Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 6/20/1997
Publication Date: N/A
Technical Abstract: Soil organic carbon concentration (OCC) generally increases when grass is planted on cropland and declines when grassland is converted to cropland. Management practices affect the decline. We determined OCC at the 0-5-cm depth of a clay loam before converting CRP grassland to cropland in 1994, 1995, and 1996, and at planting and harvest of dryland grain sorghum and winter wheat grown on the plots. Based on results from adjacent cropland and the CRP land, soil OCC increased from about 9.0 g kg**-1 to about 11.0 g kg**-1 during 8-10 years under grass. After returning the CRP land to cropland, soil OCC remained higher with no-tillage management than with moldboard plow, disk, or sweep tillage management, with soil mixing to >5 cm contributing to the decline. Removing surface dry matter by mowing and baling or burning before imposing tillage treatments had little effect on soil OCC at crop planting and harvest.