13-1039 JULY 1965 Eiieets oi Deferred Ginning oi Cotton on Cotton Fiber Quality as Reflected in Certain Fiber Properties TEXAS AScM UNIVERSITY Texas Agricultural Experiment Station R. E. Patterson, Director, College Station, Texas S UMMAR Y This research investigated the effect of different harvest periods and ginning treatments on moisture content and selected fiber properties of machine-picked cotton. The harvest periods and ginning treatments were (1) morning harvest followed by either immediate or deferred ginning and (2) after- noon harvest followed by either immediate or deferred ginning. Fiber samples were obtained at the lint slide throughout the ginning of each bale of cotton in each of the four ginning treatment periods. Statistical analyses of moisture and fiber property measurements made on these samples revealed that cotton ginned l day after harvest was not of significantly lower quality in any of the fiber property measures. However, this deferred ginning treatment did significantly improve the fiber length and length distribution. It was concluded that deferred ginning of cotton would not change the immediate value of the cotton to producers or ginners. However, this treatment would significantly im- prove the spinability of the cotton to mills and thereby strengthen the markets for such cotton in the future. Con ten ts Introduction Moisture Content .................................. .. Quality Characteristics ......................... .. ‘ Purpose ............................................................ .. Procedure Results of Analyses, 1962 and 1963 Data. Moisture Relationships ................... .. Digital 2.5 percent span length... Digital 50 percent span length ......... Percentage of fibers shorter than one-half inch in fiber array ......... .. Coefficient of fiber length variation in a fiber array ............... .. Interpretations and Implications ............. .. Acknowledgments......................._._.._._.,_________,,,__ Literature Cited...‘ ......................................... __ tcnqmsn or AMERICAN UPLAND COTTON has to Jpe with seed cotton with wide variations in a content making it necessary to install costly W e-control devices in his gin. These moisture it cannot always compensate for wide varia- seed cotton moisture and frequently result heated cotton and damaged fiber. Over- pg diminishes the natural oils and waxes in the i and subjects them to excessive breakage (1). hull spinning potential of cotton can be realized if its delicate surface properties are not damaged ghout harvesting, ginning and storing ecent research in the Mississippi Delta re- V- that when early morning-picked and after- i‘ picked cotton were stored in trailers for an ex- ~ period of time before ginning and given equal A; in the gin, the morning-picked bales lost al- la full grade in quality. A major part of the grade _i nce was associated with color loss while the f’ was stored in the trailers. Tests on cotton p. throughout the day showed that lint quality affected measurably when seed cotton con- v excessive moisture, provided the cotton was d directly to the gin and dried thoroughly (S) . study was initiated in 1961 at the Texas A8cM “ersity Plantation in the Brazos River Valley urleson County to determine the effect of field ture content of seed cotton on selected fiber frties. This report analyzes gin plant and fiber fatory data for the second and third years of a f study. Data collected the first year were not iauate for meaningful analysis. _ The cotton sampled was machine harvested with gale-type pickers. Some of the samples were from not defoliated, as prolonged dry weather prior arvest hastened maturity of the plants and pro- g-t natural shedding of the leaves. f The following characteristics were examined 1| samples of cottiion harvested in August and mber 1962 and 1963: moisture content at the er, extractor feeder and lint slide; digital fibro- E» 2.5 and 50 percent span lengths; percentage fibers shorter than 1/2 inch in a fiber array; the iistant professors, Department of Agricultural Economics - Sociology. Eiieets 0i Deferred Ginning 0i Cotton on Cotton Fiber Quality as Reflected in Certain Fiber Properties James M. Ward and james W. Gravesi‘ coefficient of