Stin 885 December I957 Research on Farrn of Sorghum Grain 4 '__m" ‘ i " ‘_ A A — j l a ‘w wuhflw m’ v‘ L. 1 T‘ ‘ ‘ z ‘\ . fmwfl whallfi 1'" ,I ' \_, ‘ t; a! ' M35“ 3'. w‘. ' ‘z \.\?"";~-\§.‘,;,j, = .3 r ‘ §I~\N\t‘ .'\ ‘z "Tfivgggflngwm '\_ “ ll’ \H§\\I||‘\‘ v ‘ __ ‘_ ‘I if \ \\\\\\\ u —- ' ° - - _ . ‘Mp3 umi 1" - l J ‘ \ Q f’. “A ‘i \\.;“~ YUL v l A<_‘\ ' .’ . T ' ~ ' . . r '1 \~*._~“"<’--» - " - 3'2’ \ . " p. . 7 \\ \\ . ~ “ ‘r A '* ;. / §' \\'\ . - ‘ a: 11h’ , h. 1‘ > \ I o | / H \ TEXAS AGRICULTURAL EXPERIMENT STATION R. D. LEWIS. DIRECTOR. COLLEGE STATION, TEXAS 1N COOPERATION WITH THE UNITED STATES DEPARTMENT OF AGRICULTURE ACKNOWLEDGMENTS The following cooperators contributed materials, equipment and funds for these tests: ‘ a Aerovent Fan and Equipment Company, Lansing, Michigan; Agricultural Stabilization and Conservation, U. S. Department of Agriculture; Butler Manufacturing Company, Kansas City, Missouri; Corn Products Refining Company, Corpus Christi, Texas; The McRan Company, Houston, Texas; and Stran-Steel Corporation, Detroit, Michigan. The authors express their appreciation for the cooperation of the following individuals: M. M. Garcia, of Substation No. 4, Beaumont, Texas, for his assistance in conducting the tests; M. D. Whitehead, formerly associate professor, Department of Plant Physiology and Path- ology, College Station, Texas, for conducting studies on fungal infestation and preparing the section on Mold Development; H. M. Stone, Corn Products Refining Company, Corpus Christi, Texas; Walter Theis, formerly with Corn Products Refining Company, Corpus Christi, Texas; R. A. Hall, formerly superintendent, Substation No. 1, Beeville, Texas; and Jack Bradshaw, State Agricultural Stabilization and Conservation Office, College Station, Texas. REFERENCES (1) Sorenson, J. W., J12, H. P. Smith, J. P. Hollingsworth and P. T. Montfort. Drying and Its Effect on the Milling Characteristics of Sorghum Grain. Bulletin 710. Texas Agri- cultural Experiment Station. June 1949. (2) Baker, Doris, M. H. Neustadt and Lawrence Zeleny. Application of the Fat Acidity Test as an Index of GrainDeterioration. Cereal Chemistry. Vol. 34, No. 4, pp. 226-33. July 1957. (3) Neal, E. M., R. A. Hall and J. H. Jones. Live and Dead Germ Sorghum Grain in Steer. .. Fattening Rations. Progress Report 1702. Texas Agricultural Experiment Station. July 1954. (4) Christensen, Clyde M. Deterioration of Stored Grains by Fungi. The Botanical Review. Vol. 23, No. 2, pp. 108-134; February 1957. / SUMMARY Research was conducted by the Texas Agricultural Experiment Station and the U. S. Department of I: 'culture at Substation No. 1 near Beeville during 7 crop years (1949-50 through 1955-56) to develop 4' thods and procedures for on-the-farm drying and storage of sorghum grain in South Texas. a High moisture and excessive trash (stems, leaves and grass seed) lead to insect. mold and heat damage, d are the basis for most of the troubles encountered in storing grain. High moisture may result from the age of outside moisture through bin walls or from the placing of high-moisture grain in storage. _ A tight structure for protecting the grain from the weather. insects and rodents was found to be essential. perly constructed conventional wood or steel buildings and bins, and a cement plaster bin painted with fwater-proofing paint and provided with adequate ventilation at the grai.n surface, were satisfactory for Spring sorghum grain. A The maximum moisture content for safe storage of sorghum grain in South Texas was found to be 12 ‘ cent. This recommendation is based on storing grain to maintain market value for a single season 'thout systematic turning or aeration, or for longer than 1 year with regularly scheduled aeration practices. rage of sorghum grain for longer than l year without turning or aeration would require limiting the _'isture to ll percent or less. Sorghum grain at 12 to l4 percent moisture, which was aerated or turned ;» ' g storage, was stored safely for 9 months. Sorghum grain with a moisture content higher than l4 rce.nt did not store satisfactorily. High concentrations of cracked grain and broken kernels provide favorable conditions for insects known 1 flour beetles or “bran bugs." The activities of a large number of these insects may cause heating and ease the moisture content of the grain. It was extremely difficult to obtain effective fumigation in grain "-'ch had a high percentage of cracked grain and broken kernels. j Excessive trash caused heating in some bins, even though the moisture content of the grain was below q percent. The temperature of low-moisture grain during storage was a good indication of its condition. Dry, clean, Ect-free grain did not heat when held in a satisfactory storage structure. Fourteen species of insects were found in grain samples taken from the experimental bins. The most levalent were the flour beetle, flat grain beetle. lesser grain borer, rice weevil and a complex of the Indian- _val, rice and almond moths. 