A re-evaluation of soil variability and soil fertility in relation to experimental forest plots at Bridgehill Flat, Craigieburn Research Area, Canterbury, New Zealand : A thesis submitted in partial fulfilment of the requirements for the postgraduate diploma of Applied Science at Lincoln University Canterbury, New Zealand

Abstract

In 1979 Forest Research Institute (FRI) established a trial on high country forest and pastoral landuse at Flock Hill Station, in Canterbury. The soils of the trial site on a terrace, fan and hill slopes adjacent to Cave Stream, were surveyed in 1978, and in 1979 forests were planted on Craigieburn and Cass (Typic Allophanic Brown) and Castlehill (composite - Acidic Sandy Brown) soils. The area was stratified on the basis of the soil map and uneroded and eroded sites within delineations were sampled separately for soil fertility assessment in 1982 and 1984. Following the 1982 survey, the area was oversown with legumes and topdressed (300 kg ha⁻¹ superphosphate; 0.2 kg ha⁻¹ sodium molybdate). The current study (1994) includes a reassessment of soil fertility, improved definition of soil mapping units, and the analysis of soils not sampled at the time of the original survey. A Landform units map, a geomorphic surfaces map and soil map for the Bridgehill Block are all recorded. In twelve years the soil fertility under the trees is different than under adjacent grassland. In many plots available phosphorus (Bray P) levels have shown a sharper decline under grassland compared with adjacent forest, while the pH has decreased more in the soils under forest compared to those under grass.