Nitrogen fertilization decrease soil CO2 emission in a rainfed maize field in Northeast China.

Abstract

Nitrogen fertilizer has considerable effects on soil carbon fluxes. However, the responses of soil CO2 emission to N fertilizer remain controversial. A field experiment was conducted to examine the effect of application of N fertilizer on soil CO2 emission in a maize (Zea mays L.) field in Northeast China. Soil CO2 emission was measured from May 2010 to April 2016. Soil CO2 emission during the growing season and non-growing season contributed 79.7-83.6% and 16.4-20.3%, respectively, to the total annual CO2 emission. Cumulative annual soil CO2 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 CO2 emission decreased on averaged by 21.2% after N fertilization (p < 0.05). 49.6-82.2% of CO2 flux variation was explained by soil temperature at 5cm depth. Q10 of soil CO2 emission in the annual scale was not significantly affected by N fertilizer. The results highlight the importance of N fertilizer on soil CO2 emission in agricultural ecosystem.