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

Commodities

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