UNIVERSAL SOIL EXTRACTANTS - THEIR COMPOSITION AND USE

Universal extraction reagents are defined as a single extractant for use on a range of soils for the determination of both major elements and micro-nutrients. The first universal extractant, so named by its developer, was the Morgan Extraction Reagent which was introduced in 1941 for use on both mineral soils and organic soilless mixes. In 1954, Mehlich introduced an universal extractant, frequently referred to as the Double Acid extractant, for assaying acid sandy textured soils. The ammonium bicarbonate-DTPA extraction reagent for use on alkaline soils was introduced by Soltanpour in 1977. In 1982, Wolf modified the Morgan extraction reagent by adding DTPA to it. In 1984, Mehlich described his Mehlich No. 3 extraction reagent for use on a wide range of acid soil types. All these extraction reagents can be assayed using a multielement analyzer such as the inductively coupled plasma emission specterometer for both the major elements and micronutrients in the obtained extractant. © 1990, Taylor & Francis Group, LLC. All rights reserved.