Essential trace elements for plants, animals and humans

A field trial, a pot experiment and a survey in organically farmed leys were undertaken to investigate whether the N-fixation in red clover pastures in Norway was limited by a low supply of Co and/or Mo. Fertilization with Mo did not cause any higher production nor Nfixation, whereas the N-yield both from established clover leys and red clover grown in pots increased slightly after application of Co to many of the investigated soils. In the organically farmed leys there was a significant and positive correlation between the Co-content and the N-content of the red clover. As many of the investigated clover-soil systems were of those previously known to be very low in Co and Mo, and the gain in N-yield obtained by extra Cosupply was marginal, it is not likely that deficiency of these trace elements is a problem that deserves any great concern in legume based forage production systems in Norway. Note: This work has previously been published in Acta Agric Scand, Sect B, Soil and Plant Sciences.