The physical condition of soil is a vital aspect of sustainable agricultural production systems and the

inherent physico-chemical characteristics of soils are essential in determining the impact of irrigated

agricultural systems on the soil physical condition. An understanding of these changes to the soil

physical condition is important in making informed decisions on changes in production systems.

This research assessed the changes to the soil physical condition following a conversion from rice

to cotton production systems on a red and grey soil. The two soils, indicative of the NSW Riverina

region, were selected to examine virgin and rice soil conditions as well as soils to have undergone

recent and longer-term conversions to cotton. Soil morphological observations, in pits excavated to

30 cm, showed the rice soils to contain a massive sub-surface while the virgin soils exhibited

coalescence and biopore development. Soil pedality improved on both cotton soils following

changes out of rice production. These observations were consistent with penetration resistance

measurements, whereby the rice soil exhibited resistance levels which would inhibit cotton root

growth. Soil bulk density, as well as sorptivity and steady state infiltration, did not correlate with

the observed soil morphology due to the high shrink-swell clay content. The morphological

observations, in conjunction with penetration resistance, showed the grey soil to recover at a faster

rate following a change from rice to cotton production. This was due to a higher Ca:Mg ratio and

greater aggregate stability.