Fertiliser requirements for peat soils in the Waikato region

Abstract

Peat soils cover approximately 94 000 ha of productive land in the Waikato and are an important soil resource for the region. Much of the research on peats in the 1950s-60s concentrated on the development of raw peats and later in the 1970s on nutrient deficiencies such as copper and selenium. Little to no work was undertaken on soil fertility/soil nutrient relationships of developed peat soils. In 1996, a series of eight field trials was established across a range of developed peat soils in the Waikato to investigate such relationships. The trials continued for 3 years. Results showed that the optimum Olsen P soil test for sustaining near maximum pasture production was 35-45, that K soil tests were of limited use on well developed peats and that winter leaching of S was likely to be important. The Anion Storage Capacity (ASC) test was found to be a valuable tool in indicating the degree of development of peat and in turn allowing interpretation of fertiliser responses. From these introductory investigations of nutrient requirements on peat soils some guidelines and recommendations are presented. Keywords: anion storage capacity (ASC), Olsen P, pasture production, peat, soil test