Cellulosic biofuel crops alter evapotranspiration and drainage fluxes: Direct quantification using automated equilibrium tension lysimeters

Abstract

An increasing number of crops are being considered as potential sources of biomass for both conventional (e.g., maize/corn) and cellulosic (e.g., switchgrass, miscanthus, and hybrid poplar) biofuels. Studies investigating the hydrologic characteristics of these crops are often conducted at either the field scale with a focus on evapotranspiration (ET) or at the plot scale where experiments generally rely on soil water storage dynamics and residual water balances. While this has led to many important insights into crop–soil water interactions under these crops, there does not appear to be any multiyear direct comparisons of the drainage fluxes under this range of biofuel crops. Furthermore, important advancements in drainage flux measurement technologies have yet to be applied to quantify hydrologic fluxes below a range of biofuel crops. Here, we use soil water content (SWC) probes and automated equilibrium tension lysimeters (AETL) to characterize detailed differences in soil water storage and drainage fluxes under conventional and cellulosic biofuel crops. The results of this study suggest that there are significant differences between subsurface water fluxes under some conventional and cellulosic biofuel crops, such as 75% greater average annual drainage and more rapid drainage accumulation under switchgrass relative to maize.

Long‐term evapotranspiration rates for rainfed corn versus perennial bioenergy crops in a mesic landscape

“…For example, in nearby sites, Hamilton et al () found similar ET gs rates for switchgrass, restored prairie, and corn. Parish et al () also found similar ET gs rates between switchgrass and corn in the upper US Midwest. In southern Ontario, Canada, Eichelmann, Wagner‐Riddle, Warland, Deen, and Voroney () found lower ET gs rates for switchgrass than for corn.…”

“…There was not much difference in the soil surface and physical conditions between the perennial and corn fields within each land use history in the first 2 years following conversion as the fields had been managed similarly for many years prior. However, the difference in crop types and management from 2013 onwards likely resulted in higher root biomass that add organic matter to the soil (Kong & Six, ; Ruess et al, ) improving soil structure and consequently the infiltration of precipitation (Bonin, Lal, Schmitz, & Wullschleger, ; Zaibon et al, ) into the soil through improved soil surface conditions in the perennial fields (e.g., Parish et al, ).…”

“…Field experiments that compare water use in rainfed annual corn and perennial (e.g., switchgrass and restored prairie) bioenergy crops are few and limited to the early‐ to mid‐establishment phases of the perennial crops; these studies have shown that crops on well‐drained soils have similar ET rates (e.g., Abraha et al, ; Hamilton, Hussain, Bhardwaj, Basso, & Robertson, ; Parish, Kendall, Thompson, Stenjem, & Hyndman, ). On tile‐drained soils with high water tables, ET rates by perennials can be higher compared with corn (e.g., Hickman, VanLoocke, Dohleman, & Bernacchi, ; Zeri, Hussain, Anderson‐Teixeira, DeLucia, & Bernacchi, ).…”

Hydraulic redistribution by deeply rooted grasses and its ecohydrologic implications in the southern Great Plains of North America

“…Field studies that have compared ET in annual crops to that of perennial biofuel crops are fairly limited, and the results have been mixed. For well-drained soils, some studies have found that both crop types have similar growing-season ET rates (Abraha et al, 2015;Abraha et al, 2020;Hamilton et al, 2015;Parish et al, 2019), while perennials have higher growing-season ET rates than annual crops in soils with high water tables (Hickman et al, 2010;Zeri et al, 2013).…”

“…Field studies that have compared ET in annual crops to that of perennial biofuel crops are fairly limited, and the results have been mixed. For well‐drained soils, some studies have found that both crop types have similar growing‐season ET rates (Abraha et al, 2015; Abraha et al, 2020; Hamilton et al, 2015; Parish et al, 2019), while perennials have higher growing‐season ET rates than annual crops in soils with high water tables (Hickman et al, 2010; Zeri et al, 2013). Similarly, mixed results come from modelling studies, as some show no difference in growing‐season ET rates (Song et al, 2016), while others show higher growing‐season ET rates for perennials than for annuals (Le et al, 2011; Schilling et al, 2008; VanLoocke et al, 2012; Zhuang et al, 2013).…”