Other Trace Elements
The other trace elements known to be essential for plant growth are manganese, zinc, iron, chlorine, and cobalt for the proper functioning of clover nodules. Cobalt deficiency severe enough to limit the proper functioning of clover nodules, and therefore nitrogen fixation, would most likely be associated with marked cobalt deficiency of sheep and cattle. If it ever existed, it would by now have been corrected. Manganese deficiency in wheat occurs in Canterbury on a few otherwise quite fertile river flats. It occurs also in a few orchards.
Iron deficiency on the other hand is known to occur in young pastures on some of the acid raw peats of the Waikato, and it is suspected on some soils in northern Hawke's Bay. The most suitable materials for supplying iron to these pastures and their rate of application are not yet known.