MN FERTILIZER REQUIREMENT TO PREVENT MN DEFICIENCY WHEN LIMING TO REMEDIATE NI-PHYTOTOXIC SOILS

Authors: SIEBIELEC, GRZEGORZ - INST SOIL SCI, POLAND; Chaney, Rufus

Submitted to: Communications in Soil Science and Plant Analysis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/15/2005
Publication Date: 2/1/2006
Citation: Siebielec, G., Chaney, R.L. 2006. Mn fertilizer requirement to prevent mn deficiency when liming to remediate ni-phytotoxic soils. Communications in Soil Science and Plant Analysis. 37(1-2):163-179.

Interpretive Summary: Soils near metal smelters are often contaminated by smelter emissions. When the soils are acidic, and/or metals have accumulated to high levels, soils may become phytotoxic. At a Ni-refinery at Port Colborne, Ontario, acidic soils were contaminated with Ni and Ni phytotoxicity occurred in sensitive vegetable crops. Liming these soils did not cure the Ni-induced iron deficiency observed in oat, or redbeet, and liming reduced yield of wheat. Plant analysis showed that liming these soils caused Mn deficiency. Thus, liming to cure Ni phytotoxicity induced Mn deficiency because the soils were depleted in Mn during soil genesis. The experiment tested the interaction of Mn fertilizer rate and soil pH for 4 levels of limestone addition. In this study, redbeet was much more severely reduced in yield than oat when grown on the acidic contaminated soils. But both species grew normally when both muck and mineral soils were made calcareous by addition of 50 t limestone/ha. Interestingly, plant Mn was lowest at about pH 6.5, and rose as soil pH was raised to 7.5 by the high limestone application. Mn deficiency was not as severe in this experiment as previous studies because the fertilizer used included ammonium-N rather than only nitrate-N. Study showed that combining Mn fertilizer with limestone gave complete remediation of Ni phytotoxicity of these soils.

Technical Abstract: Ni contamination of local soils occurred near a Ni refinery at Port Colborne, Ontario, on soils that were inherently susceptible to Mn deficiency if pH was raised by limestone to reverse Ni phytotoxicity. Previous studies showed that adding limestone to achieve full remediation of Ni phytotoxicity of these soils induced Mn deficiency such that chlorosis was severe at both low pH (from Ni phytotoxicity) and at high pH (from Mn deficiency). This greenhouse pot experiment was conducted with Welland loam and Quarry muck soils to learn the application of MnSO4 needed to prevent Mn deficiency when these soils were limed. The interaction of limestone rate and Mn fertilizer rate allowed normal growth of oat and redbeet, species known to be highly sensitive to Ni phytotoxicity and sensitive to Mn deficiency. The soils from the treated pots were also extracted with DTPA and the neutral salt 0.01 M Sr(NO3)2 which causes little change in soil pH during extraction in strong contrast with DTPA buffered at pH 7.3. 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 liming generally prevented Ni phytotoxicity. No severe Mn deficiency was observed in this experiment - fertilizer composition influenced severity of Mn deficiency symptoms. Manganese fertilization greatly improved Mn uptake by both crops in both soils.