The minirhizotron system was purchased and field use commenced in January 2002.

A standard operating procedure (SOP) and protocols for using it under field conditions is being defined at present. Technical staff in the soil management program were also trained in its use. Mr. Peter Roberts, an honours student from the Department of Crop Science at

Sydney University, connnenced a project on root dynamics of irrigated cotton under different tillage systems during 2001-02.

Initial results suggest that under irrigated conditions cotton loses a major proportion of its fine root mass, and survives on its tap root. With the end of the irrigation season in March, most of the fine root mass is replaced. Minimum~tilled cotton has more roots in the furrows than intensiveIy-tilled cotton. Root/shoot ratios during early crop growth (up to December, before irrigation commences) are in the order of 4, and not around 0.2-0.4 as previously thought.

Root growth appears to take place primarily through existing soil cracks, and not through the bulk soil.