Water an elemental
Water a fundamental
Building block of life
Water of Life
Margaret de Wet (mother and grandmother of the current owners) was the first person to bring drip irrigation into South Africa in the 1960s and the faithful Motorolla MIR 3000 computer has been irrigating 230 ha at Excelsior Estate since 1981. The computer, invented around c. 1978 by the Israelis to irrigate their crops, is still remarkably efficient despite its advanced age. But although the MIR still has the will to go on, there is nobody left who knows how to service it. We thought perhaps it was time to retire the trusty antique and bring in a new system.
The MIR is a pretty interesting piece of kit. This antiquated computer was clearly built to last and has been regularly sending pulses down cables every few seconds for the last thirty years to check flow rates, pumps in action and block being irrigated.
Excelsior Estate is in a semi-desert climate which receives c. 250mm average rainfall per annum. And it’s not uncommon for c. 200mm of this rain to arrive in one big downpour, hence the need for more evenly distributed water. Water from the Breede River is stored during winter at the Brandvlei dam in Worcester. During the summer water is released down river and directed to the farms in the area through a series of weirs and gravity fed canals. We store our water in two dams on the farm.
Without any irrigation the vines simply wouldn’t stand a chance. They would be under severe stress, drop their leaves and eventually curl up and die. Even if a weekly measure of water is skipped, particularly in hot weather, the vine could start to shut down resulting in undesirable green flavours in the wine. We carefully monitor our irrigation system to avoid this and use it to give the vines a mineral boost when necessary (roughly every 4 years) and an annual dose of Earthworm Tea.
The new irrigation system works along the same principles as the old version but it can produce fancy reports and as it runs on radio it doesn’t need cables to connect the computer with each vineyard block. We’re not so fussed about the snazzy reports but the lack of cables is a bonus – as with most famers, we experience quite a lot of cable theft in early spring. It’s more disruptive than anything and the scrap value is nominal but in between theft and replacement the vines are out on a limb.
When planting a block of vines we prepare the soil but ripping it to around 1.8m. This allows the vine roots to penetrate deeply (down to 3m in some blocks). We also practise Regulated Deficit Irrigation (RDI) means applying just enough water through a drip irrigation system to achieve properly timed mild water stress. The results are improved wine quality and conservation of water and energy. Jacques de Wet who farms alongside his brother Peter and father Freddie, thinks it’s a bit like raising children ‘You want them to have every possible benefit in life – but they have to work for it in order to bring out their character and full potential!‘
- Wine Institute Article on RDI
- Irrigation in Viticulture Article from Wikipedia
- Deficit Irrigation and Vine Mineral Nutrition Article from American Journal of Enology and Viticulture