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Food for thought


The Sustainable Groundwater Management Act (SGMA) is just beginning to reshape the future of farming in California’s San Joaquin Valley. It has been nearly a decade since the legislation was signed into law – for most of that time SGMA seemed like a distant worry. Now that is all about to change as in the next 5 to 10 years the implementation of Groundwater Sustainability Plans (GSP) begins.

In 1995 there were approximately 500,000 acres of almond trees growing in California; today there are more than 1,500,000 acres in production. Over 70% of this acreage is found in Fresno, Kern, Stanislaus, Merced, and Madera counties. California’s Department of Water Resources have designated these counties as having critically over-drafted groundwater basins. Some quick math…the estimated water demand in 1995 for 500,000 acres of almonds was 1,750,000 acre feet of water. Current demand for water is in the neighborhood of 5,250,000-acre feet – 300% of the original amount.

Groundwater restrictions will be coming into effect for most of the farmland that lies between Merced and Kern Counties. For the first time ever, growers will be forced to use a predetermined allocation of water to grow a crop instead of pumping the water necessary to meet crop demand. Farmers will be relying on what is called the Sustainable Yield, or in simple terms, the amount of water that they will always be able to pump. Most GSPs have this number expressed as the volume of water available to each acre of irrigated land. Fortunately, the faucet won’t be just shutting off all in one year, the changes will be implemented gradually through to 2040.


The Theoretical Orchard Let’s illustrate the effect of this with an example – my theoretical orchard. We know that the typical crop demand for an almond orchard is 3.5 Acre Feet per Acre (AFA.) If we assume the orchard is 100 acres (for easy math), the yearly demand of this theoretical orchard would be 350 Acre Feet per Year (AFY). Let’s also assume the orchard is located just outside of a water district in Madera County, so pumps will need to be relied on to meet crop demand. In the past I have always just gone out and turned the pumps on, but now, and every year until 2040, the reductions of what I can pump will continue until sustainability is achieved. The Madera Subbasin GSA has already established their Sustainable Yield estimates. Under the allocation plan that has been adopted it is now known that I will be able to pump 0.5 AFA per year in 2040. If we didn’t change anything about our theoretical orchard, other than available water, it means we would now have access to a grand total of 50 AFY of water in 2040. More than likely we would end up fallowing acreage or farming a different piece of ground because 50 AFY can really only support 14 acres of almonds in our theoretical orchard. While this may seem gloomy – and trust me I feel it too as my family has a couple of small almond orchards – all hope is not lost. Enter my personal favorite tree nut – pistachios. As it stands right now there are about 500,000 acres of pistachios planted in California; a number eerily like the 1995 almond acreage number. Not in the sense that I think it is a conspiracy or divine intervention, rather that market forces may be lining up for pistachios in the same way the almond boom was driven. If we replace the almonds in our theoretical orchard with pistachios, which have been found to use 30-50% less total water than almonds1, we can conservatively estimate the pistachio crop demand to be around 2.5 AFA. Our total demand would therefore be 250 AFY, but that doesn’t mean a lot if I can only access 50 AFY in 2040 as illustrated earlier. My theoretical orchard is a case for the worst of outcomes probable with SGMA implementation. More than likely if you were considering pistachios, you would have found a piece of land that had a better water situation than this. [Theorized by Joshua Dowell)


With SGMA restricting groundwater supplies, and ongoing unreliability in surface water availability in coming years, pistachios are a great option to consider. They’re hardy trees that thrive in salty soils, can tolerate drought far better than most orchard plantings, and produce similar margins at scale as other tree nuts.

Pistachios trees take longer, 5 to 7 years, before they are considered mature. However, once mature orchards are established it is not uncommon to see them produce for nearly 40 years – more than double the life expectancy of almond orchards. They are also significantly less sensitive to water scarcity during the hottest parts of the Central Valley summers – meaning the trees experience less heat stress in times of high temperatures.

In the 1980s a UC Davis extension researcher conducted the trial that gave pistachios the title for drought tolerance. David Goldhamer established an orchard near Kettleman City, about an hour south of Fresno. He turned the water off entirely for 3 consecutive years. The trees relied solely on Mother Nature and averaged about 3 inches a year of rainfall. Not only did the orchard survive this – it only took 2 full years to restore production numbers back to their original levels.

William Blake, a famous English poet said, “Hindsight is a wonderful thing, but foresight is better”. The “foresight is better” element of that quote is often forgotten. As farming becomes more technical and resource constrained in the years to come precision management is going to be the way that an enterprise can ensure they remain viable. SWAN Systems can assist with your irrigation planning and decision making. If you had your time over, would you plant the same crop in the same way in the same location? Maybe you would, maybe you wouldn’t. Food for thought.


