Phosphorus management practices for soybean production in Manitoba

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Bardella, Gustavo
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The increase in soybean production in Manitoba has raised many questions about phosphorus management for achieving high yields of modern varieties. Soybean’s tolerance to seed-placed fertilizer and response to added fertilizer P were evaluated in a 28 site-year study, and the yield response to soil test P concentrations was evaluated in seven site-years, in a second study. Plant stand reduction caused by fertilizer toxicity when applied with the seed was rare, but was most likely in soils with medium to coarse texture or when seeding equipment lightly disturbed the soil, or provided little seed bed utilization. Severe plant stand reduction decreased seed yield in two site-years. Seed yield increase to P fertilization was rarely observed, regardless of fertilizer P rate, P placement or soil test P. In only one site-year there was a significant effect of fertilizer rate, where 45 and 90 kg P2O5 ha-1 increased yield by approximately 15%, compared to the control. Regardless of soil test P, seed yield response to soil P fertility was never observed.
Soybean (Glycine max (L.) Merr), Phosphorus, Plant stand, Rate, Placement, Seed-placed, Phosphorus fertility, Soil test phosphorus