Current P and K recommendations in Ontario guide crop producers to apply a rate of fertilizer that will provide the greatest potential of an economic response during the year of application. Increases in crop yields over time have resulted in higher nutrient removal rates which have decreased the “equilibrium” soil test values where average crop removal rates equal the recommended application rates. Recent research in Ontario has demonstrated that starter fertilizer can provide significant yield and economic gains on sites with low testing soils when sufficient rates of the proper product are applied (ie. high rates of dry fertilizer). Despite this, many question whether applying sufficient rates on low or medium testing soils can equal the yield potential achieved on sites where fertility is built up to a non-responsive range and maintained. Building phosphorous and potassium levels in soil represents a significant expense to growers, and can pose economic (ie. land rental) and environmental (phosphorous runoff) risks. Due to the limited amount of data available, this research is being conducted to investigate how starter fertilizer selection (product, rate) and soil fertility management strategy (sufficiency or build and maintain) influence the economics and productivity of corn, soybeans and wheat over the long term in Ontario.