variation of fiber-length array; nonlint content and lint color. ' Moisture Content Moisture levels were determined with a Hart moisture meterl for seed cotton on the trailers and at the extractor feeder and for the lint at the lint slide. Samples were obtained for moisture readings continuously throughout the ginning process. Half of each seed cotton sample was ginned immediately, and the other half was ginned after being stored 18-24 hours. Since moisture transfer within seed cotton occurs during early stages of storage, the meter readings of the deferred ginned lots tend to be more accurate than the moisture mea- surements of the immediately ginned lots (5). Quality Characteristics The 2.5 percent span length measured on a digital fibrograph refers to the length of the longest 2.5 percent of the fibers in the test specimen. The fibers are measured as if they had been caught by a pair of rolls in the first draft zone at a yarn mill. They are parallel, randomly distributed, and the percent is determined by number count. Therefore, the 2.5 percent span length is really a distribution of length measurement relating the length of fibers to the number of fibers (6). Span lengths are fiber extension distances measured in an arrangement similar to fibers in yarn processing machinery. The “beard” which extends from the fibrograph comb is essentially the same as the “beard” which extends into machinery zones of fiber transfer Fiber extension distance encompasses fiber length, dis- tribution of length and state of randomness. The length measurement most closely associated with high yarn strength is the 2.5 percent span length (8). The average digital 2.5 percent span length and the classer’s staple on a IOO-bale. lot of even-running cotton usually correspond within a tolerance of i .02 inch (9). ‘Due to the changing moisture conditions of the cotton at the different sampling points, there was some error associated with the meter readings. During periods of moisture addition, the meter tends to read high; during drying, the meter reads low (4). The digital 50 percent span length is a mea- surement similar to the 2.5 percent span length. The 50 percent span length means that 50 percent of the number of fibers are as long 0r longer than the length indicated. One of the best predictors of ends down in the spinning process is the 5O per- cent span length. Ends down 1's a measure of break- age of yarn during the spinning process (8). Array tests were performed on the Suter-Webb fiber sorter. Briefly, this method consists of parallel- ing the fibers in a representative 75-milligram speci- men of cotton through a series of combs, separating fibers into length groups at 13-inch intervals and weighing the fibers in each length group. Although the Suter-Webb array measurement of fiber length and length distribution is time con- suming, it is the most accurate and consistent method of determining length and length distribution cur- rently available. Fiber-length distribution is opti- mized when the low, or short end, of the fiber array is minimized. Therefore, a desirable Suter-Webb array is one in which the gradation from the long to the short fiber groups occurs evenly and the per- centage of fibers shorter than 1/2 inch is low. The percentage o-f fibers shorter than 1/2 inch indicates the ratio of the weight of the four shorter 15-inch length groups t0 the total weight of the specimen. TABLE 1. PLANTATION, 1962 AND 1963. . erties examined included 2.5 and 5O percent‘ MOISTURE CONTENT OF MACHINE-PICKED COTTON AT THREE SAMPLING PO‘ FOR TWO GINNING TREATMENTS, MORNING AND AFTERNOON, TEXAS A8cM UNIVE The array coefficient of length variatio measure of the relative variability of fiber le the sample tested. It represents the standard tion of the weight-length frequencies expr a percentage of the mean length. Larger coef f indicate less uniform fiber length distributions‘ cessive fiber length variation tends to increase i, facturing waste, make processing more difficu lower the quality of the finallproduct (l0). I Fiber length distribution now is recogni being as important as conventional staple len its effects on mill operations and costs and c“ quality and value of cotton yarns (ll). Poor,‘ length distribution