Encore: Earlier Irrigation Start in Almond
Drs. Or Sperling (ARO-Volcani) and Maciej Zwieniecki (UC Davis) discuss their groundbreaking research on almond irrigation. That research has culminated in an exciting irrigation scheduling application. We also get an overview of almond production in Israel. The UC Davis Carbohydrate Observatory is also referenced.
Have feedback or questions for the researchers?
Or Sperling: orsp@agri.gov.il or +972 52 6278189
Maciej Zwieniecki: mailto:mzwienie@ucdavis.edu
Zac Ellis (Olam): Zac.ellis@ofi.com (559) 303-0599
Come to an upcoming extension meeting!
In the San Joaquin Valley: Tomorrow Tuesday April 7 there is an Almond Board of California listening session in Modesto on Cornucopia Way at 8:30 AM
UC Cooperative extension has a Regenerative Almond Orchard Field Day on Tuesday, April 21st at the UC Merced Experimental smart farm
Ceres: Wednesday April 22
Durham: Thursday April 23
Fresno: Tuesday April 28
And Bakersfield: Thursday, April 30
In the Sacramento Valley we have a Third Thursday: Nematode Management in Orchards meeting in Orland on April 16 from 11-1
Nickels Field Day is Tuesday, May 19 in Arbuckle
I have two almond variety meetings at the Chico State Farm in June. Thursday June 11 and Thursday, June 25th.
The Third Thursday on July 16 will be in Yuba City and cover Walnut Mold
The Third Thursday on August 20 will be in Orland and tackle labor economics
Following a harvest season hiatus, there will be a Third Thursday on November 19 in Yuba City recapping 2026’s IPM challenges and lessons
The views, thoughts, and opinions expressed are the speaker’s own and do not represent the views, thoughts, and opinions of the University of California. The material and information presented here is for general information purposes only. The "University of California" name and all forms and abbreviations are the property of its owner and its use does not imply endorsement of or opposition to any specific organization, product, or service.
Follow us on Twitter! @SacOrchards and @SJVtandv
Thank you to the Almond, Pistachio, Prune, and Walnut Boards of California for their kind donations. Thank you to Muriel Gordon for the music.
The views, thoughts, and opinions expressed are the speaker’s own and do not represent the views, thoughts, and opinions of the University of California. The material and information presented here is for general information purposes only. The "University of California" name and all forms and abbreviations are the property of its owner and its use does not imply endorsement of or opposition to any specific organization, product, or service.
Follow us on Twitter! @SacOrchards and @SJVtandv
Thank you to the Almond, Pistachio, Prune, and Walnut Boards of California for their kind donations. Thank you to Muriel Gordon for the music.
Transcript: Encore: An Earlier Start to Irrigation in Almonds (2025)
Luke: [00:00:00] There are numerous upcoming Orchard education meetings to take note of in the San Joaquin Valley. Tomorrow, Tuesday, April seven, there is an am Amen Board of California listening session in Modesto on Cornucopia way at 8:30 AM uc Cooperative extension has a regenerative Ammond Orchard Field Day on Tuesday, April 21st at the uc, Merced Experimental Farm.
The Am Amen. Board of California also has four upcoming IPM meetings, tackling rodents, redleaf, blotch, carpools, and other pests Ceres. Wednesday, April 22nd, durham Thursday, April 23rd, Fresno, Tuesday, April 28, and Bakersfield Thursday, April 30, and finally Wednesday, June 16. If you are an Amman variety nerd like me, you can't miss the Amman Boards crack Out event at Merced College
in the Sacramento Valley. We have a third Thursday Nematode Management in Orchards meeting in [00:01:00] Orland. On April 16 from 11 to one. Nichols Field Day is Tuesday, may 19 in Arbuckle. I have two almond. Variety meetings at the Chico State Farm in June, Thursday. It. June 11 and Thursday, June 25. The third Thursday on July 16 will be in Yuba City and cover walnut mold. The third Thursday on August 20 will be in Orland and tackle labor economics. Following a harvest season hiatus.
There will be a third Thursday on November 19 in Yuba City recapping 2026's IPM challenges and lessons. This is Growing The Valley, a podcast by the University of California, division of Agriculture and Natural Resources.
I'm one of your hosts. Luke Milliron Orchard Systems advisor for Butte to Tehama and Glenn Counties.
Phoebe: I'm your other host, Phoebe Gordon Orchard, systems advisor [00:02:00] from Madera and Merced Counties.
Luke (2): Today on Growing the Valley Podcast, I am sitting down with, Or Sperling and maciej zwieniecki to have a really interesting conversation on irrigation, not only in California but internationally. First off, we have Dr. maciej zwieniecki professor of plant sciences at uc Davis, who was on a, a recent growing the Valley Podcast with Phoebe Gordon and Katherine Jarvis Sheen.
And then we also have. Visiting Scholar, Dr. Or Sperling. He's a plant science researcher at the Volcani Institute in Israel. Welcome, gentlemen.
maciej zwieniecki: Thank you for your invitation.
