We investigated changes in soil quality associated with prescribed burning of post-agricultural pine-grassland communities restored following abandonment of agriculture in the early 20th centry (ca. 1920), frequently burned (1-2 year fire return interval) until 1960, and then treated with different fire regimes until the present. The treatments were applied as part of the Tall Timbers Fire Ecology (Stoddard) Plots long-term experiment, where three replicates of 0.2 hectare (half acre) plots have been burned in Feb-Apr at 1, 2, and 3-year fire return intervals or unburned. From 2007-2013 we measured a suite of soil characteristics within plots as well as in fields tilled from the 19th century to the present assumed to represent conditions prior to agricultural abandonment. Overall, restoration of tilled fields to burned pine-grasslands was associated with changes in soil characteristics generally considered to be improvements in soil quality, including lower soil bulk density, higher water penetration rates, higher total carbon and nitrogen, and higher mineral nutrients per hectare. Among treatments within the pine-grassland research plots, periodically burned (1-3 year) plots overall had higher total carbon, total nitrogen, mineral nutrients, and water infiltration rates than the unburned plots.  Within the 1-3 year fire return interval plots, longer fire return intervals had higher levels of total carbon and total nitrogen, lower bulk density, and lower mineral nutrient levels (K, Mg, P). Annually burned plots showed some evidence of erosion. In conclusion, conversion of agricultural land to frequently burned pine-grasslands appears to have resulted in significant improvements in overall soil quality and soil carbon sequestration, but changes associated with specific fire regimes were more complex and could not be as definitively described in terms of changes in soil quality. These results may are likely specific to post-agricultural communities and not necessarily applicable to native (never plowed) pine-grasslands.
Oral presentation and poster titles, abstracts, and authors from the Society for Range Management (SRM) Annual Meetings and Tradeshows, from 2013 forward.