Fig. 4. Effect of manure and moisture level (g H₂O g^–1 dry feedlot soil mixture [FSM]) on total volatile fatty acid (VFA) and protonated volatile fatty acid (VFA_COOH) contents of the FSM. The standard errors of the least squares mean (n = 3) for total VFA and VFA_COOH are 6.5 and 1.0, respectively.