Small, diversified farms on California’s Central Coast have been dry farming for decades, allowing farmers to use water stored in soils from winter rains to grow tomatoes and other vegetables with little-to-no irrigation in summers without rainfall. As recent water shortages in California have forced a reckoning with the precariousness of the state’s water supply, policy groups and the general public have become increasingly interested in dry farming as a promising means of achieving water conservation goals. Academic research on this practice, however, has been scarce. Amid growing urgency to develop low-water agricultural systems in the state, we interviewed 10 Central Coast dry farmers, representing over half of the commercial dry farm operations in the region where this practice was developed, to collaboratively answer 2 central research questions: (1) What business and land stewardship practices characterize successful tomato dry farming on California’s Central Coast? (2) What is the potential for dry farming to expand beyond its current adoption while maintaining its identity as a diversified practice that benefits small-scale operations? We summarize farmers’ wisdom into 9 themes about current dry farm practice, its potential for expansion and future opportunities. We also synthesize farmer-stated environmental constraints on dry farm feasibility into a map of suitable areas in California. As we consider how dry farming might expand to new areas and operations, we highlight dry farming’s history as an agroecological alternative to industrial farming in the region and the need for careful policy planning to maintain that identity. In examining this California Central Coast dry farming system, we ask if and how it can enhance the viability of nonindustrial farming operations as the food system adapts to less water availability. Because policies that encourage dry farm expansion could change economic landscapes in which dry farming operates, we caution that well-intentioned policies could edge small growers out of dry farm markets if not carefully designed. At the same time, we emphasize the opportunity for dry farm tomato systems to model an agroecological transition toward water savings in California.
1. Introduction
In California, if you want to farm, sometimes you might not have an option other than dry farming. [With] the increasing drought, how are we still gonna grow food in a drier climate? And whether or not it’s even a dry year, I’m thinking about saving water in good and bad years, and building up the market for that.
—Dry farmer on California’s Central Coast
A dry farmed Early Girl may well be the best tomato you’ve ever tasted. Any shopper at a farmer’s market on California’s Central Coast will confirm the sentiment, and these intensely flavorful, sweet, firm fruits have become a regional specialty sought after by chefs and shoppers in the nearby Bay Area’s famous food scene (Bland, 2013; Nast, 2015).
Dry farming refers to crop production over the course of a dry season without irrigation—or with extremely little irrigation—in which crops rely on water held in soils from winter precipitation (Socolar et al., 2024). Unlike dryland farming and rainfed agriculture, which time crop production so that it coincides with precipitation events, dry farming differs in that crops are not expected to experience any precipitation during their growing season. Farmers plant tomatoes into soil saturated by winter rains, counting on soils to hold on to enough water to support the crops over the course of an entirely dry summer and fall. While some farmers water in transplants and may additionally irrigate once in the first month after transplant, severe water restriction is what gives the fruits their intense flavor, and farmers trade lower yields for price premiums that consumers are more than willing to pay for higher quality fruits ($3–$5/lb vs. roughly $2/lb for irrigated tomatoes).
Beyond Bay Area consumers’ enthusiasm for high-quality local produce, dry farm tomatoes also connect to a rich culture of justice-oriented and farmer-centric food distribution in the region (Alkon, 2008; Spencer, 2019; Diekmann et al., 2020). From the Black Panther Party’s Free Breakfast Program (Lateef and Androff, 2017) to strong community support for worker-owned and consumer food cooperatives (Lingane, 2015; Sacharoff, 2016), the Bay Area has become a hub of alternative values-based supply chains in a country largely dominated by an industrialized food system (Kremen et al., 2012; Elias and Marsh, 2020). Following this tradition, dry farm tomatoes found their footing in the United States in the Central Coast region 30 miles south of the Bay. In the 1970s and 1980s, innovative growers in small-scale cooperatives and teaching farms adapted an Italian and Spanish legacy of vegetable dry farming to the region’s Mediterranean climate, maritime influence, and high-clay soils (Simmonds, 2016). While these environmental features are necessary to grow tomatoes under dry farm management, the movement that sparked the reemergence of local farmer’s markets in the 1980s also provided the access to direct-to-consumer marketing that small farms needed to win consumer attention and loyalty, allowing farmers to both grow and sell this niche product.
With their origins in local food distribution networks and local adaptations to a unique climate, dry farm tomatoes are now a signature of small, diversified, organic farms on the Central Coast and are a feature of many such operations’ business models. Dry farming has largely followed that initial course to this point and is only practiced at a small scale in the region, both in terms of geographic scope and farm size.
Agroecological transitions are multidimensional processes of change toward models of food production that are environmentally and socially sustainable (Gliessman et al., 2018; Anderson et al., 2019). Dry farming may therefore be playing a role in an agroecological transition in the region, buoying small and mid-size operations that are designed and managed to function as synergistic ecosystems using minimal external inputs.
From the Sustainable Groundwater Management Act (SGMA) to emergency orders in drought years, farmers, researchers, policymakers, and the general public have become acutely aware of California’s currently unsustainable agricultural water use and the economic ramifications of water shortages (Howitt et al., 2015; Morris and Bucini, 2016). As an option that holds promise for maintaining farmer livelihoods while dramatically cutting water use, dry farming is frequently touted by journalists and policy groups as an important system to target for significant expansion in California (Bland, 2013; Community Alliance with Family Farmers [CAFF], 2015; Simmonds, 2016; Runwal, 2019; Pottinger and Peterson, 2021; DeLonge, 2022), and growers in Oregon have recently begun adapting the practice to the Willamette Valley (Parks et al., 2021; Davis et al., 2023).
Farmers have been considering how to use dry farming to adapt to drier futures for decades, lighting the way for researchers and policymakers’ more recent interest. However, up to this point, farmers’ thoughts and knowledge about dry farming have not been clearly elicited or formally incorporated into conversations about the future of the practice in California. Grounding conversations about future expansion of the practice in the knowledge of those who are most intimately familiar with its implementation is essential. At this moment of enthusiasm for dry farming, we look to practitioners to better understand the current state of dry farming on the Central Coast and its potential for expansion across California and beyond, along with the benefits and harms that expansion may carry.
We interviewed 10 dry farmers, representing over half of the commercial dry farm tomato operations on the Central Coast, in order to collaboratively answer 2 central research questions. First, what business and land stewardship practices characterize successful tomato dry farming on California’s Central Coast? And second, what is the potential for dry farming to expand beyond its current adoption while maintaining its identity as a diversified practice that benefits small-scale operations? The majority of these farmers were part of an ongoing participatory research project in which field data were collected to better understand soil fungal communities and nutrient management in dry farm systems (Socolar et al., 2024). These interviews were extensions of conversations and relationships fostered with farmers throughout the research process.
We synthesized farmer insights into 9 key themes that broadly describe how dry farming is currently practiced on the Central Coast, its potential to expand in scope (geographies, markets, crops, etc.), and the opportunities that farmers see as particularly provident for the practice. We also used the constraints identified by farmers to map areas most likely to be suitable for future vegetable dry farming. We explore the elements of agroecological transitions described by Gliessman et al. (2018)—changes in production practices, economic relations, knowledge dissemination, and institutional frameworks—currently demonstrated by the practice and how it can maintain those features in the face of an expansion. We conclude by asking how dry farming can be a model for developing farming systems that decrease water use, and also how dry farming itself may be scaled out to other small and mid-size management-intensive operations without jeopardizing these same farms’ ability to continue profitably growing dry farm produce.
2. Methods
2.1. Study region
Interviews were conducted with farmers who have commercial operations in California’s northern Central Coast region (San Mateo and Santa Cruz counties), as well as one farm with operations in Marin and Sonoma counties. Ranges of coastal mountains in this region govern both climate and land use, trapping cool, moist air, and concentrating farming operations in valleys with fertile, alluvial soils.
The Central Coast is known for its agricultural production. Crops like berries, lettuce, and broccoli thrive in its fertile soils, and the area’s mild climate allows for year-round cultivation. Agricultural revenue in the region totals over $8 billion annually (California Department of Food and Agriculture, 2022), making it a larger agricultural producer than most countries. This intensive production has led to both high land values and environmental degradation—largely in the form of water contamination—that shape both farmer decision-making and policy interventions (Hall and LeVeen, 1978; Dowd et al., 2008; Stuart, 2010).
Within this landscape, farms often operate at industrial scales, though many farms persist at smaller scales, following the limited resource and mid-scale diversified typologies defined in the same region by Esquivel et al. (2021). Broadly speaking, cropland is consolidated into fewer, large operations. For example, 20% of farms manage well over 80% of farmland in Santa Cruz County, where the majority of our interviews took place (U.S. Department of Agriculture National Agricultural Statistics Service [USDA NASS], 2017). However, many smaller farms have found niches selling to local markets.
2.2. Interviews
After building relationships over the course of a year-long participatory field research process with 8 tomato dry farmers (representing 6 growing operations (Socolar et al., 2024), we conducted semi-structured interviews with all farmers involved in that study. We interviewed 2 additional dry farmers who were not involved in the field project—one whose farm is in Sonoma County (outside the initial study area), and one whose farm could not participate in the field study due to extensive wildfire damage—for a total of 10 farmers representing 8 operations. Interviews were conducted in person (n = 8), over the phone (n = 1), and on Zoom (n = 1) in winter and spring 2022.
