There is interest in recovering nutrients from the stream of processing of crop biomass for bioenergy so that they can be efficiently utilized as fertilizers. Phosphorus (P) can be recovered as struvite [NH4 Mg (PO4) 6H2 O]. A low P water-solubility in the mineral struvite and research with the mineral or struvite precipitated from liquid animal manure handling suggests a slow-release of P. However, a recent greenhouse study in Iowa reported similar P availability of struvite and superphosphate (0-46-0) for corn and ryegrass. Also, more information is needed about P rates that should be applied in lowtesting soils to maximize corn and soybean yield. Although two long-term P experiments are being conducted at this farm, they do not include many P rates. Therefore, a new study was established in 2009 to investigate these issues.