The adoption of round module cotton pickers expanded rapidly in Australia after their introduction in 2008. The objective of this study was to monitor changes in fibre quality as a result of storage time and changes in conditions within modules. Temperature, relative humidity and moisture content of seed cotton in plastic-wrapped round modules, and the resulting fibre quality, were monitored for extended periods of time across three locations over three seasons. All modules observed across seasons and locations had initial moisture contents of less than 12%, which was consistent with recommended practice. Moisture levels and temperature in the modules during storage closely followed but trailed changes in ambient weather conditions. With modules typically picked during late summer through to mid-autumn, conditions inside the modules typically cooled and dried during storage. The direction of the open module face affected the rate of drying and/or cooling, as did covering modules with a tarpaulin. Fibre quality was largely stable across storage periods of up to three months, although colour (yellowness) and fibre elongation consistently degraded, even after one month of storage. Over longer periods properties such as length and strength were negatively affected although changes, whilst statistically significant, were often small or inconsequential in terms of the commercial premium paid for these properties. From this study we conclude current guidelines for cotton harvesting and storage are applicable to these new round modules. Interestingly, the ‘negative’ changes in fibre yellowness often increased the value of cotton in terms of its USDA colour grade.
