A project was funded by the Cotton Research and Development Corporation and conducted by the National Centre for Engineering in Agriculture to support the industry in the continuing successful uptake of Centre Pivots and Lateral Moves (CP&LMs) across the Australian cotton industry.

In particular, the cotton industry required assistance in developing their understanding of the way irrigation water from CP&LMs moves through the soil profile in some of Australia's most difficult and challenging soil types. These soils with their naturally low infiltration rates, and in some cases an additional propensity for surface crust and seal development, present sprinkler package designers with particular challenges not encountered elsewhere, especially in terms of uniformity, application efficiency and droplet impact energy levels. The high system capacity, large machine size and extreme weather conditions encountered in combination in the Australian cotton industry exacerbate these issues and require particular design considerations for these sprinkler packages.

To assist the cotton irrigation community understand where CP&LM irrigation water has moved to in the soil profile, over 300 images of soil moisture have been developed from a set of 25 capacitance sensors sited under seven different machines, on different soil types, sprinkler types and growing conditions. A set of video images of the different sprinkler types and their interaction with crop and soil under typical field operating conditions have been produced to assist growers in their understanding of the sprinkler options available.

In addition, a simple software package was developed to assist new CP&LM irrigation managers visualise alternate irrigation strategies, and their influence on the resultant soil moisture levels across the irrigated field.

A series of guidelines have been produced for sprinkler package design and soil moisture probe placement on CP&LMs. The sprinkler guidelines will assist the CP&LM irrigation community to understand the importance of sprinkler design and methods to reduce droplet impact energy levels to below that of natural rainfall to reduce surface crusting and sealing. The probe placement guidelines will aid growers and agronomists to work through the important factors in deciding the type and placement of soil moisture monitoring equipment in CP&LM irrigated fields.

To obtain further information on this work or related matters please contact the Director, National Centre for Engineering in Agriculture, University of Southern Queensland, Toowoomba on ph 07 46 311 871 or email on schmidte@usq.edu.au .