Evapotranspiration and crop coefficients for coffee production systems in Colombia using the eddy covariance method

To optimize coffee (Coffea arabica L.) production in Colombia, adaptation strategies that improve water use must be developed. Therefore, the objective of this study was to determine evapotranspiration under standard conditions (ETc), reference evapotranspiration (ETo), and the crop coefficient (K-c) of coffee plants interplanted between maize (Zea mays L.) (coffee-maize) for the first 12 mo of growth and coffee grown without maize from 13 to 46 m after transplanting (MAT). In this study, ETc was measured using the eddy covariance method. The ETc of coffee-maize ranged from 4.17 to 4.71 mm d(-1), while ETc of coffee-sun averaged 4.32 +/- 0.07 mm d(-1) between 13 and 24 MAT and 4.09 +/- 0.03 mm d(-1) between 25 and 43 MAT for coffee trees in the reproductive stage. The K-c was 0.87 for coffee plants between 0 and 12 MAT, 0.98 +/- 0.01 between 13 and 24 MAT, and 0.97 +/- 0.02 between 25 and 43 MAT. Maize intercropped between coffee trees produced an adapted microclimate for the first 2 mo, allowing energy used for evapotranspiration processes (latent heat flux) to be greater than energy used for air warming (sensible heat flux), although there was low soil water availability. K-c values are a foundation for optimizing coffee crop water use under climate and soil conditions for the intertropical Andean hillside region.