Rates of biogeochemical cycling in desert ecosystems are inherently constrained by water availability. Water pulses resulting from discrete climate events therefore can significantly alter biogeochemical processes. The McMurdo Dry Valleys of Antarctica, a polar desert region, have experienced discrete warming events that resulted in episodic pulses of water made available through permafrost and snow melt. Increases in nutrient supply and mobility with greater water availability were hypothesized to temporarily release soil communities from the limitations constraining their growth and activity that are inherent in a polar desert. The longevity of the influence of such water pulses will have implications for food web dynamics, organic matter processing, nutrient dynamics, and other microbially-influenced soil ecosystem processes. To determine the influence of water and nutrient (N, P) pulses on dry valley soil ecosystems, we used a field fertilization experiment to create episodic pulses of both a short (1-day) and longer (4-week) duration. We measured the response of microbial biomass and stoichiometry, as well as soil nutrient content and CO₂ flux. To investigate the role of landscape history, the experiment was conducted at two sites that differ in glacial till, and therefore in situ stoichiometry and biotic potential. CO₂ flux rates ranged from -0.05 to 0.29 µmol CO₂ m^-2 s^-1. Date of measurement had the greatest influence over flux rates, presumably due to changes in physical factors (i.e., temperature). Rates also varied by site, pulse duration, and nutrient treatment. The long-duration pulse stimulated soil CO₂ flux at both sites, despite declining soil temperatures. CO₂ flux was approximately 0.04 µmol CO₂ m^-2 s^-1 greater in plots receiving the pulse than in untreated plots. This effect was more variable for short-duration pulses. The greatest positive flux rates were measured under C additions at both locations, regardless of pulse duration, suggesting C is primarily limiting. Additionally, greater amounts of soil N and P were utilized when C was also added. CO₂ flux at the two sites did not respond differently to N and P additions, despite their differing in situ N and P contents. Our results suggest that water pulses in arid soils can potentially increase soil biotic activity and alter nutrient cycling. Long-term pulse events (e.g. seasonal increases in permafrost melt) should have a greater influence on soil stoichiometry than short-term pulses (e.g. one snow-fall event). Long-term manipulations such as this are necessary to determine if dry valley soil ecosystems are responsive to climate warming events.