Abstract

This research was conducted for two years to evaluate magnesium fertilizer application (0, 24, 48 and 96 kg ha-1 year-1 of Mg) on a permanent pasture composed by Lolium perenne and Trifolium repens as an agronomic alternative of hypomagnesaemia management in grazing herds. The effect on magnesium, calcium, potassium and sodium concentration in the pasture dry matter and the ratio between cations were evaluated. The research was carried out on an Hapludand (Valdivia serie) with an initial available magnesium content of 0.8 cmolc kg-1. Pasture dry matter production was not affected by magnesium fertilization, nevertheless, the concentration of magnesium in the pasture dry matter increased proportionally to the magnesium applied. A weighed average showed an increase of 0.006 and 0.012 g kg-1 of dry matter for each kg of magnesium applied during the first and second year, respectively. In addition, the magnesium fertilization decreased the calcium dry matter concentration, but it did not affect potassium and sodium dry matter concentration. The ratios between calcium/magnesium, potassium/magnesium and sodium/magnesium decreased with the increase of the magnesium fertilization rate.