- Author: Mike Hsu
UC researchers studying how practice can help farmers manage drought, pests, other challenges
Due to severe water shortages, rice acres planted in California plummeted by 37% from 2021 to 2022, according to numbers released recently by the U.S. Department of Agriculture's National Agricultural Statistics Service. But now, thanks to University of California researchers, growers have a new tool they could potentially use to cope with droughts and other environmental and socioeconomic changes.
A crop rotation calculator provides farmers in the Sacramento Valley – where 97% of California rice is grown – with projections on the economic impacts of transitioning their fields from rice into four less water-intensive crops: dry beans, safflower, sunflower or tomato.
The tool represents an initial attempt to address the dearth of research on rice crop rotation in California, while giving growers much-needed, science-backed data on whether the practice would make financial sense for their farms.
“I believe more rice growers could benefit from the many advantages of crop rotation, and this new tool is an excellent first step by the UC to help growers look into making such a transition,” said George Tibbitts, a Colusa County rice farmer.
Funded in part by the USDA National Institute of Food and Agriculture, through the Western Integrated Pest Management Center, the calculator is a collaborative effort of UC Agriculture and Natural Resources, UC Integrated Pest Management and UC Davis to fill a major gap in rice research.
“I do think there are people who would have tried rotational crops in the past, but it's just so unknown, we didn't have anything we could give them and be like, ‘Hey, this is the recommended crop for your area,'” said Whitney Brim-DeForest, UC Cooperative Extension rice advisor. “This tool gives them some preliminary data they can use to make a more informed decision.”
Crop rotation a potential boon to growers, environment
UC Davis doctoral student Sara Rosenberg and Brim-DeForest, alongside other members of the UC rice research team, surveyed California rice growers in 2020 on their experiences with and perceptions of crop rotation. Although the practice is rare in the Sacramento Valley (only an estimated 10% of rice acreage is under rotation), some farmers reported benefits that could be crucial in a water-scarce future.
“From having conversations with growers who do rotate, one of the biggest benefits they describe is their flexibility in times of drought, where they can keep producing on their land when there isn't enough water to grow rice,” said Rosenberg, noting that crop rotation could be one option in a “toolbox” of strategies that growers also use to manage fertilizer price shocks, herbicide resistance and other challenges.
During the ongoing drought that caused about half of California's rice acreage to go fallow in 2022, Tibbitts said his water district was only able to allocate 10% of his usual allotment.
“With such a limited supply, it would have been tough to grow even one field of rice,” he said. “But it was enough water so that we could rent two of our fields to a tomato grower – tomatoes under drip irrigation use much less water than a flooded field of rice. We were also able to grow one field of sunflowers, which doesn't need any irrigation at all if you can plant the seeds into existing moisture in the early spring.”
While drought is one motivating factor to rotate crops, Tibbitts said that on principle he avoids planting all his acreage in rice and “not have all (his) eggs in one basket.”
“My primary motivation for rotating into and out of rice has been to help with weed and disease control,” he added. “Crop rotation is a primary tool of IPM (integrated pest management), and I feel it has helped me greatly over the years.”
According to Brim-DeForest, rotating cropping systems can allow for the use of different weed control tools, such as different herbicide modes of action, and different cultural controls such as tillage, reducing the chances of selecting for herbicide-resistant weeds – an increasingly pervasive issue in rice systems.
Rosenberg noted that, in some situations – and depending on the crops in rotation – the practice can also disrupt the life cycles of insects and diseases and potentially improve soil structure and increase nutrient cycling and uptake, which may lead to a reduction in inputs such as fertilizer.
More research on crop diversification needed in rice systems
The benefits of crop rotation for California rice growers are largely theoretical and anecdotal, however, so the UC rice team is looking to add evidence-based grounding through a variety of studies – from looking at long-term effects on soil health indicators to testing various cover crops (which may deliver some benefits of diversification, similar to those of rotation).
“In California, there is no quantitative data on crop rotation in rice,” said Brim-DeForest. “You'd think after a hundred and some odd years (of UC agricultural research), all the research would have been done, but, no – there's tons still to do.”
