Posts Tagged: irrigation
When it comes to watering walnuts, most California growers believe you need to start early to keep trees healthy and productive throughout the long, hot summer. But according to striking results from a long-term experiment in a walnut orchard in Red Bluff, growers can improve crop production if they hold off irrigation until later in the season and directly measure their trees' water needs.
The findings from researchers at the University of California may help farmers optimize water use.
“It's a game-changer,” said walnut grower Hal Crain, who welcomed researchers on to his orchard to test irrigation optimization. “It's clear to me you can improve nut quality and yield by applying water based on what the tree wants and needs, rather than just watering when it's hot outside and the soil is dry. That's a big deal for walnut growers and for the entire agricultural industry.”
Changing the paradigm
Crain is a second-generation farmer whose family has been growing walnuts in Butte and Tehama counties for 55 years. Like most walnut farmers, Crain had always started irrigating in early to mid-May when the days grew warmer and the trees sprouted leaves.
“That's standard practice for probably 90 percent of California's walnut growers,” said Crain, walking amid his trees on a sunny afternoon. “The theory is that when you irrigate early, you preserve the deep moisture in the soil that trees need to survive the heat of summer.”
But that's not how it works, the research shows. Instead, trees that grow in saturated soil early in the season don't develop the deep roots they need to thrive.
“With all the water right there at the surface, the lower roots suffer,” explained Bruce Lampinen, UC Cooperative Extension orchard management specialist with the UC Davis Department of Plant Sciences. “Trees end up with a very shallow root system, which doesn't serve them well as they try to extract moisture from the soil later on.”
Lampinen has long suspected that walnuts were getting too much water in the spring.
“A lot of the symptoms we see like yellowing leaves and various diseases can all be explained by overwatering,” said Lampinen.
So Lampinen did what scientists do: He set up an experiment. Five years ago, with funding from the California Walnut Board and the U.S. Department of Agriculture, he joined forces with Ken Shackel, a plant sciences professor with UC Davis, and Allan Fulton, an irrigation adviser with UC Cooperative Extension. Together, they led a team of scientists testing irrigation on Crain's ranch.
“Hal is an exceptional partner,” Fulton said. “Farmers have a lot to accommodate when they host an experiment like this, with researchers going in and out of the orchard at all hours. He had to work around our people and the timing of our water treatments. He's always eager to experiment with technology and learn new things, and he shares what he learns with other growers. Hal completes the circle.”
Tough nut to crack
When is the best time to irrigate? Researchers say the trees hold the answer. Scientists use pressure chambers, which are air-pressure devices that measure a leaf or small shoot to gauge how hard the plant is working to pull moisture from the soil.
“Just because the soil looks dry doesn't mean the plant is suffering,” said Shackel, who specializes in plant physiology. “Pressure chambers let you ask the tree how it's feeling — sort of like taking a human's blood pressure — which is a much more accurate way to measure a plant's water needs.”
For the last five years, the team has been applying different water treatments to five blocks of trees. One block is getting standard, early irrigation. Crain's orchard managers begin irrigating the other blocks when the trees reach different levels of water stress based on pressure-chamber readings.
The trees that experience moderate stress are doing the best. Their irrigation usually starts in mid-to-late June, several weeks later than when standard watering begins.
“You can tell just by looking at that block that the trees are healthier,” said Crain, standing beneath a canopy of lush, green trees. “And, we're starting to see greater yields and better nut quality.”
Translating the research
The research is helping scientists advise farmers on irrigation.
“My biggest take-away is knowing when to start watering is a really important factor to the health of your trees,” Lampinen says.
Pressure chambers — sometimes called pressure bombs — can cost more than $3,000, and high-tech versions are under development.
“I tell growers a pressure bomb would pay for itself even if you just used it once a year to determine when to start watering,” Lampinen said.
Crain is certainly convinced.
“When you irrigate based on your trees' needs, you optimize water,” Crain says. “I'm not using less water overall, but the water I do use is producing more food. That's good news for everyone.”
This story was originally published in the Fall 2018 issue of Outlook Magazine, the alumni magazine for the UC Davis College of Agricultural and Environmental Sciences.
At a recent beginning farming workshop, that was the exact question that was posed to an earnest group of beginning farmers. Many of you may have similar questions so this post answers a few of them. If you have more questions about beginning farming, come to the next workshop this fall, which will be announced on our Foothill Farming website calendar.
- How do I get into an association for the crops I want to grow or am growing?
There are a number of organizations for a variety of locally grown crops, most would be happy to help a new, teachable farmer learn and understand some of the specifics about their crop and provide networking opportunities. Here is a list of a few local, crop specific organizations that you could join. Also feel free to look under resources on the Foothill Farming website for more information about your potential crop.
