At the recent 4R Field Day in Hardin County, Ohio State soil fertility specialist Steve Culman presented on the updated fertilizer recommendations through 300+ on-farm strip trials since 2014.
He said some main take-home points he hoped to get across to agriculturalists were:
- From 2014 – 2017, 300+ on-farm strip trials were conducted across Ohio evaluating corn, soybean and wheat response to N, P and K fertilizer.
- Yield responses to P and K fertilizer in soils at or above the current maintenance range were very rare.
- Long-term data from 3 sites show that when Ohio soils are in the current maintenance range, they can supply sufficient P and K to meet corn and soybean demand for many growing seasons without fertilization.
- Recommended corn N rates were updated this spring and are based on maximizing farmer profitability, not maximizing yields.
- Corn, soybean and wheat are yielding more grain with less nutrient: Grain nutrient removal per bushel of grain is lower than it was 20 years ago.