Or Sperling: Thank you. Luke
Luke (2): maciej, brief us back on how, Or came into the picture with your lab at uc Davis. What he was researching during his, his postdoc several years ago.
maciej zwieniecki: Or came to us about 12 years ago and. Became a postdoc in my lab [00:03:00] and almost immediately changed the way that I see or view the Orchards. And at the time we focused mostly on understanding the bloom time in plants. How do they prepare themselves for surviving the winter and how they use the information from the winter to make it a bloom time decision.
And in fact, this was the part of the podcast with Phoebe Gordon and Katherine Sheen, but work with Or started to understand the timing and the clock of winter dormancy. And studying it, we realized that there are two important things that were. Influencing the timing of bloom, which is temperature and the preparation of plants for winter in terms of carbohydrate storage, end up in several publications and then or went to Israel to work on his research program in Israel.
Why is it important to mention the carbohydrates in this case? Because carbohydrates [00:04:00] are the result of. Tree performance during the summer because they photosynthesize and accumulate the carbohydrates and to do it, they have to have water.
Luke (2): Or tell us a little bit about the focus of this research program that you have in Israel.
Speaker 4: So I was going back to Israel and as much said. We figured that carbohydrates, they're very important for the trees and they dictate how it blooms and its reproduction capacity. But I'm an agronomist, so I wanted to know how I can change through agronomy, through farming the carbohydrates, and I figured there's two.
Easy manipulations that are also very common in the farm. So this would be irrigation and fertilization. So all of my research is now focused on these two applications, but things did not go as expected because I thought that there'd be a lot of similarities between the irrigation in California and the irrigation in Israel.
And I found that it was not the case at the time in Israel. The common practice was still a very, very. Deficit [00:05:00] irrigation regime, let's say about 25 to 30 inches in irrigation. And that changed my focus. It took me many years to come back to the carbohydrates because first I wanted to understand why the Israeli farmers were doing this and if that was a sustainable solution to almond farming.
It is not. That was what we found. And then the other works were works to understand what are the costs of not irrigating enough
maciej zwieniecki: or, as I recall, he was telling me the cost was much lower yields because the growers in Israel have much lower yields.
Or Sperling: I said, how about we look all over the place and see who irrigates and what they produce?
I saw the Spanish industry with their 10 inches in water allocation. They yield about 500 pounds per acre. And I looked at Israel, as I said, 30 inches and we are up to 1500 pounds per acre, which is still too low for us, and definitely unsustainable in a global and a [00:06:00] competitive market. And then California with a 50 inches and then 2,500 pounds per acre.
And then Australia, which from all the reports I've read, it suggests that they irrigate almost 60 inches and harvest about 3000 pounds an acre. So. That all comes down to one to five ratio. So everything sort of adds up in terms of the efficiency is the same, and the more you irrigate almonds, the probability of you harvesting larger yields over many years is much higher.
Luke (2): Very interesting That. You see when you look, uh, internationally, just big picture at almond producing countries, higher yield for more water. 'cause we, we just didn't see that when we did it just on a California scale at a handful of orchards several years ago when Ken Shackle, uh, led a project with David Doll, Allen Fulton and Blake Sandon.
It really depended site to site whether there was a, a response to increased water. But it's very interesting when you look at the extremes between countries, that pattern comes out so clearly. Tell us a [00:07:00] little bit more about. The situation in Israel first is that 25 to 30 inches, that's without a lot of supplemental rain.
And then what has shifted internal consumption versus export for that market as well?
Or Sperling: No, actually where we grow almonds and in fact in most of Israeli it rains. 25 to almost 30 inches. So it rains as it rains in the Sacramento region or more. And this is why the Israeli farmers thought they were safer. In some years they were.
In some years when it rained more, there'll be another between one three good seasons. But later on that the effect is lost and they'll be back to lower yields. But overall, Israeli farmers were protected by tariffs. Every year because of treaties with the us. So every year they were going down substantially to let them transition to a, an open market, and by now they're down to null.
So they had these years to work out and move from a more traditional irrigation approach to the [00:08:00] intensive one that, they also needed to change possibly some of the varieties, especially the pollinators, and, and see whether they, they can work with self pollinating varieties. Also, in Israel, they were extending the farming.
Regions to other sites, which were sometimes drier, sometimes warmer. And there were a lot of climatic considerations that they did not have. So originally they grew these almonds farms in some very specific sites in the northern parts of the country, and by now they're all over the place. Still not a very big production, especially considering that all communities in the Mediterranean like to eat a lot of table almonds.
So there is a lot of uptake, a lot of consumption, and we're not producing even what the local market needs. So there's still a lot of import from the us, which means the industry is sustainable in Israel, since even in a no tariffs in an open market, we have the benefit of being closer to the market, so no shipping exports.
So as long as we can produce somewhere near the way that [00:09:00] Californian and the Australian farms produce, then we would have a, a market. Advantage and still import a lot.
