EVALUATION OF A LOW VOLUME AGRO-CHEMICAL APPLICATION SYSTEM FOR CENTER PIVOT IRRIGATION

Authors: FARAHANI, HAMID - ICARDA; Shaner, Dale; Buchleiter, Gerald; BARTLETT, GERGORY - VALMONT

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/23/2006
Publication Date: 7/1/2006
Citation: Farahani, H.J., Shaner, D.L., Buchleiter, G.W., Bartlett, G.A. 2006. Evaluation of a low volume agro-chemical application system for center pivot irrigation. Applied Engineering in Agriculture. Volume 22(4): 517-528

Interpretive Summary: Evaluation of Accu-Pulse Precision Applicator for Center Pivot Chemical Application H. J. Farahani, D. L. Shaner, G. W. Buchleiter, G. A. Bartlett Interpretive Summary Efficient application of agro-chemicals is a challenge for farmers to maintain an economical production system while minimizing environmental degradation. To address the need of the producers, Valmont Industries (Valley, NE) recently introduced the Accu-Pulse Precision Applicator. Accu-Pulse is a low volume chemical application system and features an independently operated spray boom attached to a center pivot irrigation system. A series of tests confirmed satisfactory performance for the Accu-Pulse system. The unique spray applicators enable applications at rates much lower than conventional chemigation with greater flexibility. Successful adoption of the Accu-Pulse system will be another tool to improve application of chemicals without the constraints of operating only during the day or under very low wind conditions. Accu-Pulse appears to be a promising system that lends itself to variable rate technology.

Technical Abstract: EVALUATION OF A LOW VOLUME AGRO-CHEMICAL APPLICATION SYSTEM FOR CENTER PIVOT IRRIGATION. A low volume agro-chemical application system, called Accu-Pulse Precision Applicator, was recently introduced. Accu-Pulse features an independently operated spray boom attached to a center pivot or a linear move irrigation system. The unique sprayapplicators have adjustable discharge volumes [from 8 to 31 mL per pulse (0.27 to 1.05 oz)] and enable applications at low rates similar to ground sprayers and much lower than chemigation and pivot-attached sprayer systems. The low rates are achieved by periodic pulsing of the chemical solution through the applicators on a span-by-span basis. A series of tests were conducted to evaluate the engineering performance of the Accu-Pulse system. Entrapped air caused the most discharge variability, affecting isolated applicators on a branch line. In the absence of entrapped air, the discharge variability (CV) was less than 15% for medium to high discharge settings [19 to 31 mL (0.64 to 1.05 oz)] and varied from 13% to 34% at lower settings [below 19 mL (0.64 oz)]. Uniformity of applicator discharge is not synonymous with application uniformity as the wetting coverage tests show. Based on stained water-sensitive papers, much larger droplets were detected under Accu-Pulse than a ground rig sprayer, suggesting a greater potential to reduce spray drift. However, percent wetting coverage was about one-third to one-half smaller under Accu-Pulse than the ground sprayer. For a commercial Accu-Pulse on an eight-tower center pivot, wetting coverage values were in the 40% range as compared to coverage values of about 60% for a ground sprayer. From growers’ perspective, the uniformity of applied chemical is an important performance criterion. This study does not address uniformity in chemical application, efficacy, or cost but advances the basic understanding of spray pattern, overlap, wetting coverage, discharge uniformity, droplet size, and pulse time characteristics of the Accu-Pulse system. Additional studies are needed to evaluate and compare the performance and efficacy of Accu-Pulse with other agro-chemical systems. H. J. Farahani, D. L. Shaner, G. W. Buchleiter, G. A. Bartlett