Effects of seed-placed sulfur fertilizers on canola, wheat, and pea yield; sulfur uptake; and soil sulfate concentrations over time in three prairie soils

The form of sulfur fertilizer can influence its behavior and crop response. A growth chamber study was conducted to evaluate five sulfur fertilizer forms (ammonium sulfate, ammonium thiosulfate, gypsum, potassium sulfate, and elemental sulfur) applied in seed row at 20 kg S ha(-1) alone, and in combination with 20 kg phosphorus pentoxide (P2O5) ha(-1) to three contrasting Saskatchewan soils. Wheat, canola, and pea were grown in each soil for 8 weeks and aboveground biomass yields determined. The fate of fertilizer was evaluated by measuring crop sulfur and phosphorus concentration and uptake, and supply rates and concentrations of available sulfate and phosphate in the seed row. Canola was most responsive in biomass yield to the sulfur fertilizers. Sulfate and thiosulfate forms were effective in enhancing soil-available sulfate supplies in the seed row, crop sulfur uptake, and yield compared to the elemental sulfur fertilizer. Combination of sulfur fertilizer with monoammonium phosphate may provide some enhancement of phosphate availability, but effects were often minor.