Influence of rainfall and temperature on DTPA extractable nickel content of serpentine soils in Turkey

Influence of rainfall and temperature on DTPA (diethylene triamine pentaacetic acid) extractable nickel (DNi) and fractional (DNi / total Ni = F-DNi) concentrations of soils derived from ultramafic serpentine rock under temperate semiarid continental and Mediterranean climates were studied. All serpentinite areas in Western Anatolia and the East Thrace (ca. 400,000 km2 areas) were targeted. Meteorological data from 185 stations versus so-called phytoavailable Ni concentrations of 192 serpentine soil samples were examined. Digital elevation model (DEM), ANUSPLIN and ARC GIS 8.1 software packages for generation of climatic surfaces and analysis were employed for extrapolation of the weathering conditions in preparing comparative maps. Total Ni concentrations (TNi) were in the range of 25.7-2680 mg kg− 1, whereas DNi were between 0.08 and 143 mg kg− 1. The correlation between Ni extractability and the pH was weak (R2 = 0.175). This restricted effect may be attributed to the soil pH varying between neutral and slightly alkaline. Average DNi concentrations of the soil samples grouped within the province borders indicated that both precipitation and air temperature might be effective on the amount of DNi in the serpentine soils studied. The combined effect of annual precipitation and mean atmospheric temperature were significant (P < 0.01) on DNi. The differences between the climatic zones were distinct and generally increasing with the increase of annual rainfall and mean air temperature.