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Agronomy Update
Agronomy update: Tall stubble increases crop yield

October 8, 2023  By Bruce Barker


Moisture is often the most limiting factor in crop yield on the semi-arid Prairies. Over the past 20 years, as no-till direct seeding replaced conventional tillage, the ability to seed directly into standing stubble meant there was potential for a better micro-climate near the soil surface, which could improve crop yield.

Several research studies have been conducted at Agriculture and Agri-Food Canada’s Semiarid Prairie Agricultural Research Centre (SPARC) in Swift Current, Sask. These legacy studies conducted in the late 1990s and early 2000s – still relevant today – found that tall standing stubble was able to increase crop yield and improve water use efficiency (WUE).

In one study led by research scientist Herb Cutforth at AAFC Swift Current from 1996 to 2000, desi chickpea, field pea and lentil were seeded into six to seven-inch (15 to 18-cm) short stubble, 10 to 14-inch (25 to 35-cm) tall stubble and spring cultivated stubble. Averaged across all crops and years, tall stubble increased yields by about 13 per cent, and short stubble increased yields by about four per cent compared to yields from cultivated stubble treatments.

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In another study led by Cutforth at AAFC Swift Current from 1999 to 2002, canola yielded 24 per cent higher when seeded into 12-inch tall stubble (30 cm), compared to stubble that had been cultivated in the fall. Additionally, canola seeded into tall stubble yielded 16 per cent higher than if seeded into stubble that was left standing until spring, and then cultivated. The researchers found that tall stubble changed the microclimate near the soil surface by reducing wind speed, solar radiation and soil temperatures throughout the life cycle of canola.

Another research study was conducted to see if crop yield would continue to increase as stubble height increased to 18 inches (45 cm). The research was again conducted by Cutforth from 2001 to 2003 at AAFC Swift Current.

In this research, all treatments over-wintered as extra-tall 18-inch standing wheat stubble so that overwinter snow trapping was equal for all treatments. The four stubble treatments included extra-tall 18-inch stubble, 12-inch tall (30 cm), 6-inch short (15 cm) standing stubble and stubble cultivated just before seeding in the spring.

Spring wheat, Argentine canola, and kabuli chickpea were seeded into the stubble treatments in late April and early May with an air coulter drill. Crops were grown with recommended agronomic practices. Yield and water use efficiency were measured.

Over the three years, diverse growing conditions provided an opportunity to see how the stubble treatments performed in different years. The first year, 2001, was extremely dry with growing season precipitation at 52 per cent of normal. It was also very warm, and this severe drought year was the 2nd driest and 5th warmest year on record for Swift Current. Crop growth and yield were very stressed.

The drought persisted until the end of May 2022, and the plots had an extremely dry soil profile. The rest of the growing season was wet, especially June through September.

In 2003, the growing season started out fairly wet, but July was extremely dry and hot, while August was dry and very hot. These months were the 3rd driest and 3rd warmest on record.

Averaged across all crops and years, the overall combined crop yield increased as stubble height increased. Generally, extra-tall stubble increased crop yield by 17 per cent compared to cultivated stubble.

Wheat yield on cultivated stubble was around 28 bu/ac (1,910 kg/ha) compared to about 42 bu/ac (2,800 kg/ha) on extra-tall stubble. Canola on cultivated stubble yielded 16 bu/ac (875 kg/ha) compared to 21 bu/ac (1,175 kg/ha) on extra-tall stubble.

Chickpea also showed a linear, although not significant (P=0.108), increase in yield with taller stubble. Chickpea on cultivated stubble yielded 1075 lbs/ac (1,210 kg/ha) increasing to 1,268 lbs/ac (1,210 kg/ha) on extra-tall stubble.

Overall, WUE was also linearly dependent on stubble height. Water use efficiency increased linearly when averaged across all crops as stubble height increased. For the individual crops, WUE increased linearly for canola, and the increase was statistically significant.

There was a trend for WUE to increase for wheat with increasing stubble height, but it was not significant. Chickpea did not show a WUE response to stubble height.

An interesting twist on the research was that all stubble treatments over-wintered as extra-tall stubble, and then were cut in the spring to different heights, or cultivated. As a result, the yield increases in this research were the result of a better micro-environment within the taller stubble and not additional moisture from snow trapping.

While these legacy studies were conducted a generation ago, they still show the value of leaving stubble standing as tall as possible. Unfortunately, in drought years like 2023 when crops are severely stunted, cutting stubble high isn’t always possible. 


Bruce Barker divides his time between CanadianAgronomist.ca and as Western Field Editor for Top Crop Manager. CanadianAgronomist.ca translates research into agronomic knowledge that agronomists and farmers can use to grow better crops. Read the full Research Insight at CanadianAgronomist.ca.

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