LIBRARY» . A g; M COLLEGE, 1264-1136-6111 TEXAS AalucuuunAftiififlflmzur smmm A. B. CONNER, DIRECTOR COLLEGE STATION, BRAZOS COUNTY, TEXAS BULLETIN NO. 538 NOVEMBER 1936 DIVISION OF RURAL HOME RESEARCH E1 B R A R Y Agricultural a. Meshmical cmueae I" "m ,couege Stafivn. Thw- The 0f Exposure in the Field On Grade, Strength, @1111 (blur Of Raw Cotton AGRICULTURAL AND MECHANICAL COLLEGE OF TEXAS T. O. WALTON, President '35“! 5;}; é- s9! Attempts to reduce the costs of cotton production have resulted in the adoption of methods of harvesting which encourage the postponement of picking until most of the bolls are open. As a result the bolls which open early are often exposed to the weather for weeks or even months. This study was undertaken to measure the extent to which the cotton was lowered in grade, staple, strength, and color when thus exposed under normal weather conditions for various periods of time. The cotton used was of the same variety, grown for two seasons at Temple, Chillicothe, and Lubbock regions where soil and climate differ. The grade, strength, and color of‘ unexposed cotton and cotton exposed from one to 33 weeks were determined. A drop of one grade had occurred after one week of exposure at one station and after an average of less than 4 weeks for all stations ‘and sea- sons. A drop of 4 and 5 grades, a decrease in length of from 1/16 to 3/16 inches, and a decrease in price of from 150 to 265 points occurred during exposure. The monetary loss due to ex- posure was in some cases nearly one-half the price of the un- exposed cotton, or at 1932 and 1933 prices approximately $13.00 per 500 pound bale. All of the cotton lost strength, but not equally, upon exposure. There was an average loss of 4 per cent after 4 weeks and a maximum loss of approximately 14 per cent for the season. Cotton grown at Temple lost the lowest and that at Lubbock the highest percentage of the original strength. These differences were not due entirely to differences in rainfall but may have been due in part to greater ultra-violet in the sunlight at the higher altitude. There were regional and seasonal differences in the color. All cottons became darker and less creamy as the exposure increased. In all cases there was a decrease in either creaminess or bright- ness, or in both, within 3 to 5 weeks after opening. Precipitation apparently caused greater darkening than it did loss in creami- ness. The grades appear to follow brightness more closely than they do creaminess. Three lots of‘ lint cotton stored in a vault for one year had lost respectively 7, 15, and 18 per cent of their original strength, and after two years of storage two lots had lost 25 and 33 per cent. It is concluded that cotton should be harvested, so far as is practicable, not later than 4 or 5 weeks and preferably within 1 or 2 "weeks after opening to assure a product of high quality in grade, strength, and color. CONTENTS Page Introduction 5 Source of material 6 Method of procedure 6 The effect of exposure on the grade and staple of cotton __________________ __ 8 The effect of exposure on the price of cotton 12 The effect of exposure on the strength of cotton _______________________________ __ 13 The strength of unexposed cotton 13 The strength of exposed cotton 17 The effect of exposure on the color of cotton 23 The effect of storage on the strength of cotton __________________________________ _- 30 Summary and conclusions 32 Literature cited - 3 5 BULLETIN NO. 538 NOVEMBER 1936 THE EFFECT OF EXPOSURE IN, THE FIELD ON GRADE, STRENGTH, AND COLOR OF RAW COTTON Mary Anna Grimes, Textiles and Clothing Specialist, Division of Rural Home Researchl In the development of cotton growing in the Western Cotton Belt economies in production have been sought by the growers. Among high costs of producing cotton the expense of picking is important. Snapping of the bolls has become a general practice in some sections as a means of lowering the expense of picking, and stripping is resorted to in many instances. These methods of harvesting tend to encourage the delay of picking until a fair proportion of all the bolls is open. In consequence the indeterminate habit of growth of the cotton plant often causes har- vesting to be delayed for one or even two or more months, during which time the lint cotton is exposed to weather conditions in the field. It is conceded that permitting cotton to remain in the field for a con- siderable length of time after ripening causes a lowering of the quality. Consequently, cotton picked late in the season coméymands a. lower price than cotton from the same field picked early in the season. This price discrimination has raised many questions. What differences in the price are‘ due to exposure? What differences in quality are the cause of the difierences in price? How long may cotton remain open in the field exposed to normal weather conditions before the quality is lowered? To what extent is it lowered in one season? What attributes comprising quality are most affected? What are the effects of various lengths of exposure upon the grade, staple, color, and strength? This study was undertaken with the hope of obtaining answers to some of these questions which would serve as a basis for the formula- tion of definite advice to the cotton grower with respect to the time of picking and its effect on the quality of cotton. A profitable approach appeared to be to compare measurable character- istics of cottons, which, as classified by a cotton classer, differed in grade. Two factors, color and strength, Which are considered by the cotton classer to be of great importance in determining the grade of cotton, may be measured objectively. Such objective determinations, it was thought, might be used to ascertain to what extent two grades of cotton owe their respective grades to, differences in color, strength, or other factors. 1 The author is grateful to Mr. D. T. Killough of the Division of Agronomy for his valuable aid in formulating plans for this study, for ginning the cot- ton, and for helpful suggestions and criticisms; to Messrs. D. L. Jones, J. R. Quinby, and Henry Dunlavy, superintendents of the substations at Lubbock, Chillicothe, and Temple, respectively, for growing, tagging, picking, and shipping the cotton; to Mr. J. G. Powers of the Department of Textile Engi- neering for classing each lot of cotton; and to Mr. S. R. Senter for permission to include a portion of a previous report. 