Are Potassium Levels a Limiting Factor in Alberta Soils?
Potassium does not always get the same attention as nitrogen or phosphorus, but recent soil test trends suggest it may be quietly limiting crop and forage performance in parts of Alberta.
Soil testing data shared by AGVISE Laboratories, based on thousands of soil samples submitted across Western Canada, shows a proportion of samples testing below 200 ppm potassium in the topsoil. In several regions of Alberta, more than half of the samples fall below this commonly used benchmark, indicating potassium may be limiting in some fields.
This does not mean every field is deficient. It does highlight why potassium deserves closer attention, particularly in forage and grazing systems.
Why potassium matters
Potassium plays a key role in plant function, even though it does not directly form plant tissue. Adequate potassium supports:
Water regulation and drought tolerance
Root development and nutrient uptake
Regrowth after grazing or cutting
Winter hardiness and stand persistence in perennials
When potassium levels are low, plants are often less resilient to stress. This can show up as reduced vigour, weaker regrowth, lower forage yields, and shorter stand life.
Why potassium levels may be declining
Several factors may be contributing to declining potassium levels, especially in forage-based systems.
Nutrient removal without replacement
Hay and silage remove large amounts of potassium. If potassium is not being replaced, soil levels will decline over time.
Higher yields
Improved varieties and management increase yield, which also increases nutrient removal.
Soil type and organic matter
Lighter-textured soils and soils with lower organic matter tend to have lower potassium reserves.
Uneven nutrient distribution in pastures
In grazed systems, potassium often accumulates in high-use areas, while other parts of the field remain low.
What does “200 ppm potassium” mean?
The 200 ppm level is commonly used as a general guideline, not a hard threshold. Potassium availability depends on soil texture, moisture, crop type, and overall fertility balance. Soil test results are most useful when combined with field observations and management history.
What producers can do
Rather than reacting to regional trends alone, the most useful step is to know your own numbers.
Producers may want to pay closer attention to potassium if they are noticing:
Declining forage yields despite adequate nitrogen
Poor regrowth after grazing or cutting
Increased stress during dry conditions
Reduced persistence of perennial stands
Regular soil testing, especially in long-term forage or hay fields, helps identify trends before they become yield-limiting. Potassium decisions should be part of a whole-soil fertility plan.
A nutrient worth watching
Potassium does not always show dramatic visual symptoms, but its role in stress tolerance and forage persistence makes it particularly important in Alberta’s variable climate. As soil test trends continue to shift, potassium is becoming a nutrient worth watching in forage and grazing systems.
Sources and further reading
AGVISE Laboratories. Soil Test Trends and Nutrient Insights.
Alberta Agriculture and Irrigation. Potassium management in crops
Government of Saskatchewan. Potassium Fertility in Prairie Soils.
International Plant Nutrition Institute (IPNI). Nutri-Facts - Potassium
Farming Forward Offers Local support for soil testing
Soil testing is one of the most useful tools for understanding what is happening below ground, but it can also feel like one more thing to organize during a busy season.
Farming Forward can help make the process easier. We offer:
Access to a soil sampling truck for larger or more intensive sampling needs
Rental soil sampling probes for producers who want to collect their own samples
Support with sending soil samples to an accredited laboratory
Discounted soil testing rates through partner laboratories
Whether you are soil testing a hay field, pasture, or cropped land, our team can help. Contact us here to learn more.