Because there is no official record of tomato dry farmers in the Central Coast region, we used a snowball approach to identify farms that might be candidates for inclusion, asking each interviewee what other dry farm operations they knew of in the area. We can identify 4 dry farm tomato growers in the region who were not interviewed in this study, and we estimate that our interview subjects represented roughly 50% of commercial dry farm tomato operations on California’s Central Coast, an estimate corroborated by technical assistance providers in the region.
Interviews lasted 1–2 h and focused on dry farm management practices, environmental constraints, support, water/land access, and economics (full interview guide in supplement). Interviews were recorded and transcribed, then analyzed through an interactive process of open, axial, and selective coding (Corbin and Strauss, 1990). First, open coding was used to identify key concepts and potential codes from all interviews. Axial coding was then used to define an initial codebook that was utilized to code all interviews (see supplement). Excerpts were then grouped into 3 overarching categories (“Current Practice,” “Potential for Expansion,” and “Opening Opportunities”), with key themes in each category (see “Interview findings and applications” for the list of themes). Selective coding was then used to search for each of these themes in all interviews; themes were retained for analysis when they were mentioned in at least half of the interviews.
2.3. Suitability
In order to identify areas that might be suitable for future tomato dry farm management, we used farmer-described constraints to make a suitability map using publicly available datasets. We first compiled the environmental constraints on tomato dry farming described in each interview (Table 2), which fell into 3 main categories: precipitation, temperature, and soil texture. We limited our analysis to California as the region these farmers are most familiar with to avoid extrapolating constraints beyond the context in which they were given.
We used PRISM 30-year climate normals (1991–2020, 800 m resolution) to characterize California’s temperature (PRISM Climate Group at Oregon State University, 2022a) and precipitation (PRISM Climate Group at Oregon State University, 2022b). We used the average constraint named by the farmers; however, because these normals are a 30-year average and will stray significantly from these averages in individual years, particularly in the case of precipitation, we expect that we overestimate the extent of suitable areas. As California’s temperatures get hotter and precipitation becomes increasingly variable with climate change (Cayan et al., 2008; Pathak et al., 2018), we expect a further systematic overestimation of suitable areas identified based on the past 30 years of weather data. When given a choice, we overestimate land suitability in order to indicate all possible areas that could be considered. Areas indicated as more suitable on the resulting map are therefore a surer bet for dry farm success, while less suitable areas should be approached with some caution.
For the suitability analysis we used farmer-elicited constraints to assign temperature and soil texture to 3 categories that were each associated with a score (see Table 2 for farmer responses and associated model constraints): good (2), tolerable (1), and intolerable (0). Precipitation was divided into ranges that were suitable with no additional irrigation, suitable with additional irrigation, and unsuitable. Details on how these ranges were chosen are described below.
For temperature, we considered the average maximum temperature in the 3 hottest months of the growing season (June, July, August), categorizing them separately with the scores described above (Good: <86°F, score of 2; Tolerable: 86°F–95°F, score of 1; Intolerable: >95°F, score of 0). We then multiplied these 3 categorized scores (one for each month) together and took the cube root to get temperature suitability scores, also excluding any areas whose monthly 30-year minimum temperature was above 59°F. The resulting scores range from 0 (intolerable in at least 1 month) to 2 (good in all 3 months); for example, a pixel with an average maximum temperature of 80°F in June, 84°F in July, and 91°F in August would be categorized as 2, 2, 1, and would receive a final score of 1.6 (cube root of 2*2*1).
We followed a similar procedure for soil texture, using Soil Survey Geographic Database (SSURGO) estimates of clay content averaged across soil horizons at a 90 m resolution (U.S. Department of Agriculture, Natural Resources Conservation Service, 2008). Because farmers did not give numeric estimates of how much clay was needed in dry farm soils, we made sure our defined “tolerable” range (5%–50% clay) encompassed the full range of clay content observed in participating farms’ soils (8%–40% clay). To define the “good” range (10%–50%), we excluded the farm with the lowest clay content, which was also the only farm where farmers stated that they could not grow tomatoes of a high enough quality to consistently market them as “dry farm.”
We multiplied temperature and soil scores to make a preliminary suitability map. This multiplication reflects the interaction between temperature and soil texture, in which good texture can compensate for higher temperatures by increasing soil water holding capacity, and lower temperatures can lessen the evapotranspirative demand that would be particularly problematic for plants growing in sandier soils with a lower soil water holding capacity. We then separated this preliminary suitability map into 3 areas based off of farmers’ interview responses regarding conditions in which tomato dry farming could occur with no added irrigation (>22″ annual rainfall) and where it could occur with supplemental irrigation (14–22″), excluding areas that would not get enough winter rain to grow a suitable winter cover crop (<14″).
The final map shows suitability scores in all areas that are categorized as “cropland” in the 2019 National Land Cover Database (Dewitz and U.S. Geological Survey, 2021). These areas are superimposed onto groundwater basins categorized as high priority for monitoring and active management in California’s SGMA (California Department of Water Resources, 2020). Total acreages of crops currently grown on land that was deemed suitable for tomato dry farm management in these areas were calculated using the 2021 Cropland Data Layer (USDA NASS, 2021).
We also calculate suitability risk to highlight areas that may not be consistently reliable for dry farm production. This risk score is calculated as the ratio of annual precipitation standard deviation to its mean for each pixel, using each year in the 30-year normals (1991–2020). Because we do not have farmer input to justify picking “good,” “medium,” and “low” cutoffs for levels of rain variation, we have chosen to present it as a continuous score that demonstrates the risk of changing rain conditions.
3. Interview findings and applications
The basic characteristics of the 8 dry farm operations included in the study are summarized in Table 1. We found 4 broad themes across business and management practices that characterized this existing dry farm tomato sector on the Central Coast:
Dry farming defined: water versus quality
Motivations for dry farming: economic, environmental, and place based
Dry farm tomatoes are a preferred crop
Diversified management is key in dry farm success
as well as 5 themes identifying constraints on and opportunities for expansion:
Tomatoes hit a sweet spot
Environmental constraints
Economic constraints
Size and scope matter
Opening opportunities
Farm . | Area Cultivated (ac) . | Area in Dry Farm Tomatoes (ac) . | Percent Farm Income From Dry Farm Tomatoes . | Water Source . | Main Markets . | Price (Full Price/ Wholesale) . | Non-Tomato Dry Farmed/Low Water Crops . | Self-Described Farming Style (All Farms Are Certified Organic) . |
---|---|---|---|---|---|---|---|---|
A | 10 | 4.5 | 65% | Groundwater | Farmers’ markets | $4/− | Winter squash | Diversified organic |
B | 60 | 4 | 5% | Groundwater | Farmers’ markets, CSA, you-pick, value added products | $3/$2 | Potato | Organic |
C | 42 | 6–10 | 30% | Groundwater | Farmers’ markets, wholesale | $4.50/$2 | – | Small scale organic |
D | 1.5 | 0.5 | 40% | Groundwater, storage tank | Farmers’ markets, restaurants | $4/$2 | Winter squash | Certified organic |
E | 13 | 0.25 | 2% | Surface water/reservoir | CSA, wholesale, restaurants | $5/$2.50 | – | Diversified organic |
F | 12 | 0.2 | 2.5% | City water | CSA, basic needs program | $3.50–$4/− | Hopi dry beans | Agroecological |
G | 25 | 2 | 50% | Groundwater | Farmers’ markets | $4/− | Winter squash, watermelon | Organic |
H | 5.5 | 0.2 | Reservoir | Farmers’ markets | $5–$8 | Winter squash, melons, shallots | Diversified |
Farm . | Area Cultivated (ac) . | Area in Dry Farm Tomatoes (ac) . | Percent Farm Income From Dry Farm Tomatoes . | Water Source . | Main Markets . | Price (Full Price/ Wholesale) . | Non-Tomato Dry Farmed/Low Water Crops . | Self-Described Farming Style (All Farms Are Certified Organic) . |
---|---|---|---|---|---|---|---|---|
A | 10 | 4.5 | 65% | Groundwater | Farmers’ markets | $4/− | Winter squash | Diversified organic |
B | 60 | 4 | 5% | Groundwater | Farmers’ markets, CSA, you-pick, value added products | $3/$2 | Potato | Organic |
C | 42 | 6–10 | 30% | Groundwater | Farmers’ markets, wholesale | $4.50/$2 | – | Small scale organic |
D | 1.5 | 0.5 | 40% | Groundwater, storage tank | Farmers’ markets, restaurants | $4/$2 | Winter squash | Certified organic |
E | 13 | 0.25 | 2% | Surface water/reservoir | CSA, wholesale, restaurants | $5/$2.50 | – | Diversified organic |
F | 12 | 0.2 | 2.5% | City water | CSA, basic needs program | $3.50–$4/− | Hopi dry beans | Agroecological |
G | 25 | 2 | 50% | Groundwater | Farmers’ markets | $4/− | Winter squash, watermelon | Organic |
H | 5.5 | 0.2 | Reservoir | Farmers’ markets | $5–$8 | Winter squash, melons, shallots | Diversified |
Where cells are empty, interviewee could not provide information. CSA stands for community supported agriculture.
To be included, each theme had to be mentioned by at least 5 farmers, and representative quotes were pulled from responses that fit in each theme.
