There is a need for a reevaluation of phosphorus (P) fertilizer recommendations for soybean production in North Dakota. In general, soil P-levels are lower in ND than other states, necessitating more careful P-management and potentially more frequent applications. Recent research showed increases in soybean yield with P-application in Minnesota on soils with moderate P-levels, but not in North Dakota (Franzen, 2019). Therefore, current recommendations only allow P-applications to soybean to fields with low or very low P-levels, which may be leading to yield losses in soybean not adequately supplied with phosphorus. Phosphorus rates for soybean are not being examined in ND currently, and have never been examined with a coordinated state-wide effort.
The study will consist of 8 locations of P rate studies, rates of P at 23/46/69/92 lbs P2O5 per acre in a randomized complete block design. The work will be conducted out of the Fargo experiment station, Minot, Dickinson and Carrington REC's, with 2 sites radiating from each site/collaborator. It is hoped that a 2nd year will be funded, so that changes in P recommendation rates to soybean will stem from 16 total locations, enabling regional differences to be considered if necessary.