A model for the capture of aerially sprayed pesticide by barley

This paper sets out a novel method of modelling the capture of pesticide spray by a cereal crop. Firstly, the transport model, based upon that of Mokeba et al. (J. Wind Eng. Ind. Aerodyn. 67 & 68 (1997) 923–933), is described. This models the effect of turbulence on each individual spray droplet by using a random-walk model incorporating the Lagrangian variances and time-scale of the air velocity. The crop model, which incorporates a realistic three-dimensional parameterization of the plant, is then detailed and the effects of the crop on the airflow are considered. Some useful applications to justify the added complexity of this new method are then outlined and a perspective offered on the question of spray penetration of a crop canopy. Finally, an attempt is made at looking at the problem of drift at the scale of the field.