3.1. Current practice
3.1.1. Dry farming defined: Water versus quality
Though farmers have been dry farming tomatoes on the Central Coast for decades, there is no rule book for what that actually means. Growers expressed uncertainty when asked to define the management system and their relationship to it:
What is dry farming? There is no criteria, you know, do this and you’ll succeed. (Farmer E)
To be completely honest, I sometimes am like, are we dry? Right? …It’s a very, very loose term. (Farmer G)
Instead, the practice has been built through a colloquial understanding between both growers and customers in the region.
When asked to define dry farming, farmers took two, often overlapping, approaches. As one might expect, severe water restriction was at the heart of the concept for all 10 of the interviewed farmers:
At least for my limited experience, it’s like once the fruit is there, like, no, definitely no more water. (Farmer B)
with some farmers taking a truly purist approach:
I’m in the camp of legit, like planted into dry, no water ever. I feel like I would advertise my products as dry farmed if they’re truly dry farmed. And then if they’re not, I would say “minimally irrigated” or something like that. (Farmer I)
However, farmers were just as likely to approach the question from the opposite direction, with 8 of the 10 farmers defining a dry farm tomato by its small size, thick skin, and concentrated flavor, and calling dry farming any means to that end:
But really, when I think of a dry farm tomato, I’m all about the flavor .…I don’t care that, you know, it’s a dry farmed tomato but it doesn’t taste good. Well, then, for me, there’s no point in doing that. (Farmer D)
As one farmer succinctly put it,
If you’re telling me you’re dry farming it, and it tastes like water, then you are not dry farming. (Farmer G)
It is worth noting that the situation this farmer describes can occur when a farmer is growing tomatoes quite close to the water table, often on sandy soils. In these cases, farmers may never irrigate at all (dry farming in its purest sense) and still grow large, watery tomatoes. While we will still refer to such management as dry farming in its technical definition, it is important to establish that quality is a crucial distinction for farmers when marketing their products, and consumers currently expect a certain quality—rather than a certain set of management practices—when buying dry farm tomatoes. In other words, a functional definition of dry farming has also been created that narrows the scope of the technical definition.
Farmers noted that if two operations use the same (severely restricted) amount of irrigation water, but one irrigates after fruit set and the other does not, the first is likely to have a higher yield of more watery tomatoes compared to the second. Farmers have experimented with different approaches, landing on their own balance between yield and flavor:
So in the beginning, I would do them drier consciously because I knew like when you’re trying to develop markets, you got to have the best. And it’s worth having less to have the best because you’re getting new customers and you’re trying to grow your base. (Farmer A)
We’re focused on flavor and not so much on yield. That’s where most of our customers are. That’s what they’re attracted to. (Farmer C)
By focusing on the characteristics that limited water can give a tomato, these farmers highlight a recurring theme in understanding the functional definition of dry farming tomatoes. These farmers are quick to recognize that dry farming is only a management style that they can afford to choose for their operations insofar as it can excite customers and return a reasonable profit. In this way, the product that dry farming creates, which is valuable enough to consumers that they are willing to pay a significant premium for it in this region of high land values, is the outcome that defines the management approaches farmers can use. Currently farmers must produce what consumers have come to expect from a dry farm tomato if they are going to make dry farming an economically viable choice for their operation, though future policies that add value directly to irrigation conservation could transform these economics and definitions.
3.1.2. Motivations for dry farming: Economic, environmental, and place-based
For 9 farmers, the decision to include dry farming in their operations boils down easily to farm finances. These growers are quick to acknowledge that their motivations are:
Purely economic. I wanted to farm and I wanted to succeed, and that was perfectly obvious the crop that would make us get there …[We] wouldn’t have much of a customer base without the dry farms. (Farmer A)
However, 7 farmers more holistically pointed out the rewards of dry farming both in terms of product quality and environmental benefit. Farmers related strongly to values of land stewardship:
I would consider myself a very ecologically, you know, like a systems oriented grower, right? Not just the health of the farm, but also the health of the ecosystem and how we share resources. And, you know, this is something that just really fits into that category. And I know there’s a lot of growers that feel that way too; this responsibility to care for the land that they’re on, to make sure they’re having minimal impact on the surrounding areas. (Farmer H)
Many farmers also particularly appreciated that leaning in to their environmental values resulted in a high quality product:
I really like the tomatoes, and I like growing high quality. And also I like the horticulture, the actual farming; dry farming tomatoes, that just appeals to me. Doing it, saving water, saving electricity, saving plastic, saving this, saving that, you know, all kinds of stuff. (Farmer D)
In our case, it’s really related to the quality—or I guess the attributes—of the fruit. And so yes, it’s to minimize our water use, but it’s also to grow the type of food that we want. (Farmer G)
Four farmers also found a gestalt to the situation where land stewardship in this particular region creates a high-quality product, taking pride in a truly place-based regional specialty:
You need the microclimate. You need the soil, you need to put it in at the right time, you need to navigate the season to make sure that everything’s okay. And then in the course of following that and really tuning in nature, you grow a really fantastic product. Yeah, you know, and that’s kind of where I’m at, the niche that I’m at, is like, how do you grow the best of anything? (Farmer D)
This satisfaction at mastering a true regional specialty reveals not only the success that dry farming has had in the region, but a potential inflexibility in translating this success to other climates or growing conditions.
Though dry farming has largely gained public attention in the context of irrigation restrictions due to climate change, farmers’ decisions to dry farm were typically based in their region’s historic climate and water access rather than climatic changes. For example, while 6 farmers noted a long-term lack of water access or limited water rights on a given property as a reason for dry farming in their current operations, only 2 mentioned climate change or deviations from past weather norms as a motivation for their current or historic practice. However, 4 farmers referred to the future potential for changing climates to lead to dry farming out of necessity rather than choice.
3.1.3. Dry farm tomatoes are a preferred crop
Economic, environmental, and place-based incentives were powerful motivators, and often resulted in farmers explicitly calling on dry farm tomatoes as a preferred crop for their operations.
For 8 farmers, decreased labor needs made dry farm tomatoes preferable to other crops on the farm. Decreased labor specifically from lower weed pressure was particularly appealing to farmers. Because fields receive no rain over the summer in this Mediterranean climate, restricting surface water availability can dramatically impact weed pressure (Sutton et al., 2006):
Labor is like a huge part with dry farming. That’s honestly the impetus for a lot of farmers, more so than the environmental reasons …If you don’t irrigate, you don’t have weeds. So yeah, weed saving and irrigation labor is huge. (Farmer I)
Farmers also appreciated the low input demands associated with dry farming tomatoes. This low-input management style differentiates dry farm crops from irrigated ones, and also differentiates these farms from the surrounding region, which is one of the most intensively managed agricultural landscapes in the world:
One of the things that I like most about it is it’s actually asking less input from you than more. Whether it be time or whether in the form of actual equipment …it actually seems like this is sort of the best of both worlds. (Farmer G)
I think it’s just, it’s easier, you know, it’s easier to manage a dry farm crop …Dry farming is not intensive in the way you would look at, like, lettuce and broccoli. (Farmer C)
This perceived lack of intensity parallels the fit between region and crop that farmers described as a motivation for dry farming. With the right microclimate and soil, farmers do not have to manage intensively to mimic the appropriate conditions for dry farming, as they are already present.
While this could be said of many dry farm crops, farmers were also clear in their preference for tomatoes over other potential dry farm crops, again largely for economic reasons:
If you look at the dry farmed dry beans that we grow, that makes no economic sense. Not only are you not getting enough money on the dry beans, but also it’s so labor intensive to harvest and thresh at our small scale. Dry farm tomatoes are a total win-win. Like your costs are way down. The product is really good. And there’s definitely a market for it, and we like it in rotation. (Farmer H)
For farmers who had experienced water scarcity before, dry farming also provided an important aspect of stability for the farm, making it preferred over crops that could be a liability in dry years. As one farmer who shifted dramatically toward dry farm crops in their operation described it,
We’ve decreased the water use; I think we use 75% less than the last farmer…I’m kind of scarred from not having water. Yeah, I’d rather not max out the pond every year …I’d rather kind of go for consistency. ‘Cause hopefully even if it’s less each year, I know that I have a certain amount so that I can …plan a little bit more. (Farmer I)
Beyond all these practicalities, 6 farmers also had a soft spot for appreciating dry farming as an impressive and fascinating system:
I don’t really want to personally eat or sell non-dry farmed tomatoes. And I just think it’s amazing to be able to grow stuff without water. That’s why I really …push the limits of the plants and just see what can hang without water. Because it’s pretty crazy to see something grow all season long and not have rain for months. (Farmer I)
3.1.4. Diversified farming systems are key in dry farm success
In addition to having the appropriate microclimate and soil, farmers engage in many management practices to successfully grow dry farm tomatoes. Some of these practices (e.g., dust mulches that use cultivation to break surface capillaries in the soil for evaporation prevention) are specific to dry farm management, while others (e.g., trellising) are specific to tomatoes. On the other hand, many practices, including cover cropping, crop rotation, and organic matter incorporation, are mainstays of diversified farm management and were cited by all farmers as key components of dry farm success.
