Posts Tagged: flood

Lawn-pocalypse! Surviving Drought

Ah, summer! The season of sunburns, pool parties, and… lawn droughts. If your once lush, green carpet now looks like a crunchy brown doormat, you're not alone. Let's dive into why your yard is staging a dramatic death scene and what you can do to...

Bermuda grass and weeds overtaking drought stressed turf grass.

A patch of former lawn, mostly dead, with a few green weeds and Bermudagrass

Date palm irrigation research provides economic, environmental benefits

Historically, date palms are grown along riverbeds or in areas with groundwater because they require an abundance of water to produce a good crop. Unlike lettuce or table grapes, date palms are deceptive in that they do not immediately wilt if underwatered. Eventually, however, the lack of water hurts yields and fruit quality. 

The default for date growers is to apply excessive water, but doing so is neither economically nor environmentally sound. To help growers, Ali Montazar, UC Cooperative Extension irrigation and water management advisor for Imperial, Riverside and San Diego counties, has developed knowledge that enables growers in the region to establish irrigation guidelines they can use with confidence.

“Water issues in California's desert are very different than in the Central Valley,” said Montazar. “There is no groundwater to recharge so growers in the desert only have the Colorado River.” 

Since 2019, Montazar has been focused on irrigation management for date palms in the Coachella Valley, the largest producer of dates in the United States. Montazar's research identifies how much water is needed for the crop and the best water delivery method according to location, soil type and conditions, and date cultivars.

“Dates require a lot of heat and light, which is why they do well in the desert. But they also need a fair amount of irrigation,” said Robert Krueger, a U.S. Department of Agriculture horticulturist and Montazar's co-author of a paper on date palm irrigation management.

Much of what we know about date palm production comes from the Middle East, which has a climate similar to the low desert of California. “That information is from many, many years ago though,” explained Montazar, whose research shows that drip irrigation cannot be the only form of irrigation for date palms.

“Ali is the first to really look at micro-sprinklers and flood irrigation for date palms,” said Krueger, adding that the other advantage of Montazar's research is that it prepares growers for production during times of reduced water supply.

Albert Keck, president of Hadley Date Gardens, Inc. and chairman of the California Date Commission, described Montazar's research efforts as “subtle yet incredible and profound,” adding that his findings not only benefit other farmers but also cities relying on water from the Colorado River.

Keck, one of the largest date growers in California, is well aware of how disruptive, expensive and time-consuming irrigation for date palms can be. Montazar has enabled growers like Keck to irrigate less without sacrificing yield or quality.

“Ali might save us a tiny percentage of the amount of water we're using. It might be a 5 or 10% savings. It doesn't seem like much, but it's an incremental improvement in efficiency,” said Keck. “And if you add all of these improvements up, say, along the U.S. Southwest, then that has a pretty profound impact.”

Montazar recommends that date growers in his region use a combination of drip and two to three flood irrigation events to manage salinity levels derived from the Colorado River. “We cannot maintain salinity issues over time if we're only relying on drip irrigation in date palms,” explained Montazar.

Flood irrigation pushes the salts below the root zone, when they would otherwise build up within the root zone preventing efficient water uptake. It also aids in refilling soil profiles quickly and more effectively since drip has a lower capacity of delivering sufficient water.

“Growers know what they need to water their crop within a broader parameter. But Ali has narrowed that window and helped us become more precise with our irrigation,” Keck said. “There's still room for improvement but we're spending less money, wasting less time and using less water now, and we're still getting the same positive results.”

Currently,Montazar is collaborating with the California Date Commission on developing guidelines for best irrigation management practices in the desert for date palms, which should be available by the end of 2023. These guidelines are based on a four-year data set from six monitoring stations and extensive soil and plant samples from commercial fields located in theCoachella Valley, Imperial Valley and near Yuma, Arizona. Additionally, Montazar is working to quantify how water conservation impacts growers economically.

“Growers from United Arab Emirates, Egypt, Tunisia and Mexico have already reached out asking for this information,” Montazar said, while reflecting on a presentation he made to a group of international date growers in Mexico late last year.

To read the paper on date palm irrigation, published in MDPI's Water journal, visit: https://www.mdpi.com/2073-4441/12/8/2253.

 

Climate-Change Resources

University of California UC ANR Green Blog (Climate Change and Other Topics) https://ucanr.edu/blogs/Green/index.cfm?tagname=climate%20change (full index)

Examples:

     -  Save Trees First: Tips to Keep Them Alive Under Drought https://ucanr.edu/b/~CdD 

     - Landscaping with Fire Exposure in Mind: https://ucanr.edu/b/~G4D

     - Cities in California Inland Areas Must Make Street Tree Changes to adapt to Future Climate  https://ucanr.edu/b/~oF7

Drought, Climate Change and California Water Management Ted Grantham, UC Cooperative Extension specialist (23 minutes) https://youtu.be/dlimj75Wn9Q

Climate Variability and Change: Trends and Impacts on CA Agriculture Tapan Pathak, UC Cooperative Extension specialist (24 minutes) https://youtu.be/bIHI0yqqQJc

