Location: Crop Production Systems Research2009 Annual Report
1a. Objectives (from AD-416)
Objectives are: 1) Control off-target drift and enhance penetration of active ingredients, such as fungicides and biological control agents, into crop canopies; and 2) Develop remote sensing methods, utilize and evaluate Global Positioning Systems (GPS), develop methods amenable to rapid image processing, and evaluate flow control systems to support variable rate aerial application.
1b. Approach (from AD-416)
This project seeks to advance application technology through improvements in 1) drift management technology, 2) technologies for improved within-canopy deposition, 3) use of low-altitude remote sensing to identify stressed plants, and 4) performance of variable rate aerial application systems. While drift management is a concern for all pesticide applications, it is of particular concern for aerial applications. The potential for drift is greater for aerial application due to higher altitudes of spray release and greater air turbulence in the wake of the aircraft. Determination of optimal spray release height will be a goal, as the effect of this variable on within-canopy deposition and off-target drift has not been considered adequately. Experiments for both drift and deposition will attempt to reduce confounding of treatment data with environmental effects, preserving statistical precision of the experiments. Penetration of sprayed material to the lower portions of the canopy is critical for control of fungal spore diseases like Asian Soybean Rust (ASR). Studies will compare nozzle types paired with carefully selected formulations and tank mixes for spray penetration. The deleterious effects of off-target herbicide drift to cotton will be detected using hyperspectral, multispectral, and thermal remote sensing techniques. Evaluation of variable rate aerial application systems will be continued and improvements will be made through interaction with system component manufacturers. Experiments are also proposed to demonstrate the validity of techniques developed.
3. Progress Report
Micronair atomizers, Accu-Flo radial nozzles, and CP flat-fan nozzles with selectable tips were evaluated for droplet spectra and spray coverage using water sensitive papers placed in the aerial spray swath. These nozzles and atomizers are being evaluated both as low drift nozzles and for use in a soybean canopy penetration study to control Asian Soybean Rust (ASR). CP nozzle angles were adjusted to 15, 30, and 45 degrees, and appropriate tips were specified according to required flowrate. Droplet spectra of the water sensitive papers over the spray swath were obtained to produce four parameters including Volume Mean Diameter (VMD) and relative span, the latter which is an indication of the range of droplet sizes. Droplet data for the CPs were compared with output from the available USDA Droplet Spectrum Models at three low volumes. From visual observation of trends, the VMD appeared to be the best fit to the USDA models of all parameters across flowrates. Droplet size ranges (as indicated by the relative span) were narrow, indicating the nozzle’s potential for reducing off-target spray drift. Tests also showed spray performance of these nozzles to be insensitive to small variations in application height. Optimal CP nozzle angle for consistency of droplet deposition was found to be 30 degrees. Control of ASR is also assisted by control of alternative hosts. A patent application was approved that uses a blend of agronomic herbicides which could enable reclamation of kudzu infested land for agronomic use. This invention will improve kudzu control with lower herbicide rates and fewer applications in a shorter time-frame, and may provide greater and longer lasting levels of control because it delays or prevents re-growth of vines. A multispectral camera system (Tetracam ADC) was evaluated for use in agricultural aircraft to support detection of variable crop vigor and the effects of herbicide-induced damage caused by off-target spray drift. The GPS triggering feature for the Tetracam was evaluated, and images were acquired successfully using automatic triggering at preset field locations. Minimum updating GPS interval was limited to 2-s by limitations in the triggering software, and procedures are underway to improve consistency of image acquisition. Testing has begun to evaluate a Geospatial Systems MS-4100 camera with control and processing software on the aircraft. The variable-rate aerial application system was tested further, and the objective was to improve response time of the flow controller to step changes in flow. A site visit was made by the system manufacturer to assist with the test and to reprogram control algorithms based on analysis of spray application data using a pre-set prescription. A journal article was published in FY2009 that documents field testing of this aerial variable-rate application system.
1. The first known successful evaluation of a commercial aerial variable-rate application system was accomplished and results have been published. Technology transfer is by cooperative agreement with the flow control system manufacturer. As a direct result of continued collaboration, the controller has been improved to the point that it is a viable solution for variable-rate aerial application and the ability to change flowrates in response to changing ground speeds. Results from aircraft experiments will improve accuracy of application and achieve commensurate savings in applied chemical. The aerial flow controller is marketed throughout the world.
Thomson, S.J., Smith, L.A., Hanks, J.E. 2009. Evaluation of Application Accuracy and Performance of a Hydraulically Operated Variable-Rate Aerial Application System. Transactions of the ASABE 52(3):715-722