Field-scale Particle Transport in a Trellised Agricultural Canopy During Periods of Row-aligned Winds

The transport of particulate plays an important role in trellised agricultural canopy ecosystem processes. This includes the transport of pests, pollutants, and biological propagules. The concentrations of these particulates are typically highest very near their sources, but it is well documented that they also have the potential to be transported over large length-scales and even have the potential to be transported from field to field. In fact, the transport of propagules, pathogens, and pests from field to field is often necessary for the survival of the plant species and can also be incredibly damaging at the same time. In recent years we have performed considerable research on the dispersion patterns of particles in a trellised agricultural canopy but have primarily focused on transport at length-scales between one and seven canopy heights. Although this is the space wherein the majority of the particles are dispersed and removed from the flow, field-scale transport is also a common occurrence in agricultural canopies. In order to better understand the behavior of transport at length-scales approaching the size of the field, multiple particle release experiments were performed during a field campaign in 2013 in a vineyard near Monmouth, Oregon. During these events, inert fluorescent microspheres (10 to 45 μm diameter) were released into the canopy and were sampled at downwind length-scales between seven and 75 canopy heights. These events were performed during periods when the above canopy winds were blowing in a direction that was essentially identical to the vine row direction. It was expected that the plume shape patterns from these microsphere plumes would exhibit some similarities to those seen for dispersion at equivalent length-scales in canopies of other types, e.g., homogeneous vegetation and urban canopies. The specific effects of the vineyard canopy architecture were identified and the plume shape parameters were compared to those seen in other canopies and those observed in the same vineyard for plume dispersion at the smaller length-scales.