Nitrous oxide emissions from black soils under a continuous soybean cropping system in northeast China

W.W Chen, Y.Y Wang, Z.C Zhao, F Cui, J.X Gu, X.H Zheng
2015 Journal of soil science and plant nutrition  
A large number of natural wetlands in northeast China have been reclaimed as farmland in the last few decades, and soybean is the main rain-fed crop here. For the depth understanding of nitrous oxide (N 2 O) emission from reclaimed soybean fields, using static opaque chamber method, we conducted a four-year N 2 O flux measurement at two adjacent soybean fields cultivated after wetland drainage in 1987 and 1993, respectively, in the Sanjiang Plain of northeast China Using static opaque chamber
more » ... ic opaque chamber method,. Both sites had two treatments including soybean cropped and bare soils (i.e., SF87, BS87, SF93 and BS93). The results showed that soil N 2 O emission from all of the plots was severely inhibited by the low temperature in winter (November to March), while a N 2 O emission pulse occurred during the spring thaw (April and May). Temporal variation of the N 2 O fluxes during the growing season varied over all the four years but was mainly affected by soil water-filled pore space (WFPS). Intense rainfall events increased the intensity and duration of N 2 O pulses during the growing season, and most high fluxes were occurred at WFPS > 45%. The mean annual N 2 O emission from all treatments over four years was 4.8 ± 1.2 kg N ha -1 (ranges: 1.9-19.8), and one third of the emission originated from the spring-thaw. In addition, soybean growth did not increase N 2 O emissions during the growing season, which support the cancellation of N 2 O emission calculations from nitrogen fixed by legumes in the 2006 IPCC Guidelines for National Greenhouse Gas Inventories.
doi:10.4067/s0718-95162015005000046 fatcat:n2hzfbg33vh35p3ycvgki4beia