Thermal Radiometry to Validate Ensemble Evapotranspiration (ET) on Sustainable Small Farms

Commodities

• Agronomic: peanuts, radish (oilseed, daikon, forage), other
• Fruits: citrus, other
• Vegetables: cabbages, eggplant, greens (leafy), greens (lettuces), leeks, onions, peppers, radishes (culinary), taro, other
• Additional Plants: ginger, herbs, trees

Practices

• Crop Production: application rate management, conservation tillage, continuous cropping, cover crops, crop improvement and selection, crop rotation, double cropping, drought tolerance, fallow, greenhouses, high tunnels or hoop houses, intercropping, irrigation, low tunnels, multiple cropping, no-till, row covers (for season extension), shade cloth, stubble mulching, water management, water storage
• Education and Training: decision support system, demonstration, extension, farmer to farmer, focus group, mentoring, networking, on-farm/ranch research, participatory research, technical assistance
• Farm Business Management: whole farm planning
• Production Systems: agroecosystems, holistic management, organic agriculture
• Sustainable Communities: community development, ethnic differences/cultural and demographic change, leadership development, local and regional food systems, partnerships, public participation, quality of life, social capital, social networks, sustainability measures

California's agricultural scene is diverse, harvesting
hundreds of crops despite a notoriously variable
climate^[1]. As groundwater transitions to a
regulated resource according to SGMA
legislation of 2018^[2], smaller operations are
more likely to suffer under uniform application due to
typically having less resources to
adapt^[3]. Small farms are associated with
overall higher crop and non-crop biodiversity and higher
yields [4], and these growers deserve consideration as SGMA
is implemented through 2040. 

Since 2018 regulations, noninvasive satellite-based platforms
have emerged to effectively normalize crop water use for
farms as small as one-quarter acre. While the platform
OpenET has been integrated into irrigation management
and compliance strategies, the ensemble of equations used to
produce ET field maps assume homogeneous canopies of
theoretically large areas. 

In contrast, growers in this study operate diverse
cropping systems on less than 30 acres, thus they are
interested in ensemble performance under these constraints.
We partnered with 7 small farms in the critically overdrafted
Kings Watershed Basin to perform aerial and ground surveys at
100-1000 times satellite’s spatial resolution in thermal
bands and evaluate predictions of ET from their perspective.
Doing this, our project aims to support regulations that keep
small farms viable.

The project invites grower collaboration and two-way
education by staging twice annual extension events and
developing Digital ET Product Packages for participating
farms. Workflows and processing code will be published for
stakeholder access, research findings will be published at
academic conferences and in peer reviewed journal(s).

Research Objectives

1. Estimate the seasonal vapor flux of small farms using physical
and energy balance methods

2. Evaluate the performance of satellite based models

3. Review relevant Groundwater Sustainability Plan in support of
equitable groundwater management and preserving a natural
resource

Educational Objectives

1. Dissemination of products, information, and ideas among
growers and researchers

2. Collaboration among growers, researchers and community
stakeholders

3. Community building among those interested in and impacted by
Sustainable Groundwater Management