Topoclimate effects on agriclimates at the local scale

Topoclimates, i.e. local-scale climates due to the presence of topography, have manifest implications for agriculture and horticulture, e.g. relating to crop selection, growing degree-day values, harvest dates, and frost risk. Throughout New Zealand the costs involved in pastoral farming are rising, while profits decline. A possible solution is more intensive, specialised cropping but this requires high quality environmental information at the farm scale, and the national network of climate stations is too coarse to provide this information. A community-driven, topoclimate mapping project--the Topoclimate South project--was undertaken during 1998-2001 in the Southland region, New Zealand. It involved a temporary network of 2550 field sites across 805 000 ha of rural plains and hills. Air temperatures were measured at 1.2 m height at six-minute intervals for one year at each site. Long-term records at nearby climate stations were then used to extrapolate a 30-year record for each site, and to compute long-term mean data. Outcomes included a data set comprising 223 million measured air temperatures; soil temperature and soil type data were also collected. The project was mandated to produce two map series at 1: 50 000 scale: (a) long-term mean annual growing degree-days, and (b) soil types. Expected benefits from the project include more effective management of farmland and less risk for those who wish to establish new crops.