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

Abstract

Recovery of manure P as magnesium ammonium phosphate hexahydrate(MgNH4PO4 center dot 6H(2)O), commonly known as struvite, can mitigatethe risk of P contamination of surface water bodies from hog operations.The slow release of P from struvite may help improve crop P useefficiency. This greenhouse bioassay evaluated the agronomiceffectiveness of liquid hog manure recovered struvite. Struvite,monoammonium phosphate (MAP), and polymer-coated MAP (CMAP) wereevaluated for canola (Brassica napus L.) grown in rotation with springwheat (Triticum aestivum L.) in two low soil test P (Olsen P < 6 mgkg(-1)) soils: a sandy Gleyed Regosol (Typic Haplaquent) and a clayloamy Orthic Black Chernozem (Udic Boroll). The fertilizers were appliedeither 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, 2.4g 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 similarto those of MAP and CMAP in the first crop phase. Moreover, at the 2.2 gP m(-2) rate, struvite produced significantly greater canola DMY thanMAP in the second crop phase and both MAP and CMAP in the third cropphase. Overall, wheat did not produce significant responses to Pfertilization. These results indicate that struvite recovered fromliquid hog manure can supply sufficient P to sustain yields and P useefficiency matching or exceeding those for MAP.