Phosphorus Use Efficiency Of Canola Fertilized With Struvite Extracted From Liquid Hog Manure.

Keywords: struvite, canola, P-use efficiency

Improving phosphorus (P) use efficiency is a critical challenge for canola production in the Canadian prairies. The rates of commercial P fertilizers that can be applied in the seedrow with minimal risk of seedling toxicity are inadequate, while P placed away from the seed-row may have limited availability due to poor mobility. In this greenhouse experiment, we speculate that the slow-release characteristics of hog manure–derived struvite will enhance P use efficiency in canola grown in rotation with wheat in two low-P soils: a Dark-gray Chernozemic loamy sand and a Black Chernozemic clay loam. Struvite, monoammonium phosphate (MAP), and polymer-coated monoammonium phosphate (CMAP) were applied either in the seed-row or in a side-band at rates of 25 and 50 kg P2O5 ha-1. In the first two crop cycles, aboveground canola biomass yield, P uptake (PU), P uptake efficiency (PUE), agronomic efficiency (AE), and physiological efficiency (PE) were similar for struvite, MAP and CMAP in both soils. However, in the third crop cycle, struvite produced significantly greater canola biomass yield, PU, PUE, and AE than MAP and CMAP in the clay loam. The superior performance of struvite observed in the responsive soil after two crop cycles suggests that struvite has slow-release properties which could potentially improve P efficiency in canola production relative to conventional fertilizers.