6 BULLETIN NO. 538, TEXAS AGRICULTURAL EXPERIMENT STATION SOURCE OF MATERIAL Ferguson Triumph 406 was selected for this study because this variety is widely grown, has been line bred for a number of years, pos- sesses good uniformity of type, and is well adapted to conditions in the western part of the state where early maturity is desirable. The three stations chosen for growing the cotton used in this study are located in regions of the state differing widely in soil and climatic conditions. The Temple Station is located in Bell county, at approximately 740 feet above sea-level, on land typical of the Houston series predominating throughout the Blackland region. The average annual rainfall for twenty- three years is 35.28 inches. The Chillicothe Station is located in Hardeman county at an elevation of 1406 feet above sea-level. The soils are fine sand-y loams, loams, and clay loams of the Foard and Vernon series. The average rainfall over thirty years is 24.92 inches. The Lubbock Station is located in Lubbock county on the High Plains region of the state. The elevation is approximately 3195 feet above sea-level. The soil is of the Amarillo and Richfield fine sandy loam type, which is typical of a great portion of the region. The average annual rainfall for twenty-five years is 18.60 inches. Cotton grown for two seasons, 1931 and‘ 1932, at each of the three stations was chosen for this study. A record of the rainfall and temper- ature for each of the two seasons was furnished by each station. The plans for tagging and picking were made by D. T, Killough of the Divi- sion of Agronomy and carried out under the immediate supervision of the superintendents of these substations, J. R. Quinby, Substation No. 12 at Chillicothe; Henry Dunlavy, Substation No. 5 at Temple; and D. L. Jones, Substation No. 8 at Lubbock. ‘ A portion of the cotton from each of the three stations was used in a study on the stability of color in cotton, conducted and published by the Division of Cotton Marketing, Bureau of Agricultural Economics, U. S. D. A. (6). The cotton grown at Chillicothe during the 1931 season was analyzed, except as to color, by S. R. Senter; his study was reported as a Master's thesis (8). A portion of the data secured by Mr. Senter is included in the present report. METHOD OF PROCEDURE Tagging. When the cotton began opening freely, approximately 3000 bolls were tagged at each station. Thirty of these were picked and sent immediately to College Station for ginning, classing, and study. The EFFECT OF EXPOSURE IN THE FIELD ON RAW COTTON 7 following week, and each week thereafter as long as cotton remained in the field, thirty of the bolls were sent in for study. At those stations where cotton opened after a killing frost, 1000 bolls were tagged, 30 of which were picked at once and 30 each week following as long as cotton remained in the field. These methods of tagging and picking were repeated the second season except that the cotton was picked at intervals of two weeks instead of one. Picking. The period included in the picking for the 1931-32 season was from September 3 to February 3 inclusive, and for the 1932-33 season from September 1 to April 20 inclusive. In each of the two seasons cotton which opened before frost and cotton which opened after frost were included. Ginning. Upon arrival at College Station each lot of cotton was ginned on a hand roller gin, graded, and analyzed for color and strength. The classing of the cotton was done by J. G. Powers, an oflicial and licensed cotton classer. The data on grade and staple are based upon his classification. The nine official American grades of cotton used in classifying the samples of cotton are designated as follows: P‘ Middling fair (M F) Strict good middling (SGM) Good middling (GM) Strict middling (S M) Middling (M) Strict low middling (S L M) Low middling (L M) Strict good ordinary (S G O) Good ordinary (G O) fooo-qowmmoom Strength determinations were made by the Chandler bundle method as modified by workers in the Division of Cotton Marketing, U.S.D.A. (7 and 2). The results are the average of fifteen successful breaks for each lot of cotton and are expressed in thousands of pounds per square inch of cellulose. The method used differed in one respect from that given in A. S. T. M. (2), since corrections for variation from a circumference- of 0.125 inches were made with 1.2 pounds as the correction factor for each 0.001 inch variation (7). All tests were made under standard l atmospheric conditions. Color analyses were made with a spectrophotometer with magnesium i carbonate as a standard. The cotton was combed until all visible foreign matter was removed and the fibers were parallel. Sufficient cotton was ‘used to prevent light penetrating to the card upon which the cotton was placed. The color analysis was made on the middle portion of the fiber. This method of preparation made it possible to obtain the color analysis of the fiber and not of the leaf, soil, and other foreign material except r.- i. r 8~ BULLETIN NO. 538, TEXAS AGRICULTURAL EXPERIMENT STATION very minute particles which might cling to the fiber. i It gives results I which are of course different from those obtained when a larger area containing the normal amount of foreign matter is used for the analysis. Five such specimens were prepared and analyzed for each sample of cotton and the average of the results used. Readings were taken at every 10 millimicrons from 430 to 700 millimicrons inclusive. An average of 10 readings taken at each point was considered the true reading. A reading for 420 millimicrons was obtained by extrapolation. The re- sults thus obtained Were expressed in two ways, first as a curve with reflection expressed in percentage on the ordinate and wave lengths in millimicrons on the abscissa, and second as dominant wave length, colorimetric purity, and luminosity, according to the method reported by Judd (4) for illuminant B. Precipitation. The precipitation which was thought to have affected the quality of the cotton was divided into three periods: first, that which occurred from September 1 to the date of planting, or the preseasonal; second, that from the planting date to the first picking, or the growing period; and third, that between the date of the opening of the bolls and the date of picking, or during exposure to weathering. THE EFFECT OF EXPOSURE ON THE GRADE AND STAPLE OF COTTON The first