Strip-tillage renovation of intermediate wheatgrass (Thinopyrum intermedium) for maintaining grain yield in mature stands

Eugene P Law,Christopher J Pelzer,Sandra Wayman,Antonio Ditommaso,Matthew R Ryan

doi:10.1017/s1742170520000368

Abstract

AbstractKernza® intermediate wheatgrass [Thinopyrum intermedium (Host) Barkworth & Dewey], the first perennial grain crop to come to market in North America, can provide a number of ecosystem services when integrated into cropping systems that are dominated by annual grain crops. However, grain yield from Kernza is lower than comparable annual cereal crops such as wheat and oats. Also, although Kernza is a long-lived perennial that can persist for decades, grain yield tends to decline over time as Kernza stands age leading most farmers to replant or rotate to a different crop after 3–5 yrs. Increased intraspecific competition as stand density increases with age has been reported to cause grain yield declines. We investigated the effect of strip-tillage applied at two different timings, between the third and fourth grain harvests, from a Kernza stand in upstate New York. Strip-tillage applied in late fall as plants were entering dormancy increased grain yield by 61% when compared to the control treatment without strip-tillage. However, total crop biomass was not reduced resulting in a greater harvest index for the fall strip-tillage treatment. Strip-tillage applied before stem elongation the following spring reduced overall tiller density and total crop biomass but did not impact tiller fertility or grain yield compared to the control treatment without strip-tillage. Increased grain yield in the fall strip-tillage treatment was due to an increase in the percentage of tillers that produced mature seedheads. This suggests that grain yield decline over time is at least partially caused by competition between tillers in dense stands. Results support further research and development of strip-tillage and other forms of managed disturbance as tools for maintaining Kernza grain yield over time.

Highlights

Perennial grain crops have the potential to produce staple foods and forage for livestock while mitigating many of the environmental externalities of annual grain production (Pimentel et al, 2012; Crews et al, 2018)
Fall strip-tillage increased grain yields compared with spring strip-tillage and control treatments (Table 2)
Total tiller density m−2 was marginally reduced by 24% in the fall strip-tillage treatment when compared to the control treatment (P = 0.058)

Summary

Introduction

Perennial grain crops have the potential to produce staple foods and forage for livestock while mitigating many of the environmental externalities of annual grain production (Pimentel et al, 2012; Crews et al, 2018). Development of intermediate wheatgrass as a perennial grain crop is largely motivated by its ability to contribute ecosystem services including enhanced soil health and water quality (Culman et al, 2013; Jungers et al, 2019), and the potential for soil carbon storage to mitigate anthropogenic climate change (Sprunger et al, 2017, 2019; Pugliese et al, 2019) These characteristics have motivated food industries to develop products that incorporate Kernza as part of their corporate sustainability strategy (Lubofsky, 2016; Karnowski, 2017)

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