Luke (2): And or do you see a lot of potential for growth in the Israeli market, both as intensification of the orchard systems as well as do you see a lot more hectares going in the ground?
What do you see when it comes to, to kind of Israel on the, on the global scene?
Or Sperling: Right now the industry is at the crisis mode because the older plantations, they were planted and lower intensities and and treated with less water, and oftentimes different kinds of water, so either excessive or deficient fertilization.
Practices, and this is something that we also focus on. And then, as I said, the yields were too low to even survive the former tariff conditions, and they're pulling them out as we speak. So as it is, we're missing maybe. 20,000 acres, I would say, [00:10:00] or even more. And that would be just to supply the local demand, the almonds that we grow in every testings that happened in Davies, they don't have the qualities you need both in size.
But, uh, but good for the table almond consumers. So the Arab countries around us are interested in them. So if we could produce more of this. We could find markets that won't even compete with a bigger industry, but we're not there yet. So we could grow.
Luke (2): And then certainly as a sophisticated agronomist, part of the message here is gonna be to, to irrigate more if you have the water would've been the, the techniques and tools that, uh, you've been talking to Israeli growers about to increase their production.
Or Sperling: So we finally made a big study with carbohydrates and photosynthesis, and we showed. As I said, the losses and the losses in the amounts of carbon sequestration are massive when you do it on a seasonal scale. We also made a production survey for all [00:11:00] the years that we could collect data for and for many, many farmers, and were able to show that, yeah, it wasn't chill units.
And it wasn't the different regions in Israel that we're producing that caused most of the variability in yield. It was oftentimes just the intensity in plantings. So how many trees you have an acre, we still don't have as many trees as you have per acre, so we're not referring to higher density plantations and then later to water.
Also, what we found, because we're using, at least in Israel, we need between one to two pollinators. For the local variety and we're counting on crosspollination and a synchrony in time. Irrigation effects whether trees meet at the times they bloom, and that is creating large losses.
Luke (2): And then maa with or deep in this work with carbohydrates, irrigation, fertilization in Israel, and working with Israeli growers, what brought him back to the United States [00:12:00] for another collaboration.
maciej zwieniecki: We didn't lose touch over the last 15 years or 10 years when the R was in Israel and we were continuously collaborating or developing our own research programs. But in close proximity, we are funded by two Bard Grants, Bard, which is the Binational International Program that links the researchers from Israel and the US And while we are working on a similar topics.
Eventually find out that there is a potential for collaboration related to irrigation. Especially that in my program I collected long term data for many orchards in California, in Central Valley, and the scale what we are talking about when, Or was talking about the Israel, the entire Israel can be placed inside the Central Valley, California.
So the scale. 10 times, no, not 10 times but the scale of production here is such large that, [00:13:00] uh, if we have an ability to study, not study 10 or five Orchards, we are, we can study 200 Orchards and then we study 200 Orchards the information that we gain on a much larger scale. And you can test many more ideas, especially if you have this long-term climatic data and long-term carbohydrate data and long-term yield data to look at.
True. Responses of orchards to different treatments, not necessarily in experimental base, but the different treatments that managers of orchards apply to the orchard. So it's like a large scale experiment that Or could not potentially do in Israel because you have no. Scale for it. So when he came here, we start to look at the data that we have in California in my lab, and discover that we can ask questions that we couldn't ask before related to irrigation and performance of orchards in our climates.
Luke (2): Or once you found yourself back in California, obviously [00:14:00] matche with the Carbohydrate Z Lab website and database Maciej is sitting on a, a massive collection of, of carbohydrate data from orchards up and down the central Valley of California. But you also connected with a California ammond grower who was able to bring in some of the yield and irrigation data insights that, that you would need to do this work.
Is that right?
Or Sperling: So what I found when Maciej showed me a lot of the data from the Carbohydrate Observatory came from one company and seems that one person, and this is Olam and Zach, so I was working on this data for a long time. I had some questions at some point. A lot of the questions I could answer because.
As you said, there was also irrigation data coming from Olam through PhyTech. So they have sensors all over the place and we could compare these two data sources, but that wasn't enough. So I contacted Zach and started asking questions about the data. He [00:15:00] suggested that he come over and see what we're actually working on, and that he had some questions of his own through these discussions.
We were able to funnel the key things we wanted to answer, and they were this variability in irrigation practices. I wanted to know why there was a variability in their irrigation practices, and he wanted to know the effects of this variability on his orchards, and I think that was where our interests aligned.
Luke (2): What tools did you use to start tackling those variability questions and really start digging in into these data sets?
Or Sperling: So at first we had irrigation and yields, and we had also the locations for the farms so we could go back. Nowadays, Google Earth has available a lot of complementary data sources, so that would be climate.
But also NDVI or any other wavelength that you would be interested, but we kept it simple and used the NDVI. So that is how green and [00:16:00] how big is your canopy in the field. And then we had the carbohydrate observatory data for all of these sites so we could ask what were the conditions in the site. What was the application the farmer was doing, how this affect metabolism, even phenology through NDVI.
