DYNAMIC BEHAVIOR OF PH IN FRESH URINE PUDDLES OF DAIRY COWS
Modern livestock farming is an important contributor to ammonia (NH 3 emissions. In the Netherlands, 94% of NH 3 emissions originate from agriculture, of which 34% is emitted from commercial dairy cow barns. From current mechanistic modeling, it is known that the pH of urine puddles from cows is one of the most important variables in estimating NH 3 emissions. However, little pH data are available from commercial cow barns. Therefore, the objective of this study was to investigate pH values and to study their dynamic behavior in fresh, on floor urine puddles in these barns. To do this, the pH of urine puddles was measured for 4 h per puddle, and a model was developed to describe the pH behavior. In total, 26 fresh puddles were measured from cows at three commercial dairy farms in summer and winter. At farm level, we found initial pH values of 8.1 through 8.4, which increased to 8.9 through 9.4 after 4 h. The pH difference between summer and winter was 0.3 (p 3 emission modeling than the current situation of using a static pH value. Based on this study, we recommend using the mean measured pH curve as input for puddle simulation during NH 3 emission modeling of dairy cow barns.