New subsurface irrigation technologies: will they work in South Africa?

DNA Irrigation recently registered various patents that the company believes will revolutionise irrigation in fruit and grape production. Glenneis Kriel reports.

- Glenneis Kriel

Subsurface irrigation has been widely adopted in the production of highly mechanised crops, such as sugar cane and lucerne, because it helps to improve labour efficiencies and reduce damage to irrigation infrastructure.

Added bonuses are that water is delivered directly into the root zone, reducing water losses caused by evaporation in overhead irrigation, and farmers can apply fertiliser via irrigation, which reduces labour costs and improves fertiliser efficiency.

Hardly any fruit and grape farmers, however, are using subsurface irrigation in their orchards in South Africa. In ‘The pros and cons of subsurface irrigation’, which featured in Farmer’s Weekly on 18 August 2018, both Pieter Fouché, viticulturist of Graham Beck Wine Estate near Robertson in the Western Cape, and Dr Philip Myburgh, a retired researcher of the Agricultural Research Centre Nietvoorbij, advised against the use of subsurface irrigation.

THE CHALLENGES

Why? Fouché said that they planted 6ha of Chardonnay wine grapes under subsurface irrigation in 2004 to improve their water use efficiency. They got the idea to use subsurface irrigation during a visit to the Margaret River wine region of Australia, where farmers claimed it reduced their water usage by roughly 30%.

Fouché during the interview back then, and now again, confirmed that Graham Beck never saved more than 10% water per season on the vineyards where they installed subsurface irrigation. He blamed this on Robertson’s soils being much more diverse than Margaret Valley’s deep alluvial soils, and the difficulties in managing these variations.