And finally, how is this affecting yields and especially yields from the long run? I think the main strength of this study was that we started off with over a hundred fields. Then four years of data. I have never experienced these amounts of data in a company willing to share this amount of data for the public good and for me to do the works on.
And we drew these production functions where the first one was if we irrigated, how does this affect the yield? And we found that there was a general. Obvious trend where the more you irrigate, the better the yields were. But there were also a lot of variability and oftentimes we could see even countering effects.
So there was one year [00:17:00] when it didn't matter how much they irrigated, they had low yields, and there were some farms were more water helped and some farms that it didn't. So this is the, all these questions I told you that I had.
maciej zwieniecki: So those questions led to really a question where this variability comes from, especially that we trust the agronomist that he was doing and his farm managers were doing the best they can do to maintain high yields.
And yet still there was a variability in terms of yields. Varying from uh, 1000 to 4,000 pounds per acre, which is a large variability, and they couldn't attribute it just to irrigation or providing the nutrients to the plants. So this led to a question where this variability comes from, or whether we can even understand how we can help to manage the irrigation processes in the farms.
Luke (2): Or what have you been able to find so far as you've dug into that variability and tried to answer the question of what is not being explained by [00:18:00] irrigation and, and nutrient level, the two levers that you like to pull the most?
Or Sperling: First we found that as I suspected the farmers that we work with and the.
Farmers that we met, they're the best farmers there are. So they can explain most of what they did. Oftentimes it's just the resources that were available. Sometimes it was a hailstorm or or smoke over the valley that sort of negated any other effect that there could have been. But otherwise, we did find a very strong correlation between their actual irrigation application and the water that were available from the rains.
And the how the trees finally transpired and, and yielded over the long run. And this is why all of these studies that I did before and others did too, trying to see how an almond tree responds to irrigation on a single year is just, yeah, it's, it's ineffective. There is almost no effect on the current year for the irrigation.
It's a very fast race for almonds where they actually set the fruits when it [00:19:00] rains, and then they grow them during the early spring when weather is comfortable and they yield when the heat finally arrives. But the irrigation still have a very, very big effect. It just affects everything else but the yield.
So what we found was that the current year's irrigation may affect the sugar metabolism, especially the sugars that are available at the end of winter to grow the new canopy. And then this new canopy determines the future yields. We are able to isolate these points in time. When are the sugars important?
They're especially important at the end of winter. And when is the canopy cover or the NDVI most important? That's the first one we see, the big canopy we see in May. That is our potential for production and reproduction for the next two years at least. And if we can maintain this canopy and then also ensure that there's enough sugars to support this canopy [00:20:00] next year, then we're gonna have.
Consistent high yields for the next couple of years. And then if we want to maintain this canopy, and we've seen this in many farms that did not get their sufficient water allocation. What the trees did then is senesced and we know this from almonds, they're a very, very resilient species. What they would do in a bad year is drop their canopy, stop photosynthesizing, and wait the storm out and show up for the next year or maybe the year after.
They won't die and this is why they're supposed to be or associated with drought resiliency. So yes, the tree itself is resilient, but the yields, the almond yield is a very not drought tolerate. So then knowing what size of a canopy we can expect and work with, that also tells us how much the trees can transpire.
Therefore, what is there potential water requirements that would ensure that they have enough sugars for another year and then for another yield cycle.
maciej zwieniecki: So [00:21:00] you can think about in a way of how tree respond to environment is that through the winter they store carbohydrates the year before they store carbohydrates.
And then they use the carbohydrates to develop canopy that is later on used to produce new carbohydrates that will be feeding new crop. And then the development of the flowers depends on carbohydrates from the winter. However, the feeding up the nuts depends on carbohydrates from current year. So this is.
Two separate aspects that leads to the idea that there is a continuum in the response of Orchard for multiple years in a row that they have to use. What was last year to develop New Year. And initially, this is interesting. Part that or start to mention is that the initial development of the canopy that is producing new leaves in April, finally producing like the maximum leaf volume in May is not necessarily dependent on.
Current year [00:22:00] irrigation, but it is dependent on past irrigation or the winter water because this is what is in the soil. Trees can use what is in the soil to produce new canopy, but then this canopy has to be maintained by irrigation of current year.
Or Sperling: Then to add to this and comparing what we found and what the trees need and what many of the farmers I know from Israel and also the farmers we met here, almond farmers are very efficient in their use of water.
We were able to compare the trees transpiration to the irrigation and the rain amounts, and we have seen that the trees use everything that these farmers. Put out there. It's been put to use, but oftentimes it's put to use later than safe. So we're finishing the winter, then the soil has water.
All of this water is gonna be essentially transpired at some point, except that it is excessively used in the first half of March, where the tree finally has the [00:23:00] canopy and then April and May. And then finally we start the intensive irrigations and, and we see this if we use the irrigation coefficients or if we use the stress sensors, which are becoming more prominent in the fields.