limits speed of operatio: quality of the finished product (l2). Fiber a distribution and the short fiber content of 1 can be altered adversely in the ginning process. . report analyzes the causes and suggests remed' adverse changes in fiber-length distribution. Purpose The purpose of this study was to determ the time of harvest, the moisture content of t ton or the type of ginning treatment had any’ ficant effect on selected fiber properties. f‘? moisture content was obtained for the harvest I l’ of morning and afternoon and related to imm I and deferred ginning treatments. The fiber ‘T' Average moisture Range of mois if Sampling Harvest Ginning Point Period treatment 1962 1966 1962-66 1962 1f — —— — — — — — percent — — — — — Trailer Morning Immediate 11.6 13.2 12.3 8.6-l6.0 8. . Deferred 11.9 13.3 12.5 8.6-16.0 9. i‘ Afternoon Immediate 11.6 12.6 12.0 21.1-16.6 6. Deferred 10.9 12.1 11.4 6.4-16.0 7. i’: Morning Immediate 11.6 13.0 12.2 8.1-16.0 6. l’ and Afternoon Deferred 11.4 12.7 12.0 6.4-l6.0 7., Extractor Morning Immediate 6.7 7.8 7.2 5.0- 9.3 5. ; Deferred 6.2 7.9 7.0 5.2- 9.0 5. Afternoon Immediate 6.0 6.9 6.4 4.6-10.0 Deferred 5.9 7.6 6.7 5.0- 9.8 Morning Immediate 6.3 7.4 6.8 4.6-10.0 5. and Afternoon Deferred 6.0 7.7 6.8 5.0- 9.8 5 " ' Lint slide Morning Immediate 6.2 6.2 6.2 5.0- 8.1 Deferred 6.5 6.9 6.7 5.3- 9.0 i, Afternoon Immediate 5.9 5.8 5.9 5.0- 7.6 4.’ Deferred 6.9 6.9 6.6 59- 8.6 s. Morning Immediate 6.0 6.0 6.0 5.0- 8.1 4. c. and Afternoon Deferred 6.4 6.6 6.5 5.0- 9.0 5._ I centage of fibers in an array shorter than and coefficient of variation 0f fiber-length ificantly higher quality lint cotton can be _ from deferred ginning, mills could afford emiums for such cotton. Even though loan rough government programs may be based er measures of quality, the true worth of f0 mills is indicated by the value of their y‘ roducts less manufacturing cost. Optimum fmethods allow cotton to maintain the high- ble value for manufacturing, independent 'cial prices assigned through price support 9 . Procedure ‘ividual trailer lots of machine-picked seed were sampled and ginned in 1962-63. In fdata were obtained from cotton harvested I 21-23 and September 5 and 19; the 1963 ere taken from cotton harvested August 12, land 30. One trailer load of seed cotton was if during each morning and midafternoon of fay. One-half of each load was ginned im- ely, and the remainder was placed under cover nned 18-24 hours later. The deferred ginned i; was compared with that ginned immediately to “ine the effect of trailer storage on fiber quality. 'ght 0r more moisture readings were taken F trailers in the field immediately following. harvesting. Moisture observations on the deferred lots were made again just before ginning. Moisture content of the cotton was recorded at the extractor- feeder apron and at the lint slide. Table 1 shows the averages and ranges of the observations made at each sampling point. Samples drawn at the lint slide were combined into a composite sample and tested in a fiber laboratory to measure fiber length, fiber length distribution, color and nonlint content. Data on moisture and fiber properties were ana- lyzed by a nested analysis of variance treatment to determine if there was a significant difference be- tween days, periods (morning and afternoon) and immediate or deferred ginning treatments. A sum- mary of the variance analyses for the 1962-63 observa- tions is presented in Table 2. By grouping the samples into pairs of bales harvested at the same time and by comparing those ginned immediately with those ginned 18-24 hours later, it was possible to determine significant differ- ences due to ginning treatments. The t-test was used to determine if differences in moisture and fiber properties were due to chance or to the ginning treat- ment. The technique of pairing observation into bales picked at the same time and location allows differences in moisture and quality from factors other than ginning treatments to be minimized within each pair. The variation from one pair to another does not influence this test of the effects of deferred ginning. The results of the test of dif- E 2. SUMMARY OF VARIANCE ANALYSES FOR MOISTURE CONTENT AND FIBER PROP- _i ES OF MACHINE-PICKED