Agronomist warns repeated fertilizer cuts can lower corn yields

Tryston Beyrer, a field solutions agronomist for The Mosaic Company, said that consistently reducing fertilizer applications can lower short-term costs but may deplete soil reserves and hurt long-term crop performance.

Beyrer discussed nutrient management on RFD-TV's Market Day Report. He stated that more than 60 percent of crop yield depends on crop nutrition. As yields rise, crops remove more nutrients from the soil, creating a need for careful management.

North American average corn yields have increased by about two bushels per acre annually. Each bushel of corn harvested removes approximately 0.35 pounds of phosphorus and a significant amount of potassium from the ground.

When growers apply less than the crops remove, soil nutrient levels decline over time. Beyrer noted that producers might not see the immediate impact, but these deficits eventually limit yields. He encouraged farmers to work with agronomists and use soil sampling to identify specific deficiencies.

Fall is a key time to evaluate soil conditions and plan fertility programs for the next season. Beyrer recommended comprehensive soil sampling that measures organic matter, pH, phosphorus, potassium, and secondary and micronutrients. These results help determine which nutrients are limiting performance and where adjustments are required.

With input costs pressuring farm budgets, Beyrer cautioned against drastic changes to fertility programs without understanding soil needs. He cited the law of diminishing returns, saying the first increment of any nutrient provides the greatest return on investment. Growers can improve profitability by applying lower rates strategically rather than eliminating a nutrient entirely.

Reallocating fertilizer funds to the most limiting nutrient often yields better results than continuing to spend heavily on nutrients that are already sufficient. Beyrer advised growers to evaluate fertility products under their own conditions. Using available data to identify where nutrients are needed most allows producers to prioritize investments effectively.