Although New Zealand is water-rich, many of the intensively farmed lowland areas suffer frequent summer droughts. Irrigation schemes have been developed to move water from rivers and aquifers to support agricultural production. There is therefore a need to develop tools and recommendations that consider both water dynamics and outcomes in these irrigated cropping systems. A spatial framework for an existing systems model (APSIM Next Generation) was developed that could capture the variability in soil, cropping systems and irrigation application observed under a single irrigator with constrained water and infrastructure availability. Outputs from the simulations, such as water application, crop stress, yield, drainage and water use efficiency (WUE), could then be produced.The framework was then applied to a case study site, an 80 ha irrigated cropping area in the Hawke’s Bay region of New Zealand.EM and gamma surveys were used to guide a detailed soil survey and to delineate five distinct soil types, with known characteristics such as permeability and water storage. On the site there is a range of soil water storage potential, from 80 to 178 mm of plant available water (PAW), to a depth of 600 mm. A simulation of the study site was created to represent typical management of a maize grain crop. The irrigation scenarios considered were either uniform or variable rate (VRI) application, triggered by a soil water deficit of 40 or 50 % of PAW to 600 mm, and a refill of either 20, 30 or 40% of PAW to 600 mm. The actual trigger or refill point for VRI was determined on a patch basis, while for uniform was determined from the either the soil type with the smallest or greatest PAW, or mean values that proportionally represent the characteristics of the soil types present. It has shown that with the observed variability in soil properties and system constraints, managing uniform irrigation to a single soil type may result in low WUE or yield loss. It has also shown that VRI is comparable to uniform application that is managed by deficits and refill points that proportionally represent the characteristics of all of the soil types present.