Perennial rye crop shows potential for greener agriculture

Sep 05, 2022

Annual crops are the farmer’s bread and butter, the crops they rely on most, but at least one type of perennial grain is proving much more beneficial to the environment.

A crop of perennial rye absorbed a substantial amount of carbon dioxide, or CO2, a University of Alberta study showed, while an annual crop had no greenhouse gas uptake.

The discovery builds on previous research by the team that found environmental and other advantages to including perennial crops in farmers’ planting lineup.

“While there’s still much more research to be done, they’re emerging as one more option that farmers could use in their tool kit to contribute to sustainable agriculture,” said study co-author Guillermo Hernandez Ramirez, a soil scientist in the Faculty of Agricultural, Life & Environmental Sciences.

A four-hectare segment of perennial rye can absorb an amount of atmospheric CO2 equivalent to a vehicle burning 35,000 litres of gasoline, according to the two-year experiment at the U of A’s Breton Plots.

There are several possible reasons for this, said Keunbae Kim, who co-authored the study to earn his master’s degree in soil science.

Perennial crops, which include other grains such as wheat, as well as legumes and oilseeds, remain productive for two or more years after being planted. Annual crops are planted every year.

The study also showed that the perennial plot didn’t use more water than its annual cousin — another positive finding, Kim noted.

“We were concerned that perennial rye could lead to drought because of longer growing seasons and the fact it had more biomass.”

Earlier research by the team showed that perennial rye also mitigates nitrous oxide, another greenhouse gas, and that the crop stores more carbon in the soil.

Other U of A research has shown that annual grain crops have the potential to sequester carbon – depending on factors like crop rotation, fertilizer supplements, and climate and soil conditions – but not as much as the perennial grain in the latest research, Hernandez Ramirez added.

Food producers are more comfortable using annual crops, but he believes further research will change that.

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Video: Wheat Yields in USA and China Threatened by Heat Waves Breaking Enzymes

A new peer reviewed study looks at the generally unrecognized risk of heat waves surpassing the threshold for enzyme damage in wheat.

Most studies that look at crop failure in the main food growing regions (breadbaskets of the planet) look at temperatures and droughts in the historical records to assess present day risk. Since the climate system has changed, these historical based risk analysis studies underestimate the present-day risks.

What this new research study does is generate an ensemble of plausible scenarios for the present climate in terms of temperatures and precipitation, and looks at how many of these plausible scenarios exceed the enzyme-breaking temperature of 32.8 C for wheat, and exceed the high stress yield reducing temperature of 27.8 C for wheat. Also, the study considers the possibility of a compounded failure with heat waves in both regions simultaneously, this greatly reducing global wheat supply and causing severe shortages.

Results show that the likelihood (risk) of wheat crop failure with a one-in-hundred likelihood in 1981 has in today’s climate become increased by 16x in the USA winter wheat crop (to one-in-six) and by 6x in northeast China (to one-in-sixteen).

The risks determined in this new paper are much greater than that obtained in previous work that determines risk by analyzing historical climate patterns.

Clearly, since the climate system is rapidly changing, we cannot assume stationarity and calculate risk probabilities like we did traditionally before.

We are essentially on a new planet, with a new climate regime, and have to understand that everything is different now.