Soil Respiration and N sub(2)O Flux Response to UV-B Radiation and Straw Incorporation in a Soybean-Winter Wheat Rotation System

Field experiments were conducted in the 2008-2009 soybean and winter wheat-growing seasons to assess soil respiration (SR) and nitrous oxide (N sub(2)O) emission as affected by enhanced UV-B radiation and straw incorporation. The SR rate was measured using a soil CO sub(2) flux system; the N sub(2)O flux was measured using a static chamber-gas chromatograph technique. The results showed that in the soybean and winter wheat-growing seasons, enhanced UV-B radiation significantly decreased the SR rates and that straw incorporation increased the SR rates compared to the control treatment. The combined treatment of UV-B and straw incorporation had no obvious influence on the SR rates. Enhanced UV-B radiation, straw incorporation, and the combination treatment increased the temperature sensitivity of SR in the soybean-growing season. The study also showed that N sub(2)O emissions were reduced by enhanced UV-B radiation and that straw incorporation had no significant effects on the mean N sub(2)O emission fluxes in the soybean and winter wheat-growing seasons. Our findings suggest that enhanced UV-B radiation may lead to a decrease in SR and in N sub(2)O emissions, straw incorporation may increase SR, and the combined treatment may have no significant influence on SR and N sub(2)O emissions from soybean-winter wheat rotation systems.