In both cases, this is a very risky approach where we're depleting this resource. That the trees need to use for the rest of the summer. And although we were stepping in with irrigation, by doing so, we're exposing trees to two different risks. One is that they would actually run out of the water too soon, and this is at peak time of either fruit set or vegetative growth or any early stages of root development and even bud differentiation.
And then the other one is that for the rest of the season, the farmers would need to manage a very, very risk prone orchard because they have no more buffers. No more reservoirs in the soil. And what we suggested is that we actually take the [00:24:00] same amount of water that the farmers would irrigate otherwise, but distribute our reliance on soil water throughout the summer.
So then even if we're reaching droughts, we'd see them only in September and October where most of the important or the critical reproductive processes ended, and we try to embed this. Approach in our communications with the farmers in our, our communication with Zach, the grower from Olam that worked with us.
maciej zwieniecki: So you can describe it in a way that we propose the way to irrigate plants, not in response to stress. But in anticipation of the stress, meaning that we water for the future, not by the past. And that's kind of an important switch in a way of thinking because you don't need to rely on current measurements of plant stress, but based on the past performance of the orchards, [00:25:00] like how does orchard look a year ago?
You can anticipate, especially in California, which climate is very, very repetitive. You can anticipate what would happen in near future, prepare your watering structure for entire year, anticipating stress and shifting the stress. In the plants to later in the season, that's what or said, so we don't need to stress the plants and then start watering.
We can reduce the stress at the time when this stress is the most damaging to plants, meaning in May in, in the beginning of this season. When the canopy develops and the plants start to rely on the new photosynthates,
Luke (2): there's just so much there. But a through line is really about just the tremendous importance of early season irrigation and not being in a, certainly a moderate deficit, but even maybe a, a mild deficit.
And this has also been where my thinking has been going for a while as well. Or do you wanna jump back in?
Or Sperling: I just wanna say [00:26:00] that you're right and also given. Accounting for the rains and giving the rain all the credit. We can also now reduce the irrigations where we need to because there is other sources.
There is the rain, there is a larger soil water reservoir that we still want to use. And what I found is that while some farmers did not irrigate enough other farmers. We're maybe not accounting for the rain and therefore irrigating too much, both for the same intentions and with the right set of tools in mind.
But even thinking of most irrigation recommendations are based on reference ET and then crop coefficients. They did not let them do these. Be both safe, but also use all of the resources available.
maciej zwieniecki: Yeah. So in this case, we can also understand that in the idea that we have, we use the past performance of the Orchards, which is, in this case, the canopy size or the amount of leaves, which can easily be taken from the satellite imagery, like in this [00:27:00] NDVI parameter, which describes the how many leaves there is on the tree.
And this really reflects the potential of the orchards to evapotranspiration. So how much they can transpire so you can adjust the future watering to what you expect the tree will look like based on the past performance,
Luke (2): a totally different way of thinking about irrigation. You know, irrigating informed by past performance and also irrigating to what you want the orchard to.
To become, this is higher level chess here and it really is supported as much as I really appreciate ORs note on rainfall farm advisors. Absolutely. We do see cases in almonds, not as much as we see in walnuts, but we do see cases in Monds, especially in the Sacramento Valley, where over irrigation is likely the culprit, and that's likely because we have the most rainfall in the Central Valley and makes this a lot more complicated.
And I was part of a study with Ken Shackle and others where we tested different thresholds for starting [00:28:00] irrigation at the beginning of the season with the pressure chamber. A grower standard, two bars drier than the fully watered baseline and four bars drier. And as you both note, the impacts are not just.
On the current season, you have multi-year effects here. So the four bars drier a, a moderate stress to start your first irrigation. Not only did we see lower yields, maybe not the first year, but we saw it years, two years three. So that was clearly bad and, and there was some evidence that even two bars, which is a pretty standard start time, you know, that's.
Mild stress. There was some evidence that we weren't maximizing yield with that level of mild stress. So absolutely in line with what you're suggesting here, which is really trying to be on top of those first irrigations. So how do growers use all of these insights? You brought this all together in an app.
I understand.
Or Sperling: So at some point, Zach and Ola, they were interested to try our conclusions on a field level. So [00:29:00] we set to make irrigation tables for some very specific farms that they have, except that by now we're so used to utilizing all of these available resources from climate to NDVI from the satellite.
Any information on the farm locations that it was. Just the same effort to make an app for everybody in California as it was for these few farms down south. And that also was completely aligned with Oalm's wishes that we use the data for the public good. And in this app, we integrated, I guess most of the things that Maciej suggested.
We know how big these trees were last year. So therefore we can expect how they would act this year. We know how much it rained. We know that the farmers should be very efficient in their water use, and they are, except that we don't want you to stress the trees at all, unless it's September or October when you must.
So we had all of these understandings in mind, and then we. Program them [00:30:00] into a very straightforward decision support algorithm where you can set your location. You would get information about last year's canopy, the NDVI. You would get the range so far since November till the date that you're looking into the app.
