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Carbon Dioxide Emission from Black Soil as Influenced by Land-Use Change and Long-Term Fertilization

Li, Haibo, Han, Xiaozeng, Qiao, Yunfa, Hou, Xueying, Xing, Baoshan
Communications in soil science and plant analysis 2009 v.40 no.7-8 pp. 1350-1368
soil respiration, carbon dioxide, gas emissions, seasonal variation, land use change, grassland soils, agricultural soils, grasslands, agricultural land, fertilizer application, NPK fertilizers, organic fertilizers, rhizosphere, soil temperature, precipitation, carbon sequestration, growing season, soil management, Zea mays, China
Land-use change and soil management play a vital role in influencing losses of soil carbon (C) by respiration. The aim of this experiment was to examine the impact of natural vegetation restoration and long-term fertilization on the seasonal pattern of soil respiration and cumulative carbon dioxide (CO2) emission from a black soil of northeast China. Soil respiration rate fluctuated greatly during the growing season in grassland (GL), ranging from 278 to 1030 mg CO2 m-2 h-1 with an average of 606 mg CO2 m-2 h-1. By contrast, soil CO2 emission did not change in bareland (BL) as much as in GL. For cropland (CL), including three treatments [CK (no fertilizer application), nitrogen, phosphorus and potassium application (NPK), and NPK together with organic manure (OM)], soil CO2 emission gradually increased with the growth of maize after seedling with an increasing order of CK < NPM < OM, reaching a maximum on 17 August and declining thereafter. A highly significant exponential correlation was observed between soil temperature and soil CO2 emission for GL during the late growing season (from 3 August to 28 September) with Q10 = 2.46, which accounted for approximately 75% of emission variability. However, no correlation was found between the two parameters for BL and CL. Seasonal CO2 emission from rhizosphere soil changed in line with the overall soil respiration, which averaged 184, 407, and 584 mg CO2 m-2 h-1, with peaks at 614, 1260, and 1770 mg CO2 m-2 h-1 for CK, NPK, and OM, respectively. SOM-derived CO2 emission of root free-soil, including basal soil respiration and plant residue-derived microbial decomposition, averaged 132, 132, and 136 mg CO2 m-2 h-1, respectively, showing no difference for the three CL treatments. Cumulative soil CO2 emissions decreased in the order OM > GL > NPK > CK > BL. The cumulative rhizosphere-derived CO2 emissions during the growing season of maize in cropland accounted for about 67, 74, and 80% of the overall CO2 emissions for CK, NPK, and OM, respectively. Cumulative CO2 emissions were found to significantly correlate with SOC stocks (r = 0.92, n = 5, P < 0.05) as well as with SOC concentration (r = 0.97, n = 5, P < 0.01). We concluded that natural vegetation restoration and long-term application of organic manure substantially increased C sequestration into soil rather than C losses for the black soil. These results are of great significance to properly manage black soil as a large C pool in northeast China.