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The Center for Native Grasslands Management




Title: Selection and Improvement of Herbaceous Energy Crops for the Southeastern USA, Final Report in a Field and Laboratory Research Program for the period March 15, 1985 to March 19, 1990
Year: 1990
Author(s): Bransby, D. I., Sladden, S. E., Kee, D. D.
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Source Type: Other
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Original Publication: http://  
Abstract: The general aim of this research program was to screen herbaceous species and evaluate management practices for biomass production on marginal soils in Alabama and the southeastern USA. The program started with a 5-year evaluation of selected warm-cool season species rotations. Rainfall during the 5-year program was mostly below the long-term average, except in 1989 when it was above normal. Due to low rainfall, yields of perennial species took longer than expected to reach full production potential, increasing each year throughout the 5-year program. "Cave-in-Rock’’ switchgrass (Panicum virqatum), sericea lespedeza (Lespedeza cuneata) and johnsongrass (Sorqhum halepense) provided the highest yields from the warm season perennial species. Average yields for these species over the last two years when rainfall was near normal were 8.2, 7.1 and 5.9 Mg ha-1, with corresponding costs Mg-1 biomass of $42.2, $37.0 and $54.6. Sweet sorghum (Sorghum bicolor) was the best annual with an average yield in the last 2 years of 11.0 Mg ha-1 and a cost Mg-1 of $41.5. However, yield of annuals fluctuated more from year to year than that of perennials, suggesting that there would be a higher risk involved with growing annuals for biomass. The most significant trend in biomass composition was the notably high lignin and nitrogen content of sericea lespedeza when compared to the perennial grass species. During the course of the program additional experiments were initiated which included new species and additional varieties of switchgrass. Napiergrass (Pennisetum Duroureum) and energy cane (Saccharum hybrid) provided yields from 24 to 32 Mg biomass ha-1 in the second and third year after establishment, but sustainability of these yields are uncertain because no severely cold weather was experienced during the experimental period. In the second year after establishment "Alamo" switchgrass yielded 17.5 Mg biomass ha-1, resulting in a cost of only $19.7 Mg-1. This progress represented a major improvement on yields and production costs when compared to the original experiments. If yields of this level can be sustained and possibly improved a little more it is likely that the production basis for an economically viable herbaceous biomass-to-biofuel industry will be achieved in another 5 years. Future work should concentrate on optimizing management factors such as row spacing and harvesting regime, and on improving yield by plant breeding and selection.
Publisher: Oak Ridge National Laboratory Publication ORNL/Sub/85-27409/5
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