Conventional and organic management effects on annual and perennial root biomass

Sprunger, C.D., S.S. Snapp and S. W. Culman

Presented at the All Scientist Meeting (2012-03-15 to 2012-03-16 )

Agriculture has a tremendous ‘ecological footprint’ as it is a leading contributor to carbon dioxide emissions, and other potent greenhouse gases. At the same time, innovative agricultural practices have the potential to mitigate climate change, by sequestering carbon. A transformative approach to a more sustainable agriculture has been proposed through developing perennial grain cropping systems, which produce edible grain without the need to till and replant every year. Yet, very little is known about growth of shoots and roots in novel perennial grain crops, such as intermediate wheatgrass (IWG), which is a perennial forage that has been selected for higher grain yield. This study is the first to quantify root biomass along a species and management gradient, comparing annual winter wheat (WW) to perennial IWG under conventional and organic management practices. In June of 2011, soil cores were taken to a depth of 100cm, roots recovered at different depth intervals and separated into coarse and fine roots. Minirhizotron images were also taken to assess root turnover. The IWG root biomass was five times greater than the WW root biomass. A trend was observed towards management influencing coarse root biomass, and in the topsoil roots were significantly different under organic and conventional management. Overall, perennial cropping systems had substantially higher root biomass than annual crops, which has important implications for building soils, and enhancing carbon sequestration within agriculture.