Soybean foliar deposition and airflow distribution interrelated to nozzle type and boom travel direction in wind tunnel

Authors: RODRIGUES DA CUNHA, JOAO PAULO - Federal University Of Uberlandia; BATISTA DE OLIVEIRA, RONE - State University Of Northern Paraná (UENP); DE SOUZA LEMES, GABRIEL - The Ohio State University; OZKAN, ERDAL - The Ohio State University; Jeon, Hongyoung; Zhu, Heping

Submitted to: Plants
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/23/2026
Publication Date: 3/27/2026
Citation: Rodrigues Da Cunha, J.A., Batista De Oliveira, R., De Souza Lemes, G., Ozkan, E., Jeon, H., Zhu, H. 2026. Soybean foliar deposition and airflow distribution interrelated to nozzle type and boom travel direction in wind tunnel. Plants. 15(9). Article 1432. https://doi.org/10.3390/plants15071032.
DOI: https://doi.org/10.3390/plants15071032

Interpretive Summary: The study reveals the challenges of delivering pesticides effectively into dense soybean canopies, especially when wind is involved. This work evaluated the effects of wind and nozzle design on spray deposits in a wind tunnel that closely resembled field conditions. The results show that wind is more dominant factor than nozzle design in terms of where spray droplets are deposited. The data indicate that air turbulence at the top of the canopy helps droplets deposit, but the calmer air deeper within plants acts as a barrier, sharply limiting spray penetration regardless of application adjustments. Although angled 3D nozzles outperformed standard XR nozzles under still air, that advantage disappeared once applications were made under windy conditions. The findings suggest that applicators cannot merely rely on nozzle selection; instead, they must account for how wind interacts with canopy structure to determine whether sprays reach their intended targets. Effective spray applications for soybean plants, therefore, depend on understanding and managing the wind conditions as much as nozzle sections.

Technical Abstract: Spray deposition and coverage within soybean canopies remain critical challenges for achieving effective pesticide applications, particularly under windy conditions. This re-search investigated the influence of wind speed, boom travel direction relative to wind di-rection, and nozzle type on droplet deposition, coverage uniformity, and canopy penetra-tion, and airflow distributions inside soybean canopies under controlled wind-tunnel air-flow. Spray deposition, analyzed using a fluorometric tracer, and coverage, quantified with water-sensitive papers, were assessed in R3-stage soybeans in an 18-m wind tunnel using XR (perpendicular spray) and 3D (38° angle) flat fan nozzles under varying air speeds and boom travel directions in the wind tunnel. Potted plants were placed in the wind tunnel to mimic soybeans grown in field conditions. Droplet sizes of the nozzles were measured using a laser imaging particle sizing system. Airflow velocity and turbu-lence within the soybean canopy were investigated with a 3-D hot-film anemometer sys-tem. The results indicated that wind and boom direction were the main influential factors for spray coverage and deposition. The top canopy position, exposed to the highest air-turbulence intensity, received the greatest deposition, whereas the middle and bottom positions, characterized by lower turbulence, exhibited sharp declines in both deposition and coverage regardless of treatment. The 3D nozzle provided greater coverage and depo-sition than the XR nozzle only under no-wind conditions; however, under wind condi-tions, equivalent performance was observed from both nozzles. Therefore, it was essential to incorporate wind conditions and canopy structures into consideration when choosing nozzles to maximize spray penetration and achieve efficient and effective spray applica-tions for soybeans.