Lettuce, golf courses and gardens - wasting precious water
April 05, 2015
So, it’s finally dawning on California that there’s a water shortage. Better late than never, I suppose. But where does all the water go? Well, spectacularly inefficient irrigation of crops and golf courses, not to mention gardens, is one way it gets wasted. Like watering wheat - wheat! - above (click to enlarge)
I remember, years ago, the PR guy from one of Britain’s top garden watering companies telling me – in a tipsy moment after a press party – that 85% of the water that came out of his company’s sprinklers evaporated. Wasted. Gone. Vanished into thin air.
Research at the University of California (Davis) points out that in the southern deserts of the USA 36 inches of water per acre is typically used to grow a lettuce crop, that’s about one million US gallons per acre. Let’s say a field produces two crops of lettuce a year (an estimate probably on the low side), that’s two million gallons of water per acre per year. The water is applied from overhead sprinklers and let’s say that my tipsy PR guy overestimated the wastage, let’s say it’s only 50%. That’s a million gallons per acre per year – wasted. And the most recent figures (2012) show that California harvests about 284,000 acres of lettuce a year.
Across the border in Nevada, Google Earth reveals the patterns created by huge sprinklers - the booms can be up to half a mile long - in a naturally arid region (see below, click to enlarge).
And what about golf courses? According to the United States Golf Association “golf courses in hot, dry climates may require as much as 6 acre-feet of water per acre per year”. As it happens, this curious measure translates into almost two million gallons of water per acre per year for a dry country golf course. If we say a golf course is about 100 acres in total - well, you get the message.
So, co-incidentally, it takes about the same amount of water to keep a golf course lush and green as it does to grow two crops of lettuce – and most of it is wasted!
There are a number of conclusions to be drawn from all this. And one of them is that California’s new rule that restaurants must ask customers if they would like a glass of water before serving it is not going to solve the problem.
As gardeners, we should abandon sprinklers and install soaker hose watering instead in the shade garden, left, click to enlarge). That’s easy. As for lawns? I’m sure I don’t need to tell you. Lettuce growers, too, should use some form of furrow irrigation, many already do. Or soaker hose – and using soaker hose would also work wonders for the car tire recycling business (that’s what soaker hose is made from). Installation would be a major capital expense, of course, but charges for water use would be cut significantly as growers would use so much less – where they pay for it at all(!) And hey, we’d have to pay more for our lettuce. What’s wrong with that? Lettuce is cheap. And perhaps more crops would be grown in areas with a higher natural rainfall. It makes no sense to waste water growing lettuce in California then truck it to supermarkets in New York. But don’t forget: 80% of California’s water is used by farms and farms are not included in the mandatory 25% cut back.
I'm not sure that reducing 20% of water use by 25% is going to make much difference - that's 5% of the total use. A drop in the... you get the picture: sounds good, doesn't mean much.
And golf courses? That’s a tricky one. The men people who make the decisions about this probably agree it all out on the golf course - and we wouldn’t want to upset them, would we…?