Every farmer highlighted cover cropping as core to their dry farm regime. Though there has been considerable debate in California about whether cover crops use more water than they add to soils (Mitchell et al., 2015; DeVincentis et al., 2020), there was no doubt among farmers that they were necessary in this low water system. Among the benefits of cover crops, farmers described improved soil water holding capacity and infiltration, as well as general soil improvements:
We disc [the field] and we let it overwinter with a cover crop…And that helps the water percolate down. (Farmer D)
[With] cover cropping and stuff we’ve gone from like, one point something percent organic [matter] to like 3.7% organic. That’s the cover crop and tilling that in and all that…The soil got so crummy at first, and it was hard to grow things over there. The soil’s gotten better. (Farmer E)
Four farmers also described using cover crops as an indicator of soil fertility and a field’s capacity to successfully grow dry farm crops:
If the cover crop sucks and the year before sucks, then get nervous. But like this year, the cover crop looks great. We’ve worked so hard to make it good, so I feel pretty confident. (Farmer A)
Because soil nutrients in the top 30 cm do not seem to impact dry farm tomato yields or quality as their roots quickly move deeper in the soil profile in search of water (Socolar et al., 2024), it can be difficult for farmers to manage fertility in the regions of the soil where dry farm crops access nutrients. Rather than using surface-applied amendments, farmers have learned to rely on cover crops as an indicator of soil fertility at these lower depths. These cover crops’ roots can also create channels that allow tomato roots to penetrate deep into the soil more quickly, allowing faster access to subsurface water at a lower metabolic cost (Acevedo et al., 2022).
All but two of the farmers we interviewed included their dry farm tomatoes in a diversified crop rotation. For 4 farmers, rotation was an important measure for disease control. For these farmers, growing dry farm tomatoes year after year was not seen as a viable option:
The disease pressure is the issue there. We haven’t had hard and fast rotations, but the tomatoes have rotated with both other dry farm crops, like hard squash, and irrigated crops—zucchini or peppers. (Farmer J)
Beyond the benefits to the tomatoes themselves, one farmer expressed an appreciation for dry farm crops in rotations due to their ability to lower weed pressure:
We like it in rotation. We oftentimes say like, oh, this is where the dry farms were. We’ll plant something that we want less weed pressure on, right, because we’ve been able to manage it so well: there hasn’t been a lot of germination of weeds. (Farmer H)
Dry farm crops therefore play an important role in diversified rotations both for the benefit of the tomatoes, and to the benefit of the full farm system.
Two farms, however, did not rotate their dry farm crops, but grew them repeatedly (10 years in a row and counting), or alternated between tomatoes and fallow. These management decisions to maintain fields as dry farmed rather than rotating irrigated crops through are particularly compelling in light of recent research on many of the same fields, showing that repeated seasons without any external irrigation result in soil microbial communities that are associated with improved dry farm tomato performance (Socolar et al., 2024). To fully capture all of the rotation benefits described by farmers, it may therefore be necessary to develop dry farm rotations in which all of the harvested crops are grown with little to no external irrigation.
Eight farmers also described organic management in a more general sense as being necessary to optimize soil health and dry farm performance. This management style includes incorporating organic soil amendments (rather than synthetic fertilizers), in addition to cover cropping and crop rotation. While these organic amendments may be critical for soil rehabilitation, most farmers also described using a light fertility regime on their dry farm crops, cutting back on compost and often stopping pelleted fertilizers entirely:
Did we do compost at [the field] last spring? No. We skipped the year—it’s really expensive and seems questionable. No [fertilizers], not in the dry farm [fields]. Put the seedlings in and they just grow. That’s like how it’s supposed to be. (Farmer B)
It is important to note that this farm does still apply compost in some years to replenish nutrients; farmers do not rely on cover crops to replenish all nutrients in the soil, but do find that they are able to cut back dramatically on fertilizers and amendments. Between organic amendments/green manure applications and a general decrease in fertilizer use, farmers are able to lower their use of off-farm inputs, relying instead on on-farm ecology.
3.2. Potential for expansion
While farmers have found a clear and sustainable regional niche for tomato dry farming on the Central Coast, policymakers and the public are proposing the possibility of expanding dry farm agriculture in California with increasing urgency. Here we discuss the opportunities and possible pitfalls of growing dry farm tomatoes—and potentially other crops—on a broader scale.
3.2.1. Tomatoes hit a sweet spot
When considering the potential for dry farm agriculture to expand beyond its current scope, an obvious option would be to increase the number of vegetable crops that are dry farmed. While many of the farmers in this study have experimented with other crops (see Table 1) to varying degrees of success, none have had the staying power of tomatoes in their operations.
One reason for dry farm tomatoes’ success is a decline in the quality of commercially available tomatoes in the last century (Olson, 1969; Scott, 2008). Quality is just one consideration in modern tomato breeding programs, and many other factors—yield, storage, harvestability, and so on—take precedence (Berry and Uddin, 1991). Bland supermarket tomatoes have left consumers searching—and willing to pay—for high quality fruits. To date, this willingness to pay a dry farm premium has not materialized for other crops, including many of the prime dry farm candidates in California, either because the crop is less desirable, the quality difference is more subtle, or the quality differential is not valued to the extent seen with tomatoes:
You know, you don’t want to have summer squash or winter squash every single week. But dry farm tomatoes you can have them every day. (Farmer F)
People expect watermelon to be really cheap. Even though it’s sort of comparable to the dry farm tomato difference, it’s not enough. (Farmer J)
We would advertise this dry farm winter squash. Now, I think it’s just at a minimum worth $2 a pound, and we can’t really go higher than that. Because then people are leaving market paying like $19 for a squash; it’s a little excessive, or people just won’t do it. (Farmer I)
From the very beginning of tomato dry farming and marketing in the Central Coast, dry farm tomatoes’ superior quality—and consumers’ response to it—have been integral to dry farm tomato success. In the 1980s, farmers were able to build a consumer base around their dry farm tomatoes that has proven remarkably durable. Growers in this region are now known for these tomatoes, so much so that they have become a defining feature of local farms and businesses:
It’s something that we have a niche here on the Central Coast. Coastal growers have …a certain reputation. We have a certain customer base that’s really looking forward to them …Yeah, it’s the tomato. (Farmer C)
Though tomatoes have been a clear dry farm vegetable front-runner in the Central Coast region, it is important to note that farmers across the state have also found orchard fruits and nuts to be a desirable option (Shaw, 2022; James, 2023). These crops have similar market appeal and quality premiums, making them economically viable where the other crops discussed by farmers in this study (beans, potatoes, winter squash) may falter.
3.2.2. Environmental constraints
Due to tomatoes’ particular success in the Central Coast region, we focus the following environmental constraints on tomato agriculture; however we also discuss the potential for success in dry farming other crops when considering policy and public opinion shifts that might boost their economic viability (see Economic constraints).
Each farmer was asked what they see as the climatic and soil constraints on dry farming tomatoes. Their answers are summarized in Table 2. Farmers consistently noted the importance of wet winters, and paid particular attention to the timing of rains, often providing caveats that 20″ of soft rain over many months would likely enable a dry farm crop, while the same amount of rainfall in short bursts—particularly early or late in the wet season—could easily render dry farming infeasible without supplemental irrigation. Farmers were less consistent in providing a temperature threshold, but did generally agree that cool nights are important and that there is some upper limit on what temperatures dry farm tomatoes can consistently tolerate. These limits were used to create model constraints for a suitability analysis (see Suitability modeling).
Farm . | Precipitation . | Temperature . | Soil . |
---|---|---|---|
A | At least 15″ | Not more than 90 consistently in the summer | — |
B | — | Can’t get above 100–110 | Clay loam |
C | At least 24″ (non-irrigated); have to do a lot of pre-irrigation if less than 16″. Timing of rain matters. | Can’t get above 110 | Clay is important; too much sand relies on close water table and leads to poor quality |
D | 20″ (well-timed) | Not more than upper 80s consistently in the summer | — |
E | — | Can’t be too hot | High enough clay content, soil management history |
F | 19″ is our threshold for dry farming; timing of rains matters a lot. Need enough in winter to grow cover crop. | Has to cool off at night | Clay is important; would be hard if too sandy |
G | At least 15″ | No sustained spells >105 | Having clay is important, not too sandy |
H | — | Santa Cruz is pushing it (too hot); has to be warm enough to grow tomatoes | — |
Model constraint | Suitable without irrigation: >22″ Suitable with supplemental irrigation: 14–22″ Not suitable: <14″ | Max temp Good: <86 Tolerable: 86–95 Intolerable: >95 Min temp Intolerable: >59 | Good: 10–50% clay Tolerable: 5–10% clay Intolerable: <5% clay |
Farm . | Precipitation . | Temperature . | Soil . |
---|---|---|---|
A | At least 15″ | Not more than 90 consistently in the summer | — |
B | — | Can’t get above 100–110 | Clay loam |
C | At least 24″ (non-irrigated); have to do a lot of pre-irrigation if less than 16″. Timing of rain matters. | Can’t get above 110 | Clay is important; too much sand relies on close water table and leads to poor quality |
D | 20″ (well-timed) | Not more than upper 80s consistently in the summer | — |
E | — | Can’t be too hot | High enough clay content, soil management history |
F | 19″ is our threshold for dry farming; timing of rains matters a lot. Need enough in winter to grow cover crop. | Has to cool off at night | Clay is important; would be hard if too sandy |
G | At least 15″ | No sustained spells >105 | Having clay is important, not too sandy |
H | — | Santa Cruz is pushing it (too hot); has to be warm enough to grow tomatoes | — |
Model constraint | Suitable without irrigation: >22″ Suitable with supplemental irrigation: 14–22″ Not suitable: <14″ | Max temp Good: <86 Tolerable: 86–95 Intolerable: >95 Min temp Intolerable: >59 | Good: 10–50% clay Tolerable: 5–10% clay Intolerable: <5% clay |
The table is left blank where farmers either did not volunteer information about a given constraint or explicitly stated that they did not feel confident in giving an answer. Farmer responses were synthesized into model constraints (based on 30-year normals for precipitation and temperature) that were relaxed to encompass the least restrictive estimates in order to cover all areas potentially suitable for tomato dry farming. Constraints are reported on a farm (rather than farmer) basis, as when there were 2 farmers from the same farm, they talked to each other until they arrived at a single answer.
