Submitted to: GCTE Focus 3 Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: September 20, 1999
Publication Date: September 20, 1999
Citation: Potter, K.N., Potter, H.A., Johnson, H.B., Tischler, C.R. Carbon sequestration rate in soils of Central Texas, USA. Proceedings of GCTE Focus 3 Conference: Food & Forestry: Global Change and Global Challenges. 1999. p. 20-23. Technical Abstract: Soil organic carbon is reduced after long-term tillage operations in most soils in central Texas, USA. Returning the land to grass increases soil organic carbon, but the rate of carbon storage is poorly defined at this time. In this study, soil organic carbon concentration and total mass was determined incrementally to 1.2 m depth for three sites in central Texas. All soils were similar clay textured vertisols. Mean annual temperature i central Texas is 19 degrees C and annual rainfall is 860 mm yr**-1. Each site was comprised of a pristine prairie, a soil that has been tilled for over 100 years, and a site previously tilled which had been returned to grass. The restored grass sites were last tilled 6, 26 and 60 years ago. Soil organic carbon in the surface 0.6-m under continuous agriculture was 30 percent to 43 percent less than the prairie. A linear function, with a slope of 447 kg C ha**-1 yr**-1, described the increase in soil organic carbon under grass for periods from 6 to 60 years. The carbon sequestration rate for conversion to grass is 1 1/2 times the rate reported for conversion to no-tillage management practices on similar soils. The native prairie is an estimate of the potential amount of carbon sequestion possible in soils under current climatic conditions. As the soil organic carbon present in the surface 0.6 m after 60 years of grass is only 70 percent of the total possible carbon sequestration, an additional 44 t C ha**-1 could be sequestered in these soils. Nearly a century (98 years) would be required to fill the potential carbon pool if carbon sequestration continued at the present rate.