General Plant Characteristics

1
Simulating Switchgrass
Production in Diverse
Environments

Jim R. Kiniry
USDA-ARS, Temple, TX
Introduction Recent
increased appreciation of grasses as biofuels has
expanded the interest in switchgrass (Panicum
virgatum L.) production in the U.S. Alamo
switchgrass is one of the most productive and
versatile plants useful for biomass production
for energy. . Objective To summarize our
research on the physiology and modeling of
switchgrass
Summary Field
research at Temple, TX described the processes
leading to the high biomass productivity of
switchgrass. The ALMANAC model is a useful tool
for evaluating switchgrass yield in diverse
locations in the U.S.
REFERENCES Kiniry, J.R., C.A. Jones,
J.C. OToole, R. Blanchet, M. Cabelguenne, and
D.A. Spanel. 1989. Radiation-use efficiency in
biomass accumulation prior to grain-filling for
five grain-crop species. Kiniry, J.R., J.R.
Williams, P.W. Gassman, and P. Debaeke. 1992. A
general, process-oriented model for two competing
plant species. Trans. of ASAE 35 801-810.
Kiniry, J.R., C.R. Tischler, and G.A.
VanEsbroeck. 1999. Radiation use efficiency and
leaf CO2 exchange for diverse C4 grasses.
Biomass and Bioenergy 17 95-112. Kiniry, J.
R., M.A. Sanderson, J.R. Williams, C.R. Tischler,
M.A. Hussey, W.R. Ocumpaugh, M.C. Read, G. Van
Esbroeck, and R.L. Reed. 1996. Simulating Alamo
switchgrass with the ALMANAC model. Agron. J.
88602-606. Kiniry, J.R., K.A. Cassida, M.A.
Hussey, J.P. Muir, W.R. Ocumpaugh, J.C. Read,
R.L. Reed, M.A. Sanderson, B.C. Venuto, and J.R.
Williams. 2005. Switchgrass simulation by the
ALMANAC model at diverse sites in the southern
US. Biomass and Bioenergy 29 419-425. Kiniry,
J.R., B.L. Burson, G.W. Evers, J.R. Williams, H.
Sanchez, C. Wade, J.W. Featherston, and J.
Greenwade. 2006. Coastal bermudagrass,
bahiagrass, and native range simulation at
diverse sites in Texas accepted in Agron. J.
S. B. McLaughlin, J.R. Kiniry, C. M. Taliaferro,
and D. De La Torre Ugarte. 2006. Projecting yield
and utilization potential of switchgrass as an
energy crop. Adv. in Agronomy 90 267-297.
General Plant
Characteristics
Switchgrass has a high potential LAI of 6 and
greater (Kiniry et al., 1999 Kiniry et al.,
2006) Mean light
extinction coefficient of 0.33 (Kiniry et al.,
1999) High mean
radiation use efficiency of 4.7 g per MJ
intercepted PAR (Kiniry et al., 1999) as compared
to 3.5 for maize (Zea mays L.) (Kiniry et al.,
1989) Deep rooting, with
maximum rooting depth of 2.0 m or greater (Kiniry
et al., 1999) Model Simulations Reasonably
simulated six sites in Texas with data from two
years (Kiniry et al., 1996) Reasonably simulated
additional years with three sites in Texas, one
in Arkansas, and one in Louisiana (Kiniry et al.,
2005). Reasonably simulated mean yields for 5
years at Blacksburg, VA 2 years at Mead, NE two
years at Beeville, TX and 9 years for Tallassee,
AL (McLaughlin et al., 2006)

ALMANAC Model Description


ALMANAC (Kiniry et al., 1992) contains the
water balance and nutrient balance from the EPIC
model Simulates canopy-level LAI and light
interception Simulates biomass growth based on
radiation use efficiency (RUE), with reductions
due to drought stress, nutrient deficiency,
and interspecies competition Leaf area
development parameters and biomass growth
parameters developed in the field at Temple, TX