Around 50% of the cotton bales produced in the world are sold based on the analysis of their technological characteristics using a standardized instrument for testing cotton (SITC). In the United States of America, periodical studies of variability of the results allow the results to be accompanied by commercial tolerances to limit the frequency of claims. However, to our knowledge, no such study has been conducted in Africa. For this reason, we studied within-bale variability of fiber micronaire, length, uniformity, strength, reflectance and yellowness as measured by the SITC. We took eight samples per bale from 215 cotton bales produced by 27 ginning mills in eight Sub-Saharan countries in Africa in two cropping seasons. Our representative sample was composed of 1720 fiber samples that were analyzed in controlled conditions using the SITC in a laboratory in which international recommendations are fully respected. We measured within-bale variability and suggest a sampling method and procedure to perform technological and instrumental tests in West and Central Africa.

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 sawand 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.