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A Comparison of Perennial Polycultures and Monocultures for Producing Biomass for Biorefinery Feedstock
Author(s) -
Griffith Andrew P.,
Epplin Francis M.,
Fuhlendorf Samuel D.,
Gillen Robert
Publication year - 2011
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj2010.0336
Subject(s) - polyculture , monoculture , panicum virgatum , biology , agronomy , perennial plant , biomass (ecology) , andropogon , biorefinery , bioenergy , raw material , ecology , biofuel , aquaculture , fishery , fish <actinopterygii>
Before planting millions of hectares to switchgrass ( Panicum virgatum L.) monocultures for producing biomass feedstock for biorefineries, it has been proposed that monocultures be tested against polycultures so, among other issues, the economics of both systems can be compared. This research was conducted to determine the lowest cost lignocellulosic biomass feedstock production system from among four monocultures and four polycultures. Randomized complete block designs with four replications were established at two Oklahoma locations. Plots were managed to represent anticipated production activities if perennial species were established in a low input system and harvested once a year to produce biorefinery feedstock. The four monocultures included switchgrass, sand bluestem ( Andropogon hallii Hack.), Old World bluestem (OWB) ( Bothriochloa ischaemum L. Keng), and big bluestem ( A. gerardii Vitman). The four polycultures included mixtures of four grasses, four grasses and four forbs, eight grasses and eight forbs, and OWB with alfalfa ( Medicago sativa L.). Plots were harvested once a year for 3 yr. For every treatment that included a mix of species, a dominant species emerged by the third harvest, suggesting that over time these treatments may not differ greatly from monocultures with minor representation of other species. The average yield was 4.6 Mg ha −1 yr −1 for treatments seeded as monocultures at one location compared with 4.0 Mg ha −1 yr −1 for the treatments seeded as polycultures. At the second location, monocultures averaged 7.9 Mg ha −1 yr −1 and polycultures 6.5 Mg ha −1 yr −1 Economics favored monocultures for the location and environmental conditions that occurred during the time period studied.