This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: To protect their future harvests, Western Canadian farmers need to manage soil acidity across their entire multiyear rotation rather than crop by crop, long-term research from the University of Alberta suggests. In a study to address the challenge of how modern agricultural practices affect soil acidity, the consequences for crop production and how farmers can manage those changes before they become a serious problem, researchers found that proactively managing soil pH levels pays off across the entire rotation.
The work is published in the Canadian Journal of Plant Science. The researchers looked at how decades of fertilizer use, crop rotation and corrective lime applications affect soil acidity and nutrient availability over time. Their most important finding was that liming legume forages not only boosts their growth but also unlocks vital nitrogen for grain crops planted in future rotations.
"Managing soil acidity is about more than simply maintaining the productivity of individual crops," says soil scientist Dr. Miles Dyck, a professor in the Faculty of Agricultural, Life & Environmental Sciences and a co-author on the study with Dr. "It can also help preserve important biological processes." Historically, soil acidity hasn't been a major concern for many farmers in Western Canada, but agricultural practices have changed considerably over the past several decades, making it more of an issue, notes Dyck, who recently discussed the problem in a podcast.
"Farmers are growing more diverse and productive crops, applying more fertilizer and removing larger quantities of nutrients from their fields through harvests. These practices have many benefits, but they can also gradually increase soil acidity, often over decades. That means producers may not notice a problem until soil acidity reaches a level that begins to affect their yields.
By that point, restoring favorable soil conditions can require considerable time and expense." As soil becomes more acidic, it can become less favorable for plant growth and crop productivity by affecting the availability of nutrients and the activity of beneficial soil microorganisms. "The main prairie crops—cereals like wheat, barley and oats, oilseeds such as canola, pulses like peas and lentils, and forages such as grasses and alfalfa—vary in their sensitivity to soil acidity. If one crop in a rotation is affected by soil acidity, the crops that follow will also be affected," Dyck notes.
Drawing on data gathered between 1980 and 2020 from the U of A's Breton Plots, the researchers examined how synthetic fertilizer, manure and lime—a crushed limestone powder used to neutralize soil acidity—affected soil health, yields and nitrogen cycling within a five-year crop rotation of wheat, oats, barley and an alfalfa-brome grass mix. Results showed that legumes like alfalfa benefit most directly from liming. In fields treated with synthetic fertilizers, applying lime boosted forage yields, biological nitrogen fixation in the alfalfa and the absorption of essential nutrients.
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