In considering these stated constraints, farmers were also highly aware of changing climates and how those violate regional norms that have historically supported dry farming. Farmers were particularly concerned about changing precipitation patterns:
The main thing that I’m thinking about in terms of our ecologically based system with climate change is that, you know, if we don’t have rain at the right times, it really impacts how much biomass we can grow on our cover crop, and how long those plants are in the ground and how much root activity. I think there’s a real potential stressor there that violates the logical foundation for the farming system. (Farmer H)
Farmers have thus far handled these changes in precipitation patterns by adjusting irrigation to mimic historical climate, often watering transplants in to approximate soil saturation from spring rains when they do not occur. As climates change, farmers express feeling increasingly locked into simulating historic rainfall:
That’s essentially what we’re stuck in, I think now, is trying to manage …to simulate what we used to have…When I was just starting doing this 20 years ago, dry farming, you know, we had to wait for the soil to dry out enough to even disk in the cover crop, right? So it was always the push of trying to get them in; the plants are ready. And you’re going to disk them and put them in and then you’re going to get in and you’re going to wait and you’re going to plant them right before there’s a rain. And that to me is what I’m trying to simulate, is that general spring shower that waters them in, that normally, naturally would occur. But now we’re just in the middle of drought. (Farmer D)
This move to recreate the rainfall patterns historically experienced in the region also opens possibilities that management in regions that currently do not–and never have—met climate requirements could mimic the Central Coast’s historic climate. In particular, supplemental irrigation may be included in some areas to produce dry farm-quality tomatoes and drastically cut back on irrigation compared to other crops that might be grown on those fields.
3.2.3. Economic constraints
While it may be possible to dramatically increase dry farm tomato production from a land suitability perspective, it is also crucial to consider the economic repercussions of—and limitations on—such an expansion. Dry farming allows farms to decrease labor costs and water inputs, making it particularly appealing in areas where water and labor prices are high. Premiums for superior quality can further boost revenues, particularly in the face of drought stress-induced yield declines.
However, given the high value of crops that are typically grown in parts of California that are suitable for dry farming, land values in these areas are some of the highest in the country (Moss and Schmitz, 2008). Hence, large revenues are necessary for most farmers in the region to remain profitable. Therefore, if tomatoes were grown with little-to-no irrigation inputs but did not possess the desirable dry farm characteristics, profits would decline and it would be unrealistic to expect farmers to choose to grow them over a more water-intensive and lucrative alternative. Though farmers may ideologically have strong support for dry farming, they increasingly find themselves in situations where high returns are essential to keep up with rising land prices:
The good farmland is going into berry production because they can get the most dollars per acre out of it. [They] have to put the most dollars in per acre as well, but you get a bigger return. And as a result, the rents are skyrocketing…So we have to compete with people that don’t have to give a damn. (Farmer D)
Farmers are well aware that premiums for dry farm tomatoes are currently supported entirely by consumers, rather than by policies designed to support low-water agriculture:
The government isn’t incentivizing us to do this. It’s all the consumer, because they’re buying it. That’s the incentive that we get. (Farmer D)
Therefore, any expansion of dry farming onto soils or into climates that result in notably decreased fruit quality may not be an economically viable option for farmers, who would instead likely devote that land to an irrigated crop with higher returns (e.g., strawberries), or in the absence of water might choose not to farm the land at all. Efforts to increase production at the expense of fruit quality (e.g., shifting irrigation to after fruit set or growing on soils close to water tables) would likely meet a similar end.
Even if future dry farmers are able to maintain quality, current dry farmers expressed concern that too large of a production surge could topple the profits they have come to rely on:
All of a sudden some giant growers are doing 500 acre blocks every two weeks or something? Yeah, definitely if it’s no longer a specialty, then that’d be more of a concern. (Farmer A)
Any increased production must therefore also consider whether the consumer demand exists to support current prices.
3.2.4. Size and scope matter
Farmers were unanimously confident that tomato dry farming would be unlikely to occur at industrialized scales given current incentive structures. Interviewees did see potential for more small-scale operations to enter the dry farm tomato sector, though there are geographic and market limits to such an expansion.
All of the farms involved in this study cultivated less than 60 acres and grew less than 10 acres of dry farm tomatoes, and none knew of any larger operations. Small and mid-size farmers have found that dry farm tomatoes are a niche—and sometimes a crucial one—that their operations are able to fill (see Table 1 for percent of sales that come from dry farm tomatoes):
There’s always been dry farming involved [in our operation]. Started off smaller percentage, but quickly realized it was the ticket for a small farm to succeed in our case. (Farmer A)
As to why this niche is so well-suited to small operations, part of the explanation lies in the origins of dry farm marketing in the 1980s, when dry farm growers put extensive effort into cultivating a product at farmers’ markets that customers would then request from other food sellers:
Wholesalers and retailers had to be trained to understand what this was. And they were forced to by their customers who came in and said, “Hey, I got these at the farmers’ market. Like, can you get them? Can I find them here?” So I had to do a lot of training people in the produce business to understand that they could actually successfully sell a smaller, great, tasty tomato. (Farmer J)
The first farmers to commercially sell dry farm tomatoes in the region relied heavily on direct interactions with consumers in order to build loyalty and trust in the superior quality of their product. Because the introduction of dry farm tomatoes coincided with the start of Santa Cruz’s first farmers’ market, farmers were more easily able to come face-to-face with consumers who learned to recognize and appreciate their produce. That consumer interest, along with farmer encouragement, was then able to convince local grocers that they could successfully sell more expensive tomatoes when shoppers recognized and trusted their increased value. To this day, dry farm tomato growers rely heavily on farmers’ markets, community supported agriculture, and small grocers to sell to consumers who will recognize the value in their product, allowing farms to charge a premium for their trusted quality (Table 1).
However, farmers expect that there is a limit to both consumers’ interest in expensive tomatoes, and to larger grocers’ willingness to test the limits of what consumers might buy:
So with Safeway right now, they’re paying probably 60, or 50 cents a pound. Would Safeway be willing to pay two bucks a pound? I don’t know if that’s [something] they’re willing to put on the consumer…Why would they rock the boat? (Farmer A)
There is also a question of order of operations; large farms are unlikely to plant large areas of a crop without a guaranteed buyer, while large grocery stores are unlikely to contract a large tomato crop without having seen that there is consumer demand to sustain the elevated price. Therefore neither operation is able to test the waters before both commit.
Six farmers also pointed to their business models, which are entirely different from industrial-style growers.
[Conventional farms] are in it for a different game, right? They want more quantity, more volume. And they will not even harvest their tomato ripe. So I think you’re dealing with different segments of the market for tomato, where quality is not as important. And I think this farming technique is very much linked to a quality, appreciation for quality…When that’s not your advantage or comparative advantage, then why bother? (Farmer G)
Finally, there is also a question of capacity and capability. Even if a large farm were to develop an interest in growing dry farm tomatoes, they are less likely to use the diversification practices that have been key in dry farm management (Esquivel et al., 2021). Though it may be possible to approximate these practices or even commit to a full dry farm regime, the learning curve is steep and the product can be finicky. Everything from choosing fields and irrigation strategies to managing nutrients and building tilth involves a delicate balance of stressing plants to encourage high quality fruits without overly restricting yields. These skills take time to develop and perfect:
Yeah, more people come and compete; there are definitely more people showing up with dry farms. And that’s inevitable, but most of them still can’t do what we do. (Farmer A)
Despite their experience and skill, none of the farmers we interviewed expressed an interest in significant expansion:
Taking over this land four years ago was roughly a double in acreage, and so I feel like we’ve added a market or two since then. And then I feel like I’ve stabilized. We’re at a good spot. (Farmer B)
We’ve just had a really hard time scaling up. I find you scale up with what we do and we have a really hard time keeping up quality. (Farmer D)
Given high heterogeneity in field conditions and the resulting need to carefully tailor management to each field, scaling beyond a certain size quickly becomes infeasible. Without deep knowledge of dry farm management or the nimbleness that comes with growing and adapting management to a small acreage, large farms may simply not be able to produce a quality dry farm product at scale.
While scaling up production by increasing the size of individual operations may be unlikely given current markets, new small farms could take up the practice in the Central Coast and other regions. All of the farmers interviewed for this study agreed that they would not have trouble selling more dry farm tomatoes if they were to produce them, suggesting that the market is not yet saturated, even on the Central Coast. If small farms in other regions are able to grow dry-farm quality tomatoes, it therefore seems likely that the practice could easily expand in geographic scope.
3.3. Suitability modeling
To better understand where tomatoes might conceivably be farmed in California given the environmental constraints identified above, we modeled dry farm suitability on California cropland as a function of precipitation, temperature, and percent clay in soil. The resulting map shows what lands could potentially support a dry farm crop, with and without supplemental irrigation, using constraints that are relaxed to encompass the least restrictive farmer-elicited constraints (Figure 1). The map therefore errs on the side of including land that is not an ideal candidate for tomato dry farming, rather than leaving off land that may potentially be a good fit. With rising temperatures and less reliable rainfall, this map, which is based off of 30-year normals, likely also systematically overestimates what areas might fall into these thresholds when projecting into future climatic conditions.
