Submitted to: World Congress of Soil Science
Publication Type: Proceedings
Publication Acceptance Date: December 14, 2009
Publication Date: N/A
Interpretive Summary: Increasing atmospheric carbon dioxide concentrations have led to predictions of global climate change, with potential increases in global temperature and increased variability on rainfall. One source of atmospheric carbon dioxide is soil organic matter oxidized as a result of agricultural activities. Changing farming practices can change agriculture from a source to a sink for atmospheric carbon. Soil carbon content of central Texas clay soils are shown to have been increased by: reducing tillage, changing to higher residue crops, converting from tillage based agriculture to no-till practices, and converting from row-crop to grass based agricultural practices.
Technical Abstract: Soils in central Texas, USA (Udic and Entic Pellusterts) have been degraded by intensive agricultural practices. This was typified by loss of soil organic carbon from about 1880 to 1949 from a concentration of about 6.5 percent in the surface to about 1 percent. Agriculture practices since 1949 are slowly rebuilding the soil carbon content. Recent research has shown that modern conventional practices have increased soil organic carbon sequestration at a rate of 0.15 Mg C ha**-1 yr**-1. Intensive management practices such as no-tillage increase this rate an additional 0.3 Mg C ha**-1 yr**-1. Conversion from row cropping to perennial grass production increases sequestration to 0.45 Mg C ha**-1 yr**-1. Several management options are available to sequester carbon in central Texas soils.