- California Wool Growers Association – http://woolgrowers.org/
- Mountain Mandarin Growers Association - http://www.mountainmandarins.com/
- Placer County Vintner's Association - https://placerwine.com/placer-county-vintners-association/
- Placer County Wine & Grape Association - http://pcwga.org/
- Sierra Wine & Grape Growers Association - http://swgga.org/
- Tahoe Cattlemen's Association - https://www.facebook.com/TCA-Tahoe-Cattlemens-Association-180625651975901/
Regardless of whether or not you see your crop-specific producers association above, there are also a few other local options to connect you with other farmers and ranchers.
- California Certified Organic Farmers, Sierra Gold Chapter - https://www.ccof.org/ccof/chapters/sierra-gold
The other questions pertain to water, you can guess why. Water is critical to agriculture in the foothills and its availability to your farm is key to deciding how, when, and what you can potentially raise or grow.
- Did local irrigation districts reduce deliveries during the last drought?
Most agriculture in the foothills depends on ditch water from local irrigation districts. It takes approximately 1 miner's inch of water to irrigate 1.5 – 2 acres of pasture or about 1 acre of crops during the hot summer months. During the last drought, irrigation districts asked their customers to voluntarily conserve water, and they did. No reductions were forced. Thankfully we are no longer in a drought and both the Nevada Irrigation District and Placer County Water Association plan for full water deliveries this irrigation season, which runs from April to October.
- If I need irrigation district water past October, do I need to buy the entire 6 months of winter water?
Perennial crops often require winter irrigation water due to intermittent rains in many recent winters. NID offers a fall water supply for Oct. 15 through Dec. 1. It is important to bear in mind that winter water is usually more expensive than normal irrigation water, about 125% of normal rates and is not feasible in most cropping systems. Contact your irrigation district to inquire about the availability of winter water and how much water would be available to you during the normal irrigation season.
- Nevada Irrigation District - https://nidwater.com/
- Placer County Water Agency - https://pcwa.net
- What are the dangers of creek water?
Unless you have a deeded right to use water from creeks or streams on your property, you cannot use that water. Most producers get irrigation water from an irrigation district.
Creek water or other surface water is potentially subject to contamination from wildlife, domestic animals, or other sources and is considered a food safety risk for irrigating agricultural crops. The Food Safety Modernization Act (FSMA) Produce Rule has specific rules and guidelines for water used on crops. For more information about the FSMA, check out the Food and Drug Administration website at https://www.fda.gov/Food/GuidanceRegulation/FSMA/default.htm
Reyna Yagi (firstname.lastname@example.org), Northern California Urban Agriculture Program Coordinator, University of California Cooperative Extension - Alameda and Contra Costa Counties
Making Water Conservation a California Way of Life,” the long term trend from this point on is efficient water use and drought preparedness, especially as we face climate change challenges.
How can we as urban farmers do our part to conserve water? Turns out there are a lot of ways that not only will help to save our beautiful state's water, but also help you build a healthier farm or garden with less work on your hands!
Rainwater Harvesting allows you to capture rainwater from roofs, collect it in a cistern for diversion to your landscape for supplemental irrigation. You should also observe your site's water runoff patterns and see how you can manage and maximize your runoff to deal with large rain events, stormwater runoff and infiltration around your site. Consider a rain garden!
- Dry Farming depends on the water stored in the soil from winter rains that plants can use in the spring as the weather warms. Plants rely on good soil moisture and deep roots to seek out this extra water without needing much supplemental irrigation. Grapes, potatoes, tomatoes, winter squash, fruit trees and grains can be dry-farmed.
- Deep watering wets entire root zones which promotes deeper root growth.
- Always water early in the morning to prevent daytime water loss through evaporation.
- Keep an eye on the weather! A refreshing rain or cool, cloudy day will extend the time between watering.
- Maintenance, maintenance, maintenance. Visually inspect your drip system regularly for breaks, leaks and missing pieces. If you don't, your plants will certainly let you know with plant diseases.
California's agricultural industry is the largest in the nation and abroad, carrying with that a great responsibility to protect and conserve our resources. Urban farmers are highly cognizant of this. They are some of the most innovative and conservation-minded folks out there who understand the fragility of our water supply and their role in being model stewards of our lands and waters.
Connecting 9,000 rural households in Guatemala with improved water management and climate-smart agriculture strategies is the goal of a new project led by a team at UC Davis, to ultimately increase food security and reduce poverty in Guatemala's Western Highlands.
