Abstract
Core Ideas In this study, switchgrass grew well on marginally saline soil with limited irrigation.The southern‐origin cultivars had greater biomass yield than the northern cultivars.Irrigation increased above and below ground biomass, but not soil C and N content.Switchgrass had the potential to sequester C into the soil. Limited information is available on switchgrass (Panicum virgatum L.) productivity in semiarid environments. A field experiment was conducted in semiarid Colorado, with the objectives were to determine: 1) aboveground biomass production of six upland switchgrass cultivars, and 2) soil organic carbon content of two switchgrass cultivars grown on a marginally saline soil under rainfed and minimal irrigation conditions. The experiment was a split plot design with rainfed vs. minimal irrigation treatment as the main plot and six cultivars [three southern cultivars (Blackwell, Pathfinder, and Trailblazer) and three northern cultivars (Sunburst, Forestburg, and Dacotah)] as subplot with three replications. Aboveground biomass for the six cultivars ranged from 1.1 to 7.8 Mg ha−1yr−1 in the establishment year, and 3.2–9.3 and 3.3–11.7 Mg ha−1yr−1 under rainfed and minimally irrigated conditions, respectively, during the following three stand years. Minimal irrigation (mean annual irrigation water of 21 cm) increased biomass yield compared to the rainfed control. Southern‐origin cultivars produced more biomass than the northern lines under both rainfed and minimal irrigation. Four years after establishment, within the top 0.6 m of soil, irrigation increased root biomass, with averages of 9.9 and 5.2 Mg ha−1 yr−1 for irrigation and rainfed treatments, respectively. Soil organic carbon accumulated rapidly at 0–20 cm soil depth in Blackwell and Pathfinder plots, at the rates of 1.07–1.36 Mg C ha−1 yr−1. Switchgrass growth in the semiarid environment was improved with limited supplemental irrigation and had the potential to sequester C into soil.
Highlights
Switchgrass has considerable potential as a feedstock for bioenergy production because of high biomass yield, water use efficiency, and salinity tolerance (Jungers et al, 2015; Wagle et al, 2016)
A field experiment was conducted in semiarid Colorado, with the objectives were to determine: 1) aboveground biomass production of six upland switchgrass cultivars, and 2) soil organic carbon content of two switchgrass cultivars grown on a marginally saline soil under rainfed and minimal irrigation conditions
Our results suggest that the southern-origin cultivars had greater biomass yields than the northern cultivars
Summary
Switchgrass has considerable potential as a feedstock for bioenergy production because of high biomass yield, water use efficiency, and salinity tolerance (Jungers et al, 2015; Wagle et al, 2016). It is generally considered to have a wide range of adaptability across varied landscapes, soil types, and ecozones, and has the potential for production on marginal lands not well suited to food or feed production because of the low productivity due to inherent edaphic or climatic limitations (McLaughlin and Kszos, 2005; Schmer et al, 2008; Gelfand et al, 2013; Smith et al, 2013; Qin et al, 2015; Gu and Wylie, 2016; Oliveira et al, 2017). Competition for arable land and water resources, and the heavy reliance of fossil fuel based agricultural inputs have been of concern regarding bioenergy production (Schmer et al, 2008). Emphasis should be placed on developing energy crops that thrive with minimal inputs on marginal land
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