California Institute for Water Resources
California Institute for Water Resources
California Institute for Water Resources
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California Institute for Water Resources

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Save trees first: Tips to keep them alive during drought

Trees can be watered by drip irrigation systems or soaker hoses as well as hand-held devices. Photo by Janet Hartin.

Trees are essential to lowering temperatures and cooling ‘heat islands'

Water restrictions prompted by drought are driving Californians to prioritize how they will use their limited water. Because landscape irrigation is a major water use for many households, residents are looking outdoors to conserve water.

When choosing which landscape plants to save, "trees come first," said Janet Hartin, UC Cooperative Extension area environmental horticulture advisor for San Bernardino, Los Angeles, and Riverside counties. "Healthy communities need trees. Fortunately, new California water restrictions allow for provisions to ensure trees receive adequate water to stay alive and healthy."

"Mature trees are instrumental in cooling urban heat islands and we can't afford to lose them and start all over," Hartin said. "Shade from mature trees can reduce surface temperatures by as much as 65 degrees Fahrenheit in asphalt-covered parking lots. Shade from a single tree can reduce these surface temperatures from 165 to less than 100 degrees when air temperatures reach 110 degrees. Even with air temperatures in the 90s, surface temperatures can reach 140 degrees."

In addition to providing shade, trees absorb and store carbon dioxide, release oxygen, enhance pollinators and wildlife habitat, filter pollutants from air and water, and can reduce energy use, according to Hartin. Because trees take years to grow, they aren't as easily replaced as other plants. As residents let lawns go brown, she recommends watering trees that are near or surrounded by lawn.

"If a tree is in the middle of a lawn, it is almost certainly watered by lawn irrigation," Hartin said. "If it's not on a separate drip system, drag out a hose and allow the water to slowly trickle into the soil early in the morning or in the evening. Deep watering for two hours once every couple of weeks will keep most established trees alive."

In most jurisdictions, watering restrictions do not apply to hand watering and hand-held watering devices such as hoses, which may be used for longer periods of time than the restrictions permit otherwise. However, watering may be restricted in all cases to prescribed times of day. "Check to see if your jurisdiction also requires a hose shutoff valve," Hartin said. 

"For fruit trees, we may have to forgo fruit production for a year or so. There may not be enough water to support fruit production, but the goal is to keep the trees alive during the drought," she said.

She recommends watering trees away from the trunk, halfway between the trunk and the dripline – where the foliage ends and rain drips off the leaves – because "roots grow outward quite a distance as well as downward. Leave the hose on so the water is just trickling out," she said. "You want water to seep into the soil and encourage the roots to grow deeper. The slow water flow will seep down a foot or so and the roots will follow, which will help anchor the tree. Move the hose around every half hour to hour in quadrants around the tree for more even watering."  

Don't have time to move the hose? Hartin suggests getting a soaker hose and wrapping it in concentric circles 2 to 3 feet apart. "Soaker hoses are made from recycled tire rubber and allow water to slowly ooze out of the pores along the hose, distributing the water fairly evenly throughout the hose length. Avoid using soaker hoses longer than 75 feet due to pressure issues."   

To reduce evaporation around the tree, spreading mulch a few inches from trunk can help. "Dark mulches can heat the environment so it's best not to use them," Hartin said. "If you are in a fire-prone area, don't use organic wood-based mulches because they are flammable. Use decomposed gravel or pebbles, rock-based products instead. To keep sunlight out and discourage weeds, large wood chip mulches should be maintained 3-4-inches deep and smaller inorganic mulches at 1-2 inches."

UC Cooperative Extension specialists Amir Haghverdi and Don Merhaut are studying groundcover water use. UC Riverside Ph.D. candidate Anish Sapota monitors the test plot.

Residents may want to maintain some grass for children and pets because bare feet and paws can sustain serious burns on surfaces hotter than 120 degrees. "People don't realize how hot fake grass can get," Hartin said. "Research I conducted last summer in the Coachella Valley and Redlands found that surface temperatures of synthetic lawns can be more than 65 degrees higher than living turf and groundcover surfaces on several dates in between May and August."

For California lawns, there are drought-tolerant grasses that can thrive on 30% less water than bluegrass and other cool season varieties. Examples are buffalograss and bermudagrass. They still require maintenance, such as mowing, but are great for play and recreational surfaces for people and pets.

Jim Baird, UC Cooperative Extension turf specialist based at UC Riverside, said, "Turfgrasses offer numerous recreational, aesthetic, and environmental benefits including player safety, property value, mental health, erosion control, groundwater recharge and surface water quality, organic chemical decomposition, carbon sequestration, and environmental cooling." There are also non-turf groundcovers that are drought resistant. 

