Evapotranspiration and crop coefficient of the irrigated carrot on the alagoano agrest

ABSTRACT The water consumption of a crop is one of the main information required for proper irrigation management and to develop an efficient water usage plan. The objective of this work was to find a coefficient of water consumption for carrot crop, comparing methods of reference evapotranspiration for the Agreste region of Alagoas. The experiment was carried out at the Arapiraca Campus of the Federal University of Alagoas, located in the Agreste mesoregion of the state of Alagoas. Five drainage lysimeters were used with a surface area of 0.07 m2, on which the determination of crop evapotranspiration was performed daily, through the collection of water of the drains obtained directly from drainage lysimeters. The cultivation coefficient was calculated by the relation between crop evapotranspiration and reference evapotranspiration. At the same time, a comparative analysis of the mathematical models of reference evapotranspiration estimation was carried out using the following methods: Penman-Monteith, Hargreaves-Samani, Solar Radiation Blaney-Criddle, and Priestley-Taylor. The cultivation coefficients for carrot crop recommended for the region are 0.46, 1.3, 1.3, and 1.03 for phases I, II, III, and IV, respectively, by the standard method. The values of reference evapotranspiration obtained by the Priestley-Taylor method presented the best performances for the statistical methods studied, and in the absence of the necessary variables to determine the reference evapotranspiration by the standard method, it can be used for the studied region.