Through interviews with Sacramento Valley growers, researchers found that cost was frequently mentioned as a barrier to trying crop rotation, along with incompatible soil conditions and a lack of equipment, knowledge and experience.
To help clarify those economic uncertainties, the new calculator tool allows growers to enter baseline information specific to their circumstances – whether they rent or own their own land, whether they contract out the work to plant the rotational crop, and other factors. The calculator then generates potential costs and benefits of staying in rice versus rotating to dry beans, safflower, sunflower or tomato, during the first year and in an “average” year for those crops.
The upfront costs of rotation during “year one” can be daunting. Therefore, the tool only focuses on a short-term profitability perspective. Researchers are currently working on longer term modeling for crop rotation – incorporating the possibility of reduced herbicide use over time, and under different crop yield scenarios, for example – that could significantly change the growers' calculus.
“You could actually be profitable in the long term, whereas this first, short glimpse is showing you a negative,” said Rosenberg.
In addition, thanks to collaboration with the UC IPM team, the rice rotation calculator is an evolving tool that will be continually improved based on user feedback and additional data. Brim-DeForest also said that it could be adapted to other cropping systems – for example, alfalfa going into another rotational crop.
The rice calculator tool can be found at: https://rice-rotation-calculator.ipm.ucanr.edu/.
Other contributors to the project include Bruce Linquist, Luis Espino, Ellen Bruno, Kassim Al-Khatib and Michelle Leinfelder-Miles of UCCE; Cameron Pittelkow of UC Davis; as well as UC IPM team members Chinh Lam, Tunyalee Martin and Hanna Zorlu; and the California rice growers and industry members who participated in the research.
/h3>/h3>/h3>- Author: Dan Macon
Last week, the San Jose Mercury News published an interesting map of the state of California depicting “urban” (that is, non-agricultural) water use by region for the month of May. According to the State Water Resources Control Board, Californians used one percent more water in May 2014 that the average May over the last three years. Even in Placer and Nevada Counties, some residents don't comprehend the severity of the current drought.
In response to the slight uptick in urban water use compared to the last three years, the Board adopted new penalties for wasting water in urban and residential settings. This comes on top of Board actions that restrict water diversions and storage for “junior” water rights holders. Furthermore, irrigation water deliveries from the federal Central Valley Project and the state water project are vastly reduced this year. In Placer and Nevada Counties, our water agencies have asked for voluntary 15 percent reductions in water use to ensure that they can carryover enough water in reservoirs for next year.
On the same day that the Mercury News printed this graphic, the UC Davis Center for Watershed Sciences released its “Economic Analysis of the 2014 Drought for California Agriculture.” Lest there be any doubt that California is in the midst of a severe drought that is having profound impacts on farmers and ranchers, here are a few of the study's key findings:
- California is enduring its third driest year on record as agricultural, urban and environmental demands for water are at an all-time high. In other words, this year has been one of the driest in our history – and California's population has never been higher.
- The 2014 drought is responsible for the greatest absolute reduction to water availability for agriculture ever seen, given the high agricultural demands and low streamflows and reservoir levels. Surface water availability is expected to be reduced by about one-third.
- The 2014 drought will result in a 6.6 million acre-feet reduction in surface water available to agriculture. This loss of surface water will be partially replaced by increasing groundwater pumping by 5 million acre-feet.
- The net water shortage of 1.6 million acre-feet will cause losses of $810 million in crop revenue and $203 million in dairy and other livestock value, plus additional ground water pumping costs of $454 million. These direct costs to agriculture total $1.5 billion.
- The total statewide economic cost of the 2014 drought is $2.2 billion, with a total loss of 17,100 seasonal and part-time jobs.
- California farmers will fallow approximately 428,000 acres of farmland in 2014 (other reports put this estimate as high as 800,000 acres). Most of the fallowed land is estimated to be feed and other annual crops, including pasture. At the individual farm level, fallowing land creates significant cash-flow challenges. Some farms may not survive economically; some may be forced to sell land for development. These farms and ranches grow food for all of us! Each fallowed acre reduces the amount of food and fiber available for all Californians!
