Modeling spatial and dynamic variation in growth, yield, and yield stability of the bioenergy crops Miscanthus × giganteus and Panicum virgatum across the conterminous United States

Abstract

C4 perennial grasses are being considered as environmentally and economically sustainable high yielding bioenergy feedstocks. Temporal and spatial variation in yield across the conterminious United States is uncertain due to the limited number of field trials. Here, we use a semi-mechanistic dynamic crop growth and production model to explore the potential of Miscanthus × giganteus (Greef et. Deu.) and Panicum virgatum L. across the conterminous United States. By running the model for 32 years (1979-2010), we were able to estimate dry biomass production and stability. The maximum rainfed simulated end-of-growth-season harvestable biomass for M. × giganteus was ca. 40 Mg ha-1 and ca. 20 Mg ha-1 for P. virgatum. In addition, regions of the southeastern United States were identified as promising due to their high potential production and stability and their relative advantage when compared with county-level maize biomass production. Regional and temporal variation was most strongly influenced by precipitation and soil water holding capacity. Miscanthus 9 giganteus was on average 2.2 times more productive than P. virgatum for locations where yields were ≥10 Mg ha-1. The predictive ability of the model for P. virgatum was tested with 30 previously published studies covering the eastern half of the United States and resulted in an index of agreement of 0.71 and a mean bias of only -0.62 Mg ha-1 showing that, on average, the model tended to only slightly overestimate productivity. This study provides with potential production and variability which can be used for regional assessment of the suitability of dedicated bioenergy crops. © 2011 Blackwell Publishing Ltd.