So you can start designing your irrigation as early as possible. You can also, in many cases, especially in in the south, the farmers were, I wouldn't say it's irrigating, they were. Moving water to the fields during winter, so this is important water that we should take into consideration and adding all this information, they could now see how much to irrigate and then both on a seasonal basis.
So they can decide whether this is a good irrigation approach for them, or they think maybe they should irrigate more or less, or maybe they don't have this amount of water. And then also on a weekly basis so they can actually communicate this information to [00:31:00] the farm, uh, managers.
maciej zwieniecki: So, so the app is really constructed in the way that it takes into account the real evapotranspiration of trees based on the past year performance and many years of data.
Climatic data, because it's a predictive app and you don't really manipulate how much water you put at any month, the app taking care of it for you, meaning that you say how much water you have. Available to irrigate your field and up will distribute it to minimize the effect of stress on the plants. To the degree that you can see, oh, my orchard will perform well.
However, if there is not enough water, you might see in the app say moments when it says that your orchard will get into the water stress in particular time. You have problems,
Or Sperling: special case in California that you have a data source that we don't have in other places, and it ease the transpiration from the trees since you have the open ET platform or the T-Rex.
There are multiple names I've heard, but the [00:32:00] USDA work to map the whole valley for transpiration on a single orchard level. We use this to test our approach and you can also go back now and see that the trees are actually acting as you projected they will, and that you're still maintaining these high production levels and efficiency in water use.
maciej zwieniecki: And why this works so far is that. It's a little bit theoretical right now. We have a test on three large Orchards supplied by Olam. When we test side by side, two types of irrigation, the regular irrigations that Olam usually applied versus irrigation that we propose from our research. So at the end of the year, we see how they perform and it can compare the two approaches.
Luke (2): Very exciting. Uh. I understand you're kind of building the plane as you're flying it here in that you're still getting feedback from growers and updating the app based on that is the app accounting for weather. I know that's a big flaw of , the ET reports that we [00:33:00] send out to growers is that I believe they use historical weather and not forecast weather.
So how do you deal with, uh, extreme events like we had last June, July with crazy extreme record heat?
Or Sperling: So again, and this is this very, very conservative irrigation approach that we suggest, and it is that you always maintain a large. Soil water reservoir. It's very different than anything we have been doing in Israel, and I have found that it's also different than the way a lot of the farms manage their soil water here.
So overall, July tends to have similar weather year to year, but there is always a heat wave in July, a week long heat wave. It can be the first week, second or third week of July. So if by July you have no soil water and you won't be prepared and know that the heat wave is coming. And then irrigate more than in any other time in July.
Then yes, the trees are at risk, but in our case, there's gonna be, especially in July, [00:34:00] there's gonna be about 10 to 15 inches of water under these trees still waiting to be used for the rest of the summer. So in this case. Unless the whole of July is very different than any other July before you're good for the extreme weathers.
Another feature that now we add, and this is again in work with the Open ET and the USDA people, is to actually do a moving correction where you can see what was the water use so far. And maybe you have just experienced a very, very warm week in July and then fix up the irrigation slightly up or maybe.
This week now is exceptionally comfortable and you can reduce the amounts of water that you're applying. So there might be still a 10% water saving there, but there'll be a 10% that would never lead to a deficit. There'll be just based on, on surpluses.
Luke (2): Got it. So it doesn't sound like it necessarily factors in weather automatically, but that can be [00:35:00] done manually and you're relying on a buffer so that you're just more resilient to heat waves.
Or Sperling: I'm really trying to walk away from this reliance on the immediate conditions in the farm. If your tree is at the state where the soil, water, and the root system are so limited to the irrigation lines that any change in weather would harm it, then you're gonna see losses in a Mediterranean summer. At some point the system is not gonna keep up.
maciej zwieniecki: Yeah. So, so it's important to understand in this case, is that the idea of irrigation based on current or past weather, meaning a few days ago weather, when we have excessive transpiration and say, oh, we have to replenish what there is loss. In our opinion, it's an approach of the past, meaning it shouldn't be used because if we are, as Or said, running on the reserves, we eventually will run out of the reserves.
So the approach here is always have a little bit of buffer in the soil to [00:36:00] provide ability to respond to sudden changes in the weather conditions. And also for me. The idea of continuous adjustment to the weather beats the purpose of reliable long-term predictions. So it's easier not to use the weather because you would be pushing the app continuously, trying to see, should I water now?
Should I water now? That's not something what we expect to do. We produce. Based on the long-term predictions, we produce the Watering Management plan for a year, and you can adjust it if you want to. You can add more water if you have it, but the program predicts the best way to apply water to reduce potential for water stress under assumptions of the weather that is relatively constant in California.
Or Sperling: I wanna reinforce what Maciej just said, the app and this approach in general, yes, you can walk in any time and try it, and it would always optimize the efficiency of the water use, [00:37:00] but the sooner you do it in the season, the best program you're gonna get because this program will factor in. As much winter water allocations and as much soil water reservoirs as possible for the remaining summer.
