Site-specific Irrigation Management in Alfalfa by Estimating Crop Water Stress and Spectral Responses

Commodities

Practices

Project Title: Site-specific Irrigation Management in Alfalfa by Estimating Crop Water Stress and Spectral Responses

Alfalfa, known as the 'Queen of Forages,' ranks as the third most valuable field crop in the United States, with 9 states from the North Central region featuring in the top 15 producers list according to 2024 US Forage Statistics. The water-resilient alfalfa production under 38% drought-impacted North Central U.S. was the key factor to integrate research, extension, and education efforts for farmers, ranchers, and the overall farming community. A research trial is being conducted in Kansas in collaboration with industry, farmers, and stakeholders to achieve digital solutions in precision water management for alfalfa production and forage quality. The project aims to assess canopy temperature to develop baselines for measuring crop water stress index using thermal images collected via uncrewed aerial vehicles (UAVs). Using in-field soil sensors fails to capture the spatial variability resulting from soil type, topography, and plant health at actionable scales. Therefore, there is a need to develop high-resolution spatial water stress maps, which, combined with spatial response maps, will develop irrigation management zones for site-specific irrigation. The forage quality will be assessed across varying water regimes based on crop evapotranspiration to find a better balance between yield and quality of forage. The goal is to disseminate the findings and to promote precision water management strategies for sustainable alfalfa production. The short-term evaluation plan in 2026 will record the attendance in the field day, a Likert-scale survey, and demonstration plot visit feedback to understand the changes in attitude, knowledge, awareness of the farmers, and social media posts and engagement. The number of farmers adopting water management practices to grow alfalfa will be recorded by follow-up emails and phone calls in 2027 to measure medium-term success. Publishing project results in peer-reviewed journals and developing factsheets and extension bulletins will boost farming and scientific community outreach. Learning outcomes include developing a training program to educate alfalfa producers on canopy temperature and evapotranspiration benefits in water management. This will be useful for implementing sensor-based canopy temperature measurement for real-time water stress estimation and utilizing high-resolution water stress maps for variable rate irrigation awareness. Action outcomes involve establishing baselines for crop water stress assessment to develop spatial water stress maps for improved alfalfa quality for higher market value and supporting the adoption of precision water management strategies to enhance sustainability and economic well-being in alfalfa-growing communities.

The learning outcomes for this project include developing: (1) an extension and education program for alfalfa producers to train on the benefits of measuring canopy temperature and crop evapotranspiration based water management; (2) sensor-based measurement of canopy temperature to estimate real-time water stress in alfalfa; (3) high resolution water stress and spectral response maps will help farmers to understand the need of site-specific variable rate irrigation. This will enhance the return-on-investment for alfalfa growers and livestock growing communities through precision water management strategies while enhancing drought-resilient alfalfa production and quality of feed for livestock.

The action outcomes for this project includes: (1) developing baselines for assessing crop water stress by quantifying the level of stress in alfalfa from thermal images collected using UAVs, providing direct assistance to farmers for precision irrigation management in the North Central region; (2) creating aerial reflectance based high-resolution water stress and spectral response maps to develop water management zones promoting need-based irrigation; (3) assessment of enhanced forage quality in climate resilient alfalfa production fetching higher price in the feed market; (4) provide support by training in field day showing the importance of creating irrigation management zones to enhance the economic output by strategically utilizing natural resources and following up the next year with the attendees to check on their adaptation rate and issues during the adaptation.

We anticipate producing knowledge that will enhance precise water application for alfalfa production in the North Central region.