"As they transpire, plants cool the environment. We have more and more drought-resistant alternatives to high-water-requiring plants on the market now, and that's where we should be going," Hartin said.   

For people considering replacing their lawns and adding new landscape plants, she recommends planting low-water using groundcovers in the fall. "It's too hot to plant in summer and even native and drought-resistant plants require water several times week until they get established," she said.

For further information, check out these University of California Cooperative Extension drought and landscape tree care resources:

In addition, most counties have a UC Master Gardener Program with a helpline staffed by well-trained volunteers dispensing advice to help keep plants alive and recommend plants that are well-suited for the local environment. Find a local UC Master Gardener Program.

Posted on Friday, June 10, 2022 at 12:19 PM

California Farmer Implements Cover Cropping in Almond Orchard to Improve Soil Quality and Reduce Inputs

Rob Schuh and son-in-law Andrew Carroll standing in their almond orchard. Photo by Caddie Bergren.

Ten years ago, Rob Schuh was on the verge of retiring. As a lifelong farmer, he had become disillusioned by how his work had become a series of numbers – adding and subtracting pounds of fertilizer, herbicide, and pesticide every year. Then he discovered the concept of regenerative farming, alongside his son-in-law Andrew Carroll. Regenerative farming gave Schuh a newfound appreciation for agriculture and the land.

The more he learned, the more regenerative farming made sense when combined with his decades of experience treating his 210 acres of almond orchards in Chowchilla, California as a living, complex ecosystem. Schuh began to develop a more holistic approach for his orchard that led him to implement additional climate-smart agricultural practices that would benefit his soils.

The two climate-smart practices that Schuh decided to implement were cover cropping and compost application. He began incorporating compost in 2015 and cover cropping in 2016, while also reducing many of his inputs including synthetic fertilizer and chemical pesticides. While he has become reengaged with his land and excited about farming again, this shift has also had significant benefits for his bottom line.

Andrew Carroll walking in the almond orchard. Photo by Caddie Bergren.

Schuh plants a diverse cover crop mix – in 2021 it included 16 species – in his orchard rows every fall with a rented seed drill. When surface water is available, he floods his orchards once a month. When it is not available, the winter rains still provide enough water to produce a healthy cover crop stand. He tries to keep his cover crops growing as long as possible throughout the spring and early summer, mowing every few weeks with a flail mower and finally using a stick jack to clear the rows of residue before harvest.

Schuh has saved an average of $38,000 per year on farm inputs since beginning cover cropping and applying compost. He has reduced his synthetic nitrogen application from around 300 units/acre per year of Urea Nitrate-32 or UN32 to about 75, and plans to continue reducing. He applies almost no herbicides and pesticides now, and doesn't need to treat for navel orangeworm. He started applying nutrients through aerial sprays to achieve better precision to his tree canopies.

“Cover crops needing extra water is a myth” – Rob Schuh

For irrigation, Schuh has a mix of microsprinklers and double-line drip, and also floods once a month when water is available. Since beginning to cover crop, he has noticed better water retention and infiltration in his soil. He has reduced his irrigation sets from 48 to 36 hours. Even in years where no surface water is available, he still gets decent cover crop stands in the middle of his rows from just rainwater.

When it comes to labor, it has been difficult to quantify costs on his farm, as most of it is done by himself and his son-in-law. However Schuh estimates that labor has stayed about the same since implementing these practices. They of course spend more time planting the cover crops, mowing them, and applying compost. However, they significantly reduced their pesticide applications and no longer need to pay for orchard sanitation and mummy shakes.

Since Schuh implemented cover crops six years ago, there has been no statistically significant impact on yields. Incorporating these climate-smart practices into the orchard allowed him to reconnect to his passion for farming and agriculture.

Schuh and Carroll are avid learners about regenerative practices and the effect these practices have on the land. Hearing from farmers like Schuh and Carroll provides other farmers and ranchers with a better understanding of how implementing climate-smart practices can be accomplished in similar systems.

Thank you to T Double R Farms for your contributions! This project was supported in part by the California Department of Food and Agriculture. View the full economic case study for more information.

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Posted on Wednesday, May 11, 2022 at 9:24 AM
  • Author: Caddie Bergren
  • Author: Valerie Perez

How Can California Protect Its Water Supply From Wildfire?

Concrete water supply tanks after the Tubbs Fire complex in 2017. Photo by Faith Kearns.

It's intuitive that wildfires can affect ecosystems, harm wildlife, and contaminate streams and rivers. But wildfires can also have complex, severe, and direct effects on our water supply and infrastructure—effects that have only become clear in recent years. Scientists and policymakers must integrate insights and experience from many disciplines and sectors to understand and address the consequences.

