Reports CTRM for Agricultural and Soft Commodities

CTRM for Ags & Softs that the standards are no longer representative of the crop, special measures must be taken to review and amend the standards. Instrument standards are cottons used for instrument calibration and verification. These standards include Universal HVI Calibration cotton, Extra-Long Staple (ELS) Calibration cotton, Universal HVI Micronaire Calibration cotton, and Universal HVI Cotton Color and Cotton Trash Standards. These standards serve the USDA and many other cotton organizations worldwide as the basis for instrument cotton classification. The USDA maintains fifteen physical Upland Grade Standards and six physical American Pima Grade Standards. Cotton selected for use in instrument calibration must pass rigorous screening procedures. As a first step, the USDA conducts an extensive search in the National Database for uniform lots of cotton from the current crop that have fiber properties appropriate for their intended use. Candidate bales are purchased from producers and retested through a rigorous value-establishment process to determine whether they meet the strict certification requirements set for calibration cotton. In addition to bale uniformity requirements, each bale must meet the length and strength criteria for its intended use. For example, an Upland long/strong calibration cotton bale must have approximate length and strength values of 1.15 to 1.22 inches and 32 to 36 grams per tex, while an Upland short/weak calibration cotton bale must have length and strength values below 1.01 inches and 23 to 26 grams per tex. Currently, seven laboratories work together to establish values for calibration cottons, including five USDA facilities, one independent laboratory in the U.S. research community, and one well-established international laboratory. The independent U.S. and international laboratories are required to operate under the same rigid specifications as USDA facilities to participate in the value-establishment process. Cumulatively, the laboratories perform at least 120 tests per bale over a two-day testing period. The results are used to further evaluate uniformity and to determine the values assigned to the calibration cottons. For reference purposes, samples of previously established, or “benchmark”, calibration cottons are included in the testing, along with samples from candidate bales. These benchmark cottons then provide reference points to assure the continuity of testing levels over time. If test results within a bale are outside of the prescribed limits, the bale is rejected. If all testing criteria are met, the bale is accepted, and its contents are packaged for distribution as calibration cotton. Classification of Upland Cotton Measurements for fiber length, length uniformity, fiber strength, micronaire, color grade, trash, and leaf grade are performed by precise High Volume Instruments, in a process commonly referred to as “high volume instrument classification.” Only extraneous matter and special conditions are still officially classified by the traditional method of classer determination.    Fiber length is the average length of the longer half of the fibers (upper half mean length). It is reported in both 100ths and 32nds of an inch. Fiber length is measured by passing a “beard” of parallel fibers through an optical sensing point. The beard is formed when a clamp automatically grasps fibers from a sample of cotton, then combed and brushed into parallel orientation. Fiber length is largely influenced by variety, but the cotton plant’s exposure to extreme temperatures, water stress, or nutrient deficiencies may result in shorter fibers. Excessive cleaning or drying at the gin may also result in shorter fibers. Fiber length affects yarn strength, yarn evenness, and the efficiency of the spinning process. The fineness of the yarn that can be successfully produced from given fibers also is influenced by fiber length. Length uniformity is the ratio between the mean length and the upper half mean length of the fibers, expressed as a percentage. However, because of natural variation in the length of cotton fibers, length uniformity will always be less than 100 percent.Length uniformity affects yarn evenness and strength and the efficiency of the spinning process. It is also related to short fiber content (content of fibers shorter than 1/2 inch). Cotton with a low uniformity index is likely to have a high percentage of short fibers. Such cotton may be difficult to process and is likely to produce low-quality yarn. Fiber Strength measurements are reported in grams per tex. A tex unit is equal to the weight in grams of 1,000 meters of fiber. Therefore, the strength reported is the force in grams required to break a bundle of fibers one tex © Commodity Technology Advisory LLC, 2016, All Right Reserved 22

Reports CTRM for Agricultural and Soft Commodities | Page 23