A 1.6 ha plot of Atriplex canescens (fourwing saltbush) was established in a desert soil at a former uranium ore-processing plant, near Monument Valley, Arizona, to remediate nitrate and ammonium N contamination. The plants were irrigated to stimulate growth and N uptake. However, NO3? loss from the soil was unexpectedly rapid. Initially, the soil contained approximately 180 mg kg?1 NO3??N distributed at depths up to 4.6 m, but concentrations decreased to 80 mg kg?1 after 41 months. Losses occurred throughout the plot at all soil depths. NH4?N remained unchanged (ca.180 mg kg?1). Soil moisture was generally below field capacity and soil?water flux showed no net downward movement over the course of the study. A salt balance showed a [...]
