Seasonal variation in soil tests and nutrient content of pasture at two sites in Taranaki

Abstract Two sites in Taranaki on well developed, grazed pasture with generous fertiliser histories were selected for monitoring changes over time in Ministry of Agriculture and Fisheries soil Quick Test values and nutrient levels in mixed pasture. Soil samples were taken at 14-day intervals, and plant samples every 28 days, over a 3-year period. Large temporal variations in soil Quick Test values occurred but few seasonal trends were evident. Obvious seasonal trends occurred with plant N, S, P, and Ca, with less well denned seasonal variations in K and Mg contents. There was no correlation between soil test values and plant mineral composition for Ca, K, P, and Mg except at Stratford in the summer period. Plant mineral composition in relation to animal requirements is briefly discussed.