Soil Structure Changes In Bioenergy Crop Residue Management Systems.

Recent technology provides the ability to process cellulosic plant material for ethanol production. Previous studies suggest that removal of this material from agricultural fields may or may not affect soil quality over time. Various levels of residue removal trials were put in corn (Zea mays) and soybean (Glycine max) rotation under a no-till system starting in the year 2000 in Brookings SD; and in continuous corn and switch grass (Panicum virgatum) at Flandrean SD starting in the year 2007. A tension infiltrometer was used to characterize the mean equivalent pore radius, a type of soil structural index for measuring and evaluating soil structure in cropped fields and pastures. Our results show larger equivalent pore radius in treatments where the residue was retained in the corn-soybean rotation for the growing seasons 2008, 2009 and 2010 at Brookings SD. Similar results were observed for continuous corn and grass cropping system for the years 2009 and 2010 at Flandreau SD.  However, the equivalent pore radius was larger in the grass treatments irrespective of residue levels.