Application of a published methodology for evaluating within-bale repeatability of measurements obtained with standardized instruments for testing cotton: Gossypium hirsutum in Eastern and Southern Africa

Abstract

The possible application of conclusions from a published study concerning cottons from West and Central Africa (WCA), involving an evaluation of the within-bale variability of fiber Micronaire, Length, Uniformity, Strength, Reflectance and Yellowness in cottons from Eastern and Southern Africa (ESA) was investigated. We took eight cotton samples per bale from 240 bales produced by 32 ginning mills in six ESA countries in two crop seasons. Our representative sample comprised 1920 fiber samples that were centrally analyzed under controlled conditions using standardized instruments for testing cotton (SITC). We evaluated within-bale variability levels for both saw- and roller-ginned cottons and checked the applicability of the published conclusions to ESA. We found that (1) sampling variance levels were comparable in ESA and in WCA for saw-ginned cottons, (2) WCA recommendations for saw-ginned cottons would also apply in ESA for most fiber characteristics measured by SITC, and (3) for roller-ginned cottons, the higher within-bale variability of roller-ginned cotton fibers compared to saw-ginned cotton would require the definition of a specific sampling and testing method based on an experiment to be designed.