The soils surrounding three Iron Age settlements on South Mainland, Shetland, were sampled and compared for indicators of soil amendment. Two of the sites (Old Scatness and Jarlshof) were on lower-lying, better-drained, sheltered land; the third (Clevigarth) was in an acid, exposed environment at a higher elevation. The hypothesis, based on previous regional assessments, soil thicknesses, and excavations at Old Scatness, was that the lowland sites would have heavily fertilized soils and that the thin upland soil would show little if any amendment. Findings indicate that the Middle Iron Age soils at Old Scatness had extremely high phosphorus levels, while the soil at Jarlshof had lower levels of enhancement. At Clevigarth, where charcoal from the buried soil was 14C dated to the Neolithic and Bronze Age, there was no evidence of arable activity or soil amendment associated with the Iron Age phases of settlement. Argues that these observations indicate that not all sites put the same amount of effort into creating rich arable soils. The three sites had very different agricultural capacities, which is considered to suggest the emergence of local trade in agricultural commodities in Iron Age Shetland.