“The opportunity to impact so many farmers' lives on this scale is exciting,” said Beth Mitcham, director of the Horticulture Innovation Lab and a UC Cooperative Extension specialist in the UC Davis Department of Plant Sciences. “We're taking lessons learned from our previous research — in Guatemala, Honduras and Cambodia — and building a team to help more small-scale farmers apply our findings and successfully use these innovative practices.”
The new project is part of the U.S. government's global hunger and food security initiative, Feed the Future. The project represents an additional $3.4 million investment in the UC Davis-led Horticulture Innovation Lab by the U.S. Agency for International Development's mission in Guatemala.
The project's international team also includes representatives from Kansas State University; North Carolina Agricultural and Technical State University; the Centro de Paz Bárbara Ford in Guatemala; Universidad Rafael Landívar in Guatemala; and the Panamerican Agricultural School, Zamorano, in Honduras.
“The learning shared between these three U.S. universities and the universities in Honduras and Guatemala will be enriching for all of the institutions involved,” said Manuel Reyes, research professor at Kansas State University who is part of the team. “I find it satisfying that these academic institutions will be investing intellectually in marginalized groups in Guatemala's Western Highlands — and in turn, learning from them too.”
Helping youth envision a future in agriculture
By partnering with local youth groups and agricultural schools, the team will better prepare students for jobs in commercial agriculture and agricultural extension with knowledge of climate-resilient conservation and water management practices.
“Our local team is training youth as entrepreneurs, to see agriculture as an economic opportunity instead of just back-breaking work,” said Meagan Terry, UC Davis junior specialist who is managing the project in Guatemala for the Horticulture Innovation Lab. “They can envision a future in agriculture, with innovative ways to create value-added products or grow high-value crops for niche markets.”
As rainfall patterns vary with climate change, farmers in this region are expected to face increased competition for water. Practices such as rainwater harvesting, drip irrigation and conservation agriculture will become more necessary for small-scale farmers.
Climate-smart lessons from conservation agriculture, drip irrigation
In previous research, the Horticulture Innovation Lab has found that combining drip irrigation with conservation agriculture practices can successfully grow vegetables on small plots of land, without significant yield reductions. These practices improve soil structure, moisture retention and soil health.
Additionally, women farmers who participated in the Horticulture Innovation Lab studies in Cambodia, Honduras and Guatemala favored using these practices for another important reason: reduced labor in relation to controlling weeds, vegetable bed preparation and manual watering.
“I dream for many women, youth and their families, that their lives will be better off because of 'MasRiego' and the science behind this work,” Reyes said. “As for the research, we are learning how to improve this suite of practices so they can be tailor fitted globally. I am convinced that if this picks up, steep sloping lands can be farmed with the soil quality not being degraded — but even being enriched.”
These lessons, as well as findings from the program's “Advancing Horticulture” report about horticultural sector growth in Central America, lay the foundation for this new project.
Curious about partnering with the Horticulture Innovation Lab? The Horticulture Innovation Lab builds partnerships between agricultural researchers in the United States and researchers in developing countries, to conduct fruit and vegetable research that improves livelihoods in developing countries. The program currently has three research grant opportunities for U.S. researchers: one focused on tomatoes, another on apricots, and a third on integrated crop-livestock systems.
In California, 40 percent of agriculture is still irrigated by pouring water onto farmland, a much less efficient practice that drip and overhead irrigation. But those numbers are changing, reported Matt Weiser on Water Deeply.
Weiser interviewed UC Cooperative Extension cropping systems specialist Jeff Mitchell about the water-saving potential of using overhead irrigation, a system that is popular in other parts of the nation and world, but only used on 2 percent of California farmland. Mitchell was the primary author of a research article in the current issue of California Agriculture journal, which said that water and money can be saved using overhead irrigation in production of wheat, corn, cotton, onion and broccoli.
Mitchell said California researchers are looking more closely at overhead irrigation because they anticipate future constraints on agriculture, including water and labor shortages. Additionally, the system is ideal for combining with conservation agriculture systems, which include the use of cover crops, leaving crop residue on the soil surface and reducing tillage disturbance of the soil. The combination of overhead irrigation and conservation agriculture practices reduces water use, cuts back on dust emissions, increases yield and improves the soil.
Weisner asked how overhead irrigation could be as efficient as drip, when people typically see "water spraying everywhere from these roving sprinklers high off the ground."
Mitchell said farmers use pressure regulators and a variety of nozzles on hoses hanging down from the system to deliver water at precisely the rate and location where it is needed through the season.
"So, they're not spraying water. These are low to the ground, and there are various delivery nozzle practices that can be used," Mitchell said.