Crop and Soil Sciences Calendar
MS Exit Seminar
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Soil Science Exit Seminar
Tommy Stephenson, MS Student, Soil Science, NCSU, will present an exit seminar titled:
“Water Use and Soil Physical Property Changes Following Land Conversion to Bioenergy Cropping Systems in the North Carolina Piedmont” (under the direction of Dr. Josh Heitman)
on 10 July 2018 at 9:00 AM in the McKimmon Room (2223 WMS).
All are welcome to attend.
An increased demand for non-fossil fuels has led to a significant interest in sustainable bioenergy though the production of lignocellulosic bioenergy crops. While these crops have shown potential in other regions of the USA, their productivity and sustainability for the marginal soils of the southeastern piedmont are unknown. The overall goal of this research is to inform prospective growers on the potential water consumption and long-term soil impacts of bioenergy crop production in the southeastern piedmont. We evaluated potential bioenergy crops including perennial rhizomatous grasses switchgrass (Panicum virgatum L.) and giant miscanthus (Miscanthus × giganteus) and annual biomass sorghum (Sorghum Bicolor spp.). Our specific objectives were to 1) evaluate the growth, water use, and yields of bioenergy cropping systems by developing crop coefficients to predict water use from reference evapotranspiration; and 2) evaluate changes in soil physical properties following six years after land conversion from fescue hay (Festuca arundiainacea Schreb.) to bioenergy cropping systems. Research was conducted on a Mecklenburg clay loam in the piedmont of NC. Cropping systems at this site included switchgrass, giant miscanthus, biomass sorghum, corn silage (Zea mays) (traditional crop), and fescue hay (previous management). The perennial systems were established in 2012 while annuals were planted each spring using no-till practices. Crop water use was evaluated for the 2016 and 2017 growing season using a water balance approach. Crop coefficients were developed from water balance data, and then used to predict season long water use from weather data. Giant miscanthus had the highest two-year average biomass yield (29.1 Mg ha-1) followed by corn silage (23.55 Mg ha-1) and biomass sorghum (22 Mg ha-1). Fescue hay had the highest season-long water use in both years of the study. Perennial grasses giant miscanthus and switchgrass had similar seasonal water use, but giant miscanthus had a higher water use efficiency than switchgrass. The annual crops corn and sorghum both used less total water than the perennial systems because of their shorter growing season, and both also had higher water use efficiencies. Soil aggregate stability was evaluated following the 2016 and 2017 growing seasons using wet sieving and dispersion techniques. Soil bulk density, saturated hydraulic conductivity, and water retention was measured using intact soil cores collected following harvest in 2017. Six years after land conversion, switchgrass was the only cropping system with surface layer physical properties that differed from fescue hay, which likely occurred because of management practices during re-establishment. In the subsurface layer, miscanthus, sorghum, and switchgrass had fewer stable aggregates than fescue. Miscanthus had a lower volume of macropores than fescue, which likely resulted in greater water retention and a lower saturated hydraulic conductivity. Overall, production of bioenergy cropping systems in the NC piedmont appears feasible based on results from this study. All cropping systems considered consumed less water while producing similar to higher amounts of biomass than the previous land management (fescue hay). While perennial bioenergy cropping systems did slightly alter some soil physical properties in comparison to the previous land management, changes were modest when using no-till management practices for establishment.