Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/3/2004
Publication Date: 2/1/2005
Citation: Anthony, W.S. 2005. Moisture change of cotton bales during storage. Applied Engineering in Agriculture. Vol. 21(1): 35-42.
Interpretive Summary: The United States cotton industry produces about 20 million bales of cotton annually and over half is exported. New, less permeable bale covering materials are under consideration to provide greater protection to the baled fiber; however, they may also retard the movement of excess moisture from the bale. A recent increase in the amount of moisture restored to cotton fiber after ginning and before packaging has increased industry concern related to possible fiber degradation during storage due to the excess moisture. This study evaluated the impact of two current and two proposed bale coverings on moisture transfer during extended storage under conditions of changing humidity. Moisture transfer was substantially less for the new bagging compared to the current bagging. Thus, ginners must ensure that initial moisture levels are below 7.5% when bales are packaged in the new, less permeable bagging to avoid degradation of fiber color. Implementation of procedures to ensure that bale moistures remain below 7.5% will prevent loss of the market potential of cotton.
Technical Abstract: The purpose of this research was to determine the moisture transfer and weight gain of universal density cotton bales packaged in different materials. Bagging materials investigated included both woven polypropylene bags with extrusion-coated strips to prevent fibrillation as well as similar bags that were fully coated on the interior to reduce contamination. Three bales each were ginned, packaged, and placed in four different types of bags¿two types of woven polypropylene spiral sewn bags with alternating extrusion-coated and uncoated strips, and two types of fully coated bags. Initial moisture contents averaged 3.6%. The bales were stored for 140 days at 70% relative humidity (RH) and then at 50% RH for 88 additional days. Bales were weighed and measured for thickness twice each week. After 140 days, the strip-coated bales averaged 6.9% moisture and the fully coated bags averaged 5.3%. After an additional 88 days of storage at 50% RH, the strip-coated bales averaged 5.9% moisture and the fully coated bags still averaged 5.3%. The bales in the fully coated woven polypropylene bagging changed moisture much more slowly than those in the strip-coated materials. Bale thickness changed from as little as 0.3 cm (0.1 in.) to as much as 2.2 cm (0.8 in.) as moisture content changed for the bales in the four types of bagging. Fiber quality did not change during storage.