Fig. 6. Influence of cattle diet and rainfall (Experiment 5) on (a) crust formation and (b) ammonia emission rate (g NH₃–N m^–2 d^–1). Error bars indicate ±1 standard error of the mean (n = 3). CDC, corn, dry crust; CWC, corn, wet crust; CDWC, corn, dry then rewetted crust; GDC, grass, dry crust.