Sub-surface irrigation uses up to 70 per cent less water, and far less fertiliser, than traditional hydroponics.
New irrigation technique grows cucumbers without wasting water
ABU DHABI // Ali Ahmed Bukarrood knows the importance of saving water. As a hydroponics farmer in Dubai's Al Awir area, he believes every little helps when it comes to preserving the UAE's scarce natural resources.
"In our country, we have really sandy soil so water gets absorbed easily," he said. "This is not like Europe or the US."
Three years ago, Mr Bukarrood converted his farm from soil to hydroponics. Since then, he has been using two irrigation systems to water his tomatoes, cucumbers, eggplants and lettuce - a traditional drip system, in which the plants are fed nutrients from the top through tubes from a closed reservoir, and for his plants and herbs a "nutrient film" technique, in which the plants' roots grow in closed, water-filled trays.
"Compared to growing in the soil, it saves me 60 to 70 per cent more water," said Mr Bukarrood. Now, though, he is considering switching to sub-surface irrigation, in which an underground water tank feeds the plants' roots directly through pipes, as a potential replacement on his 2,300-square-metre farm. "Like hydroponics, it's definitely a good idea."
A company called Epic Green Solutions is trying to do just that in the UAE. Last December, it installed a sub-surface irrigation system in Al Dahra Agricultural Company farm in Al Ain to grow cucumbers. This July, it set up a landscape demonstration plot on Yas Island.
The system involves an underground water tank linked to five interconnected cells under the crops. Water flows from the tank to the cells through pipes. Water reaches the plant roots once it gets to the cells; above it is a thick layer of gravel that allows the water to travel easily across.
To test the system, half the greenhouse in Al Ain still uses drip irrigation and the water use on both sides is metered. Since last December, the farm has produced three crops of cucumbers - and the difference between the two systems has been significant.
"The sub-surface system used 185,000 litres of water compared to 818,000 with the drip," said Bart Rehbein, Epic's managing director. And while the drip-watered plants stopped producing cucumbers two weeks ago, those with sub-surface irrigation should keep producing for another three weeks.
"Most greenhouses use the drip but we're already at 82 per cent water savings," said Mr Rehbein.
And not only did it use far less fertiliser - 17 kilograms, against 27kg for the traditional system - the new system yielded four times as many cucumbers, an average of 4kg per plant, compared with 1kg before.
Nor are cucumbers the only application. As a date palm farmer on Sharjah's east coast of Khor Fakkan, Rashid Khamis Burshaid is also considering a sub-surface system as it is "much better for the sandy soil".
As the system is underground, the water does not evaporate - the most important feature, says Mr Burshaid. "Because it barely rains in the country, about 120mm yearly, and people don't have very good direction on how to irrigate their farm, a lot of water is lost through evaporation," he said.
Mr Burshaid drip irrigates his 300 date palm trees. But in his area, the water is extremely saline which makes it difficult to keep the farm healthy. "Because I'm next to the sea, I have to go get my water from a well," he said. "And I need almost 300 litres of water a tree monthly, which is a lot."
The trees receive between four and eight litres of water an hour - not much, he says. In summer, Mr Burshaid waters them three times a week and in winter, every day.
"A lot of people don't care about water savings but for me, it's very important because I don't consider it as my own water, it's for the future generations. We have to save as much as we can so we must use different systems to irrigate."
Next week, Epic will fit its system to Al Dahra's palm trees. "Usually, a palm tree uses 125 to 200 litres of water a day, so we believe we'll be able to save between 50 to 80 per cent of that water," said Mr Rehbein.
The Farmers Services' Centre, an Abu Dhabi government body that supports farmers, has supplied seeds to Epic to monitor how much water buffel grass needs in an open field. The system will also be installed in a park in Jubail, in eastern Saudi Arabia, in two weeks.
"It's also a good way to control the land and prevent soil diseases," said Laith Al Ogaili, Al Dahra Farm's manager. "We faced many problems with nematodes [worms]before and now they're eradicated."