- In the Central Valley, high-value crops including vegetables, non-tree fruits and permanent crops represent less than 13 percent of total fallowing as growers direct scarce water to the highest value use. Scarce water supplies are being used to keep almond, pistachio and walnut trees alive, rather than to grow annual field crops. These orchard crops represent significant capital expenditures; farmers can't simply fallow an orchard one year and resume production the next.
- Alfalfa hay prices have increased 40 percent since January 2014. This impacts the cost of production for dairy farmers, and to a lesser extent, for other livestock producers. Many foothill ranchers have already felt the impacts of this price increase; they had to purchase hay to make it through the exceptionally dry winter. Ranchers who market directly to consumers have had to raise their meat prices.
- The California drought, especially the lack of rain in the winter of 2013-2014 reduced pasture quality and the number of cattle [and other rangeland livestock] per acre substantially during the crucial winter and spring period of calving and raising feeder cattle on pasture. Once the grass started to grow in March and April, many ranchers did not have enough animals to fully utilize the forage, creating fuel-loading problems on many ranches. Several wildfires this summer have impacted ranches that were forced to de-stock during the winter.
- The combined socioeconomic (reduced production, job losses, economic losses, etc.) effects of the 2014 drought are up to 50 percent more severe than in 2009.
But what happens if the drought continues? According to the report, “Statistically, the drought is likely to continue through 2015 – regardless of El Nino conditions.”
- Failure to replenish groundwater in wet years will continue to reduce groundwater availability to sustain agriculture – particularly more profitable permanent crops – during California's frequent droughts. The recent plantings of almond and walnut orchards on the edges of the Valley are at risk.
- If the drought continues for two additional years, groundwater substitution will remain the primary response to surface water shortage, with decreases in groundwater pumping capabilities and increasing costs due to declining water levels.
- A continued drought also increases the vulnerability of agriculture, as urban users with largely adequate supplies in 2014 would likely buy water from agricultural areas. This means more land will be fallowed and more farms will go out of business.
Obviously, rural communities are especially vulnerable to the drought. Communities that depend on farming and ranching as their economic base are already suffering from the loss of jobs and farming income. Drought-induced reductions in food production (and related increases in production costs) will ultimately lead to higher food prices – at the supermarket as well as at the farmers' market. As the housing market recovers, many farm and ranch families may decide to sell their land for development.
So what can we do? We can't make it rain – believe me, I've tried everything I can think of! As farmers and ranchers, we must continue to hope for the best but prepare for the worst. We need to develop drought plans – what will we do if the drought continues? For my family's sheep operation, this means keeping a careful eye on our carrying capacity and stocking rates. For foothill fruit growers, this may mean deciding which trees to save and which to let die.
While most residential water users are used to having their water metered, much of the irrigation water in the foothills is delivered through a network of canals by the miner's inch (a vestige of our Gold Rush heritage, a miner's inch is equal to 11.22 gallons per minute). As an irrigator, I have two options for conserving water: I can purchase less water from my irrigation district, or I can invest in technology and management systems that allow me to irrigate more acreage with my full allotment of water. On several of our leased pastures, we've opted to make our water go further. If the Nevada Irrigation District (NID) is forced to reduce deliveries next year by a fourth consecutive dry year, we'll have to get by with less – and reduce our flock accordingly. We simply don't have the ability to replace our NID water with groundwater.
What can we do at home? We've always turned off the tap while brushing our teeth and shaving. This year, we're putting a bucket in the shower while waiting for the water to get hot – and we're using this water for plants and for drinking water for our pets. We've also limited the amount of landscaping irrigation that we're doing – our lawn is drier than normal, and we're using some of our yard space to grow food instead of ornamental plants. If the drought continues, we'll consider tearing out more lawn.
Drought has always been a fact of life for California. I've seen evidence that the last half of the 20th Century were wetter than normal for our state – perhaps drought is more ordinary than we realize. And while many farms and ranches have learned to get by on less water, the map at the beginning of this article suggests that many of our urban neighbors are not aware that we're in a drought. If our current dry spell persists, however, we'll all be forced to make some difficult decisions.
Here's the bottom line: no matter how we define “locally grown,” if the drought persists, we'll all have difficulty finding locally grown food!
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