LETHBRIDGE – Researchers have been able to significantly increase potato yields by using an irrigated sustainable rotational program instead of conventional cropping systems.
Frank Larney, a researcher with Agriculture Canada, told farmers attending a recent Irrigated Crop Production conference in Lethbridge that a trend toward better performance in sustainable versus conventional rotations is starting to emerge, especially in potatoes.
“The potato rotation story is the most interesting,” he said.
Potato yields were 31 percent higher with a five-year sustainable rotation rather than a three-year conventional rotation.
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“Thirty-one percent, that’s a huge yield effect,” Larney said.
A study to compare conventional and sustainable cropping practices began in 2000 at Vauxhall, Alta. During the 1990s the number of acres under irrigation in southern Alberta increased dramatically. During the same time, the rotation of high value crops like potatoes, beans and sugar beets shrunk and concerns increased about declining soil quality.
Researchers designed a study to measure the impact of conventional and sustainable rotations for potatoes, sugar beets, beans, soft wheat and timothy. Results were judged for crop yield and quality, wind, insect and disease pressures and soil quality.
Under the sustainable trial, researchers tried to reduce tillage or direct seed whenever possible using cover crops and composted manure as a substitute for fertilizer.
“All those things are increasing the organic soil matter.”
Yields of potatoes, sugar beets and wheat grown under conventional rotation were no different than those grown under sustainable systems for the first three years of the study.
In the following years, however, yields from conventional cropping methods started to “fall off the cliff,” Larney said.
He expects some of the biggest benefits to show up in soil quality and decreased disease over the next few years.
The potato disease verticillium wilt appeared in the conventional potato crop but not under the sustainable cropping trial.
Larney hopes to continue the rotation experiments until at least 2011, by which time he expects significant differences will begin to emerge.
“These rotation experiments, they only get interesting as time goes on. We dearly want to run this until 2011.”
