Reductions in soil water nitrate beneath a perennial grain crop compared to an annual crop rotation on sandy soil

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Nitrate ( (Formula presented.) -N) leaching into groundwater as a result of high nitrogen (N) fertilizer rates to annual crops presents human health risks and high costs associated with water treatment. Leaching is a particularly serious concern on sandy soils overlying porous bedrock. Intermediate wheatgrass (IWG) [Thinopyrum intermedium (Host.) Barkw. & D.R. Dewey], is a perennial grass that is being bred to produce agronomically and economically viable grain, which is commercially available as Kernza®. Intermediate wheatgrass is a low-input crop has the potential to produce profitable grain and biomass yields while reducing (Formula presented.) -N leaching on sandy soils compared with common annual row crop rotations in the Upper Midwest. We compared grain yields, biomass yields, soil solution (Formula presented.) -N concentration, soil extractable (Formula presented.) -N, soil water content, and root biomass under IWG and a conventionally managed corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] rotation for 3 years on a Verndale sandy loam in Central Minnesota. Mean soil solution (Formula presented.) -N was 77–96% lower under IWG than the annual crop rotation. Soil water content was greater under annuals compared to IWG early in the growing season, suggesting greater water use by IWG during this time. Interactions between crop treatments and depth were observed for soil water content in Year 3. Root biomass from 0 to 60 cm below the soil surface was five times greater beneath IWG compared to soybean, which may explain differences in soil extractable and solution (Formula presented.) -N among crops. With irrigation on coarse structured soils, IWG grain yields were 854, 434, and 222 kg ha−1 for Years 1–3 and vegetative biomass averaged 4.65 Mg ha−1 yr−1; comparable to other reports on heavier soils in the region. Annual crop grain yields were consistent with local averages. These results confirm that IWG effectively reduces soil solution (Formula presented.) -N concentrations even on sandy soils, supporting its potential for broader adoption on land vulnerable to (Formula presented.) -N leaching.

Original languageEnglish (US)
Article number996586
JournalFrontiers in Sustainable Food Systems
StatePublished - Sep 26 2022

Bibliographical note

Funding Information:
The authors would like to thank Lindsay Wilson, Katherine Bohn, and the rest of the Sustainable Cropping Systems Lab staff for their dedication and assistance with essential research activities. We would also like to thank Ryan Perish and Hannah Barrett for their invaluable contributions to data collection and site maintenance. We thank Matthew Leung and Manbir Rakkar for assisting with soil nitrate extractions. We also thank Margaret Wagner for her contribution to project administration. Funding for this project was provided by the Minnesota Environment and Natural Resources Trust Fund as recommended by the Legislative-Citizen Commission on Minnesota Resources (LCCMR).

Publisher Copyright:
Copyright © 2022 Reilly, Gutknecht, Sheaffer and Jungers.


  • Kernza
  • groundwater
  • intermediate wheatgrass
  • leaching
  • nitrate
  • perennial grains


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