Effect of magnesium fertilisers and season on levels of inorganic nutrients in a pasture on Hamilton clay loam

Magnesium fertilisers and lime had no detectable effects on levels of major elements other than Mg and Ca. Treatments which raised the soil pH slightly depressed herbage Mn levels. Mn and S were always much higher, P, K, and Na usually somewhat higher, Mg, Zn, Cu, and Fe somewhat lower, and Ca, N, and B invariably much lower in grasses than in associated white clover. The pattern of seasonal changes in levels in grasses differed from that in clover, especially in the case of N, P, and Mn. Though mixed herbage N levels were “high” (about 4%) in late winter and early spring, values for grasses indicated that nitrogen deficiency limited growth of grasses growing in association with white clover in spring and summer.