This is the Hampton District in southeast Queensland. It’s an area of rich basaltic soils perched on the ridgeline of the Great Dividing range 800 metres above sea level in a warm to sub-tropical climate.
Twenty-four years ago, farmer, Graham Thomas, moved into the area and started growing avocados on part of a small 24 ha block after observing the fertile, free draining soils and reliable seasonal rainfall of the area and determining that it was suitable for growing avocados.
The District already had some horticultural development and farmers started to work together to overcome the other major constraint to horticulture in the area which was access to a reliable water supply. As a community, they eventually invested in a $4M water supply scheme for the District but realised that they had to intensify and make better use of their land to justify their investment.
Graham had considerable success in growing his avocados, averaging up to 20 tonnes of avocados per hectare each year and his success inspired several other farmers in the District to observe that “these avo’s are the go!!!” and decide to establish plantings on their own properties as well.
Other avocado properties close to the Thomas property in Hampton, Queensland
However, the other farmers in the area did not initially investigate their microclimates as carefully as Graham before investing money in establishing avocado plantations on their properties. Even though their land was at a lower altitude than Graham Thomas’s property and on the same soil types, some of the land faced in a southerly direction (where Graham’s land sloped to the north) and there were several gullies running through the properties which trapped cold air draining off higher ground and which became frost hollows with winter temperatures below what Avocados could cope with.
The pictures below show the impact of frost on both mature avocados and new trees planted to replace trees previously killed by frost. When Topoclimate staff measured winter temperatures in this area of this orchard, their dataloggers recorded temperatures down as low as -10 degrees centigrade.
Avocados can only survive temperatures down to -4 degrees C so this orchard owner was facing diminished production over much of his orchard and regular deaths in his replanted trees in the frost hollows where cold air ponded after draining down from higher parts of the landscape.
Frost affected avocado trees on the neighbouring property at Hampton. The white areas are icicles still present at 11.30am.
The Topoclimate surveys of the Hampton district not only accurately delineated the limits of suitable areas for avocado production but also identified other crops suitable for the other microclimates measured.
Measurement and mapping of microclimates has proven to be of immense help to farmers who understand the technology and how to use the information. It has proven useful for all horticulture farming and also for many pastoral farmers in identifying the best grass and clover mixes for different parts of their farms.
Closeup of frost damage to young replanted trees.
Microclimate mapping will show you (with a little technical help from Topoclimate Climatologists) how to find the best sites on your property for new crops.
