Preparing California’s agricultural lands for climate change

Two UC Santa Cruz researchers have won funding from the U.S. Department of Agriculture as part of an $8.1 million effort through the National Institute of Food and Agriculture (NIFA) to support research that helps create sustainable "agroecosystems" in response to climate change and other increased environmental pressures.

UC Santa Cruz was one of only 10 universities across the country that won grants through the program and is the lone recipient representing the agricultural needs of California, a state that has been the country’s top agricultural producer and exporter for the past 50 years.  

The winning UC Santa Cruz projects include one to address water scarcity and quality along California's Central Coast, where agricultural communities face the dual challenges of increasingly uncertain and limited irrigation-water supplies—alongside ongoing groundwater-quality degradation from nitrate leaching that has polluted drinking water for nearly one million residents.

The other project seeks to build genetic resilience in California oak rangelands by taking the DNA of trees from historically warmer and drier areas, and introducing them into rangelands in cooler parts of the state that are projected to become hotter due to climate change. The goal is to find out if this novel strategy of "assisted gene flow" is an effective way to build drought tolerance and prevent the loss of oak trees and the benefits they provide for livestock.

Balancing water quality with water conservation

A relatively simple, yet underutilized agricultural practice called cover cropping could play a major role in addressing nitrate pollution of drinking water in California. Hannah Waterhouse, an assistant professor in the Environmental Studies Department, hopes to use her almost $900,000 in NIFA funding to show that cover cropping can be compatible with water conservation efforts in a state with growing drought risk. 

Cover crops are plants not intended for harvest that are grown in agricultural fields during the off season, between cycles of “cash crops,” to protect soil health. Cover crops also improve water quality by absorbing excess nitrates from leftover fertilizer, preventing it from being washed from the fields into the local water supply by winter rains. 

“Cover cropping is one of the most effective practices for reducing nitrate loading to groundwater, which is a huge environmental justice issue, since it disproportionately affects rural farmworker communities that are predominantly Latinx,” Waterhouse said. 

Unfortunately, only about 5% of agricultural lands in California use cover crops, partly because farmers and water managers fear it would require too much extra water. While cover crops can require some irrigation, they also take advantage of seasonal rainfall, and Waterhouse says the improved soil health they provide could result in many water conservation benefits that help to offset their water needs. 

To explore these dynamics, Waterhouse will lead a four-year study at the UCSC farm and greenhouses and with farmers in Santa Cruz, Monterey, and San Benito counties. The team will explore how different cover cropping practices impact water use and water quality, along with growing conditions for the next round of cash crop. They hope to demonstrate practical techniques for reaping the benefits of cover crops in the most water-efficient ways possible. 

Drought-tolerant DNA

The oak-rangelands project will focus on the widespread, foundational blue oak (Quercus douglasii) to see if individuals from different regions have different degrees of drought tolerance. The project also aims to understand how genetics may vary, and whether seedlings with the genetics of oaks from one part of the state can survive and thrive in a new region. The project's director is Blair McLaughlin, a climate change adaptation scientist at UC Santa Cruz, receiving a little over $700,000 from NIFA to fund the project.

"Drought and fire are increasing in the western United States, with serious consequences for California's economically and culturally valuable oak rangelands," said McLaughlin, an associate researcher in ecology and evolutionary biology. "These agroecosystems face further climatic changes over the next century that are projected to cause substantial loss of oaks and the services they provide."

Her project also seeks to create models to guide best practices for genetic climate-adaptation strategies, and conduct outreach to raise awareness about how genetic resources could improve climate change resilience.

Focusing mainly on woodland and forest ecosystems in California, McLaughlin works with students, interdisciplinary partners, land stewards, and practitioners to develop and test innovative climate-change-adaptation strategies and tools to help protect biodiversity into the future. She co-directs the Conservation Science and Solutions Lab and the UC Center for Climate-Adaptive Biodiversity Conservation.