Author: Emily Cook
While fields may be frozen, winter time is a critical decision-making period for Ontario growers. Soil test results are in hand, crop rotations are finalized, and input strategies are being evaluated long before the first pass across the field. For wheat fertility, this starts in the fall, so having soil tests and plans put in place in the summer or early fall is best. For corn and soybeans, proper fertility planning now can significantly impact yield potential and return on investment later in the season.
Ontario soils are diverse, and nutrient removal varies widely across crops. Nutrient availability also varies with soil type. Without a clear plan to manage phosphorus (P) and potassium (K), soil fertility can decline quickly—often before yield loss becomes visible.
Using Soil Tests to Drive Smarter Fertility Decisions
Soil testing remains the foundation of effective nutrient management. Down time in the winter is the ideal time to review soil test data field by field and make informed decisions before spring workloads increase.
Key steps include:
- Identifying fields below optimal P and K levels
- Prioritizing acres where yield-limiting deficiencies exist
- Aligning fertilizer rates with realistic yield goals
Variable-rate fertility strategies can be especially effective in Ontario, where soil type and productivity can change significantly within the same field. Applying nutrients where they are needed most helps maximize efficiency and reduce unnecessary input costs. Knowing your soil texture and the capabilities of it need to be considered as well. How well does my soil hold on to nutrients. Would it benefit from different management strategies such as banding P? What about a P source that isn’t water soluble so it stays in available forms all year round?
Managing Phosphorus and Potassium Across the Rotation
Each crop in the rotation contributes differently to nutrient removal:
Corn
Corn requires consistent potassium availability for stalk strength, disease tolerance, and yield stability. Corn silage, in particular, removes large amounts of both P and K, making replacement critical.
Soybeans
Soybeans remove more potassium per bushel than corn and are especially sensitive to low soil K levels. Inadequate potassium can lead to reduced pod fill and increased stress susceptibility.
Wheat
Winter wheat benefits from adequate phosphorus to support root development and early-season tillering. Maintaining soil test levels helps ensure strong establishment and uniform growth in the spring.
Replacing nutrient removal with quality fertilizer products such as Potash, MAP, and CG P2X supports long-term soil productivity and protects yield potential across the entire rotation.
Balancing Maintenance vs. Build Strategies
Not every field requires aggressive fertility building. Winter planning allows growers to recognize which fields need more attention:
- Use maintenance rates on high-testing fields
- Focus investment on acres with the greatest yield response
- Spread fertility costs strategically over multiple seasons
A targeted approach ensures fertilizer dollars are spent where they generate the greatest return.
How Sylvite Supports Fertility Planning
Sylvite’s Agronomy Solutions team works closely with Ontario growers to develop custom fertilizer programs based on soil test data, crop rotation, and yield goals. With access to custom blending, variable-rate application, and trusted fertilizer products, Sylvite helps turn soil data into profitable decisions.
Planning fertility in the winter sets the foundation for consistent yields, healthier crops, and long-term soil health.
