Fig. 4. Nitrate nitrogen concentrations in the soil profile under 120 kg N ha-1 (N120) and 200 kg N ha-1 (N200) (a) spring 1997, (b) fall 1997, (c) spring 1998, and (d) fall 1998. Vertical bars represent standard error of the mean (n = 9).
Fig. 4. Nitrate nitrogen concentrations in the soil profile under 120 kg N ha-1 (N120) and 200 kg N ha-1 (N200) (a) spring 1997, (b) fall 1997, (c) spring 1998, and (d) fall 1998. Vertical bars represent standard error of the mean (n = 9).