Goldhamer, D.A., 1995. Irrigation management. In: Fergusson, L. (Ed.), Pistachio Production Manual. Center for fruit and nut research and information, Davis





Irrigation and Nutrient Management in Pistachio during Drought, Inflation, and Growing Water Concerns.


As drought, rising input prices, and the growing concerns for water availability progress, many pistachio growers are being forced to make very complex decisions about how to manage their valuable investment. Do I cut back on inputs? How can I produce sufficient yields and quality within mandated water budgets? How do I implement a deficit irrigation program? These are just a few of the common questions that growers are asking.

As these issues persist, we need to take a step back and prioritize our response. Much of the research has been done by our industry leaders. Putting it all into perspective and practice can be a challenge.

Nutrient Management

There is growing concern about the rising price and availability of quality fertilizer. However, in times of drought cutting back on nutrient needs may not be the best solution. A better solution is to optimize nutrient placement and irrigation applications based on site-specific, soil-specific, variety-specific, and crop stage-specific needs.

In drought stress situations, potassium utilization is a critical factor in mitigating abiotic stress complications associated with water and environmental stress. One of the first processes of tree life to be affected in drought situations is the root system. Studies have shown that sufficient potassium placement in the targeted root zone enhances the total dry mass accumulation of plants under drought stress. Root growth and cell membrane stability are promoted where there is an adequate potassium supply. In potassium deficient soils, water uptake through the roots can be reduced.

Potassium deficiencies may also affect stomatal regulations. Potassium plays a critical role in stomatal movement. Some studies have shown that potassium deficiencies can induce stomatal closure and decrease photosynthetic activity in plants. In drought-stressed situations, the stomata cannot function properly where potassium is deficient which may result in even more water loss.

Excessive drying of the soil may lead to poor potassium uptake by plants. Proper timing and placement of potassium and water are crucial in managing many stages of plant development and mitigating abiotic stress conditions that can lower crop health and overall production quality. Having the ability to monitor and manage these important decisions with current and up-to-date data is imperative.

Irrigating With a Deficit Water Budget

As we all prepare for water caps and reduced water availability, the most important question I’ve heard is, “when should I cut back my water during the season?”. Fortunately, this research has been conducted and guidelines produced. A common study was done by Bob Beede and Goldhammer. This study suggests that water can be safely cut back during growth stage 2 (shell hardening), and post-harvest timing.

The trick in this is how to put it into practice. The timings and strategies for deficit irrigation are critical to producing quality crops and avoiding any negative chain reactions within the production system. There are many restraints on the farm that make it a challenge to closely monitor these parameters leaving us to make habitual or blanket management approaches or having very little oversight at all. Such restraints include lack of labor and talent, too many sites with different crops, varieties, and soil types, complicated hardware setups, lack of budget, and too many apps to monitor.

How do we bring it all together to make quick and accurate decisions? How can we compare what is working to what has not? How do we generate meaningful reports to facilitate quick responses?

SWAN Systems

SWAN Systems allows for precision irrigation and fertilizer management and is by far the best tool I have seen that enables growers to monitor and manage these many variables and much more. In deficit and drought-induced growing conditions, SWAN can mitigate the many stress points identified above. It does this by helping users to make data-driven decisions about how much to irrigate and when enabling the application of only what is needed for optimal plant growth. SWAN can read data from most hardware tools used such as moisture probes, weather stations, automation, and flow meters. By integrating this data into one system, you can make quick and informed decisions on dry-down periods, recovery periods, and nutrient timing, all while working within an established water budget.

SWAN makes available in one platform information from existing hardware, site-specific soil, weather forecast, historical weather and irrigation applications, spatial imagery, water budgets, and management constraints. All parameters are completely adjustable, including editing of crop profiles and growth stages, to allow you to create site-specific crop scenarios during the season. The SWAN dashboard allows you to view your orchards as a whole or as individual sites. The System Suggested Irrigation (SSI) module uses the configured site data, current soil moisture, and weather forecasts to provide a week’s worth of forecasted irrigation needs. This SSI module makes it simple to predict what the soil moisture will be under different irrigation scenarios. Once properly configured, generating an optimized irrigation schedule ready for the field is as easy as a click of a button. The schedule can be printed and is also available for viewing on SWAN’s mobile app. No matter where you are, you can quickly review your sites, soil moisture balance, and water use.

