Nitrogen fertilization decrease soil CO 2 emission in a rainfed maize field in Northeast China

Nitrogen fertilizer has considerable effects on soil carbon fluxes. However, the responses of soil CO 2 emission to N fertilizer remain controversial. A field experiment was conducted to examine the effect of application of N fertilizer on soil CO 2 emission in a maize ( Zea mays L.) field in Northeast China. Soil CO 2 emission was measured from May 2010 to April 2016. Soil CO 2 emission during the growing season and non-growing season contributed 79.7–83.6% and 16.4–20.3%, respectively, to the total annual CO 2 emission. Cumulative annual soil CO 2 emissions were significantly higher in no-N addition treatment (CK) than that in N addition treatment (SU) from 2012/2013 to 2015/2016 ( p < 0.05). Mean annual soil CO 2 emission decreased on averaged by 21.2% after N fertilization ( p < 0.05). 49.6–82.2% of CO 2 flux variation was explained by soil temperature at 5 cm depth. Q 10 of soil CO 2 emission in the annual scale was not significantly affected by N fertilizer. The results highlight the importance of N fertilizer on soil CO 2 emission in agricultural ecosystem.