Extra-tall stubble increases crop yield

Wheat, canola and chickpea yield and the overall average water use efficiency increased linearly as stubble height increased to 18 inches (45 cm) compared to cultivated stubble. Water use was independent of stubble height.

Previous research on the semiarid Prairies found that seeding into 12 inch (30 cm) tall stubble increased canola yield by 16%, pulse yield by 13% and wheat yield by 12% compared to seeding into cultivated stubble. With the development of no-till drills that can seed into tall stubble, further research was conducted to see if crop yield would continue to increase as stubble height increased past 12 inches.

Subsequent legacy research, that is still relevant today, had the objectives of seeing how crop yield and water use efficiency (WUE) responded at stubble heights up to 18 inches. The research was conducted from 2001 to 2003 at the Agriculture and Agri- Food Canada, Semiarid Prairie Agricultural Research Centre (SPARC), Swift Current, Sask.

All treatments over-wintered as extra-tall 18 inch (45 cm) 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% 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.

Yield increased linearly with increasing stubble height

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% compared to cultivated stubble.

Wheat yield on cultivated stubble was around 28 bu/ac (1910 kg/ha) compared to about 42 bu/ac (2800 kg/ha) on extra-tall stubble. Canola on cultivated stubble yielded 16 bu/ac (875 kg/ha) compared to 21 bu/ac (1175 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 (1210 kg/ha) increasing to 1268 lbs/ac (1210 kg/ha) on extra-tall stubble.

Source: Cutforth et al. 2011

Water use efficiency increased for canola

Water use (WU) was calculated by measuring soil water at seeding to a depth of 4 feet (1.2M) and subtracting soil water at harvest to the same depth, and then adding in growing season precipitation. Water use efficiency was then calculated by dividing grain yield by WU.

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 this research was that all stubble treatments over-wintered as extra-tall stubble, and then were cut in the spring to the 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. Additionally, if the stubble treatments had been imposed in the fall after harvest, differences in snow trapping ability may have further benefited the linear yield increase in stubble height.

This research was financed by Bourgault Industries Ltd. and AAFC-Matching Investment Initiative.

Cutforth, H., McConkey, B., Angadi, S. and Judiesch, D. 2011. Extra-tall stubble can increase crop yield in the semiarid Canadianprairie. Can.J.PlantSci. 91:783785.

OPEN ACCESS: https://doi.org/10.4141/cjps10168

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