Suitability of the plant root simulator probe for use in the Mojave Desert

To find a quick, relatively inexpensive measure for soil chemistry in the Mojave Desert (MD), we evaluated the use of the ion-exchange resin membrane (IEM) plant root simulator (PRS) probe. Tests were conducted along a floodplain of the Virgin River in Nevada. Probes were buried at 15 and 40 cm. Probes were left in place for three time intervals (30, 60, and 90 d) in two seasonal periods (wetter [WP] and drier [DP], 2004), which were delineated according to the amount of precipitation and soil temperature and moisture. The sampling design was replicated in three pits during the WP and DP. Soil moisture and soil temperature were monitored at 25, 50, 75, and 100 cm. The probes were able to detect differences in ion sorption between the two burial depths, although differences were not always statistically significant. Ion sorption onto the probes generally increased from Month 1 to 3, but the result was not linear. The sorption of some ions fluctuated during the three-month period, with ions desorbing and readsorbing or ion chemistry decreasing over the course of the study. Soil moisture and temperature did not appear to affect the probe's ability to detect differences across depths or season. Based on results from this experiment, we conclude that the burial time required for assessing relative differences in ion chemistries at our sites is one month or less and that the PRS probe may be useful for detecting relative differences in ion chemistries among other soils in the MD.