Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 1, 1998
Publication Date: N/A
Interpretive Summary: Measurement of cotton fiber strength helps establish the market value and utilization potential of 13-22 million bales per year of U.S. cotton. These high volume instrument (HVI) tests affect the value of cotton when marketed. Since cotton fibers exhibit higher strengths at higher moisture contents, expensive moisture controls are used at the testing laboratories where HVI strength is measured to control the fiber moisture content. Despite these controls, the repeatability and accuracy of HVI strength measurements needs improvement. A potential solution is to measure the moisture content of the cotton sample and adjust the strength to a common level of moisture. In order to evaluate this solution, four separate tests were conducted with a newly redesigned resistance moisture meter. Results indicated that moisture substantially affected strength and the moisture measurement adequately corrected for variations in HVI strength caused by the treatments. Implementation of a moisture measurement to correct strength measurements for moisture variations will improve accuracy and reliability of the HVI strength measurement, and relax the need to condition samples for 48 hours. Strength measurements on cotton will be of greater value to the textile mill and make cotton more competitive with synthetics.
Technical Abstract: Four tests of different designs were conducted with the assistance of two USDA Agricultural Marketing Service (AMS) offices; these tests showed a strong correlation between cotton fiber strength and moisture content. The first test, done at the Memphis classing office, demonstrated the usefulness of the resistance moisture meter and showed a relationship between moisture content and High Volume Instrument (HVI) strength. The second test was done at the Greenwood, MS, classing office during the regular classing season to determine the range of moisture contents experienced at a classing office. The measured moisture content of cotton was found to vary significantly during classing and samples with higher moisture content had higher HVI strength. Ninety-six percent of the samples were within the range of 6.3% to 7.6% wet basis (w.b.) but the observed range was 5.8% to 10.0% w.b. These variations in moisture content twere large enough to cause significant variation in the HVI strength. The third test was done at the Greenwood classing office on samples prepared at the U.S. Cotton Ginning Laboratory, USDA, ARS, Stoneville, MS, and ginned under several moisture treatments. It showed that ginning procedures affect the moisture content relatively little, but a measureable reduction in strength was attributed to ginning at moisture contents below 7% w.b. The fourth test was conducted at the Greenwood classing office where samples were subjected to nonstandard moisture conditions and then HVI classed. This test showed that even when the moisture variation was low, (0.3% w.b.) there was a measureable affect on HVI strength.