Maize grain yield variability between irrigation stands: a theoretical study

Variability of irrigation application has been mainly studied in terms of uniformity of water distribution on the field scale. However, to irrigate a whole field several days are required and therefore a within-field yield variability is expected. In this paper, the maize grain yield variability due to the time required to irrigate different stands of a field is studied. The management-oriented cropping system model MODERATO is used on that purpose. Variation in soil depth, available soil water capacity, flow rates and irrigation regime are tested. Flow rates and irrigation regimes modify the number of days required to irrigate the whole field. It is then shown that for the given tested configurations, the maximum grain yield variability is on average 1.41 Mg ha(-1) and for some specific year the value reaches 2.11 Mg ha(-1). Maize grain yield variability decreases when the flow rate increases, the soil depth increases, the gravimetric soil available water capacity increases and the irrigation amount decreases. A graphical analysis of the variability is then proposed. The integration of this knowledge in decision tools is then discussed.