COTTON, BRAZOS RIVER VALLEY, 1962 AND 1963 Array - . . . . e ent AITaY A e of Trailer Extractor Lint slide Dlgltal Dlgltal olf rfcibers “(Efficient ’ti0n moisture moisture moisture 2'5 span 50 Percent shorter of fiber = length span length len th than 1/2 . g. _ variation inch Mean Mean Mean Mean Mean Mean Mean D.F. square D.F. square D.F. square D.F. square D.F. square D.F. square D.F. square 4 57.2896* 4 7.2784 4 7.5925 4 .0008 4 0022* 4 10.6885 4 21.9471 xperiod 5 10.6089 5 2.9459 5 1.5820 5 .0009 5 .0003 5 5.9284 5 6.3472 Xperiod ‘ning 10 ll.6707** l0 2.0864** l0 3.0144** l0 .0006** 10 .0003** 10 3.9034* l0 9.2926** g 3 150.01 3 59.67 3 2.13 3 .0067 3 .02l* 3 57.23 3 72.65 yxperiod 4 5326*» 4 10.28 4 9.13 4 0021* 4 .0016* 4 15.21 4 18.17 p“ xperiod i ginning 8 7.81* 8 9.83* 8 6.82** 8 .00054 8 .0003l6 8 7.56** 8 9.59** ignificant at 5 percent probability level. .1 ignificant at 1 percent probability level. TMean squares not significant at 5 percent level were not starred. TABLE 3. EFFECT OF DEFERRED GINNING TREATMENT ON SELECTED COTTON FIBER PROPERTIES, TEXAS A8cM UNIVERSITY PLANTATION COTTON GINNED IN 1962 AND 1963 Array Array Digital Digital percent coeffi- Ginning 2.5 per- 50 per- of fibers cient of Year . treatment cent span cent span shorter fiber length length than 1/2 length inch variation mean mean mean 3331a length length percent dent 1962 Immediate 1.087 .487 10.03 31.52. Deferred 1.086 .484 9.50 31.54 Change — .001 — .003 — .53 + .02 1963 Immediate 1.051 .455 11.63 33.36 Deferred 1.059 .462 10.51 32.13 Change + .008* + .007** — 1.12* ~ l.23* 1962 Immediate 1.07 1 .473 10.74 32.34 and Deferred 1.074 .474 9.95 31.80 1963 Change + .003 + .001 —~ .79* — .54 Significance of differences tested by paired t-test. *Difference in means significant at 5 percent prob- ability level. **Difference in means significant at 1 percent prob- ability level. If means not significantly different at 5 percent level, no stars are shown. ferences between ginning treatments on the paired data are presented in Table 3. The results of the analysis of changes in fiber color and nonlint content are not reported in this publication because the deferred ginning treatment had no significant effects on fiber color 0r nonlint content. Correlation analysis was used to determine the relationship of the moisture content of cotton at the trailer, extractor or lint slide to fiber properties. Since no significant relationship was evident, the results of the correlation analysis are not presented here. Results of Analyses, 1962 and 1963 Data Moisture Relationships The lint slide fiber moisture level was signifi- cantly higher in both 1962 and 1963 for the deferred ginned cotton. Cotton picked one morning and 6 A ance. The results (presented in Table 2) indie‘ not ginned until the following morning absor moisture from cotton seed and trash. There was l moisture variation within each bale of the defe A ginned cotton than within each bale of the mediately ginned cotton, even though the range » tween bales was high in both cases, Table l. average moisture levels were significantly diffe between bales only when the deferred and immed’ ginning treatments were compared, Table 2. other words, the differences between average mois i, levels at the trailer, extractor and lint slide were significant from day to day or between mornings, afternoons, only between immediate and defe ’ ginned cotton. The lint slide moisture avera slightly higher for the deferred ginned cotton si‘ less drying was required to maintain smooth gin ' operations. l It was concluded from the analysis of moist relationships at the trailer, extractor feeder and if slide that, by deferring ginning for 24 hours, 5' moisture variation existed within each bale. Si‘ less drying was required to maintain gin plant ef ,_ ency, lint slide moisture levels were slightly hig for the deferred ginned cotton. 5- Digital 2.5 Percent Span Length Differences between means of the digital percent span lengths were tested by analysis of v’ that in 1962 the differences between the mean y percent span lengths were not significant from to day or from morning to afternoon. However, t ,6 was a highly significant difference between when they were compared separately by days, vest periods and ginning treatments in 1962. difference between means was not significant ‘A 1963 data, but there was a significant difference é tween means for morning and afternoon periods; 1963. 