Root Length Density and Carbon Content Influenced by Agroforestry and Grass Buffers Under Grazed Pasture Systems.

Agroforestry buffers have been proposed as a management system to improve environmental quality and diversify farm income. The objective of this study was to evaluate differences in root length density and soil carbon (C) content within grass buffer (GB), agroforestry buffer (AgB), rotationally grazed pasture (RG) and continuously grazed pasture (CG) treatments. Pasture and GB areas included red clover (Trifolium pretense L.) and lespedeza (Kummerowia stipulacea Maxim.) planted into fescue (Festuca arundinacea Schreb.) while AgB included Eastern cottonwood trees (Populus deltoids Bortr. ex Marsh.) planted into fescue. One-meter deep soil cores were collected from each treatment in August 2007 and 2008 with a soil probe. Three soil cores were sampled at six replicate sampling positions. Soil cores were collected in plastic tubes inserted inside the metal soil probe. Soils were segregated by horizons, and roots were separated into three diameter classes (<1, 1-2, >2 mm) by soil horizon. Root length was determined using a flatbed scanner assisted with computer software. Root length density and C were significantly higher for the buffer treatments as compared to pasture areas. Results from this study imply that establishment of agroforestry and grass buffers on grazed pasture watersheds improve soil C accumulation and root growth which enhance soil physical and chemical properties improving the environmental quality of the landscape.