Evaluation of manure-derived struvite as a phosphorus source for canola

Abstract

Ackerman, J. N., Zvomuya, F., Cicek, N. and Flaten, D. 2013. Evaluation of manure-derived struvite as a phosphorus source for canola. Can. J. Plant Sci. 93: 419–424. There is growing interest in the treatment of swine manure to mitigate water quality issues related to phosphorus (P) from livestock operations. Precipitation of P as struvite (MgNH4PO4·6H2O) is a potential strategy to achieve this. The overall objective of this growth room study was to evaluate the effect of manure-derived struvite (MDS) on canola growth and P recovery efficiency. Pure struvite (PS), monoammonium phosphate (MAP), and polymer-coated monoammonium phosphate (PCMAP) were applied to canola plants in plastic pots containing 2 kg of a sandy loam soil. Biomass yields for MDS and PS were similar at all P rates (mean = 7.6 g pot−1) and significantly smaller than those for MAP and PCMAP (mean = 9.3 g pot−1). Differences in P uptake among P sources were detected at the highest P rate where P uptake was significantly greater for MAP and PCMAP (mean = 22.7 mg P pot−1) than for the struvite forms (mean = 16.4 mg P pot−1). Our results show that although P uptake was similar for the struvites and commercial fertilizers at P2O5 rates of 38 mg pot−1 or lower, biomass yield per unit of P taken up was smaller for the struvites. This may be due to lower initial solubility of the struvites in the alkaline (pH 7.7) soil used in this experiment, which gave an early stage growth advantage to canola fertilized with MAP and PCMAP. These results suggest that it may be necessary to supplement struvite with soluble P fertilizers, such as MAP, if applied on soils such as that tested in this study.