YOUR INDUSTRY
GREATER IRRIGATION ACCURACY Glenys Christian
Bharat Bhana with an Adroit sensor in one of their potato paddocks close to Pukekohe. The yellow stick in the background marks where another sensor remains in the soil
While vegetable growers have relied on knowing how much water their crops require by the length of their irrigation round, now they need to be much more accurate, believes Pukekohe grower and Potatoes NZ director, Bharat Bhana. He and his three brothers are directors of Hira Bhana which for more than 60 years has been growing over 600 hectares of crops around Pukekohe and Onewhero, of which around 120ha is leased. Potatoes make up a consistent 30 percent of their crops followed by onions, carrots, lettuce, brassicas, pumpkin and a small amount of watermelon. Around 95 percent of their crops are irrigated with a combination of pivot and hard-hose irrigators, but only about one-third of their potatoes. “With the potato crops which are planted at the end of May, we don’t have to irrigate them unless the ground is very dry when we want to dig them in November,” he says. Water can also go on at a late growth stage to stop pest problems.
20 NZGROWER : MAY 2022
In the past, timing of irrigation and the amount of water supplied to the crops was often determined by knowledge they had built up over many years. “We’ve been at this game a long time,” he says. Irrigation would be started when the leaves of the potatoes started to droop, with timing depending on how long it would take to get around a particular block. But that could mean too much water was applied which could have been better used elsewhere. But after being approached by Auckland-based company Adroit, they now have 10 Dragino sensors placed in their fields. They give a read-out every half an hour of soil moisture, temperature and electrical conductivity, which is sent to them in real time via an app loaded on to their mobile phones. The sensors are placed in a plastic tube, which can be dug into the soil at any depth required and can be moved easily from paddock to paddock depending on different crop requirements. “You can make a lot better decisions on how much water to put on,” Bharat says. “Whereas you might have been putting on 50 millimetres every ten days, you may only need to apply 35mm to top soil moisture up.”
