Fig. 2. Soil pH as a function of fertilizer treatment and rate after 7 yr (LSD_0.05 = 0.18). Samples taken from the 0- to 5-cm depth. Fertilizer rates (Rates 1, 2, 3, and 4) were respectively 2.24, 4.49, 6.73, and 8.98 Mg ha^–1 for poultry litter and 65, 130, 195, and 260 kg N ha^–1 for ammonium nitrate.