Submitted to: Meeting Abstract
Publication Type: Abstract only
Publication Acceptance Date: 5/1/2001
Publication Date: 11/12/2001
Citation: Interpretive Summary:
Technical Abstract: Phytotoxicity is the first adverse effect of soil Ni. Methods to prevent Ni phytotoxicity of soils (Ni refinery source) were tested in a series of pot and field experiments. Oat and radish, very sensitive to excessive soil Ni, were used as indicator crops, and compared to 9 other species. Ten soils with varied Ni level and soil properties were adjusted to varied pH levels, and oat and radish grown. Oat suffered characteristic Ni-induced Fe-deficiency chlorosis with bands of higher or lower chlorosis severity perpendicular to veins which we believe can be attributed to Ni-inhibition of phytosiderophore dissolution or chelation of soil Fe. Even in soils exceeding 4,000 mg Ni/kg, raising soil pH reduced Ni solubility, reduced plant shoot Ni levels and reversed Ni phytotoxicity. Shoot yield was reduced when shoot Ni exceeded about 75 mg Ni/kg DW in oat or radish, but higher in perennial ryegrass. Soil extraction with 0.01 M Sr-nitrate gave extractable Ni highly correlated with shoot Ni across soil pH levels and across soils. Expressing results as mg Ni/L soil rather than mg extracted/kg dry soil allowed the data from both mineral and organic soils to fit one prediction equation. Ni solubility declined exponentially with increasing pH, reversing Ni phytotoxicity risk. Field tests confirmed that when soils were so acidic that Ni could be phytotoxic, liming prevented symptoms or yield reduction even on soils high in Ni. For some soils, addition of adsorbent Fe or Mn oxides may aid remediation of soil Ni risks.