Using AquaCrop to derive deficit irrigation schedules

Straightforward guidelines for deficit irrigation (DI) can help in increasing crop water productivity in agriculture To elaborate such guidelines crop models assist in assessing the conjunctive effect of different environmental stresses on crop yield We use the AquaCrop model to simulate crop development for long series of historical climate data Subsequently we carry out a frequency analysis on the simulated intermediate biomass levels at the start of the critical growth stage during which irrigation will be applied From the start of the critical growth stage onwards we simulate dry weather conditions and derive optimal frequencies (time interval of a fixed net application depth) of irrigation to avoid drought stress during the sensitive growth stages and to guarantee maximum water productivity By summarizing these results in easy readable charts they become appropriate for policy extension and farmer level use We illustrate the procedure to derive DI schedules with an example of quinoa in Bolivia If applied to other crops and regions the presented methodology can be an illustrative decision support tool for sustainable agriculture based on DI (c) 2010 Elsevier B V All rights reserved