Manganese fertilizer requirement to prevent manganese deficiency when liming to remediate Ni-phytotoxic soils

Nickel (Ni) contamination occurred near a Ni refinery at Port Colborne, Ontario, on soils susceptible to Mn deficiency. Previous studies showed that adding limestone to remediate these soils induced Mn deficiency in plants. This greenhouse pot experiment was conducted with Welland loam and Quarry muck soils to learn the application of MnSO4 needed when these soils were limed. Limestone application, along with Mn fertilizer, allowed normal growth of oat and red beet known as sensitive to Ni phytotoxicity and Mn deficiency. Strontium (Sr)-nitrate extractable Ni was a smooth function of slurry pH with much higher Ni extractable from the Welland loam than Quarry muck. Ni phytotoxicity was severe at low pH for the Welland loam but it was generally prevented by liming. No severe Mn deficiency was observed in this experiment when nitrogen was applied as combination of urea, ammonia, and nitrates. Manganese fertilization greatly improved Mn uptake by both crops in both soils.