Determination of Nutrient Availability and Elemental Toxicity by AB-DTPA Soil Test and ICPS

Abstract

The ammonium bicarbonate-diethylenetriaminepentaacetic acid (DTPA) (AB-DTPA) soil test was developed by Soltanpour and Schwab (1977) to extract simultaneously labile N0₃-N, P, K, Zn, Fe, Mn, and Cu from neutral and calcareous soils. Later, it was used for extraction of potentially toxic elements from soils and mine spoils and soils treated with sewage sludge. The list of elements whose bioavailability can be determined with AB-DTPA also include Pb, Cd, Ni, Se, As, B, Mo, and S. To use the AB-DTPA test more efficiently one can use an inductively coupled plasma (ICP) spectrometer. An ICP spectrometer is capable of simultaneous or sequential determination of the above elements in the AB-DTPA extract accurately and rapidly. The use of AB-DTPA soil test in conjunction with an ICP spectrometer enabled the discovery of Cd, Pb, and Zn contamination in garden soil samples from some Colorado mountain communities during a routine soil fertility test. The metal contamination originated from old mine spoils. As a result of this discovery and further testing by the U.S. Environmental Protection Agency (EPA) and Colorado Department of Public Health these communities were earmarked for cleanup by the U.S. Government.