Hog‐Manure‐Recovered Struvite: Effects on Canola and Wheat Biomass Yield and Phosphorus Use Efficiencies

Abstract

Core Ideas Struvite recovered from liquid hog manure is a slow‐release P source. Recovered struvite produced yields that matched or exceeded those from MAP fertilizers. Despite its slow‐release properties, struvite supplied adequate P to the crops. Recovery of manure P as magnesium ammonium phosphate hexahydrate (MgNH4PO4∙6H2O), commonly known as struvite, can mitigate the risk of P contamination of surface water bodies from hog operations. The slow release of P from struvite may help improve crop P use efficiency. This greenhouse bioassay evaluated the agronomic effectiveness of liquid hog manure recovered struvite. Struvite, monoammonium phosphate (MAP), and polymer‐coated MAP (CMAP) were evaluated for canola (Brassica napus L.) grown in rotation with spring wheat (Triticum aestivum L.) in two low soil test P (Olsen P < 6 mg kg−1) soils: a sandy Gleyed Regosol (Typic Haplaquent) and a clay loamy Orthic Black Chernozem (Udic Boroll). The fertilizers were applied either in the seed row or in a sideband at 1.1 and 2.2 g P m−2 rates. In both soils, struvite produced canola dry matter (DM) yield (DMY, 2.4 g kg−1 soil), P uptake (5.9 mg P kg−1 soil), P recovery efficiency (43%), and agronomic efficiency (0.15 g DM mg−1 P) that were similar to those of MAP and CMAP in the first crop phase. Moreover, at the 2.2 g P m−2 rate, struvite produced significantly greater canola DMY than MAP in the second crop phase and both MAP and CMAP in the third crop phase. Overall, wheat did not produce significant responses to P fertilization. These results indicate that struvite recovered from liquid hog manure can supply sufficient P to sustain yields and P use efficiency matching or exceeding those for MAP.