Kang Ni Weixin Ding Zucong Cai Yufeng Wang Xilin Zhang Baoku Zhou. Soil carbon dioxide emission from intensively cultivated black soil in Northeast China: nitrogen fertilization effect. J Soils Sediments 2012 12:1007–1018.

Abstract

Purpose The aim of this study was to understand the effect of nitrogen fertilization on soil respiration and native soil organic carbon (SOC) decomposition and to identify the key factor affecting soil respiration in a cultivated black soil. Materials and methods A field experiment was conducted at the Harbin State Key Agroecological Experimental Station China. The study consisted of four treatments: unplanted and N-unfertilized soil (U0) unplanted soil treated with 225 kg N ha−1 (UN) maize planted and N-unfertilized soil (P0) and planted soil fertilized with 225 kg Nha−1 (PN). Soil CO2 and N2O fluxes were measured using the static closed chamber method.

Results and discussion Cumulative CO2 emissions during the maize growing season with the U0 UN P0 and PN treatments were 1.29 1.04 2.30 and 2.27 Mg C ha−1 respectively indicating that N fertilization significantly reduced the decomposition of native SOC. However no marked effect on soil respiration in planted soil was observed because the increase of rhizosphere respiration caused by N addition was counteracted by the reduction of native SOC decomposition. Soil CO2 fluxes were significantly affected by soil temperature but not by soil moisture. The temperature sensitivity (Q10) of soil respiration was 2.16–2.47 for unplanted soil but increased to 3.16–3.44 in planted soil. N addition reduced the Q10 of native SOC decomposition possibly due to low labile organic C but increased the Q10 of soil respiration due to the stimulation of maize growth. The estimated annual CO2 emission in Nfertilized soil was 1.28 Mg Cha−1 and was replenished by the residual stubble roots and exudates. In contrast the lost C (1.53 Mg Cha−1) in N-unfertilized soil was not completely
supplemented by maize residues resulting in a reduction of SOC. Although N fertilization significantly increased N2O emissions the global warming potential of N2O and CO2 emissions in N-fertilized soil was significantly lower than in N-unfertilized soil.
Conclusions The stimulatory or inhibitory effect of N fertilization on soil respiration and basal respiration may depend on labile organic C concentration in soil. The inhibitory effect of N fertilization on native SOC decomposition was mainly associated with low labile organic C in tested black soil. N
application could reduce the global warming potential of CO2 and N2O emissions in black soil.