|Frank, Albert - RETIRED,USDA-ARS-NGPRL|
Submitted to: Soil & Tillage Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 24, 2005
Publication Date: May 12, 2006
Citation: Frank, A.B., Liebig, M.A., Tanaka, D.L. 2006. Management effects on soil CO2 efflux in northern semiarid grassland and cropland. Soil Tillage Res. 89:78-85. Interpretive Summary: Preservation of soil carbon is important to maintain productivity of agricultural soils. Soil respiration is a process where soil carbon is lost to the atmosphere as carbon dioxide. Soil respiration is influenced by land use, management practices, and environmental conditions. We studied the effects of grazed grassland, continuous wheat, and wheat fallow-management on soil carbon dioxide emissions. Differences in soil emissions between the three treatments were due to differences in soil carbon and microbial biomass carbon. Total carbon emissions to the atmosphere from soil respiration averaged 1.0 kg C m-2 y-1 for the grassland, 0.7 kg C m-2 y-1 for the no-till continuous wheat, and 0.6 kg C m-2 y-1 for the wheat-fallow treatments. These results show that soil carbon content and land use plays a significant role in soil carbon emissions to the atmosphere.
Technical Abstract: Soil respiration is a process that is influenced by land use, management practices, and environmental conditions. We compared soil CO2 efflux from continuous no-till spring wheat, spring wheat-fallow under no-till, and a native mixed-grass prairie with grazing near Mandan, ND. A Werner-Sen-Chama soil complex (loamy, mixed, superactive, frigid shallow Entic Haplustoll; fine-silty, mixed, superactive, frigid Typic Haplustoll; fine-silty, mixed, superactive, frigid Typic Calciustoll) was present at the grassland site and a Wilton silt loam (fine-silty, mixed, superactive, frigid Pachic Haplustolls) at the cropping sites. Soil chambers were used to measure soil CO2 fluxes about every 21 days starting about 1 May 2001 through 1 April 2003. Soil organic carbon (SOC), microbial biomass carbon (MBC), soil water, soil temperature, and above and belowground plant biomass were measured. Root biomass of the surface 30-cm depth of the undisturbed grassland was significantly greater (12.3 Mg ha-1) than under continuous wheat (1.3 Mg ha-1) and wheat-fallow (0.3 Mg ha-1). Grassland SOC content of 84 Mg ha-1 to 30-cm soil depth was 21% greater than the continuous wheat and 29% greater that the wheat-fallow. The MBC of the grassland was 2.2 Mg ha-1, or 3.6 times greater than for continuous wheat and 7.2 times greater than for the wheat-fallow treatments. Soil CO2 effluxes for the grassland averaged 10.1 g CO2 m-2 d-1, compared to 6.9 g CO2 m-2 d-1 for the wheat fallow and 6.0 g CO2 m-2 d-1 for the continuous wheat treatments. The differences in soil effluxes between the three treatments can be attributed to differences in SOC and MBC. Total C efflux to the atmosphere from soil respiration averaged 1.0 kg C m-2 y-1 for the grassland, 0.7 kg C m-2 y-1 for the no-till continuous wheat, and 0.6 kg C m-2 y-1 for the wheat-fallow treatments. The SOC and MBC of the grassland compared to the cropping sites in this study clearly suggest that land use plays a significant role in soil C efflux from respiration.