Contents and main fractions of trace elements in Typic Argiudolls of the Argentinean Pampas

Abstract

The knowledge of the trace elements in soils of the Pampas remains fragmentary. Agriculture has been intensified in this region increasing the crop demand of micronutrients and increasing the use of fertilizers, which could add measurable quantities of trace elements to soils. We analysed the status of 12 trace elements in three soil fractions of different availability. Typic Argiudolls (soil taxonomy) from six locations of northern Buenos Aires province were sampled. Arsenic (As), cadmium (Cd), chromium (Cr), cobalt (Co), copper (Cu), iron (Fe), lead (Pb), manganese (Mn), molybdenum (Mo), nickel (Ni) and zinc (Zn) were extracted with DTPA, with 2N HNO3 and with HCl–HNO3–H2SO4 and HClO4. The exceptions were bioavailable boron (B), extracted with hot water, and total B and Cr, determined through instrumental neutron activation analysis. The analysis of the other elements were performed by inductively coupled plasma-atomic emission spectrometry. The total contents were similar or below values found in other soils of the region. Extractable DTPAZn, Cu and Fe were within the range of variation for the region but Mn data were lower than those found previously in the area. As, B, Co, Cr, Fe, Mo, Pb and Zn predominated in chemical forms which are almost insoluble for plants. Our results broaden the previous information for micronutrients in the Pampean region. For heavy metals, our results corroborate the lack of soil contamination in rural areas of the Pampas.