Magnesium deficiency in pine seedlings growing in pumice soil nurseries

Abstract

Magnesium deficiency, characterised by needle tip chlorosis, has occurred in seedlings of radiata pine, Corsican pine, and lodgepole pine in two New Zealand pumice soil nurseries. Exchangeable Mg in the soil was low, as were foliage contents. Magnesium sulphate gave a rapid response, but leached from the soil within a year. The response to dolomite was slower but longer lasting. Serpentine raised the level of Mg in the foliage to some extent, but did not increase exchangeable Mg in the soil to any appreciable extent. Foliar sprays of magnesium sulphate were very effective at some times of the year. The application of a low rate of ammonium sulphate increased the uptake of Mg as evidenced lly increased foliage content and growth.

This is the first reported instance of Mg deficiency in: (1) forest trees in New Zealand; and (2) a virgin soil growing its first crop after cultivation.