California Institute for Water Resources (links to blogs, talks, podcasts, water experts, etc.) https://ciwr.ucanr.edu/California_Drought_Expertise/

UC ANR Wildfire Resources (publications, videos, etc.) https://ucanr.edu/News/For_the_media/Press_kits/Wildfire/ (main website)

      -UC ANR Fire Resources and Information https://ucanr.edu/sites/fire/ (main website)

            -Preparing Home Landscaping https://ucanr.edu/sites/fire/Prepare/Landscaping/

UC ANR Free Publications https://anrcatalog.ucanr.edu/ (main website)

- Benefits of Plants to Humans and Urban Ecosystems: https://anrcatalog.ucanr.edu/pdf/8726.pdf

 -Keeping Plants Alive Under Drought and Water Restrictions (English version) https://anrcatalog.ucanr.edu/pdf/8553.pdf

  (Spanish version) https://anrcatalog.ucanr.edu/pdf/8628.pdf

-  Use of Graywater in Urban Landscapes https://anrcatalog.ucanr.edu/pdf/8536.pdf

-  Sustainable Landscaping in California https://anrcatalog.ucanr.edu/pdf/8504.pdf

 

Other (Non-UC) Climate Change Resources

Urban Forests and Climate Change. Urban forests play an important role in climate change mitigation and adaptation. Active stewardship of a community's forestry assets can strengthen local resilience to climate change while creating more sustainable and desirable places to live. https://www.fs.usda.gov/ccrc/topics/urban-forests

Examining the Viability of Planting Trees to Mitigate Climate Change (plausible at the forest level) https://climate.nasa.gov/news/2927/examining-the-viability-of-planting-trees-to-help-mitigate-climate-change/

Reports and other information resources coordinated under the auspices of the United Nations and produced through the collaboration of thousands of international scientists to provide a clear and up to date view of the current state of scientific knowledge relevant to climate change. United Nations Climate Action

Scientific reports, programs, action movements and events related to climate change. National Center for Atmospheric Research (National Science Foundation)

Find useful reports, program information and other documents resulting from federally funded research and development into the behavior of the atmosphere and related physical, biological and social systems. Search and find climate data from prehistory through to an hour ago in the world's largest climate data archive. (Formerly the "Climatic Data Center") National Centers for Environmental Information (NOAA)

Think tank providing information, analysis, policy and solution development for addressing climate change and energy issues (formerly known as the: "Pew Center on Global Climate Change"). Center for Climate & Energy Solutions (C2ES)

Mapping Resilience: A Blueprint for Thriving in the Face of Climate Disaster. The Climate Adaptation Knowledge Exchange (CAKE) was launched in July 2010 and is managed by EcoAdapt, a non-profit with a singular mission: to create a robust future in the face of climate change by bringing together diverse players to reshape planning and management in response to rapid climate change. https://www.cakex.org/documents/mapping-resilience-blueprint-thriving-face-climate-disaster

Cal-Adapt provides a way to explore peer-reviewed data that portrays how climate change might affect California at the state and local level. We make this data available through downloads, visualizations, and the Cal-Adapt API for your research, outreach, and adaptation planning needs. Cal-Adapt is a collaboration between state agency funding programs, university and private sector researchers https://cal-adapt.org/

Find reports, maps, data and other resources produced through a confederation of the research arms of 13 Federal departments and agencies that carry out research and develop and maintain capabilities that support the Nation's response to global change. Global Change (U.S. Global Change Research Program)

The Pacific Institute is a global water think tank that combines science-based thought leadership with active outreach to influence local, national, and international efforts to develop sustainable water policies. https://pacinst.org/our-approach/

Making equity real in climate adaptation and community resilience policies and programs: a guidebook. https://greenlining.org/publications/2019/making-equity-real-in-climate-adaption-and-community-resilience-policies-and-programs-a-guidebook/ 

Quarterly CA Climate Updates and CA Drought Monitor Maps (updated each Thursday) https://www.drought.gov/documents/quarterly-climate-impacts-and-outlook-western-region-june-2022

 

 

 

 

Study offers insights on reducing nitrate contamination from groundwater recharge

Light irrigation before flooding stimulates microbes to remove nitrates from soil

With California enduring record-breaking rain and snow and Gov. Gavin Newsom recently easing restrictions on groundwater recharge, interest in “managed aquifer recharge” has never been higher. This process – by which floodwater is routed to sites such as farm fields so that it percolates into the aquifer – holds great promise as a tool to replenish depleted groundwater stores across the state.

But one concern, in the agricultural context, is how recharge might push nitrates from fertilizer into the groundwater supply. Consumption of well water contaminated with nitrates has been linked to increased risk of cancers, birth defects and other health impacts.

“Many growers want to provide farmland to help recharge groundwater, but they don't want to contribute to nitrate contamination of the groundwater, and they need to know how on-farm recharge practices might affect their crops,” said Matthew Fidelibus, a University of California Cooperative Extension specialist in the UC Davis Department of Viticulture and Enology.

