Increasing phosphorus (P) and potassium (K) fertilizer prices over the past decade have resulted in less P and K being applied by some Ontario grain and oilseed producers. At the same time, crop yields have increased resulting in greater P and K removal through nutrient uptake. The current OMAFRA recommendations were established a number of years ago when yields were lower. There is concern that the current OMAFRA recommendations do not adequately provide for modern crop yield potentials. The OMAFRA recommendations are also based on the sufficiency approach which aims to supply the needs of the current crop by taking into consideration the soil test level and the immediate economic return to applied P and K. It is also called the “feed the crop” approach. Another strategy to fertilizer recommendations is to “feed the soil”. This method is called the “build-up and maintenance” approach. 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.

Read the entire report here: Re-evaluating Phosphorus and Potassium Management for Soybeans 2014