Understanding the effects of nitrogen fertilization on soil respiration rate and its temperature sensitivity ( Q10
) is of critical
importance to predict the variability of soil respiration in cropland． A field experiment was established in a rain-fed spring maize
cropland ( Zea mays L． ) in the State Key Agro-Ecological Experimental Station in the Loess Plateau in Changwu County，Shaanxi
Province，China． The experiment comprised of two treatments: no N-fertilizer application ( CK) and N-fertilizer application with 160
kg N·hm － 2 ( N) ． Soil respiration rate，soil temperature，soil moisture，yields，aboveground biomass and root biomass were measured
in two continuous spring maize growing seasons from April 2013 to September 2014． The cumulative soil CO2 emissions were increased
by 35% in 2013 and 54% in 2014 in N treatment as compared to CK treatment． Though nitrogen fertilization significantly increased the
cumulative soil CO2 emissions ( P ＜ 0. 05) ，it did decrease evidently the temperature sensitivity of soil respiration ( P ＜ 0. 05) ． The
Q10 values in N treatment were decreased by 27% and 17% compared with CK treatment in 2013 and 2014，respectively． Nitrogen
fertilization significantly increased the maize yields，aboveground biomass and root biomass ( P ＜ 0. 05) ． Ｒoot biomasses in N treatment
were 32% and 123% greater than those in CK treatment of 2013 and 2014，respectively． Nitrogen fertilization had no marked influence
on soil temperature or moisture． Ｒoot biomass was a critical biotical factor for variation of soil respiration under nitrogen fertilization．
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