3 a No satisfactory protective treatment to prevent infestations was found. Pyrethrum dusts were only _-- ially effective and protected the grain only through the fall. Ryania was effective, but no tolerance has 1t been established. Various liquid fumigants were effective in controlling insects after infestation developed. A minimum rate of 6 gallons per 1,000 bushels was necessary under the most favorable conditions. A Aeration systems were effective for fumigating by recirculating the fumigant through the grain. A i 'rculated dosage rate of 4 pounds of methyl bromide per 1,000 cubic feet killed all the test insects, as - an application rate of 4 gallons of a 60-35-5 mixture of carbon tetrachloride, ethylene dichloride and uylene dibromide per 1,000 bushels of grain. v Mineral oil sprayed on the grain surface in August and October prevented infestation by the various ies of moths. Pyrethrum dusts were not effective at the concentrations used. ‘A Rats and mice were difficult to control and probably were responsible for considerable losses. Effective “trol was obtained through approved rodent control procedures. Aeration was practical and economical in cooling grain during storage. Effective cooling was obtained t~- air flow rates as low as 0.25 cubic feet per minute (cfm) per 100 pounds of grain (about 1/3 cfm per L: el). Fan and air distribution systems used for drying supplied air at a higher rate, and also were y»: actory for aeration. a Molds that cause deterioration during storage, such as Aspergillus and Penicillium, did not develop {long as the grain was stored in a weather-tight structure and a maximum moisture content of 12 percent -» maintained. 5 Of the several methods of drying used on farms in Texas, bin drying with unheated air seems the most ctical. To prevent loss in grade, an air-flow rate of 4.5 cfm per 100 pounds of grain (2.5 cfm per A el) was found necessary to dry grain with 18 percent moisture. The maximum grain depth for the 5: economiqalfidrying was 8 feet at this moisture level. ~ 5 In unheated air drying applications in South Texas, the grain moisture in the wettest layer had to be ‘f ced to 15 percent in 8 days or less to prevent undesirable mold development. Further reduction in jture to a safe level was done over a longer time. 1' A simple fan-operating schedule, based on pushing air up through the grain, was developed. y j A column-type dryer, using heated air, was required when high drying capacities were needed. t CONTENTS Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .v . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 References . . . . . . . . . . . . . . . . . . y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1.’ . . . . . . . 2 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11.‘ . . . . . . . 3 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 51 I Equipment and Test Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Storage Bins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 5 Insect Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 6 A V. Aeration . . . . . . . . . . . . ._ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 8 ‘ Drying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 With Unheated Air . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 7 With Heated Air . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 7 Quality Determinations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Instruments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 8 Grain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 8 For Saie Storage oi Grain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 8 f; Bin Construction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Moisture Content oi Grain . . . . . . .' . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Below ll Percent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 9 ll to 12 Percent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 9 12 to 13 Percent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .._. . . . . . . . . . ..18 1 l3 to 14 Percent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..1U 14 to 15 Percent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10 Cracked Grain and Trash . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10 l Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .ll Eiiect oi Structure and Bin Wall Color on Temperatures . . . . . . . . . . . . . . . . . . . . . . . . . ..ll Insects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11 H Rodents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..14 t Mold Development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .- . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14 Aeration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15 Weight Losses in Storage. ._ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ._ . . . . . . . . . . . . . . . .15 Handling In and Out oi Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16 Drying High-moisture Grain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18 '. With Unheated Air . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..16 V‘ Bin Drying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..l6 A Drying Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . g . . . . . . . .16 Air Flow Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..l7 ‘t Grain Depth . . . . . . . .' . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18 Drying Time . . . . . . . . . . . . . . . . ." . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8 . . . . . . . . . . . . .19 Fan Operating Schedule . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..l9 é Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28 With Heated Air. . . . ._ . . . . . . . . . . . . . . . . . . .1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21 Bin Drying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21 Batch Drying . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21 Portable Batch Dryer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..2l Column-type Dryer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . : . . . . . . . . . . . . . .22 g esmra/z 01/1. . . . . FARM DRYING AND STORAGE 0F SORGHUM GRAIN I. W. Sorenson, lr., G. l. Kline, l. M. Redlinger..M..G. Dauenportund W. H-Aldred* HE IMPORTANCE OF GRAIN SORGHUM in Texas has grown steadily during the past 20 Airs. The development of varieties and hybrids ble for mechanical harvesting and an in- sed demand during World War II contributed yard making grain sorghum a major crop in l th Texas. The demand for sorghum grain was so great ing most of the 1940’s that the crop was mov- “directly from the field to the waiting market. 1a result, the storage of sorghum grain did not Ame a serious problem to farmers in South p} as until the late 1940’s, when there was a sud- i‘ o and sharp decline in market price. Storage ice available to hold the grain for a more favor- - market would accommodate only about 10 ent of the grain produced in that area. The warm, humid climate of South Texas ikes it necessary to store grain at a lower mois- content than is required in a cold, dry cli- ite. The lower is the moisture content of stor- ; grain under these climatic conditions, the less bathe danger of insect infestation. In an effort to solve the problems peculiar fthis area, research was started in 1949 by the ‘pectively, professor, Department of Agricultural En- ‘ neering, College Station, Texas; agricultural engineer, f? S. Department of Agriculture, formerly stationed at ville, Texas; formerly entomologist-in-charge, U. S. ;partment of Agriculture Stored-Product Insects Lab- tory, Houston, Texas; formerly assistant professor, d assistant professor, Department of Agricultural En- eering, College Station, Texas. Texas Agricultural Experiment Station and the U. S. Department of Agriculture to develop meth- ods and procedures for the safe storage of sor- ghum grain on the farm. This study provides in- formation on types of storage structures, maxi- mum moisture content for safe storage, effect of storage conditions on grain quality, insect and rodent control, aeration during storage, losses in weight during storage, grain handling equipment and drying high-moisture grain. EQUIPMENT AND TEST PROCEDURE Sorghum grain was stored at different mois- ture contents at Substation No. 1 near Beeville. Results were obtained for 7 crop years, 1949-50 through 