Water Use Efficiency of Coffee {Robusta) Under Mulch and Drip Irrigation on the Tay Nguyen Plateau, Viet Nam

摘要

This paper attempts to separate the transpiration and evaporation components from total evapotranspiration (ET) and compares the water use efficiency (WUE) of coffee (Robusta) under furrow and drip irrigation practices, with and without mulching. Theexperiments were conducted on a 10-year old coffee plantation on a clay soil of the Tay Nguyen Plateau, in the central part of Viet Nam. The plantation is relatively homogeneous in terms of crop height, with a leaf area index (LAI) ranging from six to seven. The study showed that transpiration was the highest contribution (95 ± 5 percent) to ET during flowering (February-March), and the lowest (47 ± 3 percent) during the mature and canopy reformation stages (October-November), as separated by the isotopic technique. Drip irrigation (Drl) combined with plant residues (mulch) increased the WUE of coffee up to 2.13 kg clean bean per m3 of irrigated water (kg/m3), while WUEs under Drl and furrow irrigation (Fl) without mulch were only 1.93 and 1.78 kg/m3, respectively. Due to the improvement in WUE, the local farmers are making extra profit from the application of Drl with mulching from their coffee crop. Local farmers in the Tay Nguyen Plateau are now advised to use Drl with mulch from plant residues to all coffee plantations.