Soil fertility status of the Taranaki hill country

Abstract

Abstract A survey of 35 farms in the eastern Taranaki hill country was conducted to determine fertiliser practices and the fertility status of hill soils using the New Zealand MAF soil test methods. Two north-facing and two south-facing slopes on each farm were soil sampled. Most sites sampled (69%) were predominantly volcanic ash soils (average phosphate retention (PR) = 91%), with the remaining 31% being predominantly sedimentary soils (average PR = 45%). The volcanic ash soils had an average Olsen phosphate (Olsen P) value (0–7.5 cm) of 8.3, with only 14% of samples with Olsen P values > 12. The sedimentary soils had an average Olsen P value of 11.4, with 41% of samples with a value > 12. Volcanic ash soils had higher soil sulphate test values (average 16.4) than sedimentary soils (average 8.6), with 76% and 41% of the samples respectively having soil test levels > 10. There was no effect of aspect on soil test levels for either volcanic ash or sedimentary soils. Soil sulphate levels and pH increased, ...