Posts Tagged: forest

Extreme weather accelerates nitrate pollution in groundwater

Extreme weather spurred by climate change, including droughts and heavy rains, may increase the risk of nitrates from fertilizers ending up in groundwater, according to a recent study from researchers at the University of California, Davis. The study found heavy rains after a drought caused nitrates to seep 33 feet under farm fields in as little as 10 days. The study was published in Water Resources Research.

“The conventional wisdom was that it could take several weeks to years for nitrates to move from the crop root zones to reach groundwater,” said corresponding author Isaya Kisekka, a professor in the Departments of Land, Air and Water Resources and Biological and Agricultural Engineering. “We found these extreme events, such as California's atmospheric rivers, are going to move nitrate more quickly.”

In this study, different methods were used to measure how much nitrate, a component of nitrogen fertilizer, was seeping down through the soil in a tomato and cucumber crop near Esparto, California. Scientists conducted their research from 2021 until 2023 when California was experiencing periods of drought followed by atmospheric rivers. They measured nitrate during both the growing seasons and the rainy seasons.

Drought can leave more nitrogen in soil

Previous studies have shown about 40% of nitrogen fertilizer used for vegetables isn't absorbed by the plants but remains in the soil. During droughts, crops don't use nitrogen efficiently, leading to excess nitrogen in the soil. This study found that if a drought is then followed by heavy rainfall, that sudden burst of water causes nitrate to seep in groundwater more quickly. The nitrate concentration in the shallow groundwater exceeded the U.S. Environmental Protection Agency maximum contaminant level of 10 milligrams per liter for drinking water.

“In California, we often say we swing between droughts and floods,” said Kisekka. “These extreme events that come with climate change are going to make the risk of these chemicals ending up in our drinking water much more severe.”

Groundwater is the primary source of drinking water for most of California's Central Valley. In some regions, such as the Tulare Lake Basin, nearly one-third of drinking and irrigation wells exceed the EPA's safe nitrate level. High nitrate levels in drinking water can increase health risks, especially for young children. It may also increase the risk of colorectal cancer.

Need for real-time soil nitrate monitoring

Central Valley farmers are required to report to the Regional Water Board how much nitrogen they applied to their field and how much was removed as part of the crop's yield. The study compared different ways of monitoring when nitrate from fertilizers seep into groundwater. Kisekka said the results highlight the need for affordable, real-time soil nitrate monitoring tools to help farmers manage fertilizer use efficiently.

By using conservation practices that limit leftover nitrates in the crop's root zone after harvest, farmers can help reduce nitrate contamination in groundwater.  

This study's data will also help improve a model called SWAT, which is used to track nitrate seepage into groundwater across California's Central Valley. This effort is part of the Central Valley Water Board's program to regulate irrigated farmlands.

Other UC Davis authors include Iael Raij Hoffman, Thomas Harter and Helen Dahlke.

The study was supported by the USDA Natural Resource Conservation Service through its Conservation Effects Assessment Project. The national project is designed to assess the effectiveness of conservation practices across different watersheds. The study also had support from the USDA National Institute of Food and Agriculture.

More than Fighting Fires: A Conversation with CALFIRE San Luis Obispo Unit Forester Dave Erickson

This July, San Luis Obispo county's first cultural burn since 1850 took place. This reintroduction of indigenous, ‘good fire' to the landscape was led by...

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

Forest Stewardship Branches Out with California Tree School- Hopland

5,000 acres of Mendocino County oak woodlands provided the backdrop for UC ANR's first California Tree School session on May 4, which saw 45 forest landowners, natural resource professionals, and students join the UC ANR Forest Stewardship...

Public invited to observe prescribed fire training in Santa Cruz County

 

First Forester TREX to be held June 3-6

California's first-ever Forester Prescribed Fire Training Exchange event focused on bringing together professional foresters, forest managers and fire practitioners will occur June 3-6 near Watsonville. The four-day event is being hosted by the Central Coast Prescribed Burn Association, which empowers the public to build a culture of good fire and supports private landowners in conducting prescribed burns in Monterey, San Benito and Santa Cruz counties.

There will be one burn conducted during the event, likely on June 4 or 5, which will be open for the public to observe.

Prescribed Fire Training Exchanges (TREXs) first came to Northern California in 2013, and have made a positive cultural shift concerning prescribed fire, within both regional fire services and the general public. These “good fire” TREX events have drawn significant attention, especially in the context of more severe wildfire seasons.

After months of cross-organizational planning, the four-day long training will be focused on exploring the connections between sustainable forest management, wildfire resilience, timber harvesting, prescribed fire, and will include a burn within a commercially harvested redwood forest. The TREX will provide experiential training opportunities to forest managers and planners to advance statewide knowledge of how to conduct prescribed fire in merchantable timber stands.

Along with the prescribed burn, the program will include lectures, local tours, and open discussions on how to incorporate fire into timber management, burn planning and timber harvest planning, pre- and post-fire considerations, and permitting mechanisms for fire and timber harvesting. Presentations will be given by local forestry consultants, University of California Agriculture and Natural Resources, CALFIRE and local fire practitioners.

The burn location will occur near Mount Madonna, on private land with access allowed for accompanied observation only.  Be advised, while the ForesterTREX planning team works closely with theMonterey Bay Air Resources District to assure good smoke dispersal, smoke may be seen and be present in these areas during and after a burn. Please see the Central Coast Prescribed Burn Association webpage at calpba.org/centralcoastpba for updates close to the burn date.

Participants and partners include the Mount Madonna Center, members of the Amah Mutsun Tribal Band and the Esselen Tribe of Monterey County, University of California Agriculture and Natural Resources, Resource Conservation District of Monterey County, CALFIRE, local land trusts, scientists, ranchers, students, researchers, land managers and others. The Central Coast Prescribed Burn Association is currently funded via California Coastal Conservancy grants.

For more information or to join a group of observers, contact Barb Satink Wolfson, UC Cooperative Extension area fire advisor at bsatink@ucanr.edu.

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