Jeff Mitchell, UC Cooperative Extension cropping systems specialist at UC Davis, and Lauren Haled, USDA Agricultural Research Service scientist, examine soils in the project field at the UC West Side Research and Extension Center in Five Points. (Photo: Jeff Mitchell/UC ANR)

By Natalie Willis, Reporter, Valley Ag Voice

Agriculture in the Central Valley is a beautiful thing to behold — poetic in its stoic desire to feed the world. As resources have grown limited — or restricted — valley farmers have led the effort to do more with less, from groundwater recharge to regenerative agriculture practices.

A recent Public Policy Institute of California report found that Kern County has led recharge efforts since 2017. Last year, it reported 2.9 million acre-feet of onsite recharge — 54% of the total volume reported.

The report, Replenishing Groundwater in the San Joaquin Valley: 2024 Update, explained that basins on the valley’s eastern side, including Kern, have the most suitable soils for recharge and the largest overdraft levels. These areas also host most of the region’s recharge activity.

The juxtaposition of the Kern River Valley being the most overdrafted basin but leading the way in groundwater recharge is indicative of the agricultural industry in the Central Valley—optimism is found even in restrictive regulations and scarce resources. The ingenuity of the region’s farmers finds a way to balance the necessary disruption of the natural environment while still outperforming the nation in agricultural outputs.

GROUNDWATER RECHARGE

Since the Sustainable Groundwater Management Act was passed in 2014, strategies to replenish the San Joaquin Valley’s critically overdrafted basins have come into focus. According to the PPIC report, the survey respondents recharged 5.3 million acre-feet within their service areas, but the estimate for the total valley-wide recharge volume was 7.6 million acre-feet — a 17% increase over 2017.

According to PPIC, more local water agencies are engaging in recharge and increased investments in 2023. The most common recharge efforts include allowing aquifers to replenish by replacing groundwater use with surface water, spreading water on farmland, and building dedicated basins to allow for water percolation into aquifers.

PPIC explained that favorable wet conditions last year allowed for more productive recharge, leading to the second wettest year in the valley’s southern half and the reappearance of Tulare Lake for the first time since the late 1990s.

However, not every year will be productive, as drier years narrow the window for aquifer recharge. Half of all local agencies fall back on four recharge methods: in-lieu recharge, recharge basins, unlined canals, and spreading water on farmland.

Aside from the recharge activity local agencies lead, farmers and researchers are increasingly investing in sustainable agriculture practices.

REGENERATIVE AGRICULTURE

Maintaining healthy soil is water in the bank for Central Valley farmers, and regenerative agriculture may be a lucrative investment.

UC Cooperative Extension Specialist Jeff Mitchell dedicated 20 years to studying regenerative agriculture alongside his colleagues and recently released his findings to the “California Agriculture” journal in June.

According to Mitchell, conservation agriculture practices were used on less than one-half of 1% of annual crop acreage in California. No-till farming is widely used in the Midwest and Southeast U.S. but with the development of irrigation infrastructure in the 1920s, California farmers experienced tremendous yields over the past century resulting in little incentive to deviate from regular tillage, the report explained.

With limited resources and increasingly strict regulations, regenerative agriculture practices present an opportunity to adapt conservation agriculture to California.

Mitchell began the 20-year study at the West Side Research and Extension Center in Fresno County in 1998, according to a news release from the University of California Agriculture and Natural Resources.

“We started this because, way back when I first began my job, nobody was doing this,” Mitchell said. “This was brand-new, uncharted territory for California.”

General regenerative agriculture practices include cover cropping, eliminating or reducing tillage, and preserving surface residues.

While the study faced initial challenges — struggling with the planting techniques in a no-till, high-residue system — after eight years, significant improvements in soil health were observed. The site in Fresno County has since become a vital training resource for farmers looking to adapt regenerative practices.

According to the release, one demonstration shown to farmers entails dropping two clumps of soil into two separate containers — one clump from heavily tilled land and the other from no-till, cover-cropped land.

Quickly, the heavily tilled soil breaks apart and the water turns dark, but the other no-till soil holds together, and the water remains largely clear. The stability of the soil shows its ability to increase water infiltration and water retention.

Notably, Mitchell’s study found that the amount of carbon sequestered in the soil through regenerative practices far exceeded that of tilled soil without cover crops. At the annual California Cotton Ginners and Growers conference, an agriculture professor at the University of Chico, Dr. Cythnia Daley explained that carbon is tied to water storage.

