Switchgrass Cultivation Impact on Water Resources Across Different Soils in Michigan.

Growing switchgrass on marginal land for biofuel feedstock production has received attentions not only because of switchgrass potential to produce sizable biomass with little agricultural production inputs but also because it may cause changes to the regional water cycle. The objective of this study was to evaluate the impact of switchgrass production on evapotranspiration and soil water content across good agricultural soils and marginal land in Michigan using the Systems Approach to Land Use Sustainability (SALUS) model. The model-required historical weather and soil information were derived from the North American Regional Reanalysis dataset and the Soil Survey Geographic (SSURGO) database. Soil marginality was obtained from the SSURGO database as well. The model was run for switchgrass grown across different quality of soils under rain-fed and unfertilized scenario between 1979 and 2012. The SALUS model was validated using switchgrass growth data from the Kellogg Biological Station. Preliminary results showed that the average switchgrass yield on marginal and agricultural soils were 7.3 Mg/ha and 8.1 Mg/ha, respectively. The average switchgrass evapotranspiration were 509 mm and 454.0 mm, respectively but the yields were not correlated to the evapotranspiration (r2<0.25). The average annual switchgrass transpiration from the two soils were 459 and 461.6 mm, respectively and were more correlated with the yields (r2>0.5) . Soil water evaporation was higher from marginal soils (321 mm) than crop soils (278 mm).