From AgVenture's Seeds for Success Agronomy Update, April 2014
Soil fertility specialists note the crop actually benefits only 5-10 percent of the time from having the phosphorus banded with nitrogen. The rest of the time, nitrogen gives the full response. In most cases, 28-percent urea ammonium nitrate is equivalent or better than ammonium polyphosphate (APP) as a starter fertilizer. There are some situations where including phosphorous in starter fertilizer is beneficial:
- Planting into cold, wet soils
- No-till is practiced
- Soil testing shows low phosphorous levels
- Soils are irrigated or consistently high yielding
APP efficacy actually depends on soil temperature, tillage, soil phosphorous level, irrigation and yield potential. AgVenture strongly urges customers to plant into ideal soil conditions and into a well prepared seed bed. See: http://news.uns.purdue.edu/x/2009a/090317CamberatoStarterfert.html.