4 The mean digital 2.5 percent span lengths the immediate and deferred ginning treatments '5 presented in Table 3. The deferred ginned cot had an insignificant change in mean length for but in 1963 an increase in mean length of .008 was significant at the 5 percent level. The c i for both years combined was positive but not si _ cant at the 5 percent level. A From the paired t-test it can be concluded if deferring the ginning of cotton 18-24 hours did i significantly reduce the digital 2.5 percent J length in either year but actually improved the. percent span length by a significant amount in If This change would have no influence on the U; ment loan price but would mean a significant provement in the spinability of the cotton f The increased digital 2.5 percent span length my that the length of the longest 2.5 percent of; slightly greater, and less breakage would spinning. 50 Percent Span Length f“! results of the analysis of variance treat- -| the 50 percent span length shown in Table 2 'lar to those for the 2.5 percent span length. was a highly significant difference in all of lengths for 1962 but not for 1963. Part explanation for this degree 0f significance is Jere was considerable variation from day t0 f: 1962-63. This day-to-day variation is eli- i,’ from the analysis by pairing the observa- ‘shown in Table 3. Since there was not as I< variation in the 50 percent span length from g to afternoon in 1963 as in 1962, the overall if ce in the means in 1963 (day x period x f ) was not significant. able 3 shows that by comparing only changes l ing treatments, there was a highly significant i" in the digital 50 percent span length for Q0 ginned cotton over immediate ginned cotton :3. The slight changes in 1962 and for both combined were not significant, however. De- . ginning did not significantly lower the 50 It span length but did raise it in 1963. I was concluded that by delaying the ginning hours after harvesting, the digital 50 percent 1 ngth could be improved slightly 0n the aver- 5-" during the spinning of the deferred ginned A, than the cotton ginned immediately after ting. intage of Fibers Shorter Than one-half Yin a Fiber Array 3 e percentage of fibers shorter than 1/2 inch ~-iber array is one measure of damage to-cotton if during ginning. Over-drying and over-clean- use fiber breakage and result in a higher per- of fibers shorter than l/Z inch. There was a _i'cant difference in the means of this measure- only when the ginning treatment was brought the analysis of variance model, Table 2. In v this difference in mean percentages was signifi- at the 5 percent level, and in 1963 it was signi- at the 1 percent level. can be seen from Table 3, deferred ginning sed the average array percent of fibers shorter p. 1/2 inch for both years. This change was signi- A at the 5 percent. probability level for 1963 for both years together. JIt was concluded that deferred ginning did icantly reduce the percentage of fibers shorter inch in a fiber array and would thereby reduce aste to mills in spinning. ‘ This means that there would be fewer ends a Coefficient of Fiber Length Variation in a Fiber Array The array coefficient of fiber length variation is an indication of the uniformity of the length of cotton fibers in the sample. Lower coefficients mean less variability in the fiber length and hence more desirable cotton for spinning. The analysis of variance tests showed that the means of the array coefficient of fiber length varia- tion were significantly different at the 1 percent probability level for both the 1962 and 1963 samples only when the ginning treatment was brought into the analysis. From day to day and from period to period the difference in mean coefficient levels was not significant at the 5 percent probability level (Table 2) . By pairing the observations and analyzing the differences, the 1963 samples of deferred ginned cotton were found to have a mean coefficient of 1.23 less than the immediately ginned cotton for that year. This difference was significant at the 5 per- cent level, meaning that the