Every productive farm in Ontario operates within a nutrient cycle. Soil provides nutrients to crops. Crops remove specific quantities of nitrogen, phosphorus, and potassium at predictable rates tied to yield. Livestock consume those crops and produce manure containing most of those same nutrients — but in different ratios and different forms.

The goal of nutrient management is to close this loop: returning manure nutrients to cropland at rates that match crop removal, account for soil reserves, and minimize environmental loss. This is not a theoretical exercise. A 200-bushel corn crop removes approximately 134 lb N, 70 lb P₂O₅, and 50 lb K₂O per acre (IPNI removal coefficients). A dairy operation applying 5,000 gal/acre of liquid manure may supply approximately 70–150 lb N, 35–55 lb P₂O₅, and 150+ lb K₂O — depending on dilution, bedding, and storage.

The mismatch is the challenge. Manure rarely matches crop needs perfectly. Phosphorus tends to accumulate. Nitrogen is lost through volatilization, denitrification, and leaching. Potassium is usually oversupplied. Without soil testing, manure analysis, and careful rate calculation, farms either waste nutrients or build environmental risk.