Kernza and Perrenial Grains

Wes Jackson, from the Land Institute in Kansas has been working on perennializing what for over 30 years, in an effort to save our agricultural soil from the damage of annual grains.  He has a biblical way of speaking: “The plow has destroyed more options for future generations than the sword,” he says. “But soil is more important than oil, and just as nonrenewable.” Soil loss is one of the biggest hidden costs of industrial agriculture — and it’s created at literally a glacial pace, maybe a quarter-inch per century. The increasingly popular no-till style of agriculture reduces soil loss but increases the need for herbicides. It’s a short-term solution, requiring that we poison the soil to save it.  With global climate change and the need to maximize use of water, the time to worry about this is now.

Perennial grain cropping systems could address a number of contemporary agroecological problems, including soil degradation, NO₃ leaching, and soil C loss. Since it is likely that these systems will be rotated with other agronomic crops, a better understanding of how rapidly perennial grain systems improve local ecosystem services is needed. A recent study quantified soil moisture, lysimeter NO₃ leaching, soil labile C accrual, and grain yields in the first 2 yr of a perennial grain crop under development [kernza wheatgrass, Thinopyrum intermedium (Host) Barkworth & D.R. Dewey] relative to annual winter wheat (Triticum aestivum L.) under three management systems. Overall, differences between annual and perennial plants were much greater than differences observed due to management. In the second year, perennial kernza reduced soil moisture at lower depths and reduced total NO₃ leaching (by 86% or more) relative to annual wheat, indicating that perennial roots actively used more available soil water and captured more applied fertilizer than annual roots. Carbon mineralization rates beneath kernza during the second year were increased 13% compared with annual wheat. First-year kernza grain yields were 4.5% of annual wheat, but second year yields increased to 33% of wheat with a harvest index of 0.10. Although current yields are modest, the realized ecosystem services associated with this developing crop are promising and are a compelling reason to continue breeding efforts for higher yields and for use as a multipurpose crop (e.g., grain, forage, and biofuel).