Yield and forage mineral composition of a permanent pasture fertilized with magnesium

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 past ure composed by Lolium perenne and Trifolium repens as an agronomic alterna tive of hypomagnesaemia management in grazing herds. The effect on magnesiu m, calcium, potassium and sodium concentration in the pasture dry matter an d 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 cmol(c)kg(-1). Pasture dry matter production was not affected by mag nesium fertilization, nevertheless, the concentration of magnesium in the p asture dry matter increased proportionally to the magnesium applied. A weig hed average showed an increase of 0.006 and 0.012 g kg(-1) of dry matter fo r each kg of magnesium applied during the first and second year, respective ly. In addition, the magnesium fertilization decreased the calcium dry matt er concentration, but it did not affect potassium and sodium dry matter con centration. The ratios between calcium/magnesium, potassium/magnesium and s odium/magnesium decreased with the increase of the magnesium fertilization rate.