“You put more carbon in your soil, you’re using your water more efficiently,” Daley said. “You irrigate less…you capture more of that free water.”

While the investment into regenerative agriculture practices does not provide an immediate return, as Mitchell’s study shows, it is a long-term investment that pays out in future economic return.

To get started, the California Department of Food and Agriculture’s Healthy Soils Program offers farmers and ranchers incentives of up to $100,000 to implement these practices over a three-year timeline.

The Healthy Soils Program promotes the development of healthy soils, providing financial incentives through reimbursements paid directly to California growers and ranchers to implement conservation management practices that sequester carbon, reduce atmospheric greenhouse gasses, and improve soil health.

CDFA is currently accepting proposals for new practices to be considered for inclusion in its Health Soils Program, and proposals are due by Aug. 2.

Regenerative Agriculture education has also taken root in Kern County, with the grand opening of Bakersfield College’s Regenerative Agriculture Education Center in November of 2023.

COVER CROPPING

One of the more widespread regenerative practices is employing cover crops in the winter which condense and capture water particles from the air whilst protecting the wet solar surface from solar radiation — the main cause for soil evaporation according to Daniele Zaccaria, associate professor and agricultural water management specialist at UC Davis.

Using water — the most essential resource to agriculture’s livelihood — for anything other than income-producing crops is not generally a popular idea, especially in the era of SGMA.

A new study claims that cover crops, while non-income generating, can improve pollinator habitat, infiltration, soil health, carbon capture, and most importantly, water storage. The potential benefits of cover cropping would be prominent in the San Joaquin Valley where SGMA implementation, the study admits, is the most restrictive.

The study is a collaborative effort from over 100 multidisciplinary experts and a partnership between the California Department of Food and Agriculture, the University of California Agriculture and Natural Resources, the U.S. Department of Agriculture, Sustainable Conservation, and the California Association of Resource Conservation Districts.

Three questions were posed within the collaborative initiative — what are the impacts of cover crops on water cycles; how does SGMA management account for cover cropping and is it effective; how can we ensure this practice remains available to growers where and when it makes sense?

The use of cover crops in Mediterranean climates can be traced back thousands of years, according to the study. In California, they were utilized primarily in orchards and vineyard systems from the early 1900s to improve soil fertility, reduce erosion, and improve water infiltration.

Simply put, cover cropping is an agricultural practice involving planting non-cash crops to protect and improve soil quality and fertility — they are generally planted after the cash crop has been harvested.

One of the primary concerns with cover crops in regions like the San Joaquin Valley is their water usage. In an email, Zaccaria explained that cover crops use minimal water if seeded and established during late fall or early winter, growing mainly during the winter months when water demand is low and seasonal rainfall occurs. Termination of the cover crops before the onset of higher temperatures and increased atmospheric water demand in late March or early April is crucial to minimizing water use​​.

Cover crops require a minimum of four to six inches of water from rainfall to establish and grow sufficient vegetation, Zaccaria explained.

“If not timely and properly terminated, cover crops can keep growing during the Spring and Summer months when the temperature and atmospheric water demand increases,” Zaccaria said.

Another factor to consider is the economic viability of implementing cover crops which require initial investments in terms of seed costs and water input. Still, according to the study, long-term benefits such as improved soil health and water management may offset initial costs.

Policy support is also critical for wider adoption of cover crops in the Central Valley, Zaccaria explained.

“Under SGMA framework, growers are often penalized for growing winter cover crops over the Fall, Winter, and early Spring months due to unrealistic estimates of consumptive water use by cover crops obtained using satellite remote sensing models and tools, or outdated estimation models that are based on unrealistic assumptions,” Zaccaria said.

FUTURE OUTLOOK

Central Valley farmers continue to demonstrate resilience and innovation in the face of water scarcity and regulatory challenges. The growing interest in regenerative agriculture is indicative of the ingenuity and adaptability of farmers to feed the world under harsh and unfavorable circumstances.

The resilience and adaptability of Central Valley farmers serves as a beacon of hope and a model for agricultural regions worldwide. By continuing to invest in sustainable practices and leveraging the support of policy frameworks and educational resources, the Central Valley can maintain its position as a leader in agricultural innovation and productivity.

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