pickings of the 1931 cotton which opened before frost at Chillicothe and Lubbock were classified as strict middling and that at Temple as strict middling spotted. The cotton at Temple maintained this grade, with the exception of that exposed one week, which was classed as strict middling plus, until the seventh week of exposure when it dropped one grade, as shown in Table 1. The cotton from Lubbock dropped one grade after only one week of exposure and that from Chillicothe dropped one grade after three weeks, as shown in Tables 2 and 3. A drop of two grades had occurred after 3, 4, and 11 weeks and a drop of three grades after 8, 5, and 13 weeks, at Lubbock, Chillicothe, and Temple respectively. After 14 to 17 Weeks the grade was lowered to strict good ordinary at the three stations; after this there was little change, All 1932 cotton was also strict middling at the first of the season and had dropped one grade after 3 to 5 weeks of exposure and two grades after 5 to 7 weeks, as shown in Tables 4, 5, and 6. After exposure of 16 to 21 weeks the cotton had dropped to strict good ordinary. ‘After 25 weeks of exposure the Temple cotton was. classed as good ordinary. The lowering in grade may have occurred somewhat earlier in the 1932 season but cotton in this season was picked at less frequent intervals than in 1931. EFFECT OF EXPOSURE IN THE FIELD ON RAW COTTON 9 TABLE 1. The grade, staple, premiums, qnd discounts of cotton grown at Temple in 1931-32 and subjected to» exposure. Grade Cumu- Price Price Date Weeks ha; q. Length lative Points* per 1b. of of ex- Drop in precipi- + on 7/8 M cotton picking posed from inches tation —— off Houston as Name No. 1st in basis picked ‘ picking inches 9/ 3/31 o SM Sp s 0 31/32 . . . . . . .. +50 6.25 6.75 9/10 1 SM+ 3% +36 31/32 . . . . . . . . +88 6.20 7.08 9/18 2 SM sp 5 0 31/32 0.38 +50 5.90 6.40 9/24 3 SM sp 5 0 31/32 0.38 +45 5.75 6.20 10/4 4 SM sp 5 0 31/32 0.38 +45 5.00 5.45 10/8 5 SM sp 5 0 31/32 0.38 +45 5.10 5.55 10/15 6 SM Sp s 0 31/32 0.33 +45 5.60 6.05 10/22 7 M sp 6 1 31/32 0.58 even 6.10 6. 10 10/29 8 M sp 6 1 15/16 1.16 —-10 6.10 6.00 11/ 6 9 SLM 6 1 15/16 1.16 —— 5 6.20 6.15 11/12 10 SLM 6 1 15/16 1.20 + 5 6.10 6.15 11/19 11 LM 7 2 31/32 1.70 —30 5.75 5.45 11/27 12 LM 7 2 15/16 2.11 -—20 5.65 5.45 12/ 3 13 LM sp 8 3 15/16 2.96 —-80 5.70 4.90 12/10 14 LM sp 8 3 31/32 3.72 -—-70 5.60 4.90 12/17 15 SGO+ 7% 2% 15/16 5.08 —-50 5.70 5.20 12/28 16 SGO 8 3 31/32 5.65 —60 5.85 5.25 12/31 17 GO 9 4 15/16 5.65 ——120 6.00 4.80 1/ 7/32 18 SGO 8 3 15/16 8.51 —-70 5.90 5.20 1/14 19 SGO 8 3 15/16 9.68 —70 6.20 5.50 1/21 20 SGO 8 3 15/16 9.84 -——70 6.20 5.50 1/28 21 SGO 8 3 15/16 10.57 —-70 6.20 5.50 2/ 4 22 SGO 8 3 15/16 10.87 -—-70 6.35 5.65 2/11 23 SGO 8 3 31/32 10.87 —-60 6.30 5.70 *Ba.sis—H0uston middling "A. TABLE 2. The grade, staple, premiums, and discounts of cotton grown at Lubbock in 1931-32 and subjected to exposure. .'\ k Grade i: L P‘ Cumu- ' 1 ‘Price Price Date Weeks Length lative Points* per 1b. of ex- Drop in precipi- + on 7/8 M cotton picking posed from inches tation —— ofi Houston as Name No. 1st in basis picked picking inches 10/ 3/31 0 SM 4 . . . . . . .. 15/16 . . . . . . .. +60 5.00 5.60 10/10 1 SM sp 5 1 31/32 . . . . . . . . +45 5.30 5.75 10/17 2 SM sp 5 1 15/16 0 57 +30 5.90 6.20 10/24 3 M sp 6 2 15/16 3 46 —-10 6.35 6.25 10/31 4 M Sp 6 2 29/32 3 46 —30 6.10 5.80 11/ 4 s M Sp 6 2 15/16 3 46 —10 6.00 5.90 11/ 7 6 M sp 6 2 31/32 3 46 + 5 6.15 6.20 11/21 7 M sp 6 2 29/32 4 37 ———25 5.60 5.35 11/28 s SLM Sp 7 3 15/16 4 79 —40 5.70 5.30 12/ 5 9 SLM sp 7 3 15/16 5 10 —4O 5.65 5.25 12/12 1o SLM Sp 7 3 15/16 s 39 ~40 5.60 5.20 12/19 11 SLM sp 7 3 15/16 6 02 —-40 5.90 5.50 12 26 12 SLM sp 7 3 15/16 6 29 —-40 5.90 5.50 1/ 4/32 13 LM 7 3 15/16 6 29 —-30 5.75 5.45 9 14 LM 7 3 15/16 7 12 —-30 6.00 5.70 1/17 15 LM 7 3 15/16 7 21 —-30 6.25 5.95 1/23 16 LM 7 3 15/16 7 21 —-30 6.15 5.85 1/30 17 SGO 8 4 29/32 7 22 —-90 6.30 5 40 2/ 6 18 SGO 8 4 29/32 7 22 — 80 6.35 5 55 2/13 19 SGO 8 4 15/16 7 25 —70 6.45 5 75. "Ba.sis—Houston middling 7,4. 10 BULLETIN NO.6538, TEXAS AGRICULTURAL EXPERIMENT STATION TABLE 3. The grade, taple, premiums, and discounts of cotton grown at Chillicothe in 1931-32 and subjected to exposure. Grade Cumu- Price Price Date Weeks Length lative Points* per lb. of of ex- Drop in precipi- + on 7/8 M cotton picking posed from inches tation —— off Houston as Name No. 1st in basis picked picking inches 9/15/31 0 SM 4 . . . . . . .. 1 . . . . . . .. +100 6.20 7 20 9/22 1 SM 4 0 15/16 0.03 +60 5.70 6.30 9/29 2 GM 3 +1 15/16 0.18 +75 S 45 6.20 10/ 6 3 SM sp 5 1 15/16 0.18 +30 5 20 5.50 10/14 4 M sp 6 2 15/16 2.63 ——10 5 60 5.50 10/20 5 SLM sp 7 3 31/32 3.11 -—60 6 10 5.50 10/27 6 LM 1 5 15/16 4.46 -60 6 25 5.65 11/ 2 7 LM 7 3 15/16 4.46 —-60 6.10 5.50 11/10 8 SLM 6 2 15/16 4.46 —— 5 6 20 6.15 11/17 9 SLM 6 2 15/16 5.49 —- 5 5.85 5.80 12/ 1 11 LM 7 3 15/16 7.93 ——30 5.60 5 30 12 8 12 LM 7 3 15/16 7.98 —-—30 5.55 5 25 12/15 13 LM 7 3 15/16 8,18 -—-30 5.65 5 35 12/22 14 SGO 8 4 15/16 10.36 ——70 6.00 5 30 12/ 9 15 LM 7 3 15/16 10.36 —-30 6.00 5 70 1/ 6/32 16 SGO 8 4 15/16 11.51 ——70 5.90 5 20 17 SGO 8 4 15/16 11.58 ——70 6.00 - 5.30 1/19 18 SGO 8 4 15/16 12.05 \,/0 6.25 5.55 1/26 19 LM 7 s 15/16 12.46 -30 6.20 5 9o COTTON OPENED AFTER FROST 12/29/31 0 M sp 6 . . . . . . . . 1 1/32 . . . . . . .. +26 6 00 6 26 1/ 6/52 1 SLM Sp 7 1 1 1/32 1.15 —17 5 90 5.73 1/12 2 SLM sp 7 1 31/32 1.22 ——3O 6 0O 5.70 1/19 3 SLM sp 7 1 1 1/32 1.69 —17 6 25 6 08 1/26 4 SLM sp 7 1 15/16 2.10 —40 6 20 5 80 *Basis—Houston middling Z5. TABLE 4. The grade, staple, premiums, and discounts of cotton grown at Temple in 1932-33 and subjected t0 exposure. Grade Cumu- Price Price Date Weeks Length lative Points* per lb. of _ of_ ex- Drop in precipi- + on 7/8 M cotton picking posed from inches tation -— off Houston as Name No. _1st in basis picked f picking inches 8/25/32 0 SM 4 . . . . . . .. 