It is important to note that, given the limits of publicly available data, and farmers’ experience that is inherently limited to areas where they already know dry farming to be successful (as opposed to a more systematic testing of the suitability of different climate, edaphic, and management combinations), our estimates of suitable areas are meant only as an initial assessment of what could be possible in the state. A field’s true capacity to be dry farmed could of course differ from our estimation depending on crop type and future climate scenarios, and as more empirical information is gathered on the limits of the practice. Furthermore, management history and management choices will factor heavily in dry farm success even in the most suitable locations. Highlighted areas should therefore be considered candidates for long-term dry farm management, rather than ready-to-go dry farm fields. The extent of dry farm adoption in suitable areas is also uncertain and will depend on market and policy conditions (see “Takeaways for agroecological transitions and policies” below). We also note that rainfall variability creates an additional risk for dry farm management. This risk, which we operationalize as the ratio of rainfall standard deviation to mean, increases in a north (lower risk) to south (higher risk) gradient in the state (Figure S1), with southern regions showing a higher variability in annual precipitation that may increase the need for supplemental irrigation—or even prevent cover crop growth—in some years.
A suitability map for dry farming crops beyond tomatoes would require crop-specific information. Particularly when it comes to grains and perennials (e.g., orchards), the range of possible locations is likely much broader. In the case of grains, winter varietals can be planted that take advantage of rain in winter months, while tree crops have far more extensive root systems that can reach water well beyond that which might be available to a tomato, in both cases relaxing the temperature and precipitation constraints that tomatoes need to survive without irrigation. Tomatoes are likely a better proxy for other vegetable crops (e.g., squash, potatoes), though each will have its unique requirements (and economic limitations as discussed above).
As we imagine a shift toward dry farm agriculture in California, it is also important to consider how land that is suitable for dry farming is currently being used. Combining areas that are suitable for tomato dry farming with and without irrigation, we compiled a list of the top 10 crops by area (as identified by the 2021 Cropland Data Layer) that are currently grown on these lands (Table 3). Some of them (grapes, winter wheat, and of course tomatoes) are currently being dry farmed with some regularity in the state and could signal particularly easy targets for a shift to low-water practices. Others (almonds, walnuts) are dry farmed in other Mediterranean climates and suggest an important opportunity for management exploration in lands that might be particularly forgiving to experimentation. The remaining crops (pasture, alfalfa, hay) are some of the most water intensive in the state and would therefore lead to substantial water savings if the land could be repurposed.
Crop . | Area in CA High Priority Groundwater Basins (ha) . | Average Annual Water Use per Acre . | |
---|---|---|---|
Acre-Feet . | Gallons . | ||
Grass/Pasture | 98,138 | 4.05 | 1,320,000 |
Grapes | 86,340 | 1.86 | 606,000 |
Alfalfa | 84,520 | 5.05 | 1,650,000 |
Other Hay/Non Alfalfa | 45,625 | 1.39 | 453,000 |
Almonds | 40,507 | 3.54 | 1,150,000 |
Fallow/Idle Cropland | 36,240 | NA | NA |
Walnuts | 33,661 | 3.30 | 1,080,000 |
Winter Wheat | 31,355 | 1.39 | 453,000 |
Shrubland | 26,088 | NA | NA |
Tomatoes (irrigated) | 21,878 | 2.15 | 701,000 |
Crop . | Area in CA High Priority Groundwater Basins (ha) . | Average Annual Water Use per Acre . | |
---|---|---|---|
Acre-Feet . | Gallons . | ||
Grass/Pasture | 98,138 | 4.05 | 1,320,000 |
Grapes | 86,340 | 1.86 | 606,000 |
Alfalfa | 84,520 | 5.05 | 1,650,000 |
Other Hay/Non Alfalfa | 45,625 | 1.39 | 453,000 |
Almonds | 40,507 | 3.54 | 1,150,000 |
Fallow/Idle Cropland | 36,240 | NA | NA |
Walnuts | 33,661 | 3.30 | 1,080,000 |
Winter Wheat | 31,355 | 1.39 | 453,000 |
Shrubland | 26,088 | NA | NA |
Tomatoes (irrigated) | 21,878 | 2.15 | 701,000 |
Current crops and land uses, as classified by the 2021 Cropland Data Layer, in areas that our analysis indicates as suitable for dry farming. Water usage data from the California Department of Water Resources.
While unrealistic in the near future, calculating potential water savings from a complete conversion of suitable lands to dry farming allows for comparison with other water saving strategies. Even assuming that an acre-foot of irrigation is added to each acre of dry farm crops every year (an overestimate compared to the 0–10 inches that farmers in this study use), if all the land listed in Table 3 were converted to dry farming (and otherwise irrigated to the statewide averages listed in the table; California Department of Water Resources, 2010), California would save 700 billion gallons of water per year, or nearly half the volume of Shasta Lake, the largest reservoir in the state. Given the overlap between suitable dry farm areas and high priority groundwater basins, these potential water savings are especially valuable as water districts scramble to balance their water budgets in light of the SGMA, which requires local agencies throughout California to develop and implement groundwater sustainability plans.
Perhaps the largest caveat to these potential water savings—and any analysis of dry farm suitability that relies solely on environmental constraints—is the economic reality in which conversions to dry farming currently occur. As discussed above, while a dramatic reduction in irrigation inputs might be feasible from a crop physiological perspective, whether farms can remain profitable through such a transition is an entirely different question.
3.4. Opening opportunities
Farmers are all too aware of the challenges they will likely face as temperatures rise and water access becomes less reliable. With climate risk looming, farmers are looking to dry farm tomatoes as one of the safest bets they can make on their fields:
I think of all the crops that would survive in climate uncertainty, this is the one that would be the cornerstone of resiliency. (Farmer H)
Given dry farm tomatoes’ ability to offer resiliency to coastal farmers, they are unsurprisingly looking to other crops and varieties that might be able to make the transition to dry farming. In addition to other crop species, farmers are also searching for tomato varietals (e.g., a dehybridized Early Girl called the “Dirty Girl”) that would allow them to save seed and better adapt their crops to their local context, as the currently preferred Early Girl varietal is a hybrid and therefore cannot support seed saving.
We could be adopting a lot more varieties for dry farming. Because Early Girls is like a fluke that they dry farm well, but then Dirty Girls is more intentional selection for dry farming. And we could be doing that with way more crops. I think like chili peppers—definitely. And beans for sure. There’s a lot of stuff we could be pushing, like selection boundaries for a lot more melons. (Farmer I)
If somebody was like, “this is a dry farm winter squash” and save seed from it, we could probably do it. But it hasn’t been developed, right? And right now, we don’t have the programming to support it. But I think it’d be really fun. (Farmer H)
Even in its current scope, dry farming offers farmers access to land that might otherwise not be arable. Eight farmers in the study had actively farmed in areas that would otherwise not be suitable for crop production:
I’m here because I felt like I could dry farm and because there’s very insufficient water to produce other stuff here. But on dry farming, I feel like all we got to do is water them in, and then we’re good. You know, so that’s a lot of times I take these pieces that have substandard water. (Farmer D)
It does give you some flexibility to grow things in certain areas where I wouldn’t even consider growing something else. (Farmer C)
This possibility of gaining access to marginal lands for vegetable cropping also opens opportunities for incoming and marginalized farmers who otherwise can face extreme difficulties securing fields to farm (Carlisle et al., 2019).
Farmers also expressed excitement about ways dry farming can help them better steward their land. Rather than use saved water to irrigate other crops, farmers were intrigued by the prospect of returning that water to natural ecosystems:
We are rainwater catchment, but we’re still diverting—ultimately it’s water that would be going to the creek, so if we can figure out how much water we really need and it’s way less, we could be doing more creek releases for fisheries. [It] would be awesome because supposedly there is salmon in [the] creek and we do certain creek releases right now with NRDC. Our obligation to do that ends next year, but it’d be great if we could keep doing that. (Farmer I)
By aligning lands well-suited to dry farming with conservation goals, areas to target for dry farming could be optimized to serve non-human interests as well, particularly if the right policy support is provided.
Amid the myriad opportunities and benefits dry farming offers, it has also emerged as an important avenue for outreach and education. Farmers see dry farming as a key model for what climate resilience can look like, and an important teaching tool that can be used to illustrate many aspects of sustainable farming in an era of climate change:
So educationally, that’s the easy one. It just totally makes sense…It has roads into climate change. It has roads into agronomy, and soil science, and understanding soil water dynamics. And so I think it’s a really important crop to contrast with the irrigated lands, you know, in an era of climate change and really climate unpredictability. (Farmer H)
Several farmers are already using dry farming as an education tool, and still more have benefited from learning about dry farming at organizations like the Center for Agroecology at UC Santa Cruz (formerly CASFS) that have served as hubs for understanding, refining, and teaching the practice. Eight of the farmers in this study could trace their dry farm lineage back to the Center for Agroecology in some way, highlighting the importance of farmer-to-farmer education and farmer field schools. Because tomato dry farming is such a localized specialty, education and research hubs may be all the more important in not only teaching farmers the practice in a final or static form, but for teaching more versatile principles and forging long-lasting learning communities where farmers can continually return and convene to hone the practice to fit new crops and landscapes.
