Contrasting Physiological and Environmental Controls of Evapotranspiration over Kernza Perennial Crop, Annual Crops, and C 4 and Mixed C 3 /C 4 Grasslands

Caitlyn E. Sutherlin, Nathaniel A. Brunsell, Gabriel de Oliveira, Timothy E. Crews, Lee R. DeHaan and Giulia Vico
Additional contact information
Caitlyn E. Sutherlin: Department of Geography and Atmospheric Science, University of Kansas, 1475 Jayhawk Blvd., Lawrence, KS 66045, USA
Nathaniel A. Brunsell: Department of Geography and Atmospheric Science, University of Kansas, 1475 Jayhawk Blvd., Lawrence, KS 66045, USA
Gabriel de Oliveira: Department of Geography and Atmospheric Science, University of Kansas, 1475 Jayhawk Blvd., Lawrence, KS 66045, USA
Timothy E. Crews: The Land Institute, 2440 East Well Rd., Salina, KS 67401, USA
Lee R. DeHaan: The Land Institute, 2440 East Well Rd., Salina, KS 67401, USA
Giulia Vico: Department of Crop Production Ecology, Swedish University of Agricultural Sciences, Ulls väg 16, Uppsala 75007, Sweden

Sustainability, 2019, vol. 11, issue 6, 1-14

Abstract: Perennial grain crops have been suggested as a more sustainable alternative to annual crops. Yet their water use and how they are impacted by environmental conditions have been seldom compared to those of annual crops and grasslands. Here, we identify the dominant mechanisms driving evapotranspiration (ET), and how they change with environmental conditions in a perennial Kernza crop (US-KLS), an annual crop field (US-ARM), a C 4 grassland (US-KON), and a mixed C 3 /C 4 grassland (US-KFS) in the Central US. More specifically, we have utilized the omega (Ω) decoupling factor, which reflects the dominant mechanisms responsible for the evapotranspiration (ET) of the canopy. Our results showed that the US-ARM site was the most coupled with the lowest decoupling values. We also observed differences in coupling mechanism variables, showing more sensitivity to the water fluctuation variables as opposed to the radiative flux variables. All of the sites showed their lowest Ω value in 2012, the year of the severe drought in the Central US. The 2012 results further indicate the dependence on the water fluctuation variables. This was especially true with the perennial Kernza crop, which displayed much higher soil moisture values. In this regard, we believe that the ability of perennial Kernza to resist water stress and retain higher soil moisture values is both a result of its deeper roots, in addition to its higher Ω value. Through the analysis of both the site comparison and the comparison of the differences in years, we conclude that the perennial Kernza crop (US-KLS) is more similar in its microclimate effects to the C 4 (US-KON) and mixed C 3 /C 4 (US-KFS) grassland sites as opposed to its annual counterpart (US-ARM). This has implications for the role of perennial agriculture for addressing agricultural resilience under changing climate conditions.

Keywords: perennial agriculture; annual crops; grasslands; water and radiative fluxes; decoupling factor (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2019
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