Abstract
Pneumatic spraying is especially sensitive to spray drift due to the production of small droplets that can be easily blown away from the treated field by the wind. Two prototypes of environmentally friendly pneumatic spouts were developed. The present work aims to check the effect of the spout modifications on the spray quality, to test the convenience of setting the liquid hose out of the spout in cannon-type and hand-type pneumatic nozzles and its effect on the droplet size, homogeneity and driftability in laboratory conditions. Laboratory trials simulating a real sprayer were conducted to test the influence of the hose insertion position (HP), including conventional (CP), alternative (AP), outer (OP) and extreme (XP), as well as the liquid flow rate (LFR) and the airflow speed (AS) on the droplet size (D50, D10 and D90), homogeneity and driftability (V100). Concurrently, the droplet size spectra obtained by the combination of aforementioned parameters (HP × LFR × AS) in both nozzles were also classified according to the ASABE S572.1. Results showed a marked reduction of AS outside the air spout, which led to droplet size increase. This hypothesis was confirmed by the droplet size spectra measured (D50, D10, D90 and V100). A clear influence of HP was found on every dependent variable, including those related with the droplet size. In both nozzles, the longer the distance to CP, the coarser the sprayed drops. Moreover, LFR and AS significantly increased and reduced droplet size, respectively. A higher heterogeneity in the generated drops was obtained in XP. This position yielded V100 values similar to those of the hydraulic low-drift nozzles, showing an effective drift reduction potential. The classification underlines that the variation of HP, alongside AS and LFR, allowed varying the spray quality from very fine to coarse/very coarse, providing farmers with a wide range of options to match the drift-reducing environmental requirements and the treatment specifications for every spray application.
Highlights
Grape production represents one of the most important agricultural businesses worldwide, with7.5 million hectares and five countries representing 50% of the world vineyard harvested area: Spain (13%), China (11%), France (10%), Italy (9%) and Turkey (7%) [1]
The classification underlines that the variation of hose insertion position (HP), alongside airflow speed (AS) and liquid flow rate (LFR), allowed varying the spray quality from very fine to coarse/very coarse, providing farmers with a wide range of options to match the drift-reducing environmental requirements and the treatment specifications for every spray application
In detail we evaluated i) the possibility to increase droplets size by adjusting the water income position out of the nozzle spouts and ii) its effect on the droplet size population and homogeneity
Summary
Grape production represents one of the most important agricultural businesses worldwide, with7.5 million hectares and five countries representing 50% of the world vineyard harvested area: Spain (13%), China (11%), France (10%), Italy (9%) and Turkey (7%) [1]. Grape production represents one of the most important agricultural businesses worldwide, with. Considering the total grape production, Italy ranks second after China, with 8.4 and 13.7 Mt respectively, followed by USA, France and Spain [1]. Considering wine grapes, only the EU ranks first with 61.3% of total world production [1]. The high number of spray applications during the vegetative season in intensive production systems determines a massive Plant Protection Product (PPP) use that can cause undesirable effects related to pesticide residues on food and adverse effects to the environment. For that reason, controlling all factors is nearly impossible, and as a result PPP applications could be inefficient. This fact led the European Authorities to develop Directive 2009/128/EC on sustainable use of pesticides [4]
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