Fig. 2. Extractable mineral N pools measured during the 6-wk incubation of manured and control soils. NH₄–N (top), NO₃–N (middle), and NH₄–N + NO₃–N (bottom). n = 107 for the manured soil. n = 6 for the control soils. Error bars are the SEM. The least significant difference (LSD) according to a t test is shown.