Modelling evapotranspiration of corn (Zea mays) under different plant densities

Simulating evapotranspiration (ET) from agricultural crops requires models capable of describing energy partitioning over the entire range of crop cover, between bare soil and a full canopy. Double-layer models can satisfy this requirement. A doublelayer model that calculates soil evaporation and plant transpiration in a parallel approach is proposed. Its performance is compared with the Penman–Monteith and the Shuttleworth–Wallace ET model performances, against ET measurements from a corn crop obtained by soil water balance during 1995/96 at Balcarce, Argentina. Corn grew at two different plant densities (22,000 and 91,000 pl ha-1), reaching maximum leaf area indexes (L) of 1.5 and 5.5, respectively. The soil evaporation component was weighted by a factor considering crop cover. Predicted and measured values fit better when the new model was applied.