So if you designed an irrigation based on May or June, then probably you are already running on reserves and it is very hard to recreate these conditions. But if you did this in March. You have a very, very comfortable irrigation plan
maciej zwieniecki: and buffer of water in the soil for unusual events.
Luke (2): Got it. Really interesting.
And of course, I'm concerned about Phytophthora and, and things like that. If, if folks are, are irrigating more so, soil drainage and not having standing water and, and all these things, of course must be considered. And, each site is so unique in the, uh, the soil and irrigation system and drainage capacity.
And all of this. What are your thoughts there Or?.
Or Sperling: I have seen a lot of over irrigation, and I've seen this more [00:38:00] often in fields, that the trees could not keep up with this water application. Their potential was lower to start with, in Israel, this could be a, a rocky terrain or this could be a, a low density orchard.
And in this case, when farmers were trying to replicate these conditions or these recommendations, they were over-irrigating and more moisture and then more disease. And this is why it's very important when you use this approach, you suit this to the field that you're asking the question about. Because oftentimes you would find that these fields need much less water than were generally discussed for the region that you're working and this way, 'cause I have seen one next to the other a very vigorous orchard that no matter how much water we were applying, there was no phyophthora.
And just next to it, another one. That for multiple reasons, couldn't use this water, and then was very, very susceptible to every pest that was out there.
maciej zwieniecki: So this is why it's important to know that [00:39:00] the app or our approach is re relating to the canopy size or so the true transpiration capacity of the orchard, which means that you do not.
Over irrigate. You only irrigate to what this orchard can transpire, so there shouldn't be a problem and over time, if you use the app in our approach in research, we do increase the stress over time in trees. So there is, there is at the end, by the end of summer you might run out of water that you apply, but you try to replenish it later in the, in the fall.
Or Sperling: Also I come from Israel. We use peach, almond rootstocks, and then oftentimes we have heavy clay soils. When we over irrigate, we kill the trees. We don't have the benefits of either the coarse soils that you use in the south or the plum rootstocks that you use in the north. So over irrigation is a big problem and nothing that I would ever advocate that you try in almonds.
I know other crops they can stand this, not [00:40:00] almonds.
Luke (2): So many fabulous points there, and I just love this concept of you have to work with what you've got, and there's restraints there. You can't take your junker car and be nice to it and try to soup it up. It's not gonna turn into a Ferrari. But I think that using the, the NDVI, using the satellite imagery is really helping you with your app to have much more tailored irrigation recommendations for what would be appropriate for the potential growth of your orchard, whether you're on the smaller trees or wider space, or, uh, whether you already have a, a much more intensive and productive potential.
Or Sperling: Yet you're still in a resolution that makes sense for the farmer. We're seeing many, many suggestions of a single tree resolution or variability within the rows, which the farmer then cannot use this data. So we are trying to keep this on a field level, on a farm level, something that can be applied but also would produce the highest.
[00:41:00] Level of efficiency we can work for,
maciej zwieniecki: so to support. Or's statement is that our approach is to go away from the precision irrigation or precision agriculture at the level of a tree, but shift it to the level of a field which is much easier to manage.
Luke (2): So critical because we can do so much measurement down to the.
The scaffold or the leaf or the tree. But our irrigation systems cover the entire blocks often with different soil types. And so you really need to make an average decision over that. So it sounds like, , your app is trying to integrate that variability across the field to help a grower make a single decision.
We've been kind of talking about , in many situations, likely , a recommendation for increased irrigation. And we'll link to the app in the show notes, , if you're interested, but with that potential that if, if you follow the app, it may indicate that. That your orchard could use, use higher amount of irrigation.
You already referenced [00:42:00] with Olam, uh, their situation across the San Joaquin Valley where they have orchards where they just don't have the water available, and that was limiting what they were able to produce, and that's only gonna become more intensified now. Groundwater regulation, really taking form in California with this overall picture of increased irrigation and potentially increased yield.
Probably too early to say, but do you think there's potential in California that big picture growers should be using fewer orchards and higher production, or is there a threat there? Water is limited, that if you don't irrigate enough, you're you're just reducing yield and yet you still have really high cost of farming.
How do you think about this in the future of, of irrigation in California?
maciej zwieniecki: First of all, I don't think that we necessarily say you have to irrigate more, but we say you have to irrigate in a different pattern. Meaning that if [00:43:00] you have a certain allocation of water in the past, but you respond in the past, want to this stress.
My plants got into distress. Now I have to over irrigate to overcome the stress. What we try to say is that you can redistribute water in a way that you remove or reduce the potential of plants getting into distress, and also you can redistribute water in the way that stress come in the moments when you really want to have it.
For example, in July or August when you want to prestress plants for shaking and then add additional water if you have it later on in the season in September and October. So we don't say that we will necessarily use more water, but we try to redistribute water that you have in the most efficient way, which is an important part.
If you don't have water obviously. orchards will be stressed and there is no way you can overcome it. You have to either reduce your expectation for yields or you have to cut half of your orchards and remove, move water to the orchards that can have higher potential. [00:44:00] So , that's something that you cannot overcome.
