM was not added to the manure. The NH4-N content of LHM was higher where MCPM was added to the manure. Conversely, the NH4-N content tended to decrease with aeration in the absence of MCPM. Total N content of LHM was significantly decreased where MCPM was not added to the manure. Aeration had no significant effect on total N. It was concluded that addition of MCPM can increase the NH4-N content of LHM by decreasing NH3-N losses through acidification of the manure. Key words: Aeration, Ca(H2PO4)2∙H2O, hog manure, pH reduction, NH3 loss