Residual effects of various magnesium fertilisers on grassland

After ending topdressing with magnesium fertilisers on a field trial on a magnesium‐deficient yellow‐brown pumice soil, residual effects of six of the fertilisers were compared with effects found from continued annual applications of kieserite. Compared with the regularly topdressed kieserite, all treatments showed a decline in dry matter yields, concentrations of magnesium in the herbage, and magnesium uptakes. Residual effects were smaller from serpentine superphosphate and magnesium phosphate than from dolomite treatments. Over a 6‐year period, the percentage of applied magnesium recovered in herbage and soil ranged from 29 to 61 percent, suggesting high losses by leaching from the added magnesium.