Or Sperling: I think that with the information we have about the production function, meaning water versus yields and the potential to transpire and yield for each of your fields, if you now have a limitation on water, you can first see how critical is this limitation. In many farms we've seen that if you just, yes, there, there was a difference in a couple of inches and that would've caused a drought condition in October or maybe in September, and that is.
Probably a sustainable irrigation approach still. But oftentimes if you're seeing that if you manage this field with this amount of water, you're gonna be drought stressed in July, then yes, consider removing some of the trees because an almond farm. That is stressed in water. By July, within three years, you're gonna be draining money, not [00:45:00] water in this case.
And, and we have seen this happen, so I think this kind of approach lets you both consider cases where you can still manage the farm or fix the farm or the irrigation due to changes.
Luke (2): Or let me know if I have this right from an example that you gave at an earlier presentation, I think from an an Olam field where water was limited, that even if they shifted irrigation earlier, you were seeing that Yeah, they were likely to.
To keep a, a decent canopy on the trees, but they were just never going to be able to irrigate with the water they had available at a level that could really produce sustainable yields. So like , at some point, unless your water availability situation is, uh, is expected to turn around in the years to come, you should kind of cut bait and move on in that case.
So could you talk a little bit more about that, being at a. Total irrigation level, even if it's [00:46:00] shifted earlier in the season, that your production function is mediocre.
Or Sperling: Yeah. So we've seen that, I guess up to 15 inches in irrigation or maybe even more. Then you're still at the part that I guess the more water you apply, you have maybe better trees, maybe lasher canopies, but you're not seeing these.
As returns in yields. And then we're seeing this sweet zone between I guess 35. And again, this is, I'm saying the irrigation you have to consider if you're growing where, where it rains. And now we have a. A solution of how to compute the rain into your computations. But over there you're seeing a lot of benefits for the added irrigation.
So if you are below this amount, then no matter what you do, you'll be probably investing more than harvesting. And that's not only in water, because almonds, they cost a lot in, , in machinery and in fertilizers and in gas. So I would say, and this is [00:47:00] oftentimes people associate between. Limiting water to farms and sustainability.
And I, and I don't think that's true. I actually think that not applying, uh, the right amount of water might cause farms to be less environmentally sustainable.
Luke (2): Good point there with the environmental sustainability of a low producing orchard that still requires all these inputs and still requires, you know, a substantial amount of water, but you're not getting the kernels for it.
Or Sperling: I just wanna reiterate, if you don't have enough water, then maybe consider not growing these almond trees. A final thought. I have to go back to Israel and now convert everything we have done here to help farmers, and that is something that I'm looking forward to do.
maciej zwieniecki: But also I think that I want to enforce the idea that this research would not be possible with out continuous support of, in this case, almond board and the CDFA, but also [00:48:00] growers.
And what I mean by continuous support is that we really need a long term data from multiple sites, and that's really important that the support is not focused on one year return. Like many. Industry experts expect this year input. We have something to show next year. No, this is an effect of eight years of data collection for Carbohydrate Observatory that can finally be used to show how to manage the orchard.
In a more efficient way that we really need the long term approach to research the trees. 'cause they are long living organisms and one year is not the same as the other. And we have to have multiple repetitions from orchards. And another part is that I wanna encourage is that experimental approaches are good or specific questions, however.
General questions related to production of the fields in California requires large scale. In this case, we try to use [00:49:00] entire Central Valley as an experimental field, and that's really important to be able to do with support of growers. Another part that I wanna encourage growers to share their data and information about their Orchards, like without Olam, we will not be able to do it because they were willing to share.
Yield data, willing to share the irrigation pattern, everything about their Orchards, which is important.
Luke (2): So many important points there. Maciej, the tremendous support in the funding that made this work possible. And again, over many years, eight years plus, that the work that has led up to where you guys are at right now.
And the importance of looking at these large data sets that really require grower buy-in , and , allowing some of their data to be used. We're all concerned about data and privacy and things, but when growers step up , and share data and responsible platform like you facilitated, for example with the Carbohydrate Observatory, it may not yield the immediate [00:50:00] answers for growers on what they should do, , next year, but.
Again, you've built these data sets and you've worked with so many growers up and down the valley that now we're starting to get to some really interesting potential solutions for growers and tools. So this is just really, really exciting. And then also with, Or I think this is a, a really awesome example of international collaboration.
I think we just often see other places where they grow our California crops as competitors, but here we have an amazing. Example of,
, how we can help each other out. So, or thank you so much for coming to California and, and doing so much work that could really benefit our growers as well as Israeli growers.
Thank you so much.
maciej zwieniecki: Thank you for having, thank you for having us.
Luke (2): Thanks for listening to Growing the Valley, a UCANR podcast. You can find out
more about this episode at our website growing the Valley podcast.com.
Phoebe: We'd like to thank the almond pistachio walnut and prune boards for their [00:51:00] support. We'd also like to thank my sister Muriel Gordon for writing and recording the theme music.