probability was only 1 in 20 that the difference was due to chance and not to different ginning treatments. In 1962, the mean coefficients were almost exactly the same, and for both years combined the slight improve- ment in the array coefficient was not significant at the 5 percent level (Table 3). It was concluded that coefficient of fiber length variation in a fiber array was lowered slightly by deferred ginning treatments. Less variation in fiber length would mean less waste and delay in spinning operations. Interpretations and Implications This study revealed that a more desirable length distribution of ginned cotton fiber was found in cotton which was stored for 18-24 hours before ginning. The moisture levels at the extractor feeder apron were more uniform due to a transfer of mois- ture from the seed and trash to the fiber of the seed cotton during the deferred storage period. This uniformity allowed the cotton to be ginned with less drying and, as a result, less fiber damage. The de- ferred ginning treatment produced significantly more uniform length distribution in the lint cotton. A study of the effects of storing seed cotton prior to ginning was conducted in Arkansas and Missouri in 1961; no adverse effects of storing seed cotton were observed in those tests (l4). Tests of the effects of cleaning and drying cotton at selected gins in Califor- nia and Mississippi indicated that such practices damaged fiber properties even though the grade was improved (11) . Seed cotton ginned with lower drying tempera- tures has less waste during processing at the mill and produces a yarn of more uniform quality with less delay from breakage.‘ This study indicated that storing seed cotton for 1 day prior to ginning pre- conditioned it sufficiently to allow less drying dur- ing ginning which resulted in improved quality. Un- fortunately, current pricing methods do not reflect these improvements in cotton quality, but improved ginning techniques must eventually be recognized in stronger markets. Recent studies by the U. S. Department of Agriculture found that improvements in fibrograph length uniformity ratios increased the spinning potential yarn number considerably more than did increases in the classers grade (l3). Acknowledgments Acknowledgment is made to Joe Varisco, owner of the Joe Varisco Gin, and E. Roberts, F. A. Wolters and H. H. Maniord of the Texas A8cM Farm Service for their cooperation in obtaining the data for this report. G. A. Niles and T. R. Rich- mond, Department of Soil and Crop Sciences, gave helpful assistance in planning the analysis. Literature Cited (l) National Cotton Council of America, “The Quality Situation, 196l.” _ (2) Elting, J. P., “Short Fiber Content is Most Important of Five Key Qualities Needed by Mills,” The Cotton Trade journal, March 4, 1960. <3) (5) (7) (8) (9) <10) <11) (12) <13) <14) Montgomery, R. A. and O. B. Wooten, “Lint f and Moisture Relationships in Cotton Through ing and Ginning,” ARS 42-14, U. S. Depart i Agriculture. ' Mitchell, Orville, Sr., “Moisture Control in Cotton Research Clinic Marketing Conference, - Georgia, April 9-11, 1963. Hoover, Marvin, “Harvest-Aid Chemicals,” Weste ton Production Conference, yPhoenix, Arizona, V; 5-6, 1963. "1 "l: Pi News From Spinlab, Knoxville, Tennessee, Sep‘ October, 1962. s Spinlab Bulletin, Knoxville, Tennessee, February Calkins, Edward W. S., “Mil1-USDA Study: Fiber g vs. Ends Down,” Textile Industries, December, '_ News From Spinlab, Knoxville, Tennessee, No, 1962. . Annual Cotton Quality Survey, Crop of 1963, USD Ross, john E., “Some Effects of Gin Drying and l?‘ of Cotton on Fiber Length Distribution an Quality,” Marketing Research Report N0. 666,1 ERS, AMS, July, 1964. Berkley, Earl E., “Research and Progress in the? Industry During the Past Twenty-Five Years ' 1964.” Presented at American Cotton Congress‘ Texas, June 5-6, 1964. l‘ Rouse, J. T., “Finding Spinning Potential,” Mar p. 68, Textile World, talk given at 16th annual? Research Clinic at Pinehurst, N. C. * ' Anderson, Fred, Alonzo Metcalf and B. A. , Storing Seedcotton in Trailers, Trailer Bashe Cotton Houses in Arkansas and Missouri in 1961 " Effect on Quality and Value 0f Lint. Mi Series 119, Arkansas Agricultural Experiment‘ November, 1962. Y