TY - JOUR
T1 - Switchgrass composition and yield response to alternative soil amendments under intensified heat and drought conditions
AU - Ashworth, A. J.
AU - Weiss, S. A.
AU - Keyser, P. D.
AU - Allen, F. L.
AU - Tyler, D. D.
AU - Taylor, A.
AU - Beamer, K. P.
AU - West, C. P.
AU - Pote, D. H.
N1 - Funding Information:
Support for this research was provided by a grant from the Southeastern Sun Grant Center with funds provided by the U.S. Department of Transportation Research and Innovative Technology Administration (DTOS59-07-G-00050). In addition, authors thank the Agricultural Research and Education Centers in St. Croix, USVI and in Greenville, TN (Rob Ellis) and Knoxville, TN (Lee Ellis) for their help in collecting data and making this research possible. Lastly, gratitude is extended to the laboratory of Dr. Samy Sadaka at the University of Arkansas for the production of biochars used in field investigations.
Publisher Copyright:
© 2016
PY - 2016/10/3
Y1 - 2016/10/3
N2 - Switchgrass (Panicum virgatum L.) and guinea grass (Panicum maximum Jacq.) have been proposed as sustainable alternatives to fossil fuels in subtropical and tropical environments, respectively; although still requiring non-renewable inputs, notably, fertilizer-nitrogen (N). Furthermore, climatic intensification forecasts suggest southeastern USA may emulate more tropical or subtropical growing conditions resulting in altered N dynamics and plant physiology. Objectives were to determine: (i) effects of biochar (1 and 2 Mg ha−1), two intercropped legumes [sunn hemp (Crotalaria juncea L.) and pigeon pea (Cajanus cajan L.) intercrops] versus inorganic N [67 kg ha−1and 0 kg ha−1] on feedstock and soil characteristics and biomass yield; (ii) how feedstock composition is affected over three harvest dates; and, (iii) switchgrass adaptation to more extreme (tropical) growing conditions. For both species, yield and feedstock composition were influenced by harvest timing (P < 0.05), whereas soil amendments influenced composition to a lesser extent over the duration of this study (P > 0.05). In general, initial harvests had greater digestible 5- and 6-carbon sugars and N, P, and K tissue levels, whereas in subsequent harvests, higher acid- and neutral-detergent fiber levels were observed, suggesting lesser potential fermentability. Desired feedstock characteristics can therefore be manipulated by harvest timing. Yield results suggest pigeon pea and sunn hemp intercrops, and biochar (1 Mg ha−1) may result in equivalent yields as N fertilizer per harvest (P < 0.05). However, the 2 Mg ha−1 biochar rate in the tropics adversely impacted yields, perhaps due to N immobilization by biochar. Switchgrass adaptation and competitiveness was moderate (5–30% weed cover) under an intensified climate. Growth can therefore be maintained under a stochastic climate due to its C4 pathway and competitive growth on marginal soils.
AB - Switchgrass (Panicum virgatum L.) and guinea grass (Panicum maximum Jacq.) have been proposed as sustainable alternatives to fossil fuels in subtropical and tropical environments, respectively; although still requiring non-renewable inputs, notably, fertilizer-nitrogen (N). Furthermore, climatic intensification forecasts suggest southeastern USA may emulate more tropical or subtropical growing conditions resulting in altered N dynamics and plant physiology. Objectives were to determine: (i) effects of biochar (1 and 2 Mg ha−1), two intercropped legumes [sunn hemp (Crotalaria juncea L.) and pigeon pea (Cajanus cajan L.) intercrops] versus inorganic N [67 kg ha−1and 0 kg ha−1] on feedstock and soil characteristics and biomass yield; (ii) how feedstock composition is affected over three harvest dates; and, (iii) switchgrass adaptation to more extreme (tropical) growing conditions. For both species, yield and feedstock composition were influenced by harvest timing (P < 0.05), whereas soil amendments influenced composition to a lesser extent over the duration of this study (P > 0.05). In general, initial harvests had greater digestible 5- and 6-carbon sugars and N, P, and K tissue levels, whereas in subsequent harvests, higher acid- and neutral-detergent fiber levels were observed, suggesting lesser potential fermentability. Desired feedstock characteristics can therefore be manipulated by harvest timing. Yield results suggest pigeon pea and sunn hemp intercrops, and biochar (1 Mg ha−1) may result in equivalent yields as N fertilizer per harvest (P < 0.05). However, the 2 Mg ha−1 biochar rate in the tropics adversely impacted yields, perhaps due to N immobilization by biochar. Switchgrass adaptation and competitiveness was moderate (5–30% weed cover) under an intensified climate. Growth can therefore be maintained under a stochastic climate due to its C4 pathway and competitive growth on marginal soils.
KW - Alternative soil amendments
KW - Biochar
KW - Climatic intensification
KW - Feedstock composition
KW - Legume intercropping
KW - Plant adaptation
UR - http://www.scopus.com/inward/record.url?scp=84991511941&partnerID=8YFLogxK
U2 - 10.1016/j.agee.2016.09.041
DO - 10.1016/j.agee.2016.09.041
M3 - Review article
AN - SCOPUS:84991511941
VL - 233
SP - 415
EP - 424
JO - Agriculture, Ecosystems and Environment
JF - Agriculture, Ecosystems and Environment
SN - 0167-8809
ER -