To improve the management of grain crops in the Mallee region of Victoria using precision agricultural technology: and more specifically, to improve the understanding of the causes of spatial variability within a paddock and its interaction with seasonal conditions as this knowledge is regarded as essential to developing appropriate management strategies in precision agriculture.

Experiments were conducted in a commercial lentil crop (2006) in a paddock considered representative of the southern Mallee region of Victoria (McCellands Jil Jil East). The study identified that seasonal variations in the spatial pattern for grain yield were explained principally by differences in the ‘effective plant available water’ (ePAW) rather than differences in nitrogen supply. ePAW was considered to be related to both the textural properties of the surface soil (eg. small rainfall events at the season break are more effective in coarser textured soils than in clay soils) and the presence of physio-chemical in the subsoil, which can limit crop access to stored water.