Key Messages
- Climate and soil property data can be used to develop farm-scale maps which can provide a platform to drive models that predict other agronomically relevant variables, such as pasture yield.
- These maps can be used to explore spatial and temporal dynamics at the farm scale and inform decision-making on pasture management to meet feed demands.
- The temperatures measured on the warm dry sites at Mt. Grand and Willesden suggest annual clovers such as subterranean clover may be more suited than white clover on many north facing slopes across New Zealand.
About the study site
Mount Grant is a 2,127 ha high country run located in the Upper Clutha Basin, Central Otago. The farm is immediately east of Lake Hawea and the homestead has stunning views across Hawea Flat, towards Lake Hawea. The property was gifted to Lincoln University in 1988 as a bequest from LJ and LJ Struthers and operates as both a commercial farm and a resource for student research. Over 70% of the property is moderate to steep hill country, the rest of the farm consists of productive flats or alpine vegetation. Annual rainfall is between 600 to 700 mm and the altitude of the property ranges from 330 to 1400 m a.s.l. The property is predominantly west facing so subject to summer dry conditions.
What was trialled
- On farm climate data from different altitudes and aspects were compared with estimates generated by NIWA’s Virtual Climate Station Network (VCSN) at the two closest sites.
- Climate data, including soil and air temperatures and precipitation, were monitored over a period of 17 years (2001-2018) at seven sites.
- The data, collected at six altitudes (450, 535, 620, 755, 920 and 1290 m a.s.l.) were compared with estimates from NIWA’s VCS network at four nearby co-ordinates.
Key findings
- Air temperatures from NIWA’s VCSN data were overall an accurate representation of the Mt. Grand temperature and climate.
- Rainfall data from VCSN and farm data was very similar.
- Soil temperature estimates from VCSN data were 1 to 4 °C lower than on-site data and there was an observed difference in soil temperatures recorded on north- and south-facing slopes.
- These results were consistent with the summer dry Willesden site which showed north facing slopes in dry environments are warmer than predicted from VCSN data.
- The temperatures measured on the warm dry sites at Mt. Grand and Willesden suggest annual clovers such as subterranean clover may be more suited than white clover on many north facing slopes across New Zealand.