Numerical simulation of soil water dynamics under stationary sprinkler irrigation with MOHID-Land.

Water distribution in sprinkler irrigation systems remains one of the most challenging problems in irrigation water management. Due to lack of water distribution uniformity, parts of a field may be over-irrigated while others may be under-irrigated, thus affecting root water and nutrient uptake and crop yield. The objective of this paper was to show the capabilities of the MOHID-Land model in simulating soil water dynamics and maize growth under a stationary sprinkler irrigation system with low water distribution uniformity (56%). A 3D simulation domain (28×26×1m) was defined to consider different water application rates at the soil surface and the variability of the soil hydraulic properties (two soil types). The model was able to take into account the effect of water distribution and soil variability on soil water content and fluxes, root water uptake reductions due to water stress, soil evaporation, leaf area index and total dry biomass. The resulting soil water balance revealed that irrigation inputs were lower (329 mm) than those theoretically defined to fulfil crop water requirements when the variable-rate application of water was not considered (540 mm). Consequently, the range of variation of soil water stress in the simulation domain was relatively large (between 1 and 64%). MOHID-Land has thus the potential of becoming an important tool for precision irrigation by focusing on site-specific irrigation and crop management rather than the current field unit approach.