31/32 . . . . . . .. +45 8.15 8.60 9/ 1 1 SM 4 O 31/32 0.01 +45 8.10 8.55 9/15 3 M 5 1 15/16 3.07 +15 7.10 7.25 9/29 5 SLM+ 5% 1% 1 3.97 +19 6.75 6.94 10/13 7 SLM 6 2 15/16 3.97 ——20 6.30 6.10 10/27 9 SLM 6 2 15/16 4.04 -—20 6.25 6.05 11/10 11 SLM 6 2 15/16 4.13 —-20 6.25 6.05 11/28 13 SLM 6 2 1 4.60 even 5.60 5.60 12/ 1 14 SLM 6 2 15/16 4.60 —-20 5.70 5 50 12/19 15 SLM 6 2 15/16 5.79 ——15 5.90 5 75 18 LM 7 3 29/32 8.48 ——70 5.85 5 15 1/12/33 20 SGO 8 4 13/16 9.41 —-—190 6.10 4 20 1 2 22 SGO 8 4 7/8 9.77 -—90 6.00 5.10 2/11 23 SGO 8 4 7/8 10.88 —-90 5.95 5 05 2/23 25 GO 9 5 7/8 10.98 —-120 5.85 4 65 3/9 27 M B1 St 9 5 13/16 13.04 --220 6.10 3 90 3/23 29 M B1 St 9 \ 5 13/16 13.07 -220 6.20 4.00 4/ 6 31 9 5 7/8 13.40 -—-120 6.40 5 20 4/20 33 SGO 8 4 13/16 13.51 —180 7.25 5 45 *Basis——-Houston middling 71;. EFFECT OF EXPOSURE IN THE FIELD ON RAW COTTON 11 TABLE 5. The grade, staple, premiums, and discounts of cotton grown at Lubbock in 1932-33 and subjected to‘ exposure. Grade Cumu- Price Price Date Weeks Length lative Points* per lb. of of ex- Drop in precipi- + on 7/8 M cotton picking posed from inches tation —— off Houston as Name No. 1st in basis picked picking inches 10/12/32 0 SM 4 . . . . . . . . 1 . . . . . . .. +70 6 60 7.30 10/26 2 SM 4 0 1 0.95 +70 6 20 6.90 11/16 5 M 5 1 31/32 0.95 +25 6 25 6.50 11/30 7 M sp 6 2 1 0.95 even 5 70 5.70 12 21 10 SLM 6 2 1 1.78 + 5 5 80 5.85 1/ 4/33 12 SLM Sp 7 3 1 3.43 ——30 6 O5 5.75 14 7 3 15/16 3.77 ~45 6 00 5.55 2/ 1 16 SGO 8 4 29/32 3.80 ~80 5 70 4.90 2/15 18 LM 7 3 29/32 4.19 ——40 5 85 5.45 3/ 1 20 SGO 8 4 7/8 4.75 ~80 5 90 5.10 COTTON OPENED AFTER FROST 11/ 9/32 0 GM sp 4 . . . . . . . . 1 . . . . . . .. +65 5.95 6 60 11/16 1 GM sp 4 0 1 . . . . . . .. +65 6.25 6 90 11/23 2 GM sp 4 O 1 . . . . . . . . +65 5.85 6 50 11/30 3 GM sp 4 0 1 . . . . . . .. +65 5.70 6 35 12/21 6 GM sp 4 0 1 0.83 +65 5.80 6 45 8 7 GM sp 4 0 1 2.46 +65 5.80 6 45 1/ 4/33 8 GM sp 4 0 1 2.48 +65 6.05 6 70 /11 9 Msp 6 2 1 2.73 + 5 6.10 6 15 1/18 10 M sp 6 2 31/32 2.82 —- 5 6.00 5.95 1/25 11 SLM sp 7 3 15/16 2.85 —-50 6.05 5.55 2/ 1 12 SLM sp 7 3 31/32 2.85 —45 5.70 5.25 2/ 8 13 SLM sp 7 3 1 3.22 -—35 5.90 5.55 2/15 14 LM 7 3 15/16 3.24 —-35 5.85 S 50 2/22 15 SLM sp 7 3 15/16 3.24 ——40 5.90 5 50 *Ba.sis—H0uston middling Z5. TABLE 6. The grade, staple, premiums, and discounts oi cotton grown at Chillicothe in 1932-33 and subjected to expoure. Grade Cumu- Price Price Date Weeks Length lative Points* per lb. of of ex- Drop in precipi- + on 7/ 8 M cotton picking posed from inches tation -— off Houston as Name No. 1st in basis picked picking inches 9/23/32 0 SM 4 . . . . . . . . 1 . . . . . . . . +65 7.15 7 8O 10/ 6 2 SM 4 0 0 89 +70 6.90 7.60 10/19 4 M-l- 4% M; 31/32 0 89 +40 6.30 6.70 10/31 5 SLM 6 2 31/32 1.54 —10 5.95 5.85 11/16 s SLM+ s34 1% 15/16 1 19 - s 6.25 6.20 1/ 2/33 14 LM 7 3 15/16 S 50 ——45 5.85 5.40 1/16 16 SLM 6 2 15/16 5 03 -—-15 5.95 5.80 2/ 1 18 LM 7 3 15/16 S 65 ——45 5.70 5.25 2/18 21 SGO 8 4 7/8 5 85 -—-80 5.95 5.15 3/ 2 23 LM 7 3 29/32 6 84 -—40 5.90 5.50 3/16 25 SGO 8 4 29/32 7 13 ——70 6.60 5.90 4/ 4 28 SGO 8 4 29/32 7 36 -——7O 6 . 25 5 . 55 "Ba.sis—Houston middling %. 12 BULLETIN NO. 538, TEXAS AGRICULTURAL EXPERIMENT STATION The two lots of cotton which opened after frost were spotted. The cotton grown at Chillicothe in 1931 was middling spotted and after one week of weathering had dropped one rgrade, where it remained after 4- weeks of exposure -(Table 3). The cotton grown at Lubbock in 1932 which had opened after frost was good middling spotted and showed no change in grade until after 9 weeks of exposure, when the classer found it to be two grades lower, but it dropped another grade after two more weeks (Table 5). A comparison between seasons at each station with respect to the weeks of exposure necessary to lower the grade shows that in two-thirds of the cases the grade was lowered earlier when the precipitation was greater. It is evident that the rainfall was an important factor in lowering the quality of the cotton (Tables 1-6 inclusive). But when stations are compared, differences in exposure periods occurring with lowering of quality are not explained entirely by differences in precipita- tion. For example, in 1931 the cotton at Lubbock was exposed only one week with no precipitation yet the quality was lowered one grade, in contrast to the cotton at Temple which required 7 weeks with 0.58 inch of precipitation which fell during the second and seventh weeks of exposure before it was lowered one grade; and in contrast to the cotton at Chillicothe which was lowered one grade in 3 weeks of exposure and after 0.18 inch of precipitation. Further evidence that precipitation is not the only factor affecting quality is shown in the cotton from Temple, which in 1931 and 1932 had after 23 weeks of exposure received equal precipitation (approximately 11 inches) on the same number of rainy days (43 days), but the 1931 cotton had lowered three grades and the 1932 four grades. After an average of approximately 4 weeks of exposure at the three stations for two seasons the cotton had dropped one grade, after 6 weeks two grades, after 12 weeks three grades, after 18 weeks four grades, and after 25 weeks five grades. The quality was lowered one grade for each period of approximately 4 weeks. While the lowering in grade was not uniform at each station for each season these findings indicate that to be classed as a product of the highest grade, cotton should be picked as soon as possible after opening and within the first four weeks. As the period of exposure in the field lengthened, the staple was classed as shorter, probably because the ends of the fibers were weakened and more easily broken during ginning and classing. The decrease in the length of the cotton as classed during the exposure periods was 1/16 to 3/16 inches. The greatest decrease occurred in the 1932-33 season. THE EFFECT OF EXPOSURE ON THE PRICE OF COTTON The grades and staples assigned by the cotton classer to the cotton picked at the various intervals of exposure were used in determining the monetary value of the cotton. The quotations for middling 7/8 cotton at EFFECT OF EXPOSURE IN THE FIELD ON RAW COTTON 13 Houston on the same dates were used as a base in determining the premiums, discounts, and prices of each ‘lot of cotton. These data are given in detail in Tables 1 to 6 inclusive. The unexposed cotton received a premium of 45 to 100 points, with an average of 65 points. After only one week of exposure there was an average drop of 5 points. After 4, 8, 14, 20, 25, and 31 weeks of ex- posure the average drop in points was 54, 80, 112, 140, 160,»and 185 points respectively. When these points are used in conjunction with the average price at Houston at the time of the first pickings as the basis, there was a loss of approximately 8, 11, 16, 19, 22, and 26 per cent after 4, 8, 14, 20, 25, and 31 weeks of exposure respectively. If the price is determined on the basis of the grade