Partitioning of net radiation and evapotranspiration over a superintensive drip-irrigated olive orchard

To evaluate the partitioning of net radiation (R (n)) and actual evapotranspiration (ET (a)), measurements of R (n), sensible heat flux (H), soil heat flux (G), latent heat flux (LE), reference evapotranspiration (ET (o)), transpiration (T (p)) and soil evaporation (E (s)) were taken during the 2009/2010 and 2010/2011 growing seasons on a flat and uniform olive (cv. Arbequina) orchard, located in the Pencahue Valley, Regin del Maule, Chile (35A degrees 23' LS; 71A degrees 44' LW; 96 m above sea level). Olive trees were trained on a triangular hedgerow system with a plant density of 1333 trees ha(-1) (superintensive). An eddy covariance system, sapflow sensors and microlysimeter were used to measure ET (a), T (p) and E (s), respectively. Results indicated that the eddy covariance measurements showed a lack of the energy balance closure of 12.8 %. Values of LE, H and G were between 28-47, 34-68 and 2-6 % of R (n), respectively, while ratios of T (p) and E (s) to ET (a) ranged between 0.64-0.74 and 0.26-0.36, respectively. During two growing seasons, the single crop coefficient (K (c) = ET (a)/ET (o)) was between 0.27 and 0.66, while the dual crop coefficient (T (p)/ET (o) + E (s)/ET (o)) ranged between 0.26 and 0.56. According to these results, H and T (p) were the main component of R (n) and ET (a), respectively, for the particular conditions of the drip-irrigated olive orchard with a fractional cover of 30 % and wetted area of 4.5 %.