Extractability of nickel and its concentration in cultivated plants in Ni rich ultramafic soils of New Caledonia.
L'Huillier L., Edighoffer S.
Author Affiliation: Agropedology Laboratory, ORSTOM, B.P. A5, 98 848 Noumea Cedex, New Caledonia.
Plant and Soil 186 : 255-264
Abstract : The presence of higher-than-normal quantities of nickel is one of the most general features of ultramafic soils and is often suspected as the reason for their infertility. This study on the bioavailability of Ni in ultramafic soils derived from peridotites in New Caledonia showed important variations depending on the position of the soil in the landscape. Crop/fruit species used were maize, tomatoes, radishes, bananas, carrots, Chinese cabbages, courgettes, eggplants, lemons, mangoes and pawpaws. In piedmont and non hydromorphic colluvio-alluvial soils, Ni was poorly absorbed by cultivated plants. In contrast, crop species grown in the plain soils, especially those found in the colluvio-alluvial and plain soils subject to temporary reducing conditions, possessed very high and even toxic Ni concentrations. Extraction of Ni by DTPA 5 mM was an effective method of estimating Ni bioavailability in these soils. The regression equation developed with only DTPA-extractable Ni explained 88% of the variability in tomato Ni concentration. It is suggested that extractable Ni might originate from the association of Ni with primary alterable minerals, organic matter and goethite.