and staple of the first picking, but at the price prevailing at the time of the various exposure periods, the average losses are approximately 7, 12, 17, 20, and 23 per cent after 4, 8, 14, 20, and 25 Weeks of exposure respectively. Even at the low prices prevailing during these two seasons the loss due to late harvesting was in some cases as much as $13.00 for a 500-pound bale. It is evident that exposure in the field reduces the monetary value of the cotton and the reduction increases with the exposure period. As short an exposure period as 4 weeks may materially reduce the price received. THE EFFECT OF EXPOSURE ON THE STRENGTH OF COTTON The Strength of Unexposed Cotton There was wide variation in the strength of the cotton grown at the three stations, as shown in Figure 1 and Tables 7 to 9 inclusive. The TABLE 7. The grade, length, strength, and color of cotton and the cumula- tive precipitation at various periods of exposure. TEMPLE 1931-32 Grade Strength C u m u - Color lative Date Wks. Length precipi- of ex- in 1000 lbs. Loss tation picking posed Name No. Drop inches per sq. in. in in Purity Lumi- % inches nosity 9/ 3/31 0 SM sp 5 31/32 67.9i0.98 . . . . . . . . . . . . .. .15873 .734 10/ 4 4 SM sp 5 0 31/32 64.9i0.97 4.42 0.38 .14655 .746 11/ 6 9 SLM 6 1 15/16 65.2i0.75 3.98 1.16 .15244 .751 14 LM sp 8 3 31/32 62.5i0.51 7.95 3.72 .09259 .678 1/14/32 19 SGO 8 3 15/16 64.7iO.96 4.71 9.68 .O6570 .661 2 11 23 SGO 8 3 31/32 62.9i0.73 7.36 10.87 .126SS .576 TEMPLE 1932-33 8/25/32 0 SM 4 31/32 68.4i0.62 . . . . . . . . . . . . .. .11208 .773 9 29 5 SLM+ 5% 1% 1 65.9i0.58 3.65 3.97 .10155 .746 11/28 13 SLM 6 2 1 66.81076 2.34 4.60 .10212 .668 12/31 18 LM 7 3 29/32 66.8i-0.83 2.34 8.48 .09783 .653 2/11 23 SGO 8 4 /8 63.5i0.78 7.16 10.88 .10102 .632 3/23 29 M Bl st 9 5 13/16 63.5i0.76 7.16 13.07 .07112 .564 4/20 33 SGO 8 4 13/16 61.1i0.90 10.67 13.51 .07141 .581 14 BULLETIN NO. 538, TEXAS AGRICULTURAL EXPERIMENT STATION TABLE S. The grade, length, strength, and color of cotton and the cumula- tive precipitation at various periods of exposure. LUBBOCK 1931-32 _ Grade Strength C u m u - Color lative Date Wks. Length precipi- of ex- in 1000 lbs. Loss tation picking posed Name No. Drop inches per sq. in. in in Purity Lumi- . % inches nosity 10/ 3/31 O SM 4 . . . . . 15/16 62.6i0.93 . . . . . . . . . . . . .. 10105 780 10/31 4 M 5p 6 2 29/32 62.4i-1.29 0.31 3.46 09768 739 12/ 5 9 SLM sp 7 3 15/16 61.4-l_-0.92 1.92 5.10 07620 685 1/ 9/32 14 LM 7 3 15/16 57.3i1.34 8.47 7.12 08973 686 2/13 19 SGO 8 4 15/16 54.7i 1.07 12.62 7.25 07380 637 LUBBOCK 1932-33 10/12/32 o SM 4 ..... 1 56.3 $0.97 . . . . . . . . . . . . .. .142s2 .722 11/16 5 M 5 1 31/32 51.5i0.87 8.53 0.95 .14936 .665 12/21 10 SLM 6 2 1 48.3i0.90 14.21 . 1.78 . 14029 .650 1/18/33 14 LM 7 3 15/16 49.1i1.08 12.79 3.77 .13897 .615 3/ 1 20 SGO 8 4 7/8 53.1i2.12 5.68 4.75 .13121 .603 LUBBOCK COTTON OPENED AFTER FROST 1932-33 11/ 9/32 0 GM Sp 4 1 59510.81 . . . . . . . . . . . . .. .2352; .764 12/21 6 GM sp 4 0 1 57.9i1.23 2.69 0.83 .22584 .717 1/18/33 10 M sp 6 2 31/32 56.3i0.81 5.38 2.82 .22416 .684 2/22 15 SLM sp 7 3 15/16 55.5 i 1.27 6.72 I 3.24 .21848 .658 TABLE 9. The grade, length, strength, and color of cotton and the cumula- tive precipitation at various periods of exposure. CHILLICOTHE 19 3 1-3 2 Grade Strength Cum u- Color *1 lative Date Wks. Length precipi- of ex- in 1000 lbs. Loss tation picking posed Name No. Drop inches per sq. in. in in Purity Lumi- % inches nosity 9/15/31 0 SM 4 1 55.9i1.50 . . . . . . . . . . . . .. .14212 .735 10/14 4 M sp 6 2 15/16 54.4i1.16 2.68 2.63 .14205 .703 11/17 9 SLM 6 2 15/16 55.5j:1.09 0.72 5.49 .14989 .659 12/22 14 SGO 8 4 15/16 52.7i-1.17 5.72 10.36 .14336 .652 1/26/32 19 LM 7 3 15/16 53.8i-1.09 3.76 12.46 .11905 .644 COTTON OPENED AFTER FROST 12/29/31 0 Msp 6 1 1/32 . . . . . . . . . . . . . . . . . . . . . . . . .. .17212 .707 1/26/32 4 SLM sp 7 1 15/16 . . . . . . . . . . . . . . . . . .. 2.10 . 12079 .678 CHILLICOTHE 1 9 3 2- 3 3 9/23/32 0 SM 4 1 59.5i().96 . . . . . . . . . . . . .. .14684 .762 10/19 4 M 4% % 31/32 55.5i0.96 6.72 0.89 .14043 .735 11 16 8 SLM-I- 5% 1% 15/16 56310.63 5.92 1.79 .14743 .673 1/ 2/33 14 LM 7 3 15/16 54.7i0.60 8.07 5.50 .13856 .666 18 LM 7 3 \15/16 53.9i1.30 9.41 5.65 .13285 .668 3/ 2 23 LM 7 3 29/32 51.5i0.86 13.45 6.84 .13032 .617 4/ 4 28 SGO 8 4 29/32 51510.91 13.45 7.36 .12387 .567 15 EFFECT OF EXPOSURE IN THE FIELD ON RAW COTTON 3.2 922R 1 NQQR 2.3 $1.2 SRNR 1 SR R 2;: QR R 1 Sh R 2182 . .. an 5.2 $R<~ 1 SR R 8.3 Qvi. 8R R 1 122R $3 S\:R 1 8} R Si?“ .....2E=@e 3g 2R R 1 QRNR 3.2 3.2 QRNR 1 SRNR 2H8 ~32}. 1 S} R RTQRH .. an 3.3 ~32} 1 HQBR 3Q 00.», SRQR 1 $5.1m S. 3 .22} 1 8} R S132 ...1.fi¢uEEo E4. MRRNR 1 Nm\§\oH 2.5 wwfi NQSRH 1 ~32? Si NQSR 1 S} R mmémi d0 B.» ~QfiR .1 SR >5 3.2 m9“. SR >5 1 SDQm fifi 33in 1 21> R $132 .:.V_SHE=A 3:05 Dada mason“ Gm monufi oumfi @0225 wflwQ mntsofi u Us.» nowwow coifim wvbommwwvkn v3.5a wknmoaxm 130B woiua marflohO woioa _wnowwwm-o._m Ancmfiun i050 HQH flaw-wan i050 v6 mwomuwfi hi GO-wflZ-uqovn-m 5n nmflmmdnfi 16 BULLETIN NO. 538, TEXAS AGRICULTURAL EXPERIMENT S'I‘A'I'I()N 68-. c1- o I: . s -' — — '— mnlfl-Lxfi S" I’ 51-! \ es_. ,_ - ’ QSU-H .52 5w mIPIB w“ ° \ \ '5“ eff/f o \ L! P s00 \ \5°° 1121s: e- - —- -—- o \ BM o \ V firs? sco MS =>—e$,PL [E5005 1 \ 931x32 ‘ N \ a sui up c» t- I m a I 3 I f Strougth in thousand paundu per lq. inch of cellulose —-% / 60 a S11 ss__ \ sa- \ \ 011.! s1__ \ S“ \ sun 0 a: 56"‘ s“ ° \\ / / /s1.m\ ILI'@ w.’ » \ 1.35 J3 55- y Q45; e11 o sso 9, \ 20 \ M_T ll “P \ QQ \ an s00 \ \ % \ o sco sa- \ \ / \ 5°° /\ sz- \ u \ o / a - -- - -- o 50° \£ 51- e / Nib? / 50—- 1.9 / m? Q0‘? / ‘9__ \ H v / a 0 LH \ Q /,/ 4B 51W“ I ° I Octnh-r I llovmher I December 9 I Jmu-rv I February I Much I Lori] Figure 1. The strength of cotton at various periods of exposure at each of three stations each of two seasons. cotton grown at Temple was significantly stronger each of the two seasons than the cotton grown the same seasons at Chillicothe and Lubbock. This difference was apparently due to soil differences, and to climatic conditions other than rainfall, as evidenced by the 1932 season when the total precipitation during the preseasonal and growing period were approximately equal at the three stations (Table 10). I The cotton grown at Lubbock in 1931 was much stronger than that grown at Chillicothe each of the two seasons. The cotton grown at Chillicothe in 1931 and that grown at Lubbock in 1932 were approxi- mately equal in strength and less strong than that from Lubbock in 1931 or that from Chillicothe in 1932. There was no significant seasonal difference in the strength of the cotton from Temple. The precipitation was below normal both seasons, with the lower rainfall during the 1931 growing season (Table 10). The cotton from Chillicothe was slightly stronger in 1932 than in 1931. This difference may have been due to a difference in rainfall. Although the rainfall for both years was below normal, that during the growing season in 1932 was nearly three times as great as that in 1931. The cotton EFFECT OF EXPOSURE IN THE FIELD ON RAW COTTON 17 from Lubbock in 1931 was much stronger than that from Lubbock in 1932. The cotton grown at Lubbock \in 1931 received more nearly normal rainfall than did that at Lubbock in 1932, which received approx- imately 5 inches above normal rainfall during the growing season. The Strength of Exposed Cotton All of the cotton suffered a loss in strength upon exposure, the loss generally increasing with the exposure period and amount of rainfall. However, the decrease in strength was not uniform in rate or extent. These variations are no doubt due, in part, to the imperfections in the method of testing and in part to variations inherent in the cotton sample. Figures 2 to 7 inclusive give the strength and grade, and cumulative rainfall (on an inverted scale) at various periods of exposure. To eliminate differences which might be attributed to variations in sampling and method of breaking, the significance of the differences in strength for the various periods of exposure was tested by the method recommended by Snedecor (9). It was found that by this method of determining strength significant differences in strength were between 2.2 and 3.5 thousand pounds per square inch of cellulose and highly significant differences between 3.0 and 4.7. The differences between weeks and the significance of the differences for each station each season are given in Table 11. r- ahnohel &— a 1 °’ F‘ | I ~—-> 20x l Cll ‘9 av 4 m <—— Cumulative prgcipitation in O1 ‘ I ‘IN l °‘ 1 I ---) Strength 1n thousand pmznLl per sq, inch of eellulooo <—- Undo (—- 63 1o _"' U O 0'“ 8 n 5g I September I October l November l December | January Figure 2. Temple 1931-32. The cumulative precipitation, and the grade and strength of cotton at various periods of exposure. 18 BULLETIN NO. 538, TEXAS AGRICULTURAL EXPERIMENT S'l'A']’|()N 63 i _§-IQ% 61 A. 2 \L_ g n ‘E \ -s gee-g \ 3 ‘is; \ t a PAIITFALL \ é a __6 3' 1‘! ‘ fr; n '0 5 E - g i OI a or on m l o» -—-> St k 0-8 ., 5a._. | QQQQBQI ] now-b» | Member | Jwwr! | February Figure 3. Lubbock 1931-32. The cumulative precipitation, and the grade and strength of cotton at various periods of exposure. »56__° ' ._‘ o _. a F n Ln thousand pound: per lq, inch of eollulou -) w- Cumulative precipitation in inches 4- l a l a l l‘ 4 l. no l 5L 101 w n - i 1a ---T 1: ~- 52- o 8 | “was” l October | lumber [ Deember I Jumnry ] Figure 4. Chillicothe 1931-32. The cumulative precipitation, and the grade and strength of cotton at various periods of exposure. and strength of cotton at various periods of exposure. EFFECT OF EXPOSURE IN THE FIELD ON RAW (‘OTTON 19 0 x \ S6 a 4 1 S5 a 5 n5-’4__; ___5 i 3 4E a 5s:- 5 2s“; \ x l = I €52,_E' \ __63 a g g e * 35:4 \ l v1 5 5 g \“L';Q_>' gso-f K3’ .-_1 i i’ \ ., 2J4 \ 48- o-a 5 October | Fovember | Doaanbor | JUNE?! | 7'5""? j Figure 5. Temple 1932-33. The cumulative precipitation, and the grade and strength of cotton at various periods of exposure. o _ 0 ___a 1 69 2 _ x 68— 3 _ §\ _5 .3 41614.; g % 53 _ ‘g 566-5 -—s e§— '7 l g o 8a 8. _7 .1 _ 8 10i6§__:é \ 0-‘6 11 — E \ 62-" 12 - T \ L3 e;_ x___9 14 - Ben] September‘ October ] Iovnbor | Dooonbor | Jluuary | rum-q | mm- | April Figure 6. Lubbock 1932-33. The cumulative precipitation, and the grade 20 BULLETIN NO. 538, TEXAS AGRICULTURAL EXPERIMENT STATION TABLE 11. Differences in strength at various periods of exposure.‘ (In 1000 lbs. per sq. in. of cellulose.) Temple 1931-32 Temple 1932-33 Weeks Weeks ex- 0 4 9 14 19 23 ex- 0 5 13 18 23 29 33 posed Dosed O 0 3.0 2.7 5.4 3.2 5.0 0 0 25 1.6 1.6 4.9 4.9 7.3 4 0 —-3.0 2.4 0.2 2.0 S 0 —0.9 —0.9 2.4 2.4 4.8 9 0 2.7 0.5 2.3 13 0 0.0 3.3 3.3 5.7 14 0 —2.2 0.4 18 0 3.3 3.3 5.7 19 0 1.8 23 0 0.0 2.4 23 0 29 0 2.4 33 0 Chillicothe 1931-32 Chillicothe 1932-33 Weeks Weeks ex- 0 4 9 14 19 ex- O 4 8 14 18 23 28 posed posed 0 0 1.5 0.4 3.2 2.1 0 0 40 3.2 4.8 5.6 8.0 8.0 4 0 —1.1 1.7 0.6 4 0 —0.8 0.8 1.6 4.0 4.0 9 0 2.8 1.7 8 0 1.6 2.4 4.8 4.8 14 0 —1.1 14 0 0.8 3.2 3.2 19 0 18 0 2.4 2.4 23 0 0.0 28 0 Lubbock 1931-23 Lubbock 1932-33 Weeks Weeks ex- 0 4 9 14 19 ex- 0 5 10 14 20 posed posed 0 0 0.2 1.2 5.3 7.9 0 0 4.8 8 0 7.2 3.2 4 0 1.0 5.1 7.7 5 0 3 2 2.4 -1.6 9 0 4.1 6.7 10 0 —0.8 —4.8 14 O 2.6 14 0 —4.0 19 0 20 0 Lubbock 1932-33 Cotton opened after frost Weeks ex- 0 6 10 15 posed 0 0 1.6 3.2 4.0 6 0 1.6 2.4 ‘ 10 0 0.8 15 0 \ ‘Blackface indicates significant differences. Italic indicates highly significant differences. Ql h, (-—— Cumulative precipitation in inchon (-— ab m 2- repeated with the same results. EFFECT OF EXPOSURE IN THE FIELD ON RAW COTTON X o m L u: Q L-> .51.“... in 1......“ rm i .1. 1.4. .. an... . J; a1 F!‘ m 1F l tn u m N 51 Dconmbor _ | October | Sartxnbcrl Iovonber l January | gApril Chillicothe 1932-33. and strength of cotton at various periods of exposure. Figure 7. The cumulative precipitation, and the grade In the cotton grown at Chillicothe in the 1931 season there were no significant differences in the strength between Weeks, as shown in Table 11. The tests on this cotton were made previous to refinement in the method (8). The data for this cotton include the results obtained from the 15 bundles which most nearly met the requirements of the improved method, but not all of the 15 bundles were within the limits set for size. Had a sufiicient quantity of the cotton been available for further testing, it is thought the improved technique would probably have revealed significant differences in the strength for various exposure periods. In 4 of the remaining 6 lots of cotton for the two seasons at the three locations there is no doubt that significant losses in strength had occurred after 4 and 5 weeks of exposure in the field. Highly significant losses had occurred in each of the six lots after 14 or 15 weeks of exposure, with the exception of the cotton from Temple in 1932, in which 23 Weeks of exposure elapsed before the loss was significant. The breaking strength of the cotton from Lubbock in 1932 exposed 14 weeks of exposure. between the tenth and twentieth weeks showed the same trend. satisfactory explanation has been found for this difference. 