Since the early 1960s, global agricultural output has increased at rates and to levels that are unprecedented in human history Much of the productivity increase is attributed to the breeding of high-yielding crop varieties, intensive use of inorganic fertilisers and pesticides, expansion of irrigation and capital-intensive farm management. However, over the last few decades the euphoria surrounding this 'Green Revolution' has subsided, due to a growing community awareness of the long-term environmental consequences of these practices. Since then, agricultural research has expanded its scope to include sustainable and resource-efficient cropping systems and farm management practices.

A major issue facing the cotton industry in Australia is the potential for surface and groundwater contamination from the inefficient application of nitrogenous fertilisers. This dissertation appraises the merits of applying site-specific nitrogen management to irrigated cotton in Australia, as this system has been hypothesised as being economically and environmentally more sustainable than the traditional 'blanket' approach to the application of crop production inputs. Site-specific crop management (SSCM) utilises new technologies such as Global Positioning System (GPS), yield monitors, orbital-satellites and variable-rate crop applicators to identify within-field crop and soil variability as well as their causes. The rational behind SSCM is 'by identifying within-field variability in crop and soil attributes and their origin', it then becomes possible to optimise crop production inputs such as pesticides and fertilisers on a point- by-point basis. Implicitly, this lowers the potential for their over- and under-application.