1. Phosphorus Management in the North Central Region: A Brief History, Current Unknowns and Next Steps

The history of phosphorus (P) reflects the history of agriculture in the North Central region. The yield-limiting importance of P, secondary to nitrogen, was recognized as at the turn of the 19th century. An overview of key developments and unfinished business following the picking of these low hanging fruit in the 20th century that face researchers, agronomists, and producers will be discussed. These include assessing P mobility, P sources from fertilizer versus soil, the concept of... A. Margenot