Developing a Thermal Imaging System for On-demand Corn Temperature Profiles for Variable Rate Irrigation

View the project final report

Commodities

• Agronomic: corn

Practices

• Crop Production: irrigation
• Farm Business Management: feasibility study, whole farm planning
• Production Systems: general crop production
• Sustainable Communities: employment opportunities, sustainability measures

Irrigated farms use 80 percent of the fresh water in the United States. Based on the need to maximize the return of applied water, significant ongoing research in the North Central Region (NCR) of the United States (U.S.) provides better tools and management methods for irrigation. Irrigation studies use increased canopy temperatures to indicate crop water stress because of a decreased transpiration rate due to leaf stomata closure. Although most research has focused on single point approaches to measure canopy temperatures, Thermal Infrared (TIR) imaging, thermography, is a novel sensing approach for determining high spatial crop temperature profiles to characterize crop water stress. My objective is to develop an environmentally compensated Computer Aided Thermographic (CAT) system for measuring on-demand corn temperature profiles for future research studies aboard small unmanned aerial systems (sUAS) for assessing crop water stress for variable rate irrigation. My hypothesis is that a CAT system tested under strict laboratory conditions (i.e., air temperature, relative humidity, air-flow, light intensity, and sensing distance) will produce empirical calibration curves for accurate measurements under varying environmental conditions. In addition to measuring surface temperatures, the CAT system will be integrated into a commercial sUAS telemetric flight controller system. A telemetric system will geo-reference each thermal image with Global Positioning System (GPS) coordinates and will compensate for the orientation of the camera by orthorectifying each image. Stationary tests in greenhouses and field plots will be conducted on corn where irrigation significantly increases yield potential to ensure measurement accuracy. The expected project outputs will be a thermal imaging system with settings, guidelines, and recommendations for operation for subsequent research aboard sUAS to create high spatial canopy temperature maps for variable rate irrigation. The CAT system would provide a high throughput of surface temperatures for monitoring production systems not limited to crop water stress but also heat tolerant breeds, environmental, and animal health indicators for end-users such as producers, agriculture service providers, and researchers. Overall, it would provide a technology that could aid crop water stress monitoring to optimize available water to improve the economic and social sustainability of corn growers and the economies of their rural communities and help NCR-SARE achieve its goal of ‘sustainable agriculture’. 

This project’s goal is to develop an environmentally compensated Computer Aided Thermographic imaging system capable of measuring high spatial surface temperatures (±0.25°C) while linking position and camera orientation information to each image for subsequent research aboard Small Unmanned Aerial Systems (sUAS). By simplifying image acquisition and application solutions for capturing full-season crop water stress parameters of irrigated corn, producers, agricultural service providers, and researchers will have site-specific crop water requirements for management decisions to better allocate available water resources for variable rate irrigation.  

The development of a CAT system to quantify crop water stress under uncertain field conditions relies on an exhaustive evaluation of the integrated commercial components’ inherent behavior for actual performance, operational procedures, and sensor setting recommendations for greenhouse and field-based temperature measurements. Success indicators during stages of the project are as follows:

1) Evaluate the integrated TIR camera’s ability to measure surface temperatures at or below an accuracy of ± 0.25°C.

2) Prototype and evaluate performance of CAT system’s image capture speeds, telemetry integration accuracy, and secure storage of image.

3) Evaluate empirical calibration curves ability to compensate for environmental conditions in the sensing environment.

4) Evaluate CAT operational settings by monitoring corn grown in greenhouses with static environments and with in-field evaluation with dynamic environments during various growth stages of irrigated corn.

Constant feedback from researchers, agricultural service providers, and producers will validate that the system can meet performance expectations, easily be adopted into a precision cropping system, and become an economically viable sensing technology for measuring crop temperature profiles. By retrieving feedback on how producers make irrigation management decisions, the end-user’s expectations will be addressed during development. Additionally, providing the temperature profile images in formats easily analyzed is important so correct observations can be made for ongoing and future research in crop water stress.