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The concentration of nitrous oxide (N2O) and carbon dioxide (CO2) in the atmosphere has increased considerably over the last century, but few studies are available showing their production from soils in semi-arid areas. Soils from the tropical semi-arid Central Depression of Chiapas were sampled from fields cultivated with maize (MAI treatment), under canopy of Acacia angustissima (TIMBRE) or outside the canopy of the trees (OUT), adjusted to 40%, 60%, 80% or 100% of water-holding capacity (WHC) and amended with 0, 15 or 50 mg (NH4NO3)-N kg(-1) dry soil. The production of N2O, CO2 and concentrations of NH4+, and NO3- were monitored in the laboratory under aerobic conditions. Production of N2O in the first 3 days was significantly larger from the MAI and OUT soils, compared to the TIMBRE soil, while the addition of 50 mg inorganic N doubled the production of N2O. In all treatments, soil at 100% WHC had the largest production of N2O. The emission of CO2 was significantly larger from soils at 60% and 80% WHC compared to the soil at 40% and 100% WHC, although the addition of inorganic N had no significant effect on CO2 emission. The application of inorganic N and the absence of vegetation increased the production of N2O. (c) 2005 Elsevier Ltd. All rights reserved.