Fig. 1. Changes in hydrolyzable forms of soil N during incubation (25°C, 85–90% relative humidity) after treatment of 5-g soil samples (four replicates) with sufficient deionized water to achieve 60% of the soil's water-holding capacity. Samples incubated for 4, 8, or 12 wk were leached at biweekly intervals with 0.01 M CaCl₂. Error bars representing one standard deviation above and below the mean are shown when they exceeded the size of the data marker.