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The nitrogen cycle in desert soil ecosystems is particularly sensitive to changes in precipitation, even of relatively small magnitude and short duration, because it is already under water stress. This suggests that desert soils may have preserved past evidence of small variations in continental precipitation. We have measured nitrate (NO3-) concentrations in soils from the Atacama (Chile), Kumtag (China), Mojave (US), and Thar (India) deserts, and stable nitrogen and oxygen isotope (N-15, O-17, and O-18) abundances of the soil NO3(-). O-17 anomalies (Delta O-17), the deviations from the mass-independent isotopic fractionation, were detected in soil NO3(-) from almost all sites of these four deserts. There was a strong negative correlation between the mean annual precipitation (MAP) and soil NO3- Delta O-17 values (Delta O-17(NO3soil)). This MAP-Delta O-17(NO3soil) correlation advocated Delta O-17(NO3soil) as a new precipitation proxy and was then used to assess precipitation changes in southwestern US at the Pliocene-Pleistocene boundary, in South America during the Miocene, and the Sahara Desert in the past 10 kyr using NO3- Delta O-17 in paleosols or ancient aquifers. Global and the US maps of surface Delta O-17(NO3soil) were also projected with available MAP datasets based on the MAP-Delta O-17(NO3soil) model. (C) 2016 Elsevier B.V. All rights reserved.