FERTILISER REQUIREMENTS OF GISBORNE-EAST COAST HILL COUNTRY

Abstract

Soil fertility has a dominant influence on the productivity of many hill country pastures. In the Gisborne-East Coast hill country the dominant soil groups - the yellow-brown earths (YBEs) from mudstone/argillite and the yellow-brown pumice soils (YBPs) from Taupo pumice tephra - show variations in response to fertiliser inputs. Results from a series of eight field trials, commenced in 1980, indicate widespread phosphorus (P) deficiency across both groups with optimum Olsen P soil test values being calculated as 11.5 and 20.1 respectively. Sulphur deficiencies appear less important, in the short term, than previously thought. Lime (L) and molybdenum (MO) deficiencies appear widespread on YEEs with an indication on some sites that lime effects are over and above that due to increased MO availability. Potassium (KI is the dominant deficiency (after P) on YBPs. Element deficiencies in decreasing order of importance were - Y BEs, P > L/MO > S > K; Y BPS, P > K > S > L. Keywords: Fertilisers, hill country, pasture production.