Resumen de Possible use of struvite as an alternative phosphate fertilizer
N Nongqwenga, P. Muchaonyerwa, J. Hughes, A Odindo, I Bame
Struvite, from human urine, is an alternative phosphorus (P) fertilizer. This study evaluated P release from struvite and its effectiveness for maize in Inanda (Ia), Sepane (Se) and Cartref (Cf) soils. Phosphorus sorption isotherms were determined, an incubation study determined the release pattern of P from struvite, and a pot trial compared struvite with single superphosphate (SSP) on maize P uptake. The amount of P at equilibrium (where Q = 0) in the Cf was 1.39 mg L-1, followed by Ia and Se with values of 0.17 and 0.13 mg L-1, respectively. Buffer coefficients were in the order Ia > Se > Cf with values of 454, 71 and 50 mg kg-1/mg L-1, respectively. The extractable P in all three soils increased with time, with evidence of declining P release after Day 8. Struvite was most effective as a P source in the Cf followed by Se and Ia. Compared to SSP, there was significant improvement in maize grown on the Cf, while the reverse occurred in the Se. Maize grown in the Ia did not respond to either struvite or SSP. It was concluded that the phosphorus sorption was the main limiting factor that governed struvite effectiveness as a P source.
