5 MIN READ
Maximizing Cotton Fiber Quality
July 8, 2024
- The US cotton industry is known for producing high quality cotton.
- There are three main components that affect fiber quality in cotton: variety selection, environmental conditions, and crop management.
- Certain management practices can be implemented throughout the growing season to help maximize fiber quality and avoid discounts at the gin.
Variety Selection
Variety selection, crop management, environmental conditions, and the ginning process all contribute to cotton fiber quality. Considering the fiber quality characteristics of a cotton variety during product selection is an important part of the process. Plant breeding progress over the last 50 years has made considerable improvements to cotton fiber quality and yield potential, and breeding efforts continue to help balance the inverse relationship between yield potential and fiber quality.1
Fiber quality plays an important role in both the creation and quality of the final product. Excellent fiber length produces stronger yarn, which leads to improved spinning qualities and more product opportunities for mills and textile industries. Cotton with higher yarn counts can be spun down into finer yarn, which produces a higher-quality product. Cotton with high fiber quality can provide a market advantage and a greater opportunity to increase profit potential.
Crop Management and Environmental Conditions
Reducing stress is fundamental for maintaining the high fiber quality potential of a cotton variety. Fiber quality is built throughout the entire growing season, and certain production practices can help protect the potential of the planted product.
Micronaire is an indication of average fiber fineness and maturity. Micronaire is typically determined by environmental conditions instead of by variety selection. Fiber with micronaire values that are too high or too low can limit how the fiber can be used within the textile industry. Fibers with high micronaire are a result of excessive carbohydrate production during development, which results in coarser fibers. High micronaire cotton is used for products like denim, blends, and unwoven materials. Fibers with low micronaire result from low carbohydrate production. These fibers are often immature and can easily form neps that can lead to yarn breakage during the ginning process.2
In certain situations, management decisions may help producers avoid high or low micronaire fiber. High micronaire can occur when conditions lead to severe boll shed, which can occur when plants are water-stressed or exposed to high heat. When only a few bolls are retained on the plant, high amounts of carbohydrates become available to those remaining bolls, resulting in high micronaire. If high micronaire is anticipated, applying harvest aids earlier than usual may be considered. Low micronaire can be caused by a shortened growing season or the crop not having enough carbohydrates available. Disease, frost, and early harvest aid application can prevent a cotton crop from reaching maturity and consequently producing low micronaire fibers. Potassium (K) deficiency can also impact micronaire. Plants deficient in K will move available K from leaves to support boll production leading to leaf senescence and a reduction in plant photosynthesis. Without enough photosynthesis, the crop cannot produce the carbohydrates required for boll maturation, leading to low micronaire. Excessive irrigation, fertilizer, and high plant populations can also contribute to a low micronaire value. Moderate weather conditions may also cause increased boll production and retention, limiting the carbohydrates available for each boll and lowering micronaire.3 Managing for earliness and uniformity is important to help prevent high or low micronaire. This requires season-long crop management from planting date, fertility, pest management, plant growth regulator application, and harvest.4
For more information, read Causes of High Micronaire in Cotton and Low Micronaire in Cotton Production.
Fiber strength is primarily determined by the variety; however, the environment and certain cultural practices can have an effect on lint strength. Severe K deficiency and extreme weather conditions may cause physical or microbial damage to fiber, resulting in reduced lint strength.
To help maximize fiber length, proper management and ideal growing conditions must be available during the elongation phase of fiber development. Fiber elongation takes place in the first 16 to 25 days of boll development.2 During this time, high temperatures, water stress, and K deficiency can result in shorter fibers. Extended weathering of open bolls due to delayed harvest may also shorten fibers.4 Fiber length can also be affected by the ginning process. If cotton moisture is low during ginning, fiber length can be compromised due to breakage. The ideal ginning moisture range is six to eight percent.5 When lint moisture is below five percent, each percentage lower is equivalent to 1/100 of an inch reduction in fiber length.
Grade includes color and trash content. Weathering of bolls in the field, poor defoliation, and inefficient harvesting can lead to poor color and higher trash content. Very hairy leaves (high leaf pubescence) can attach to cotton lint, increasing trash content. Any contamination of the lint lowers yarn quality.1
Maintaining Fiber Quality During and After Harvest
Harvest aid applications should be made according to the recommended timing (see the article, Cotton Harvest Aid Application and Timing). Delayed applications can increase the potential for poor late-season weather, which can affect cotton quality. Harvested cotton must be stored until ginning, and any vegetative material or green trash left in the cotton module can result in excess moisture content, high trash count, and stained cotton lint.
Spindles on pickers, and bats and brushed on strippers, should be checked and replaced if needed prior to harvest. The lower third of the cotton plant typically matures before the rest of the plant. These bolls can be exposed to poor environmental conditions for longer. Lower spindles can have degraded harvesting efficiency because they are subject to more wear due to abrasion from soil particles.
Once cotton is harvested, it is either stored in round modules or large rectangular modules placed on the edge of fields until it is transported to a ginning facility. To help protect cotton during storage, round modules are wrapped with plastic that covers the circumference of the bale and a few inches on the ends (Figure 1). Rectangular modules should be covered with a high-quality tarp. Tarps should be checked for any tears or pinholes before use. Any excess moisture in the cotton can cause condensation, so modules should be monitored. When elevated moisture levels occur, temperatures increase within the module, compromising lint grade and potentially causing seed germination. Extreme cases of increased temperatures can result in spontaneous combustion.
Cotton module or bale temperature should be monitored for the first five to seven days. Ideally, cotton harvested at correct moisture levels should only increase 10 to 15 °F in the first five to seven days of module storage, then level off or decrease in temperature. A 15 to 20 °F temperature increase during the first five to seven days indicates a high moisture problem and that the module should be ginned as soon as possible.5 After the initial daily temperature check, modules should continue to be checked every three to four days. If a module reaches a temperature of 120 °F at any time during storage, the cotton should be ginned immediately.
Sources
1Constable, G., Llewellyn, D., Walford, S.A., and Clement, J.D. 2015. Cotton breeding for fiber quality improvement. In V.M.V. Cruz and D.A. Dierig, Eds. Industrial Crops, Handbook of Plant Breeding 9. Springer. https://doi.org/10.1007/978-1-4939-1447-0_10
22001. Producing for quality. National Cotton Council, Cotton Physiology Today. 12(1): 1–8. https://www.cotton.org/tech/physiology/cpt/fiberquality/upload/CPT-v12No1-2001-REPOP.pdf
3Hake, K. Bragg, K., Mauney, J., and Metzer, B. 1990. Causes of high and low micronaire. National Cotton Council, Physiology Today. 1(12). https://www.cotton.org/tech/physiology/cpt/fiberquality/upload/CPT-Sep90-REPOP.pdf
4Silvertooth, J.C. 2015. Crop management for optimum quality and yield. The University of Arizona Cooperative Extension. az1219. https://extension.arizona.edu/sites/extension.arizona.edu/files/pubs/az1219-2015.pdf.
5Hake, S.J., Kerby, T.A., and Hake, K.D. 1996. Cotton production manual. University of California Division of Agriculture and Natural Resources. Publication Number 3352.
Web sources verified 06/24/24. 1414_75901
