The majority of the Australian cotton crop is harvested using the John Deere round-module harvester, which has led to an increase in the overall axle loads being applied to the soil, and a subsequent increase in the risk of soil compaction. The extent of any actual compaction will depend on soil characteristics, tillage history and prior soil structural condition, and especially the soil moisture content at the time of harvest. Soil compaction leads to several hidden issues for the cotton industry which can limit productivity and affect resource use efficiency. Once soil degradation occurs at depth in the soil profile root growth can be severely restricted affecting water and nutrient use and ultimately profitability. Sodicity is also a major constraint in many cotton subsoils. Subsoil sodicity leads to decreased rooting depth and is often exacerbated due to increased irrigation frequency in irrigated cotton. This project conducted in-field and laboratory studies to address soil compaction and cotton production; management of soil dispersion under sodic soil and irrigation water conditions; and development of improved analytic methods.