In September, 23 scholars and practitioners with a diversity of water and fire expertise came together to answer a critical question: How can California proactively protect its water supply from fires? Their findings, combined with the insights of the author team, form the basis of a new scoping report, released by the University of California Division of Agriculture and Natural Resources' California Institute for Water Resources and the UCLA Luskin Center for Innovation.

Tracy Schohr, UC Cooperative Extension advisor, samples a stream below the town of Paradise, CA, after the Camp Fire in 2018. Photo by Ryan Schohr.

“Different people have different pieces of the puzzle, but it's really hard to put them together. That is why we assembled this cross-sector group,” said Faith Kearns, academic coordinator at the California Institute for Water Resources.

Illustrated by the 2017 Tubbs Fire in Wine Country, it has been recognized that community water systems face effects that last long after the fire is quenched. For example, Boulder Creek residents in Santa Cruz County still did not have reliable water access more than a year after firefighters extinguished the 2020 CZU Lightning Complex Fire. 

“This is truly an emergent issue,” said co-author Peter Roquemore, project manager at the Luskin Center for Innovation. “We have only seen wildfires directly affect community water systems in the past few years.”

The Tubbs Fire was the first known wildfire that had direct impacts on water infrastructure. Photo by Faith Kearns.

To help California policymakers, researchers, affected communities, and water system operators understand the complex relationship between wildfire damage and water supply, the report authors and participants in this workshop present a set of recommendations:

  • Make communications more accessible, consistent, and trustworthy. Residents must receive timely, unified messaging, translated into appropriate languages, and in accessible venues, telling them if their water is unsafe and how to access clean water.
  • Invest in local capacity and expertise. The challenges faced vary widely for different communities, and it is important to provide each community with the resources it needs to address the risk it faces. As part of this, efforts should support Indigenous leadership, knowledge, and practices to help manage healthy ecosystems.
  • Provide guidance to update regulations. Guidance such as building codes and infrastructure regulations will help individuals and communities make informed decisions and address risk appropriately.
  • Conduct research and build a broader base of knowledge. There is still much to learn, and it is important to illustrate the exact challenges water systems face and how best to address them.
  • Make funding accessible and targeted. Increased earmarked funding for emergency water supplies, housing assistance, and support for water systems, local organizations, and others will help advance solutions. 
  • Further coordinate efforts to address water and fire issues. Focusing on these interconnected issues together, rather than tackling them separately, can lead to substantial benefits.

To read the specific recommendations identified, read Wildfire and Water Supply in California. Funding for this research was provided by the U.S. Geological Survey through the California Institute for Water Resources.

Posted on Wednesday, December 8, 2021 at 9:59 AM
  • Author: Lauren Dunlap

Climate-smart agriculture in California: Increasing the resilience of livestock operations

Zuppan’s manure solid separator system funded by a CDFA AMMP grant. Photo by Dana Yount.

When liquid manure sits in storage lagoons on dairies or other livestock operations for too long, methane can form and contribute to climate change. To address concerns about methane emissions, the California Department of Food and Agriculture (CDFA) developed the Alternative Manure Management Program (AMMP), which supports farmers in reducing their methane emissions with both financial and technical assistance.

The objective of CDFA's AMMP is to encourage dairy and livestock producers to adopt climate smart practices to reduce methane emissions in animal agriculture systems. The program incentivizes the development of manure management practices that reduce greenhouse gas emissions, as well as protect water and air quality.

These practices fall under four main categories: pasture-based management, solid separation, conversion from flush to scrape, and alternative manure treatments and storage. For example, running manure through a solids separator helps to reduce potential surface and groundwater pollution as there is less nitrogen and other elements in the separated liquids. In the most recent round of grants from the program, livestock and dairy operations could apply for up to $750,000 to implement these kinds of methane reduction practices.

In addition, producers can receive technical assistance from the University of California Division of Agriculture and Natural Resources (UC ANR) Climate-Smart Agriculture educators. This team was established with the support of UC ANR, the Strategic Growth Council, and CDFA, and has educators based in ten counties around the state. The effort is led by Doug Parker, director of the California Institute for Water Resources, in collaboration with several UC ANR county based Advisors.

Zuppan’s solid separator and manure storage pit funded by a CDFA AMMP grant. Photo by Dana Yount.

The Climate-Smart Agriculture educator team has been working on a case study project highlighting the work of two dairies that received a CDFA AMMP grant for solid separation practices.

Zuppan Dairy, a family-owned farm, milks around 600 cows in Glenn County. With the help of the CDFA AMMP grant, they were able to purchase and install a manure solids separator, handling equipment, a pump for the pond, a concrete slab, and an agitator. The project was completed within a year and has now been operating for almost two years. By implementing these climate-smart manure management practices, Zuppan's greenhouse gas reduction is equivalent to removing 176 cars from the road per year. Not only are there environmental benefits, but Zuppan Dairy is also seeing a yearly average savings of $29,000 - $37,000 due to fertilizer savings, reductions in manure hauling with the excavator, and diesel fuel reductions.

