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

Simulating evapotranspiration (E-T) 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 E-T model performances, against E-T 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 9 1,000 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. (C) 2002 Elsevier Science B.V. All rights reserved.