Assistant professor
OSU-Extension

The 4R’s concept is being promoted by Ohio State University extension and other government agencies. The concept means using the right fertilizer source at the right rate, right time and the right place (Fertilizer Institute). The goal is to keep the nutrients on the land and not in the air or water while increasing agricultural production and profitability. That requires matching nutrients applied with nutrients taken up by the plants while minimizing losses. For more information on this concept, visit the Fertilizer Institute website at nutrientstewardship.com.

Using the right fertilizer rate starts with knowing your crop nutrient requirements. The right rate should be based on soil and tissue tests taken from an accredited laboratory and should be based on Tri-state agronomic fertilizer guidelines. Soil tests should be taken a minimum of every 3-5 years. A study of agricultural testing laboratories found that while a majority were testing and reporting nutrient levels correctly; their guidelines for the amount of fertilizer to apply were vastly different. So in many cases, fertilizer was being recommended when it was not needed (Mullen and Dayton, 2011). Farmers need to keep good fertilizer records to see how their soil tests change over time.