Growing urban population, declining groundwater levels, and drought are factors leading to reduced water quantities for irrigated land in the semiarid western U.S. Developing sustainable limited irrigation systems necessitates an understanding of how reduced water availability affects soil microbial processes and ecological interactions critical to crop productivity and soil conservation. The objective of this study was to determine the effects of deficit-irrigated maize cropping systems on rhizosphere microbial communities and activities. Maize rhizosphere soil samples were collected from furrow or sprinkler irrigated field plots in 2006 and 2007, shortly after tasseling. Samples were collected from replicate plots of the following cropping systems per furrow or sprinkler irrigated treatment: maize-alfalfa rotation, 740 mm anticipated annual consumptive maize water use (ET) (fully irrigated); maize-alfalfa rotation, 410 mm ET; and maize-sunflower-winter wheat rotation, 310 mm ET. Soils were analyzed for microbial biomass carbon (MBC), glucosidase activity, and microbial community fatty acid methyl ester (EL-FAME) structure. In 2006, MBC was not significantly affected by type or amount of irrigation. Glucosidase activity was significantly lower in sprinkler-irrigated plots than in furrow-irrigated plots and lower in rhizosphere soil from the deficit-irrigated maize-sunflower-wheat rotation compared to other treatments. Principle components analysis of EL-FAMEs separated rhizosphere communities according to deficit irrigation-rotation systems; microbial communities became more dominated by Gram-positive bacteria and less dominated by fungi as the amount of irrigation water decreased. Fungal EL-FAME biomarker concentrations were negatively impacted by deficit irrigation. Bacterial stress ratio 17:0cy:16:1ù7c was not affected by deficit irrigation but was greater in furrow than in sprinkler-irrigated soil. These preliminary results indicate that fungi and glucosidase activity responded negatively to deficit irrigation, perhaps due to reduced biomass inputs of maize residue in these systems, and that furrow irrigation, which floods soils, posed a greater stress to soil bacteria than did decreased water availability.