%0 Journal Article %A L. B. Owens %A G. C. Starr %A D. L. Lightell %T Total organic carbon losses in subsurface flow under two management practices %D 2002 %J Journal of Soil and Water Conservation %P 74-81 %V 57 %N 2 %X Greenhouse gases and global warming have become major topics. Much of the greenhouse gas discussion has dealt with carbon dioxide (CO2) and methods to sequester or store atmospheric carbon in soils and forests. The entire carbon cycle needs to be studied to better understand the overall process. The major carbon transformations are loss of CO2 to the atmosphere or the storage of carbon in sinks such as soil. Although it is a minor pathway, carbon leached through the soil and into groundwater needs to be quantified. Numerous carbon studies have been performed, but concentrations and losses of total organic carbon (TOC) moving through a soil profile have received little attention. Therefore, this study was to assess TOC levels in subsurface flow under two management practices. TOC was determined monthly in the percolate from large soil blocks, called lysimeters, (2.4 m [8 ft] deep) with undisturbed soils under row crops. Most of the TOC concentrations in the percolate ranged from 0.5 to 6.0 mg/L with the corn/soybean-rye rotation. Developed springs in two rotational grazing systems were sampled for 10 years. TOC concentrations in the groundwater from the springflow developments had less variability than in the lysimeter percolate. Most TOC values from these pasture systems were in a concentration range of i to 3 mg/L. Annual averages of TOC transport were similar for the lysimeter percolate and groundwater springs, ranging from 3.7 to 6.0 kg/ha (3.3 to 5.4 lb/ac). %U https://www.jswconline.org/content/jswc/57/2/74.full.pdf