Short-term nitrous oxide profile dynamics and emissions response to water,nitrogen and carbon additions in two tropical soils

Tropical soils are potentially the highest and least studied nitrous oxide (N2O) production areas in the world. The effect of water, nitrate and gluco se additions on profile concentrations and episodic emissions of N2O for tw o volcanic soils in Costa Rica was examined. Magnitudes of episodic N2O pul ses, as well as overall N2O emissions, varied considerably and consistently , depending on soil texture, soil water content, and kind and availability of substrates. Emission pulses began within 30 min, peaking no later than 8 h after wetting. Production in the soil occurred mainly in the layer betwe en 5 and 20 cm deep, but depended directly on the temporal dynamics of the water profile. Changes in soil NO3- were associated with soil N2O concentra tion changes. Depending on the treatments, one episodic N2O production even t driven by one moderate rain could account for less than 15% to more than 90% of the total weekly production. Previous survey studies may have undere stimated the contribution of N2O emissions from tropical soils. In order to improve budgets and models of N2O emissions. episodic emissions driven by rain events and amendments must be considered.