Water use in California: the inside story

Walter K. Thut, the Swiss co-founder of Aqua4D, is now based in California. On a recent visit to Gemperle Family Farms in Turlock, he wanted to find out more about water use in the almond industry, beyond the headlines. He spoke to Richard Gemperle about this and more:

Could you firstly give us a little insight into your irrigation habits?

Richard Gemperle: I try and stay just above the demand curve and keep a water balance. All of our irrigation decisions are based off of soil moisture monitoring and our real-time water budget. During the peak irrigation season, on average, every 4 or 5 days we would do a 24-hour irrigation. Everybody has their own philosophy, but I like to see the ground wet but not the trunk, otherwise it has a detrimental effect on the bark.

When the trees are fully mature we do one day on, three days off – in the heat of the summer.  That essentially just keeps up with tree demand. We have invested in very efficient micro-sprinkler systems. This provides efficient use of water as well as frost protection during the bloom period.

Tell us a little about how the geography and the climate here affects your water use?

Richard: When you look at water use, annual rainfall around here is about 14 inches. These trees need about 36 inches a year if you’re efficient with your water use, maybe 40 on a hot year.

We are blessed with a very reliable and inexpensive surface water supply; reservoirs supplied by Sierra snowpack. During the drought is when we have to rely on conjunctive use, where we still get reduced surface water allocations from the districts but we have to pump groundwater to supplement it. During drought periods we go into deficit irrigation where we try get by with the least amount of water possible.

So how did the years of drought affect almond crops?

Richard: Well, to give you an example, during the drought there were of course farmers with a significant lack of water. They were having to grow these trees with maybe a 20% water allocation – normally you want to put on 40 inches, but they had 8 inches to work with through the year. And of course, that first year they had a minimal yield, but the trees were stunted and there was no new growth. This went on for two years, but even after the drought subsided, the effects continued, with reduced yields for several years…

The Almond Board of California has set a goal to save around 25% water – how realistic do you think this is?

Richard: The goal is simultaneously less water use and converting to extremely efficient systems; I think it’s very much achievable. For example, when we redo new orchards and switch from flood irrigation to micros or double-line drip we easily reduce our water by 25%. If you’ve already installed high efficiency irrigation systems and have state of the art monitoring, reducing water use becomes more difficult.

Gemperle & Aqua4D’s CTO at the orchard, March 2019

What do you say to the common reports of significant water use by the almond industry in California?

Richard: There’s a water function for every single commodity you grow, whether it’s wheat, olives, almonds, whatever. And almonds are pretty much on the middle of that. They have quantified water use for essentially all commodities – pound of cherries, ounce of almonds, and the food value from that. When you compare various protein sources, almonds require 23 gallons/oz, peas require 45 gallons/oz and beef requires 106 gallons/oz. When you look at the “big picture” of agricultural water use in California, almonds comprise 12% of irrigated agricultural land, but the water use is actually only 8% of the total agricultural water use, which would indicate that we’re a slightly lower water user than average. My conclusion from this is that almonds are actually a very efficient conversion of water to food value.

On top of this, it could be said that due to the carbon capture and evapotranspiration these trees offer, you are in a way CO2 positive, right?

Richard: Well yes, they’ve done carbon footprint studies of almond orchards and yes, they are a net positive, in a sense.

Would you agree that the issue of water consumption in California is mainly political and that the discussion is somewhat skewed?

Richard: I think there is a philosophical battle between agriculture and environmental concerns. I consider myself an environmentalist, actually. We try to be the best stewards possible for the land we farm; after all, the goal is to hand over a sustainable operation to the next generation. My only concern is that water decisions made on behalf of environmental goals are not always science based.

The real water battle is between the competing end uses of water. Water defies the fundamental laws of physics: it doesn’t flow downhill under the force of gravity, it flows towards money. LA has a lot of money, there’s a lot of water going to LA.

You’re currently conducting trials with the Aqua4D  system on two plots. As a system which improves water efficiency, what attracted you to use Aqua4D?

Richard: Well firstly, there’s a big variability in the cost of water in the Central Valley; in some places it’s really expensive and it’s hard to get enough. There you have to do everything in your power to make it the most efficient system possible and improve the efficiency of your irrigation. If Aqua4D can contribute to that, that’s a big selling point.

We’re lucky here that we have fairly inexpensive water but we still use it very efficiently. So from my point of view I’m just looking at the response of the trees to see if it affects yields. We currently have two studies ongoing and we will see how it compares; it will take a couple of years to see the yield differences but we’ll start to see the differences early on in the tree growth response.

Richard Gemperle, thank you!

For more about the use of Aqua4D’s technology for water savings in almond crops, see here.


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“When you look at the “big picture” of agricultural water use in California, almonds comprise 12% of irrigated agricultural land, but the water use is actually only 8% of the total agricultural water use, which would indicate that we’re a slightly lower water user than average.”