A recently published study by UC scientists sheds new light on how nitrates move through an agricultural recharge site and how growers might reduce potential leaching. Researchers analyzed data from two grapevine vineyards at Kearney Agricultural Research and Extension Center in Fresno County – one flooded for two weeks, and other for four.

Understanding initial nitrate levels crucial

A key factor in mitigating contamination is understanding how much nitrate is in the soil at the outset, said study author Helen Dahlke, a UC Davis hydrologist and leader of UC Agriculture and Natural Resources' strategic initiative on water. In areas with little precipitation and cropping systems that require greater amounts of synthetic fertilizer, the accumulation of residual nitrate – resulting from nitrogen in the fertilizer not taken up by the plants – can be quite high.

“The percentage of nitrates in some soils can really increase over the years, particularly if you have many dry years in a row where you don't have access to irrigation water or natural precipitation flushing some of those nitrates out of the soil,” Dahlke said.

While intense rains in recent weeks have helped dilute nitrate concentrations naturally, farmers looking to participate in recharge during the dry years ahead should consider flooding their fields with greater volumes of water.

“If you're doing this for the first time – on-farm recharge in the winter – check your residual soil nitrate levels because if they're very high, you should apply a lot of water in order to make sure that the residual nitrate is diluted down,” said Dahlke, who also added that growers should check their soil properties for suitability of recharge projects.

She recommended using, as a “good first approximation,” the online Soil Agricultural Groundwater Banking Index map, a project led by Toby O'Geen, a UC Cooperative Extension soil resource specialist. 

Researchers looking at other ways to reduce nitrates

Even before flooding the fields for recharge, there are several practices that can lower initial nitrate levels and risk of leaching. Cover crops such as alfalfa and triticale, for example, can help take up residual nitrates that accumulate from fertilizing a main crop over time.

Dahlke and Fidelibus – a co-author of the San Joaquin Valley vineyard study – both pointed to pre-flooding irrigation that encourages denitrification, a process in which soil microbes transform nitrates into gaseous forms of nitrogen.

“Those denitrifying microbes need to be stimulated to do the work,” said Dahlke. “What we have found is that if you do a little bit of irrigation before you start the flooding, increasing the soil moisture can get those microbes started and they can take out more nitrate from the soil.”

The timing and quantity of fertilizer applications are also major factors in reducing leaching. Although more growers are following high-frequency, low-concentration practices to maximize uptake by crops, Dahlke said there needs to be more emphasis on incorporating nitrogen transformation processes – such as denitrification – in the nutrient management guidelines that farmers follow.

“Implementing thoughtful nutrient management plans will play a particularly important role in participating farms,” Fidelibus added.

A more holistic view of groundwater recharge

In short, choices made during the growing season can affect those in the winter recharge season – and vice versa. For example, applying compost or other organic amendments to soil can give microbes the “fuel” they need for sustained denitrification.

“What we have found is that our denitrifying bacteria often run out of steam because they don't have enough carbon to do the work,” Dahlke said. “Like us, microbes need energy to do the work, and for microbes this energy comes from soil carbon.”

Then, adding moisture via recharge to that field with high organic content can stimulate mineralization and nitrification, processes in which microbes transform the organic nitrogen into ammonium – and subsequently nitrates – that the plants can then take up. Those naturally occurring nitrates would thus reduce the need for the grower to apply synthetic fertilizer.

“The winter on-farm recharge experiments have shown that altering the moisture regime in the winter has consequences for the nitrogen budget in the summer growing season,” Dahlke explained. “Theoretically, what we need to be doing is better integrating both seasons by keeping an eye on the soil-nitrogen balance across the whole year so that we can ensure, at the end of the growing season, the residual nitrate in the soil is minimized.”

The study, published in the journal Science of The Total Environment, was part of the post-doctoral work of former UC Davis researcher Elad Levintal. In addition to Fidelibus and Dahlke, other authors are Laibin Huang, Cristina Prieto García, Adolfo Coyotl, William Horwath and Jorge Rodrigues, all in the Department of Land, Air and Water Resources at UC Davis.

Where, Oh Where, Can They Bee?

The nectarines are bursting into bloom, but where are the honey bees? Well, they're huddled inside their colonies as California storms erupt with a vengeance reserved for politics. The bees venture out...one here...one there...on sun breaks, but never...

A honey bee, cooped up in a hive for weeks due to the rain and cold, heads for a nectarine blossom in Vacaville, Calif. (Photo by Kathy Keatley Garvey)

A honey bee, cooped up in a hive for weeks due to the rain and cold, heads for a nectarine blossom in Vacaville, Calif. (Photo by Kathy Keatley Garvey)

Find the bee! There's one pollinating a nectarine blossom. (Photo by Kathy Keatley Garvey)

Find the bee! There's one pollinating a nectarine blossom. (Photo by Kathy Keatley Garvey)

A pollen-packing bee exits a nectarine blossom.(Photo by Kathy Keatley Garvey)

A pollen-packing bee exits a nectarine blossom.(Photo by Kathy Keatley Garvey)

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