Perennial grains stay in the ground for more than one year, allowing deeper roots and longer periods of growth with less repeated soil disturbance. A University of Alberta experiment compared those traits with an annual rye crop and measured exchanges of carbon dioxide and water.
What the Breton Plots experiment found
Across two years, a four-hectare perennial rye plot absorbed an amount of atmospheric carbon dioxide comparable to the emissions from burning 35,000 litres of petrol. The annual comparison crop recorded no net carbon uptake over the same experiment.
Researchers linked the difference to a longer growing period, greater biomass and a larger, deeper root system. Earlier work by the team had also found more soil carbon storage and lower nitrous-oxide emissions in perennial rye.
More growth did not mean more water use
The team had been concerned that a longer season and larger crop might consume more water and add drought risk. In this trial, the perennial plot did not use more water than the annual rye. That makes the carbon result more interesting for water-limited regions, although one site and two years cannot represent every climate or soil.
The crop is not ready to replace annual grain at scale. Researchers still need to improve yield, disease management and winter survival, and farmers have decades more management knowledge for annual crops. Perennial rye is best understood as a promising additional tool that needs continued breeding and field testing.
Read the university report
Perennial rye crop shows potential for greener agriculture was written by Bev Betkowski for the University of Alberta. The original syndicated destination is no longer reliable, so this brief links to the university source. The study appeared in Agricultural and Forest Meteorology (DOI 10.1016/j.agrformet.2021.108805).