Renati Dairy, is a third and fourth-generation run farm that was established in 1958 and milks 750 cows in Sonoma County. They installed a pump, agitator, mechanical scraper, and concrete trough to connect manure to an existing manure solids separator. Renati Dairy's greenhouse gas reduction for this project is equivalent to removing 111 cars from the road each year. In addition, a dairy of this scale can expect to see yearly savings of approximately $93,000.

Along with annual cost savings for each of the dairies, both are seeing additional related benefits including lower levels of solids in manure ponds and a reduction in labor costs. Reduced solids in the collection ponds means the farmer does not have to worry about a crust forming that could create methane gas, and can also more evenly distribute the water onto their various fields for irrigation.

Taken as a whole, the CDFA AMMP program has led to a reduction of 1.1 million metric tons of carbon dioxide equivalents over five years, the equivalent of 243,310 cars being taken off the road.

For more information, please visit the UC ANR Climate-Smart Agriculture web pages to read the full stories and economic analyses for these dairies.

Posted on Monday, August 16, 2021 at 4:26 PM

Tips for saving water and money in home landscapes

Irrigation scheduling can be used to reduce the amount of water needed to maintain a landscape. Photo by John Karlik.

By John Karlik, UC Cooperative Extension, Environmental Horticulture/Environmental Science Advisor, Kern County

In a previous article, I noted another dry year is underway. Excessive landscape irrigation is wasteful and can lead to turf and landscape diseases. However, rarely is it necessary to do a landscape makeover to save water, nor will modifications necessarily result in water savings.

The key to saving water outdoors is irrigation scheduling. Modifications to a landscape are of no benefit for water conservation unless the irrigation amount is reduced. Although water conservation is a large topic, here are a few tips and ideas for saving water in landscapes and other outdoor plantings:

Check the irrigation system

Periodically run the irrigation system during the day to check for leaks, missing heads, broken risers, and sprinkler coverage. Repair as necessary.

Determine how much to water

Water needs of plants in home gardens, landscapes, and orchards change by a factor of 10 from winter to summer in much of California, though the exact factor is location specific. Therefore, irrigation schedules should be changed at least four times per year: spring, summer, fall, and winter. In winter, you may be able to turn the system off completely.

Irrigation amounts are usually expressed as depth of applied water.  For example, during winter in the southern San Joaquin Valley, about 0.02 inches per day are needed, while in summer the value rises to about 0.25 inches per day. These values do not mean water needs to be applied every day. Weather conditions will affect water needs of plants.

You can measure how much water your sprinklers deliver by placing cans or coffee mugs in the landscape and running sprinklers for a set amount of time. You can also estimate total landscape water use from your water bill by considering water use during winter months as the baseline indoor value, and water in addition as used outdoors. That assumes sprinklers are shut off during winter.

Finally, irrigate and monitor. In other words, check soil moisture between irrigations with a shovel, soil probe, or screwdriver, and adjust the irrigation schedule accordingly.

Determine how often to water

Irrigation scheduling is a combination of frequency (how often) and duration (run-time). As a rule-of-thumb, plan to fill the soil volume containing plant roots and then irrigate again when about half the available water has been used. Therefore, set run-times for each irrigation zone and then add or subtract days depending on season of the year.

Determine when to water

Early morning is best since wind speeds and temperature are low, and less evaporation and wind-loss occur.

Mulches can help to save water. Photo by John Karlik.

What about mulches?

Mulches, such as wood chips or shredded leaves, help save water by reducing evaporation from soil.

What about turfgrass?

Turfgrass is water-thrifty if irrigated carefully. However, turf is often over-irrigated, so reducing the area of turf may lead to water savings. Experimental data show warm-season grasses, such as bermudagrass and the UC release ‘El Toro' zoysia, offer water savings over cool season turfs, such as tall fescue or bluegrass. Buffalograss is even more drought tolerant, but not often planted in California.

What about “drought-tolerant plants?”

Research-based water-use data do not exist for most plants used in landscapes.  We often infer drought tolerance from seeing where a plant grows in nature. However, many California natives and plants adapted to Mediterranean climates may not perform well under irrigated conditions. These plants may be susceptible to root rot, for example, if irrigated. Drought-tolerant plants do not of themselves save water. Saving water is instead accomplished by changing irrigation schedules to reduce applied water.

Posted on Monday, May 24, 2021 at 5:53 PM
  • Author: John Karlik

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