Abstract:  Farmers often fallow their fields for various reasons, including soil degradation and nutrient depletion, water management and availability issues, economic factors and market dynamics, government policies, and environmental factors related to climate change. In California, previous studies have suggested that to achieve the goals of the Sustainable Groundwater Management Act (SGMA), which aims to bring groundwater basins into balance within the next two decades, farmers would have to fallow between 0.5 and 1 million acres of irrigated agricultural lands. While some of the reasons to fallow irrigated lands have inherent benefits, the practice of fallowing may also result in potential consequences for the health of farm workers. During this presentation, we will explore two of those consequences, associated with dust and heat in Central Valley - a region that accounts for more than 50% of all U.S. crops, like fruits, nuts, and vegetables, and contain 75% of the irrigated land and about 77% of fallowed agricultural lands in California. We will show that fallowed fields dominate anthropogenic dust sources in California, contributing to the worsening air quality in the Central Valley. In addition, we will also show that, because of surface exposure of these fallowed fields, absorption of solar radiation can result in cropland heat island effect – a concept similar to urban heat island – with outward radiating heat of about 3.5 oC from the fallowed lands that can influence nearby cropland up to about 500 meters – that is about the size of five baseball fields. Furthermore, the cropland heat island effect from fallowed fields can impact evapotranspiration and crop water demands of nearby croplands, with significant consequences for crop yields. 

Abstract: The San Joaquin Valley was once a vast mosaic of rivers, floodplains, oak savannahs, and expansive desert oases with a rich diversity of wildlife. Years of urbanization and intensive groundwater-dependent agriculture have led to substantial habitat loss, putting some species on a path toward extinction—especially in the San Joaquin Desert. Today, chronic water scarcity and other environmental concerns are forcing a fundamental rethinking of this landscape. To meet groundwater sustainability goals of California’s 2014 Sustainable Groundwater Management Act, an estimated 500,000 acres of irrigated farmland may need to be retired by 2040. Rehabilitating land at this scale is a daunting challenge, and without strategic planning, land fallowing could worsen air quality, harm local economies, and create uninhabitable lands. This transition, however, also presents a once-in-a-lifetime opportunity to restore wildlife habitat in the Valley. Building on past San Joaquin Desert restoration efforts, The Nature Conservancy (TNC) and partners developed a vision for large-scale habitat restoration on retired farmland, prioritizing areas with the highest potential to support 25 imperiled San Joaquin Desert species. In 2022, TNC and the Tule Basin Land & Water Conservation Trust launched the Capinero Creek project in Tulare County to explore scalable, sustainable restoration. Adding topographical complexity, seeding native forbs and non-native grasses to suppress weeds, and managing vegetation through grazing and harvesting have already produced ecological benefits, including increased pollinator activity and the return of endangered species like the blunt-nosed leopard lizard. Capinero Creek demonstrates that with strategic planning, restoration can support groundwater sustainability, improve air quality, and create vital wildlife habitat, offering a replicable model for the broader San Joaquin Valley.