Projects
EVALUATING WITHIN-CANOPY AIRFLOW, PLANT STRUCTURE, AND SPRAY TECHNIQUES TO IMPROVE DROPLET PENETRATION
Topic: Foresight
Summary
Non Technical Summary
The challenge is to achieve thorough spray coverage of foliage, when the foliage itself blocks spray droplet penetration. Deeper spray deposits are reduced several orders of magnitude and certainly contribute to pesticide resistance and reduced efficacy of applications targeting diseases/pests shielded by foliage. Simply put, effective spray application is more than "painting" a simple horizontal flat surface. Spray mechanics are the critical interactions between spray droplets, plant foliage, and ambient wind.Modern agriculture tends to reduce pesticide diversity, reduce row spacing, increase plant populations, and to increase droplet sizes. These production practices are often adjusted for a single outcome, without consideration of the impact on spray mechanics. The project recognizes the unique opportunities to use sophisticated large, low-speed wind tunnels to create repeatable test conditions to measure spray penetration and deposits in crop foliage under controlled ambient wind conditions, and to measure "internal canopy openness" with LiDAR using pixel-resolution laser distancing to leaves and plant parts, "internal canopy air velocity" with nano-CTA CMOS thermal anemometry, and "canopy foliage density" with Leaf Area Index (LAI) as a baseline indicator. These factors correlate with spray access, movement, and blocking within the foliage. In other words, a systematic scientific approach addresses an otherwise highly-variable field condition to link governing principles with improved production practices that integrate the details of spray application with cropping practices and anticipated weather conditions.
Objectives & Deliverables
Goals / Objectives
This research delineates the combined effects of crop foliage conditions, spray characteristics, and ambient weather necessary to do more with less, or in other words minimizing the amount of active ingredient applied, while being cognizant of the need for maxmimum spray application efficiency. The overall goal is to systematically evaluate foliar canopy and sprayer factors to improve spray penetration into field crop foliage for a field crop under variable wind conditions. Soybeans are used as a model crop to represent field crops.The first objective is to determine the guidelines for increasing "internal canopy openness" and air velocity within a soybean row crop.The second objective is to determine the guidelines for selecting spray parameters coupled with increased "internal canopy openness" and air velocity to increase spray penetration in a soybean canopy.The third objective is to determine the guidelines for selecting and using air-assist spray technology coupled with increased "internal canopy openness" and air velocity to increase spray penetration in a soybean canopy.
Challenges
Project Methods
1. Wind tunnels create controlled wind conditions for experiments with foliage.2. "Internal canopy openness" conditions are created with soybean maturities, varieties, plant populations, and row spacing. Soybeans are used as a model crop to represent field crops. Plants are grown in pots in outdoor conditions to create representative canopy structures, then oriented in the wind tunnels.3. Soybean "internal canopy openness" is quantified using a low-cost LiDAR (i.e. laser-based) camera system mounted to take RBG image and laser distance synchronized to each pixel. Three sensors are budgeted for each of the two tunnels in the Univ. of Tenn. budget. LiDAR camera will be positioned in the canopy to avoid lens contact or being too close to plant vegetative elements. Short-range depth camera control settings will be prioritized to not saturate the laser receiver with reflectance from close vegetation.4. Air velocity within the soybean canopy in the wind tunnel is measured with compact sensors such as the Surrey Sensors "Nano-CTA" CMOS thermal anemometry system for air velocities as low as 10 mm s-1. The sensor has data acquisition for up to 8 channels to allow for simultaneous velocity measurements at different locations by additional sensors.5. Air velocity validations are with a high precision hot film probe by Dantec, already on site in Wooster, Ohio at OSU wind tunnel. This $140,000 instrument provides for in-canopy air velocity validations.6. Leaf Area Index (LAI) will use above-canopy and below-canopy sensors to measure foliage density. Difference in wavelength (320-470 nm) radiation between the two sensors is simultaneously measured at five viewing angles to determine an average LAI value. Leaf area index (LAI) will be measured as a standardized measure of canopy foliage density.7. Spray deposits reaching in-canopy foliage are quantified with a fluorimeter or colorimetry. Dye degradation should be minimal without exposure to sunlight.8. Foliar deposits distinguish abaxial versus adaxial deposits to better understand how the spray deposit is parsed on the leaf surface.9. Spray deposit characteristics, beyond quantification, are determined with water sensitive paper (WSP) analyzed with DepositScan software developed by collaborator Dr. Heping Zhu, USDA-ARS, Wooster Ohio. Data include droplet spectra (Dv0.1, D0.5, Dv0.9), coverage, spot density, etc. In addition to foliar locations, spray reaching the ground level are quantified with WSP.10. Data are examined for outliers that are logged and then investigated. If no rationale supports that the outlier is reasonably a valid value, it is left tagged as an outlier and not processed any further.
Principle Investigator(s)
Planned Completion date: 31/07/2026
Effort: $590,005.00
Project Status
ACTIVE
Principal Investigator(s)
National Institute of Food and Agriculture
Researcher Organisations
Recipient Organization UNIVERSITY OF TENNESSEE 2621 MORGAN CIR KNOXVILLE,TN 37996-4540
United Kingdom