EVALUATION OF THE AQUACROP MODEL TO SIMULATE THE BIOMASS ACCUMULATED IN ALFALFA FROM HISTORICAL YIELDS IN RAFAELA, SANTA FE

Abstract

AquaCrop is a model developed by the FAO Land and Water Division that simulates the growth of arable crops as a function of water consumption. It integrates the effect of edaphic and climatic variables, together with management variables, to represent production in response to water in the soil-plant system. In the present work, it was calibrated for alfalfa (Medicago sativa L.), using cutting data available from the INTA Rafaela cultivar network for the years 2000 to 2018, and the last four years corresponding to the cuts used in the validation. The model provided a good simulation of the accumulated aerial biomass in each cutting. The statistical tests that evaluated the calibration of the model. Their results were the coefficient of determination (R²) of 0.92; the root mean square error (RSME) with the value of 178 kg of DM ha-1; Nash efficiency coefficient (E) with values of 0.91; the normalised mean square error of 15% and the agreement index (d) with a value of 0.97 for each cut. The variables and parameters used in the validation showed an adequate level of accuracy. The accumulated aerial biomass shows a deviation that does not exceed ± 200 kg DM ha-1 comparing the simulated and measured values, so the model is able to reliably reproduce the analysed variable.