5 for 20 weeks was found to be significantly greater than that after 10 and Tests using the same and two other methods were Strength tests for other exposure periods No <--0nd0 4- 22 BULLETIN NO. 538, TEXAS AGRICULTURAL EXPERIMENT STATION The cotton which opened after frost at Lubbock in 1932 was stronger than the cotton which opened before frost (Table 8). It showed a significant loss in strength after 10 weeks of exposure and a highly sig- nificant loss after 15 weeks (Table 11). No strength tests were made on the cotton which opened after frost at Chillicothein 1931. It was somewhat longer and more uniform than the cotton which opened before frost, no doubt because of more favorable growing conditions, as it was from a June 30 planting which received more rainfall than did the cotton in the earlier planting (8). From a comparison of the curves for strength, precipitation, and grade in Figures 2 to 7 inclusive, it seems that there is somewhat closer correla- tion between precipitation and grade than between precipitation and strength. Rainfall during exposure evidently lowers other qualities in- cluded in grade, color among them, more than it does the strength. A comparison of the strength of the various cottons with their cor- responding grades shows that there were wide variations in strength within each grade (Figure 1). The range of variation within a grade was approximately 12 to 19 thousand pounds per square inch of cellulose. It is evident that strength was only one of the qualities considered of importance in determining the grade. The losses in strength which occurred after four and five weeks of exposure in the field extended from less than one per cent to approxi- mately 7 per cent, as shown in Table 12. The maximum loss for the TABLE 12. Grade, cumulative precipitation, and loss in strength at various periods of exposure. Grade Loss in strength Cumulative Weeks Number expressed in percentage percipitation in inches o exposure Chi11i- Chilli- Chilli- Lubbock cothe Temple Lubbock cothe Temple Lubbock cothe Temple 1931 0 4 4 5 . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . 4 — 6 6 6 S 0.31 2.68 4 42 3.46 2 63 0.38 8 — 10 7 6 6 1.92 0.72 3 98 5.10 5 49 1.16 13 - 15 7 8 8 8.47 5 72 7 95 7.12 10 36 3.72 18 — 20 8 7 8 12.62 3 76 4 71 7.25 12 46 8 51 1932 0 4 4 4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 — 6 5 4% 5% 8.53 6.72 3.65 0.95 0.89 3.97 8 — 10 6 5% —- 14.21 5.92 . . . . .. 1.78 1.79 . . . . .. 13 -15 7 7 6 12.79 8.07 2.34 3.77 5.50 4.60 18 —20 8 7 7 5.68 9.41 2.34 4 5.65 8.48 23 —— 7 8 . . . . .. 13 45 7.16 . . . . .. 6.84 10.88 28 — 29 — 8 9 \ . . . . .. 13 45 7.16 . . . . .. 7.36 13.07 33 — —- 8 . . . . . . . . . . .. 10.67 . . . . . . . . . . .. 13.51 EFFECT OF EXPOSURE IN THE FIELD ON RAW COTTON 23 total exposure period was approximately 14 per cent of the original strength. The loss after 13 to 14 Weeks was approximately 2 to 13 per cent and after 23 to 33 weeks approximately 7 to 13 per cent. The cotton exposed at Lubbock suffered in most cases greater loss than that exposed for the same periods at Temple or Chillicothe. The average loss in strength, including four exposure periods from the first through the 18th to 20th weeks, was approximately 4 per cent for Temple, 5 per cent for Chillicothe, and 8 per cent for Lubbock. After 23 and 29 weeks of exposure the cotton grown the second season at Chilli- cothe had lost a higher percentage of the original strength than had that at Temple. These regional differences cannot be attributed to differences in precipitation, for it is apparent that the greatest loss in percentage of strength did not occur at those stations where the rainfall during the exposure periods was greatest. Comparisons of figures for loss and precipitation, given in Table 12, show that the reverse is more nearly true. For example, as regards increasing loss in strength for the first season after from 4 to 6 weeks of exposure, Lubbock, Chillicothe, and Temple appear in order, but as regards precipitation during the cor- responding periods the stations are in exactly the reverse order. This same relationship occurred in three of four cases for the first season. ' During the second season, for the three periods when comparisons may ' / be made, the least loss in strength occurred at the station where there was the greatest precipitation. In each exposure period where cotton from Temple appears, the loss in strength was less and the precipitation greater than for the one or two other stations recorded for the same periods. These data suggest that the greater loss of strength of the cotton from Lubbock, as compared with that from Temple, was not due to greater rainfall during exposure. Two explanations of the somewhat greater rate and extent of the loss in the strength of the cotton from Lubbock, as compared with that from Temple or Chillicothe, are suggested. It may be that there were dif- ferences inherent in the cotton itself. It seems possible that the greater ultra-violet in the sunlight to be expected at Lubbock where the altitude is greater and the atmosphere more arid than at Temple or Chillicothe, may have increased the degradation of the cellulose with a corresponding decrease in the strength of the fibers. These findings suggest that early harvesting may be more imperative at Lubbock and similar regions than it is at lower altitudes such as at Temple, even though the rainfall may be greater at the lower altitudes. The data indicate that if a loss in strength is to be avoided cotton should be harvested within the first four or five weeks after opening. THE EFFECT OF EXPOSURE ON THE COLOR OF COTTON The color of the unexposed and exposed cotton, as determined with a spectrophotometer, are given in terms of percentage reflectance and wave length in Figures 8 to 11 inclusive. These data have been con- 24 BULLETIN NO. 538, TEXAS AGRICULTURAL EXPERIMENT S'l‘/\'I‘[()N CBILLIDWBI Nil-H IIHHXII “Bl-a! IIILIIRIOI II RRQIIHDI T mnuwm ma-u l I I I I I l I I I I I I I I I I I I I I I I I l I 1 l l l no no uu no s00 sac no sec we wo em no uo no 10o no no 000 m: m m m an m coo no no uo an m In‘ mm unmnm‘ IAVILEDTIXIIILLKCROIB - Figure 9. Color curves for cotton £1- §saaackc"ixss $225211: grown at m 1W0 and exposed for various periods. and exposed for Varlous perlods‘ 11o so 5,,11|1|111111111f_oIIIIIIIIIIIII 3.1?" _,__-_. ‘ ‘ ‘I M‘ l‘. J ‘,.1_:__‘__,-.