Canopy resistance to evapotranspiration of a soybean crop

Latent heat flux measurements were carried out on a soybean crop with the Bowen Ratio Energy Balance method and aerodynamic and canopy resistances to water vapour flux were calculated. Canopy resistance values in different growth phases and water availability conditions are presented. As a first attempt to parametrize diffusion resistance of the crop, a simple relation between solar radiation and canopy resistance of the well watered crop is suggested. Parametrization of canopy resistance would, in fact, promote a more generalized utilization of the Penman- Monteith formula in evaluating crop water requirements, as recently suggested by FAO.