Matt Ruark and Kolby Bray-Hoagland: yield and sustainability of switchgrass for biofuel.

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Kolby Bray-Hoagland

Matt Ruark (Soil Science, University of Wisconsin - Madison) and master’s student Kolby Bray-Hoagland (Agroecology, University of Wisconsin – Madison) are investigating soil fertility issues related to sustainability of switchgrass? (Panicum virgatum) for biofuel? in southwestern Wisconsin. These researchers, in collaboration with Mark Renz and Randy Jackson (Agronomy, University of Wisconsin – Madison) have evaluated yield and quality in response to various management practices of switchgrass grown as for use as bioenergy? feedstock?. The research was carried out in the Driftless Area of western Wisconsin on land that is deemed unsuited to annual row crop production because of moderate to high soil erodability.

In the Driftless Area nitrogen and sediment loss from agricultural soil have widespread ecological repercussions in the Midwest and Gulf of Mexico. The production of switchgrass as a bioenergy crop has been put forward as a remediation strategy to improve the region’s nitrogen and sediment loss. Quantifying the possible ecosystem services? from switchgrass cropping systems has proved difficult to accomplish because little is known regionally on how management practices influence dry matter (DM) yield and the quality of switchgrass grown for bioenergy. Achieving adequate yields and minimizing nitrogen loss are necessary considerations for growers that intend to be profitable and environmentally sound stewards of the land.

The research conducted by Ruark and Bray-Hoagland investigated five nitrogen fertilizer rates (0, 50, 100, 150 and 200 lbs. of N/ acre) and three harvest timings (fall, winter and spring) over two years on established switchgrass stands. Switchgrass was measured for DM yield, moisture content and concentrations of nitrogen, phosphorus, potassium, sulfur, chloride and ash. Soil from the study sites were analyzed for pH, soil P and soil K. The thermal energy content of switchgrass was also analyzed from a sub-set of the treatments.

The ecosystem services that switchgrass is expected to produce will result from how switchgrass cropping systems are managed. The results and conclusions from the Ruark and Bray-Hoagland research will hopefully aid growers and scientists to better understand probable outcomes from nitrogen fertilizer application and harvest timing on switchgrass grown for bioenergy. Preliminary data was presented at the International Biomass? Conference in St. Louis, MO (May , 2011). Final data analysis has been completed and will be submitted to refereed journals by the end of the year. Research results will be presented at the Soil Science Society of America Meeting in San Antonio, TX (October 16-19, 2011).

The research was funded by the Southwest Badger RC&D, Focus on Energy, NRCS and USDA Seed Grant.
For more information contact Kolby Bray-Hoagland: brayhoagland@wisc.edu

Anerobic Digestion and Biogas

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A visit to switchgrass? trial plots run by Iowa State University researchers; near Ames, IA. Photo by CL Williams, 2010.