____ w ao_- _/~' ~'—'—»--_ I I A’ ‘ro- ______ __“}."_.I'. -.-:_.:_.;:::::__ __'ro f/M “h n,‘ , ‘ _ ------- \.\- , _ _ _ . I ' " - ' — ~ — - - . _ , _ _ l‘ . L-I,» \' /'/ I’. I ‘\. ,/ 2'-‘ JP“ _ I w,‘ I»! a —~—---'“‘° _ _,_. -- . /,;:7"" "°— , ,/' . 1au..?'.'§.'.f__,___ uo_.;.-/' J° - . , , 5 - _____...-- --....,_..... g l - -~_,___ I" I ' r .-"' u _ _n" E nzlru nn-u E ; ',-- - _oo iao’,..--~"~"""' —l° B . ' Z E - l ¢ ' : '1,‘ LUBWC‘ 1931-53 5 2 l mo: tron onto: >< l? __5o glo- ,9_'.'~_~F_ -'° a 4"‘ _/-" y _________________ ._, _t_./ #1“ F‘? -------------- .-- .... _, ',. - ‘ n- .40 “qty-tr "III t g , _ . g -. _\ ---- m‘ — ~-—-~._---_.n,__\_ °__‘_"_.- ’ _,._ g _':_.. Z ark?” _. ,1“ 1'1‘. - ’ 1o~ ./ .1" _1o " 0o w’ 1 "f ........ -- ____;:~_ -,_, ~ ,- _'.':..r_"'z'9th In: ____ "‘ """" “ /"' K" l a ' ,~' oo- ------ -;_-“.:-~' muucorn wax-a: _ao w_ "In: i932.“ __w '__,.~‘ mu nun. “ma: uo- so 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 I I I I I I I I I I - u: no no no m no no m no ooo no w: no m 1w m’ “° "II "II w m m I“ "II '°° m “° "° "° l°° "v! LIE’. a lzu-Imcm-a Ilrl ll’! II IIUJICRDE Figure 10. Color curves for cotton FIgure 11- Color curves for cotton grown at Temple for two seasons °I3‘?n?d after frog? at Lubbock 3nd and exposed for Various periods_ Chillicothe andpeenggssed for various verted into terms of dominant wave length, colorimetric purity, and luminosity by the method described by Judd (4), using illuminant B; they are given in Table 13 and in Figures 12 to 17 inclusive. The term purity is used to denote the creaminess, and the term lumi- nosity the light-to-dark quality of the cotton. The dominant wave length designates the hue or color name. Since the dominant wave lengths are all within the relatively narrow range of approximately 570 to 585 millimicrons, they have been omitted EFFECT OF EXPOSURE IN THE FIELD ON RAW COTTON 25 .1o—- "7 -75 N I 4 w ~l Oi O m II flumulative proclpisation iq inches %- I q h) In l ~I Q o >-1 ---> Luminosity ——-) ID on o P’ m (i O1 UI >4 1 _.. .07“ - I . ombw I - mvwb» i I “Mr-MP . I v-nwr I - 1. Fair“ 1:1 Figure 12. Lubbock 1931-32. The color of cotton expressed in terms of purity and luminosity with the accompanying cumulative precipitation (shown on an inverted scale) at various periods of exposure. \ l \ ._.1i 4; -- ' I g \ 5 a _ , ——'-7O .1 - I 6E —1- T ' ~69? E13 ->. \ t 1 <1 . a \ ° s “ E \ l; a ca“ 5 o ._s_ —' T \\ T 9 E — \ "-67 1Q r ‘t \ v o 11 _ —'-66 12 - \ g § ——-|55 13 - \ s g 1 y I isepteiibor | October | Iovmibor I " A I Jnnudr! 4 Figure 13. Chillicothe 1931-32. The color of cotton expressed in terms of purity and luminosity with the accompanying cumulative precipitation (shown on an inverted scale) at various periods of exposure. 26 BULLETIN NO. 538, TEXAS AGRICULTURAL EXPERIMENT STATION o ac ° —.1s 1 .1_s m —..14 - " T ‘.1: 2 _ ___n .14- 3 __ -_ Lu- -—i-7° .' _ d h; _ o_.es ¢.1?. '1 ggT '5 d 55 "T / “"2 31.11: _663 s: -:~ ' — Q o l- _ 6E -— g l —,65"' .1o— - .=. T ~ s4 6-‘ 4 ._ 1 -' -~- ._ss 5.0.- . __. -.fl! a if .08 — 9 - -—‘.60 n, _ <59 1o —_ _§8 . q \ .._ 11,0. 1 w-w-rh- il ewe" . I , "we" . 1 - “re-w | “"3"” ‘ 51 Figure 14. Temple 19331-32. The co1or_of cotton expressed in terms of purity and luminosity with the accompanying cumulative precipitation (shown on an inverted scale) at various periods of exposure. q .15 —— 73 _. 72 1 - -m l —-r7O 3 l‘? .14 5g i 1 2: -' 155 5 1 —-51 3 3 s i g as .= D- _:_ T 3 a —- ~55 3.13 54 ,1, .6: Q —< 62 51 60 5 .13 I ma“, e I I January I Iobruny u, Figure 15. Lubbock 1932-33. The color of cotton expressed in terms of purity and luminosity with the accompanying cumulative precipitation (shown on an inverted scale) at various periods of exposure. EFFECT OF EXPOSURE IN THE FIELD ON RAW COTTON 27 N (—- Cumulative precipitation 1n incholi—- w- l OI 0| 1'» I l -—> Purity ——> (S V! vii 0| --> Luminosity —9 Q -_. 59 45B 7 _ _ 7 J2 pta-iberl October I ‘ I December I January. | February l 1:11 6 Figure 16. Chillicothe 1932-33. The color of cotton expressed in terms of purity and luminosity with the accompanying cumulative precipitation (shown on an inverted scale) at various periods of exposure. :1? .75 ,4 I b: b: (D 6D -—-> Lunino a it? __> b; ~i l U) 0i I U: m b: vP l Cymilntivo precipitation in inches B 01 OI 1o m _6Z i1 1r ‘J31 _¢fi° 12 c: I o _ _ __O_§9 13 _ ,x_,5a 14 —- / i n s» enm- | October I Iavuinbor I December I Jnnulry I FODHIII‘! I Ihrch,“ I im-ii "s Figure 17. Temple 1932-33. The color of cotton expressed in_ terms of purity and luminosity with the accompanying cumulative precipitation (shown on an inverted scale) at various periods of exposure. 28 BULLETIN NO. 538, TEXAS AGRICULTURAL EXPERIMENT STATION from Figures 12 to 17 inclusive, in which the purity, luminosity, and cumulative precipitation are given, but are given in Table 13. The precipitation is given on an inverted scale in the figures. TABLE 13. The color analysis of cotton by seasons and Weeks at each of three stations. ‘ 1931-32 1932-33 Dominant Dpminant Wks. Grade wave length in Purity Lumi- Wks. Grade wave length in Purity Lumi- millimicrons nosity millimicrons nosity LUBBOCK 0 SM 579 .10105 .780 0 SM 577 .14282 .722 4 M sp 580 .09768 . 739 5 M 576 . 14936 .665 9 SLM sp 581 .07620 .685 10 SLM 576 . 14029 .650 14 LM S79 .08973 . 686 14 LM 576 . 13897 . 615 19 SGO 580 .07380 . 637 20 SGO 577 . 13121 . 603 CHILLICOTHE 0 SM 579 . 14212 . 735 0 SM 575 . 14684 . 762 4 M sp 577 . 14204 . 703 4 M —|- 580 . 14043 . 73S 9 SLM 579 . 14989 .659 8 SLM + 577 . 14743 . 673 14 SGO 580 . 14336 . 652 14 LM 580 . 13856 . 666 19 LM 580 . 11905 . 644 18 LM 577 . 13285 .668 23 LM 580 . 13032 . 617 28 SGO 578 . 12387 .567 TEMPLE 0 SM sp 577 .15873 .734 0 SM 577 .11208 .773 4 SM sp 575 . 14655 . 746 5 SLM + 579 . 10154 . 746 9 SLM 570 . 15244 .751 13 SLM 576 . 10212 .668 14 LM sp 579 .092S9 .678 18 LM 578 .09783 .653 19 SGO 582 .06570 . 661 23 SGO 577 . 10102 . 632 23 SGO 578 . 12655 .576 29 M Bl st 583 .07112 .564 33 SGO 581 .07141 .581 COTTON OPENING AFTER FROST Chillicothe Lubbock 0 M sp 580 . 17212 ".707 0 GM sp 571 . 23523 . 764 4 SLM sp 583 . 12079 .678 6 GM sp 577 .22584 .717 10 M sp 576 .22416 .684 1s I SLM Sp s71 1184s .