SWAN also offers fertilizer budgeting. An amazing feature is being able to use data from your water quality analysis. Once this data is uploaded into SWAN, you will be able to monitor what nutrients and minerals are going into your soil such as N, B, and Cl. You can also keep track of applied nutrients and set nutrient budgets. Having this data available for quick review is vital for managing a deficit irrigation program and for managing important nutrient decisions such as the placement of potassium.

In a Nutshell

In these times of inflation and scarcity, it is critical to make every drop count. We all need to be able to maximize with precision water and nutrient use and ensure that not one drop is wasted. Water and nutrients must be placed at the right time and at the right rate like never before. SWAN Systems can ensure that your team has the best tool for this job. SWAN Systems will help to reduce costs, increase yields, ensure you get the most out of your limited water supply, and enable you to apply the right amount of nutrients for your crops.



Cool Climate Viticulture



Farming quality wine grapes in a cool climate provides different challenges to those faced by farming in a hot climate vineyard. Cool climate water needs are more about optimization of the water accumulated in the soil and surface water. SWAN Systems uses tools already in the vineyard, such as soil probes, weather stations, and remote sensing, to enhance the understanding of what’s happening in the soil and within the canopy. Using every drop of water to its full potential and managing the canopy and berry quality, SWAN Systems creates an all-encompassing forecasting tool ideal for use in cool climate growing regions.


California has vast microclimates where wine grapes can thrive. The cool climate regions of California can be found in the coastal areas, parts of Northern California, and areas with elevation changes. Cooler regions in Northern California have wet winters, while coastal areas have cooler winters with less rainfall. Though both areas are within Winkler Index I and II, the rain patterns are different, and the irrigation needs will vary. Cool climate regions have their challenges, but a coordinated irrigation plan can help manage the needs of the vineyard and optimize water use. Using tools like soil probes, weather forecasts, and remote sensing allows for a complete picture of the irrigation needs throughout the year.


Regions with longer winters, fog, and rain will have unique challenges and different timings for their vineyard practices. Irrigation planning in cool climate areas can be started by monitoring soil moisture in the soil profile early in the season. Understanding the amount of water in the vineyard’s system can help plan the needs for the rest of the year.

From winter to spring, irrigation needs are likely to be low during a wet winter. With the full soil profiles, reservoirs and waterways flowing, there is no urgency to irrigate. However, understanding what’s in the water bank will allow for educated irrigation choices when spring comes around. By looking at soil moisture readings from probes at the start of the year, insight will be gained as to what’s happening underground and provides an opportunity to set a water budget.

Spring allows for fertigation and early irrigations to occur. As canopies begin to develop, balance in vigor is needed to supply enough energy to the vine but not allow the canopy to grow too big. Canopy growth can be controlled through irrigation practices and leafing. Leafing can help keep mildew levels low in moist vineyards while allowing a suitable amount of sunlight and wind to enter the canopy. It also assists in the proper spray applications of fungicides.

During spring and summer, the focus turns to cluster maturation and Brix accumulation. Both over-irrigating and under-irrigating can be a problem in cool climates. Too much water will result in watery berries, split berries, and excessive foliage. Water-stressed vines can begin to shut down, and berries will shrivel if the permanent wilting point is reached. Further insights into summer irrigations and canopy growth can be gained through an understanding of the crop coefficient of the vines and analysis of data (e.g. NDVI) obtained from spatial imaging.

SWAN Systems

SWAN Systems is a prime instrument used by irrigators in cool climate areas due to its ability to pair with existing hardware in the vineyard. SWAN Systems can read data from most existing devices already sitting in the soil and estimate dry-down periods. These tools, paired with weather forecasting, historical data, water budgets, and spatial imaging, can give a clear view of what’s happening underground and above-ground. The SWAN dashboard allows you to view your vineyard as a whole or as individual sites. The System Suggested Irrigation (SSI) module uses the configured site data, current soil moisture and weather forecasts to provide a week’s worth of forecasted irrigation needs. This tool can be customized to allow the soil to dry while maintaining enough soil moisture for the vines to cope with any forecasted heatwaves that may be approaching. The SSI is ideal for cool climate areas due to its ability to suggest practical and substantiated irrigation plans based on growth goals and quality targets.

The ability to properly irrigate cool climate vineyards will help control vine vigor, berry health, disease, water logging, and overuse of resources and budgets. Cool climate viticulture areas can present challenges different to those experienced in warmer climates. Still, with the right tools, farmers can make the best choices allowing the cool climate viticulture characteristics of higher acidity and unique aromatics associated with these softer-bodied wines to shine in the wine.