Masters Thesis The use of multinutrient extractants has been increasing in recent years, Mehlich 3 (M3) being one that has gained wide acceptance. The objective of this study was to see how M3 compared with methods currently used in Ireland for Cu, Zn, Mn and Fe extraction, and to investigate if it could be used to determine available Mo. Samples from eight mineral soil types, four of sandstone/shale and four of limestone origin and some organic soils were analysed for the micronutrients Cu, Fe, Mn, Mo and Zn using M3 and conventional extractants. Herbage samples were taken from specific mineral soils and analysed for the same range of elements. M3 results showed good correlation with EDTA and DTPA extractable Cu and Zn, and with easily reducible Mn, but poor correlation with DTPA extractable Mn and Fe. It was not possible to measure Mo in the M3 extract. Inclusion of soil properties and interacting elements in multiple regression models improved the coefficients of determination. Different relationships between extractants were displayed for mineral and organic soils. All extractants were equal in their ability to predict micronutrient content of herbage. Differences between sandstone/shale and limestone soils in relation to herbage micronutrient content were also found; the better relationships were generally found on the sandstone/shale. Results are generally in line with published data, but disagree with those of some studies. M3 is subject to the same shortcomings as existing extractants, but it’s versatility and range does offer an advantage.