The U.S. cotton industry is known for producing some of the highest quality cotton in the world.
Spinning mills continuously look for high quality cotton fiber to use in production for competition with improved synthetic fibers.
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.
The most critical component for producing high quality cotton is variety selection. The genetic makeup of a variety can play a large role in fiber quality. When selecting a variety, producers should look at all fiber quality characteristics to help make a decision for their fields.
Considerable progress has been made over the last 50 years in plant breeding to improve cotton yield potential and fiber quality. With continued breeding efforts, new varieties can help balance the inverse relationship between yield and fiber quality.1 For years, the breeders at Deltapine have been working with growers to increase the yield and fiber quality potential of its varieties. After extensive HVI and AFIS fiber quality measurement testing, as well as ginning performance testing, Deltapine Select™ varieties (Table 1) have demonstrated the best fiber quality and yield potential in the Deltapine lineup for the production of high-quality yarn and textiles.
Fiber quality plays an important role in both the creation and quality of the end product. The excellent fiber length found in Deltapine Select™ varieties means stronger yarn, and stronger yarn leads to improved spinning qualities — benefiting mills and textile industries with more opportunities. Cotton with higher yarn counts can also be spun down into finer yarn, which leads to a higher-quality end product. Deltapine Select™ cotton varieties give growers a strong advantage in today’s cotton market and ultimately a greater opportunity to increase their profit potential.
For more information about Deltapine Select, follow this link: https://www.dekalbasgrowdeltapine.com/en-us/deltapine/varieties/deltapine-select.html.
Effects of Management and Environment on Fiber Quality Characteristics
Once a variety is planted, the crop must be maintained throughout the growing season. Crops under less stress can produce higher quality fiber. Fiber quality is built throughout the entire growing season, and certain production practices can help protect the potential of the product planted.
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 more coarse 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. This 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. Applying harvest aids earlier than usual can reduce micronaire, but this approach is not usually recommended with many current varieties that stay in a moderate micronaire range. Low micronaire can be caused by a shortened growing season or the crop not having enough carbohydrates available. Disease, frost, and applying harvest aids too early can prevent a cotton crop from reaching maturity. A potassium (K) deficiency forces plants to pull K from the leaves, leading to senescence and the inability to photosynthesize. Without photosynthesis, the crop cannot produce enough carbohydrates to mature the bolls, leading to low micronaire. Excessive irrigation, fertilizer, and high plant populations can also contribute to a low micronaire value. Moderate weather conditions may cause too much 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 includes total crop management, from planting date, fertility, pest management, plant growth regulator application, and harvest.4
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 6 to 8%.5 When lint moisture is below 5%, each percentage lower is equivalent to 1/100 of an inch reduction in 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 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 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 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 may have lower harvesting efficiency because they are more subject to wear due to abrasion from soil particles.
Once cotton is harvested, it is either stored in round bale modules or large rectangular modules placed on the edge of fields until transported to a ginning facility. To help protect cotton during storage, rectangular modules should be covered with a high-quality tarp (Figure 2). Tarps should be checked for any tears or pin holes before use. Round modules are wrapped with plastic that covers the circumference of the bale and a few inches on the ends. 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 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 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.
For more information, please read the article, Cotton Harvest Considerations.
1 Constable, G., Llewellyn, D., Walford, S.A., and Clement, J.D. 2015. Cotton breeding for fiber quality improvement. Industrial Crops, Handbook of Plant Breeding 9. Ch. 10 pg 191-224.
2 Producing for quality. 2001. Cotton Physiology Today. National Cotton Council. Vol. 12 No. 1.
3 Hake, K. Bragg, K., Mauney, J., and Metzer, B. 1990. Causes of high and low micronaire. National Cotton Council. Physiology Today. Vol 1. No 12.
4 Silvertooth, J.C. 2001. Crop management for optimum quality and yield. The University of Arizona Cooperative Extension. AZ 1219. http://cals.arizona.edu/crops/cotton/cropmgmt/fiber_quality.html.
5 Hake, S.J., Kerby, T.A., and Hake, K.D. 1996. Cotton production manual. University of California Division of Agriculture and Natural Resources. Pub. 3352.
6 Kazama, E.H., da Silva, R.P., Ormond, A.T.S., Alacântara, A.S., and do Vale, W.G. 2018. Cotton and fiber quality in function of picker harvest speed. Revista Brasileira de Engenharia Agrícola e Ambiental. V.22, n.8, p.583-588.