Irrigation Efficiency: What it is and can we improve it? provides some useful definitions of efficiency that irrigators can use to evaluate how efficient their irrigation is. It also guidelines on best management practices to help irrigators improve their performance.
Assessment of Irrigation Performance at Regional and Property Scale (.PDF) describes a method by which irrigation performance on a whole farm scale can be assessed by using an annual water balance approach.
Soil surveys maps the types and distribution of soils on a property. A knowledge of what soil types are present greatly assists irrigation management.