Using remotely piloted aircrafts to evaluate potato water stress in
Central Wisconsin
Abstract
Groundwater depletion in Central Wisconsin, due in part to agricultural
high-capacity wells, has sparked an interest in precision irrigation to
reduce groundwater pumping without a significant reduction in yield. A
key challenge for bridging precision irrigation research and application
is how best to monitor water stress in real-time. Aerial and satellite
imagery are potential solutions. Drawbacks of these methods include
cost, spatiotemporal resolution, and cloud interference, especially in
humid regions. Recent advancements in remotely piloted aircrafts (RPAs)
have made frequent, low-flying imagery collection more economical and
feasible than ever before. We partnered with the Wisconsin Potato and
Vegetable Grower Association to generate high-resolution maps of crop
water stress using remotely sensed thermal and multi-spectral RPA
imagery. Data were collected at a commercially irrigated potato field in
the Central Sands region of Wisconsin from June to August 2019. Missions
were flown weekly using a quadcopter RPA system instrumented with a
newly released, combined multispectral/thermal camera developed for
agricultural applications. Each mission included flights at 30, 60, and
90 m above ground level to assess tradeoffs between resolution, area,
and flight time. We used biophysical data from an eddy covariance system
installed within the flight domain to validate crop water stress maps
generated from the remotely sensed RPA data. Ground measurements of
surface temperature and soil moisture were collected throughout the
domain within fifteen minutes of each mission. Ongoing results will be
used to develop best practices for integrating RPAs into precision
irrigation programs.