4. Takeaways for agroecological transitions and policy
As policymakers increasingly focus on dry farming as a solution to California’s water crisis, there is significant interest in expanding dry farm management beyond its current scope. Nonprofit policy advocacy groups have been calling for increased dry farm production in California (CAFF, 2015; Pottinger and Peterson, 2021; DeLonge, 2022), beginning conversations about how such a transition toward low-water agriculture might be supported. Though California once had extensive dry farm production (Macdonald, 1911), particularly in orchard and vineyard crops, this practice all but disappeared as irrigation water became more available in the state. It is only in recent decades that dry farming has begun to attract attention again, this time in annual as well as perennial systems. Here we focus on vegetable (annual) production, as it is most directly implicated in findings from tomato management.
We conclude by exploring how dry farming can act as a model for a transition to both low-water agriculture and a more agroecological food system, as well as the policies that hold the most promise for dry farm expansion.
4.1. Central Coast dry farming as an agroecological transition
As agroecology1 gains recognition as an alternative to industrialized agriculture, processes of transition toward agroecological food systems have also garnered considerable interest (Duru et al., 2015; Gliessman, 2016; Tittonell, 2020). As has been done previously in other systems (e.g. Gaitán-Cremaschi et al., 2020), we use the 4-part framework developed by Gliessman et al. (2018) to analyze how the tomato dry farmers we interviewed demonstrate one case of such a transition. We identify several ways in which the cultivation of this unique crop has catalyzed a shift in participants’ entire farming systems, and even elements of the regional food system, away from industrialized production and toward agroecology.
Changes in production practices. The specialized management involved in non-irrigated vegetable production is perhaps the most obvious change in dry farm systems. From the lack of water inputs to the cover crops and dust mulches that allow dry farm tomatoes to thrive, a unique management regime sets dry farming apart from irrigated, industrial-style production practices in the region.
Changes in knowledge generation and dissemination. Successful dry farming must tailor management decisions to the specific field that is being farmed and the weather conditions that year (see “Motivations for dry farming” above). This localized knowledge has been shared through farmer-to-farmer conversations and teaching farms (most notably the farm at UC Santa Cruz) that mirror the rich history of campesino-a-campesino exchange and farmer field schools that exemplify farmer-led agroecological knowledge exchange throughout the globe (Holt-Giménez, 2006; Waddington et al., 2014). Though very little academic research and technical assistance exist to date on the topic of vegetable dry farming in California, the work that does exist has been participatory in nature (Socolar et al., 2024), and a rich collaborative has developed around participatory dry farm resource gathering, network building, and varietal selection at Oregon State University. These participatory methods are a notable departure from traditional agronomic research and extension at Western universities, and indicate a shift toward agroecological frameworks of knowledge generation and sharing (Warner, 2008).
Changes in social and economic relations. Farmers’ ability to market products directly to consumers—who in turn developed trust in certain farms to provide particularly high quality tomatoes—was key to allowing farmers to charge a price that made dry farm tomatoes economically feasible to grow. The concurrent development of the Slow Food movement in the region, with its focus on local cuisine and calls for quality over quantity, was key to supporting this dry farm premium. Likewise, local chefs’ praise for the intense flavor of dry farm tomatoes reinforced this development of a food culture centered on this unique regional specialty (Waters, 2006).
Changes in institutional framework. Dry farming follows a long history of agroecological transition in spite (rather than because) of government policy. Farmers interviewed for this study could not point to a single government program that assisted in the development or continued viability of dry farming as a practice. Rather, tomato dry farming has been driven by a small group of highly motivated farmers.
As climate and policy-driven water scarcity (e.g., SGMA) grow, many of the farmer interviewees indicated that they would be likely to shift their operations toward dry farming, and other farmers in the state may follow suit. However, as Blesh et al. (2023) suggest, expanding this dry farm tomato niche into a new normal of water-conserving and diversified agroecological farming will require more robust institutional pathways. Though progress has thus far been slow, climate change is a powerful driver of policy in California (Mazmanian et al., 2020) and has the potential to act as a crisis that drives institutional pathways that support low-water agriculture (Mier y Terán Giménez Cacho et al., 2018).
4.2. A model for water saving
Our suitability map shows potential for vegetable dry farming to be practiced on California croplands that are currently irrigated, though its expansion is inherently limited. Even if markets could be adapted to support an influx of dry farmed vegetables, our map indicates that climatic constraints will largely require vegetable dry farming to be practiced in coastal regions or other microclimates that can provide cool temperatures and sufficient rainfall. The Central Coast’s tomato dry farming offers principles—but not a blueprint—for low water agriculture in other regions.
Based on themes from our interviews, these principles show a cycle of water savings that connect reduced inputs, management diversification, and market development (Figure 2). The cycle begins with lower irrigation (reducing water inputs), which can be accomplished in concert with soil health practices (e.g., cover cropping, adding organic amendments) that build soil water holding capacity and increase long-term fertility. Reduced weed pressure and lower biomass production can then lead to reducing other inputs, such as labor and fertilizers, while also allowing for further water savings. The combination of reduced inputs and soil health practices then gives rise to a product that is unique in its water saving potential, and for tomatoes, of unusually high quality. By encouraging consumers to value quality, farmers can develop markets that will provide a premium for these low-water products. Alternatively, novel policies could directly compensate farmers for the practice of dry farming. Either way, the added value associated with dry farming creates an opportunity to expand the practice, further lowering inputs.
All manner of water saving strategies will be necessary to accommodate unpredictable and diminishing water availability in California, from building soil health to adopting deficit irrigation, less water-intensive crops, and/or dry farming (Richter et al., 2017; Acevedo et al., 2022). While principles of dry farm management are applicable across all of these water saving practices, each will occupy a different space both politically and on farms. For example, while dry farming may appear attractive in areas where surface and groundwater are most precarious like the San Joaquin Valley, extremely high summer temperatures and low winter rainfall render vegetable dry farming infeasible. (Though crops like pulses may still be dry farm candidates in these areas, their unique physiology and low market value require a different analysis from the one presented here.) Instead of—or in addition to—dry farming, farms may apply deficit irrigation to all fields, fallow or sell a portion of their land and concentrate irrigation on smaller areas with high value crops, or grow new crops altogether (Wallender et al., 2002; Wichelns and Cone, 2006; Tortajada et al., 2017). Here we examine the path of tomato dry farming as a model for vegetable dry farming specifically, though it must ultimately join a fuller constellation of water saving practices in the state.
4.3. A forking path
Thus far vegetable dry farming has been limited to a handful of small farms; however, given its potential for water savings, expansion—and policies that encourage it—have become desirable if not inevitable. As we ask how policies may impact dry farm production systems, we find a forking path in what types of expansion may result from different policies. An increase in production can be accomplished through both scaling size (increasing the size of individual vegetable dry farm operations) and scaling number (increasing the number and geographical scope of dry farm—or dry farm-informed—operations). Both options can tap into the water saving cycle to decrease water usage. However, the search for just, agroecological transitions has pointed time and again to the need for scaling number (Gliessman et al., 2018; Anderson et al., 2019; Ferguson et al., 2019).
On the Central Coast, small, diversified farms have used this water saving cycle to both cut water use and develop a specialty product that allows growers to farm in areas with high land values by increasing their land access, profits, and resilience to local water shortages. However, it cannot be taken as a given that this water saving cycle will continue to uplift the smaller, diversified operations on which it started. Recent work highlights the potential for biophysical and sociopolitical conditions to combine in ways that diminish—rather than expand—the viability of agroecological systems (Ong and Liao, 2020). In the case of dry farm tomatoes, sociopolitical attention is already beginning to target the biophysical need to decrease water consumption. If well-intentioned policy interventions designed to decrease irrigation water use build markets that value dry farming’s low water use, rather than the high-quality fruit it produces (e.g., labeling and payment for practice programs), growers will be able to scale the size of dry farm operations without needing to rely on the highly localized knowledge required to produce high quality fruits. As large grocers scale up dry farm produce sales without worrying about quality-based markets that may quickly saturate at industrial scales, the agroecological systems that originally produced dry farm tomatoes may be edged out of the market. On the other hand, if policies build guaranteed markets for small farms growing dry farm produce, dry farming may grow by scaling out to more small to midsize diversified operations.
Policies focused on water savings via dry farming may then favor industrial or smaller-scale farms, depending on how interventions shape the “Market Development” aspect of the cycle. We therefore examine this cycle not only as a means to save water, but ask if and how it can enhance the viability of nonindustrial farming operations as the food system adapts to restricted water availability. We consider Blesh et al.’s (2023) analysis of how institutional pathways can act synergistically with farmer networks to enable agricultural diversification (by supporting tracking systems, cost share programs, seed/land access, research/education, and public procurement), asking which of these pathways have the potential to point future dry farming toward scaling size versus scope.
4.4. The trouble with scaling size
To better situate these policy options in the local context, we first look to the outcomes of institutional intervention in organic strawberry production in a very similar region on the Central Coast, and consider the analogous options for dry farm tomatoes.
