Pictured Above: The extent of South Africa’s macadamia orchards is mapped to assist the industry in production forecasts and marketing assessments

At the end of 2021, SAMAC and the research team from the Applied Agricultural Remote Sensing Centre at the University of New England teamed up with two objectives in mind: to build a national map of macadamia orchards and to develop satellite-based tree age and yield forecasting models for the South African industry.

Until recently, the size of the macadamia industry in South Africa was inferred from tree sales and planting data from nurseries and growers respectively, which resulted in an under-estimation of the size of the industry.

With the expected exponential increase in macadamia production forecasted and currently experienced globally, it is important to know what South African production will amount to in future to ensure consumption is increased in current markets and that new markets are developed ahead of supply. Results confirmed the exponential increase in plantings over the last seven to ten years, but with actual numbers now available for the number of hectares established and tree age distribution in industry. This will assist SAMAC with the development of a more accurate crop forecast strategy going forward.

Mapping relied on satellite imagery and the correct classification of crops was further informed by supplementary data from various sources. This included publicly accessible information such as street view imagery, field work and engagement at regional study groups. To date, 72 652 hectares of macadamias have been mapped in South Africa. This is 16 284 hectares (or 29%) more than the 56 368 estimated previously. 15 068 ha have been mapped in Limpopo, 29 083 ha in Mpumalanga and 23 806 ha in KwaZulu-Natal, with smaller plantings also present on the highveld, Eastern Cape, Southern Cape and Western Cape.

From left, Dr Elrea Strydom (SAMAC), Craig Shepard and Joel McKechnie (AARC).

Historic information

Historic block-level tree age information was used alongside historic Landsat satellite imagery to build an algorithm able to predict planting year with a 1.8-year average prediction error. In Limpopo, where the macadamia industry in South Africa originated, 23% of trees are older than 20 years, and 32% of trees are younger than ten years in age. In Mpumalanga, which is currently the biggest producing area, 10% of trees are older than 20 years, and 66% of trees are younger than ten years. KwaZulu-Natal is the new frontier in the South Africa macadamia industry, with only 5.5% of orchards older than 20 years, and a whopping 78% of orchards less than ten years old. An accurate yield forecasting model could not be developed as a result of the small historic block-level yield dataset which was available. This will be explored further once a more comprehensive data set is available.

Accurate information

Accurate information on the spatial distribution and area under macadamias in South Africa, as well as the age distribution of orchards will allow industry to plan more accurately. The map will also support the dissemination of aggregated industry information and research outcomes at block level in future. This tool is invaluable to the macadamia industry, and the map will only maintain its value if it is continually updated by industry. Growers are thus encouraged to keep their block-level information updated. The map can be viewed through the interactive dashboard, and updated through the industry engagement web app. Both platforms can be accessed through the member section of the SAMAC website.

Other SAMAC research projects

A number of SAMAC research projects are being finalised, and growers can look forward to seeing the results in the next few months. This includes projects on the advantages of macadamia husk compost, classification of sites suitable for macadamia production in South Africa, climate change modelling, technology deployed for mechanical harvesting in Australia, husk rot, Phytophthora root rot and more.