Die Bodenkultur - Journal for Land Management, Food and Environment

Saylan L. and J. Eitzinger:

Estimation of the aerodynamic and surface conductance of a faba bean field (Vicia faba var. Arista)


Evapotranspiration is a complex physical-physiological process and of great importance for the water balance in the system soil-plant-atmosphere. The best approach used in science is the so called Penman-Monteith combination equation and its variants, in which a number of the relevant evapotranspiration parameters are considered. Therefore the knowledge of these parameters given under the specific conditions (soil, climate, plant canopy) for the specific application is necessary.

The difficulty in using of the Penman-Monteith equation lies in the estimation of the aerodynamic and surface conductances for the specific conditions. For the estimation of these parameters the sensible and latent heat flux of a faba bean (Vicia faba var. Arista) field has been measured and the actual evapotranspiration has been estimated by using the Bowen ratio energy balance method. In this connection the surface conductance has been calculated from the Penman-Monteith equation by using the measured actual evaporranspiration. The measurements were carried out during three different growth stages of fababean in the field. The surface conductance lies under approximately 20 mm s-1 and 10 mm s-1 in the first and the last period, respectively. In the second measuring period, which was within the main growth period, the surface conductance varied between 20 mm s-1 and 75 mm s-1.The aerodynamic conductance ranged during the measuring periods from 15 mm 5.1 up to 140 mm s-1. A significant correlation was found for the whole vegetation period between surface conductance and vapor pressure deficit, leaf area index and soil water content (r2 =0.83).

Key words:  Agrometeorology, fababean, evapotranspiration, surface conductance, bowen ratio.