Similar to dry farm tomatoes, organic strawberry production was launched into the spotlight by government-mandated input curtailments (water restrictions in the case of dry farm tomatoes, a methyl bromide ban in the case of strawberries). For strawberries, the development of an organic strawberry production system also coincided with the adoption of an organic certification process by the US Department of Agriculture. Growing public interest in organic strawberries and the methyl bromide ban led to the rapid expansion of industrial-scale organic strawberry production–blatantly scaling size of production (Jaffee and Howard, 2010; Arcuri, 2015; Guthman, 2016). As production increased, organic strawberry markets saturated and prices crashed, leaving an economic landscape where only the largest operations could remain viable selling strawberries at market prices (Guthman, 2004b). At this point, agroecological growers had to redouble their efforts to target local consumers with direct marketing strategies, as the organic label no longer added the necessary value to profitably sell their product.
4.4.1. Tracking systems
In an analogous case for dry farm tomatoes, it is easy to see the immediate appeal of establishing a “dry farm” label that can incorporate the social value added to dry farm tomatoes into the price of the product without relying on consumers trusting and paying a premium based solely on higher qualities. However, by divorcing dry farm practices from quality premiums and long-standing relationships with customers, a dry farm label would make it much easier for large-scale growers to enter the dry farm market. These larger operations—which may struggle to produce high quality fruits or maintain direct relationships with customers but can still decrease water usage enough to produce a certified dry farm tomato—could easily grow dry farm produce at large enough scales to edge smaller growers out of markets that are not reliant on quality. While dry farmers may still be able to market their product as “better than the mainstream,” they would likely see a contraction in their customer base as some consumers would be siphoned into mainstream markets.
As has been seen in the organic program, industrial growers could also lobby for an official relaxation—a literal watering down—of label standards (Guthman, 2004a). This sidestep of the dry farm practices described in the above interviews would not only further advantage large scale farmers, but would also undermine the very water savings that they are meant to encourage.
4.4.2. Cost share programs
Larger scale growers may also be favored when farmers are paid to implement specific practices. The administrative costs of enrolling in payment-for-practice programs can be a cumbersome barrier to entry, while low payouts at small scales dissuade small farmers who implement the practice from enrolling (Reimer and Prokopy, 2014; Cronin, 2023). These patterns are currently seen in programs offering cost shares for cover cropping, where farm size is significantly larger for participants than nonparticipants (Sawadgo and Plastina, 2021).
4.5. Policy options for scaling the scope of vegetable dry farming
Rather than scaling size, policies that might encourage dry farming to “scale number” include increasing dry farm vegetable production via more crop varieties and accessible land (seed/land access), encouraging small growers (education), and expanding markets for them to sell to (public procurement). Here we focus our analysis on dry farm production of high value crops, which we expect to be analogous to tomatoes in both production/land suitability and marketing approach. We also note a potential to include dry farm grains and commodity crops in a broader discussion of dry farming’s role in California agriculture (Pottinger and Peterson, 2021).
4.5.1. Crop varieties
Given farmers’ interest and current experimentation with dry farming non-tomato vegetables, expanding the set of crops that can be dry farmed and adapted to local conditions is a clear target for future policies. Support for research and participatory breeding programs/variety evaluation could spur development of locally adapted dry farm varieties. By compensating farmers for experimentation with diversified dry farm rotations and development of locally adapted varieties, policymakers can also absorb some of the risk inherent to on-farm experimentation and encourage innovation on the farms that are most familiar with the practice, while simultaneously lowering barriers for farmers new to the practice.
4.5.2. Land and water access
To create a policy environment where experimentation feels more accessible to farmers, minimum lease terms (e.g., 10 years) could be set for farmland, allowing farmers to feel more secure investing in localized practices (Stevens, 2022). Priority could also be given to creating programs that connect farmers—particularly new farmers and those with underrepresented identities—to available farmland. Without the burden of securing water access, lands that would otherwise be impossible to farm with summer crops could become arable, particularly in conjunction with the concurrent support of the other policies discussed here. As these areas are likely to be far cheaper than land with stable water rights, lower land values can also alleviate what is often a significant barrier to farmers looking for new land (Buck et al., 2014; Figueroa et al., 2020). Though many areas will still require some access to water to successfully dry farm (i.e., orange areas on suitability map in the case of dry farm tomatoes), crops’ need for water coincides with points in the season when surface water is most available (Schlenker et al., 2007), making areas with inconsistent water access over the course of the season likely candidates for dry farm success. Policy changes that reallocate surface water toward seasonal usage in the spring, when farmers need to establish dry farmed crops and surface water is more plentiful, could allow more farmers without year-round water access to successfully establish a dry farm crop. Areas that rely on groundwater are also scrambling to cut back on water usage due in large part to SGMA, a policy that requires that groundwater basins be managed sustainably in 20 years (Leach et al., 2021). High priority groundwater basins (in pink in Figure 1) will need to cut water use dramatically and are therefore areas where dry farming may become increasingly valuable as a management strategy.
In years or areas with particularly restrictive water use limits, industrial-scale operations may even choose to sell/lease land that they do not have enough water to manage to smaller operations that can successfully dry farm on those same areas. Land and water in areas shown as suitable on the map might initially be given priority for these land/water access policies, but as new and locally adapted crop varieties emerge, suitability may also extend.
4.5.3. Farmer support
In addition to land access, new and transitioning dry farmers will require education and support to successfully implement the practice. Funding for field days, demonstration farms, and farmer-to-farmer networking events can encourage the spread of knowledge to new farms and farmers (Teixeira et al., 2018; Carlisle et al., 2019). Thus far the farm at the University of California Santa Cruz has served as a hub of knowledge that provides long-term training, demonstrations, and published guides to interested growers, and has played a key role in dry farm adoption for 8 of the 10 interviewed farmers. Similar programming offered in multiple languages and at other universities that span a wider geographic extent, along with accessible examples of working dry farm operations (as modeled in the newly established California Farm Demonstration Network) are needed to familiarize farmers with the practice and create support networks for growers at all levels of experience. Given the relative newness of dry farming annual crops in the state, the novelty of its application to vegetable crops beyond tomatoes, and a potential expansion beyond the region in which it has historically been practiced, forums such as workshops, listservs, and social gatherings can facilitate key knowledge-sharing and practice development, especially where guidance from research and technical assistance may not yet exist.
4.5.4. Markets
Finally, increased dry farming must be met with increased capacity for markets to accept dry farm produce at prices that support farmer livelihoods. While some market expansion is inherent to a geographical expansion beyond the Central Coast region, additional markets throughout the state can offer dry farmers more security in a production expansion. Public procurement programs (e.g., the Farm to School Incubator Grant Program currently aiming to expand farm to school supply chains) could serve to connect dry farmers to guaranteed markets, especially if they are prioritized for entry into the program.
5. Conclusion
As water shortages are exacerbated by changing climates in California and across the globe, there is an increasingly urgent need to adapt agricultural systems to use less water. By nearly or entirely cutting irrigation to tomato crops grown in the summer season, dry farming has particular appeal as a low-water alternative to irrigation-intensive agricultural systems. While tomato dry farming is an inherently localized farming practice, suitable only for implementation in a specific region, it also offers a general model for how farming systems might shift toward low-water agriculture.
Beyond decreasing water use, with the right policy support, dry farming also presents an opportunity to support innovation on small, diversified farms, transitioning the food system toward an agroecological future. We see significant potential for vegetable dry farming to expand to areas in which it is not currently practiced, and see potential for such an expansion—even on the exact same land area—to occur in a way that favors either large numbers of operations each managing a small area, or small numbers of operations each managing a large area. Policy strategies could have a large impact in favoring scaling number versus scaling size, with important ramifications for the future of the agroecological transition that has begun in dry farm tomato operations and markets on the Central Coast. Policies that support participatory breeding programs, establish minimum lease terms, fund workshops, and create markets through public procurement, can support and encourage a transition in which areas suitable for dry farming are managed by many small-scale operations with ecologically motivated management practices.
Data accessibility statement
Due to privacy/ethical restrictions, interview audio recordings cannot be shared publicly. Transcripts that support the findings of this study are available from the corresponding author upon reasonable request.
Supplemental files
The supplemental files for this article can be found as follows:
Supplemental Text.pdf
Acknowledgments
Our deepest thanks go to all of the farmers who participated in this project. We also thank Jim Leap for his invaluable guidance throughout this project, and Melanie Rodríguez for their help with transcriptions.
Funding
This material is based upon work that is supported by the National Institute of Food and Agriculture, U.S. Department of Agriculture, through the Western Sustainable Agriculture Research and Education program under project number GW21-224. USDA is an equal opportunity employer and service provider. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the authors and do not necessarily reflect the view of the U.S. Department of Agriculture.
Competing interests
The authors have declared that no competing interests exist.
Author contributions
Contributed to conception and design: YS, TMB, LC.
Contributed to acquisition of data: YS.
Contributed to analysis and interpretation of data: YS, TMB.
Drafted and/or revised the article: YS, TMB, LC.
Approved the submitted version for publication: YS, TMB, LC.
Note
Here we define agroecology as a form of agriculture based in small-scale, management-intensive, diversified farming systems and the sociopolitical movements necessary to defend and advocate for their wider adoption.
References
How to cite this article: Socolar, Y, Carlisle, L, Bowles, TM. Tomato dry farming as an agroecological model for California’s drought resilient future: Farmers’ perspectives and experiences. Elementa: Science of the Anthropocene 12(1). DOI: https://doi.org/10.1525/elementa.2023.00139
Domain Editor-in-Chief: Alastair Iles, University of California Berkeley, Berkeley, CA, USA
Knowledge Domain: Sustainability Transitions