High molybdenum land values in Ireland: Possible implications

Up to 4000 μg g^-1 Mo exists in surface material (till/peat) in Ireland over porphyry CuMo mineralized granodiorite at Mace Head, Galway. Dispersion of Mo in surface material is controlled by high rainfall, peat, loss on ignition content of till, E_h and pH. It accumulates in organic-rich till, limonite-strained till in oxidizing conditions, and in lower horizons of deep peat in slightly reducing conditions where subsurface drainage occurs. High Mo values are often, but not necessarily, associated with Fe-enrichment and more oxidizing conditions. The mobility and widespread dispersion of Mo permits its uptake by a wide range of pasture. Much lower Mo soil levels found elsewhere in Ireland and Britain have caused molybdenosis and hypocuprosis in farm animals. Whilst the Mace Head area is relatively unimportant agriculturally, clinical trials could be carried out at Mace Head to evaluate land suitability for agriculture. Such trials could be used as a model study for determining impacts of high Mo levels in surface material on agriculture in similar regions elsewhere.