Efficacy of Broadcast Phosphorus Fertilizer Applied in Fall or Spring for No-Till Corn and Soybean

Broadcast fertilization could be an inefficient placement method with no-till because phosphorus (P) tends to accumulate at or near the soil surface. However, long-term research at this farm has shown no difference between banded and broadcast P fertilizer placement methods for corn and soybean managed with no-till or chisel-plow tillage, even with significant stratification of soil-test P. One possible explanation for this result is that broadcast P was always applied in the fall because this is what most Iowa farmers do. We theorize that such an advance application could provide sufficient time for fertilizer granules or dissolved P to move below the residue cover as a result of rain, freezing and thawing, and/or macrofauna activity. To test this hypothesis, a study was conducted to compare fall and spring broadcast P fertilizer application for no-till corn and soybean