How Straw is Returned to Soil Can Make a Major Difference in Nitrous Oxide Emissions

Sep 29, 2026

Returning crop straw to farmland is widely used to recycle nutrients and improve soil quality. But new research shows that the way straw is returned to soil can strongly influence how effectively it limits emissions of nitrous oxide, a potent greenhouse gas.

Researchers compared several straw management strategies in nitrogen-fertilized saline-alkali soil and found that pelletized straw produced the strongest reduction in nitrous oxide, or N₂O, emissions. Under low nitrogen conditions, pelletized straw reduced cumulative emissions by 45.7% compared with soil receiving no straw, while the reduction remained 43.2% under high nitrogen input.

“Our results suggest that straw return should not be treated as a single management practice,” said corresponding author Yuping Zhuge of Shandong Agricultural University. “The physical form and processing pathway of straw can alter microbial nitrogen cycling, which in turn affects how much nitrous oxide is released from soil.”

The study focused on saline-alkali soils, which are often characterized by high pH, elevated salt levels and relatively low soil organic carbon. Farmers commonly rely on nitrogen fertilizer to sustain crop production in these soils, but added nitrogen can also stimulate microbial processes that generate N₂O.

The researchers conducted a 90-day incubation experiment using soil collected from a saline-alkali land improvement demonstration site in Weifang, Shandong Province, China. Two nitrogen application rates, equivalent to 120 and 240 kilograms per hectare, were tested. The team compared soil receiving no straw with four straw-derived treatments: crushed straw, pelletized straw, composted cattle manure derived from straw-fed livestock, and carbonized straw biochar.

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Video: From Students to Solutions | On The Brink: Season 2, Episode 14

Ask Canada’s most decorated soybean breeder his favourite part of the job and he doesn’t name a single variety. He names the students.

Istvan Rajcan is a professor of soybean breeding and genetics in the Department of Plant Agriculture at the University of Guelph, where he has run the soybean breeding program for 28 and a half years. In that time he has developed 87 soybean cultivars, published 140 refereed papers and trained 51 graduate students. In 2025 he received the Public Sector Impact Award from the National Association for Plant Breeding.

He is also worried. In this episode he says Canada is at a crossroads, pointing to recent government cuts to plant breeding programs and to the facilities that support them. His prescription is structural. "Plant breeding funding formula has to be a long-term one," he says.

The formula he is defending is the public-private matching arrangement his program runs on. Private seed companies fund the work, provincial or federal money matches it, and the combined pool stretches each dollar further than either source could alone. At the National Association for Plant Breeding annual meeting in June, he says American public breeders were often surprised at how well that collaboration works in Canada.

He also describes how the people entering plant breeding have changed. His early graduate students came mostly from farms. More recently they include, in his words, "city kids who just became excited about genetics."

Topics covered:

Why public-private plant breeding funding in Canada needs a long-term

commitment rather than a larger one

How matching private seed company investment with provincial and federal

dollars multiplies research capacity

How the graduate student pipeline into plant breeding has shifted from

farm kids to city kids