Cotton harvesting is a complex process. For farmers, a reputation for high quality can be the difference between avoiding discounts and capturing premiums.
Determining what harvest aid chemicals to use depends on factors including late-season crop vigor, patterns of boll set and relative boll maturity, weather conditions, and desired timing for harvest. Chemicals can be used to control plant growth, cause defoliation or desiccation, and stimulate boll opening.
Pre-harvest Inspection
Cotton grows in a variety of climates around the world, and its harvesting, processing, and consumption is an important international business. The United States is a major producer, and the country’s cotton goes to local textile mills and to market worldwide. As with many other agricultural products, the quality of cotton is often determined prior to harvesting and sale. Cotton can be sold for premium or discount prices depending on its fiber quality. The factors that influence cotton quality before harvest are numerous and can vary from field to field, growing season to harvest season, and even from gin to gin.
The USDA classing system quantitatively describes cotton bales, giving buyers, merchants, and textile manufacturers an accurate, dependable determination of each crop’s properties and value. The cotton industry uses the system globally, and is a standard recognized by many foreign governments and trade organizations.
A significant portion of cotton in the US is processed at two USDA classing offices located in Memphis, Tennessee, and Macon, Georgia. These facilities process 20 million bales per year and are the global benchmark in cotton quality control.
Before a cotton field is harvested, it must be inspected to determine its grade and potential quality. For example, the percentage of open bolls is an important indicator of potential quality. Ideally, the percentage of open bolls should be 60% or higher.
If the percentage of open bolls is below 60%, it is recommended that the fields be defoliated to improve the chances of high fiber quality. However, the amount of defoliant required to reach this goal varies widely among regions and varieties. The optimum level of defoliation depends on weather conditions, plant maturity, and soil moisture levels.
Pre-harvest inspections should also focus on the appearance and condition of the lint. Poor lint will negatively affect the grading process, and a lower-grade lint will be less attractive to consumers.
Another critical factor in the lint’s quality is the presence of Neps, entangled and knotted fibers resulting from faulty handling or ginning procedures. Neps can affect both a gin’s and grower’s reputation, as buyers are willing to pay premiums for quality that is free of them.
Post-harvest Inspection
Postharvest handling includes all procedures that occur after a commodity is harvested from the field and before it is sold. This can include harvesting, cooling, curing, ripening, packing, transporting, storing, wholesaling, and retailing. A high level of management is needed to ensure that quality is maintained throughout these steps. Since a product can change hands so many times during postharvest processing, it is very important to maintain quality at each step. If a quality problem is not identified and corrected at this stage, it can become more difficult to address later in the process.
The quality of cotton fiber depends on a variety of factors, including plant genetics, environmental conditions, and crop management practices. However, certain steps can be taken to improve the quality of cotton and avoid discounts at the gin. These steps include using the proper variety, monitoring the environment, and implementing good crop management practices.
To maintain quality, the first step is to monitor plant health through regular scouting and inspection. This is done to determine whether the crop has been affected by disease, insect infestations, or environmental stresses. It is also important to keep up with plant nutrition, as it can affect the yield and quality of the fiber.
In addition, the use of defoliants and growth regulators should be minimized. These chemicals can affect harvester efficiency, cotton trash content, lint staining, and fiber micronaire. In addition, they can lead to nutrient imbalances that reduce lint strength.
It is important to use a clean and safe working environment during the harvesting process. Keeping the area free of debris and other contaminants can help prevent accidents and injuries to workers. Using a proper cleaning system can also improve safety and reduce the time spent on cleanup.
It is also important to use a high-quality picking machine that can handle large volumes of cotton quickly and efficiently. Choosing the right machine will reduce labor costs and increase productivity. Moreover, it will improve the quality of the cotton fiber, which can increase the profits of farmers, traders, and handlers.
Post-ginning Inspection
In the cotton industry, ginning separates the fiber from seeds and impurities. This process is critical to achieving high-quality textiles. It begins with proper harvesting and continues through processing at the ginning mill.
Once harvested, the long and strong cotton fibers are placed in round modules and wrapped in plastic to protect them while storing and transporting them to the gin for ginning. This mass is called seed cotton. Once at the gin, it is separated into the fiber (lint) and seeds. It is also inspected to make sure it meets certain standards for its final use.
Cotton ginning involves using precise mechanical processes to separate the fibers from the seeds and other foreign matter. This is a complex process that must be carried out in such a way as to preserve the intrinsic properties of the lint while at the same time making it suitable for textile production.
The ginning process must be carried out at the optimum temperature for maximum efficiency and quality. The optimum temperature is between 65 and 75 degrees Fahrenheit. This is the best temperature to achieve the most efficient ginning and to avoid dehydration of the fibers.
During the ginning process, the lints are separated from the seeds, and the seeds go on to become cotton-seed oil or used as feed for animals. The lints are then made into yarn and fabrics.
Once the ginning is complete, all the modules or bales are stored in the warehouse. They must be clearly labeled to identify their producer, field, and location. This helps trace the cotton and ensures it arrives at its destination in good condition.
During the ginning process, removing plastic contamination is one of the biggest challenges. This is caused by pieces of the plastic used to wrap the round module that break off and are carried into the first machine of the gin. This problem costs the cotton industry more than $100 million per year. Several solutions have been developed to remove plastic contamination, including an automated system that detects and actuates solenoids to eject the plastic from the gin-stand feeder apron.
Final Inspection
The USDA cotton classing system is an international standard for a dependable determination of each bale of cotton’s quality characteristics and value. In addition to providing a uniform, marketable description of cotton, the quality characteristics and grades associated with each cotton crop enable producers, merchants, and textile manufacturers to compete in the world markets. As the cotton production industry continues to evolve, automated systems can play an increasing role in weed control, plant growth regulator applications, and harvesting and ginning.
In the near future, autonomous harvesting systems may help to eliminate human error and reduce labor costs and risks. The system must be reliable and flexible to meet a wide range of growing conditions. The current round module harvester used in the US uses a single, once-over process that is simple to use and easy to maintain. However, a more versatile robotic system may be possible to harvest a field repeatedly and then load the fiber bales for transport.
A robot that identifies cotton bolls and can determine when the boll is ready for harvest would be a valuable tool in improving quality. Machine vision tools are being developed to identify cotton bolls under different lighting conditions. This technology could also be applied to monitor the condition of the cotton as it moves through the ginning and processing processes.
As the demand for cotton increases, maximizing the quality of the lint produced is important. Growers can receive a 2.5 cent per pound premium for above-average fiber quality but lose income if the quality drops below standards. This is why achieving a high USDA fiber grade is important for growers.
Discounts can occur due to a variety of factors, including planting dates, varieties, defoliation, weather, and harvest conditions. Leaf grade and trash discounts are the results of non-lint particles contaminating a sample of lint, including bark, seed coat fragments, small “pepper” trash, dirt, spindle twist, oil, and whitefly stickiness.
Trash content also affects the overall quality of the fiber. It is difficult to measure but is related to the percentage of open bolls at the time of defoliation. Research has shown that using the multi-spectral vegetation index to optimize PGR rates can increase boll opening and lower the trash content of the cotton.