1955-56. STORAGE BINS Fifteen conventional farm-type bins, two steel buildings, one cement plaster bin, two tem- porary-type bins, one glass-lined steel, air-tight bin and five underground pits were used in these tests. Concrete block, earth fill and concrete slab foundations were used. The conventional bins, shown in Figure 1, were constructed of wood and steel. Capacities ranged from 28,000 pounds (500 bushels) to 123,- 000 ppunds (2,200 bushels). Shapes were round andrectangular. Bin wall colors of white and aluminum were used and some of the bins were left as unpainted galvanized steel. Grain depths were 6 to 10 feet. Figure 1. Types of conventional farm-type bins used in sorghum grain drying and storage tests. A. Two 12 x 16-foot two 14 x 16-foot bins of wood construction, such as shown. were included. B. Two 56.000-pound capacity steel bins 'pped with fans and air distribution systems for bin drying grain with unheated air. Capacities of steel bins used in these _-ranged from 28.000 to 123.000 pounds. Figure 2. These steel buildings were used for drying and storage tests. A. This 16 x 28-foot building was equippedlwii a tan and air distribution system for drying and aerating grain. B. Two SILOOU-pound capacity bins were constructed y this 32 x BO-foot steel building. One of the steel buildings was 16 feet wide and 28 feet long. It had a capacity of 123,000 pounds (2,200 bushels). The other was a 32 x 60-foot building in which two 50,000-pound (900 bushels) capacity bins were constructed in one end. These buildings are shown in Figure 2. The cement plaster bin is shown in Figure 3. This bin was 14 feet in diameter with 8-foot walls and had a capacity of 56,000 pounds (1,000 bush- els). A screw-conveyor was installed in the floor to facilitate unloading. The temporary-type bins are shown in Fig- ure 4. A bin was considered temporary when it was designed for emergency use for a short time, usually for 1 year or less. Temporary-type bins used in these tests were constructed of a low-cost, hardwood veneer material with asphalt-resin-im- pregnated paper on both sides. The material was black in color and was made in 4 x 8-foot sheets with an overall thickness of 1/7 inch. One pf the bins was 12 feet wide, 16 feet long and 4 feet Figure 3. This 56,000-pound capacity cement plaster bin was equipped with a screw conveyor in the bin floor to facilitate unloading. A removable cover. shown in raised position, was used to keep water out of the unloading pit. To prevent spoilage of grain in the surface layer, it later was necessary to install a revolving head ventilator in the bin rooL 6 deep. A 2 by 4-inch framework was constructe over the bin to support a tarpaulin cover. Th. capacity was 45,000 pounds (800 bushels). Th other bin was 14 feet in diameter with 8-foo walls. Its capacity was about 62,000 pound (1,100 bushels). A glass-lined steel, air-tight bin, shown Figure 5, was used to store grain ranging in moi; ture from 12.4 to 26.3 percent. The bin was i feet in diameter with 8-foot walls. It had a A pacity of 56,000 pounds (1,000 bushels). Four small-scale and one- large-scale unde A ground pits were tested. Each small pit was , ” proximately 6 feet long, 2 1/2 feet wide and 5 fed, deep. Each was filled to within 1 foot of the t‘ and had a capacity of about 2,800 pounds (5 bushels). The large-scale pit, shown in Figure .- was 8 feet wide, 18 feet long and 8 feet deep Wit a capacity of 40,000 pounds (700 bushels). Ma terials used to line the floor and walls include asphalted roll roofing, moisture-resistant rei , forced building paper, poured concrete, ceme p, plaster and wood. One pit had an earth botto and walls. - INSECT CONTROL Tests to control insects were conducted in t round, steel bins and in the smaller of the st, buildings. Studies were made to determine possibilities of using protective treatments, to velop surface treatments as a means of retard' invasion of insects from outside sources and evaluate and improve standard fumigation pri tices. The test bins were sampled at regular 5f tervals and the species of insects and their abu dance were recorded. § AERATION .. Aeration is the moving of small amounts outside air through stored grain, for purpo other than drying, to maintain or improve '2 value. During the first 2 years, grain was turn (moved from one bin to another) when heati Figure 4. These temporary-type bins were used to U-pound capacity bin to support a tarpaulin cover. covered with roll roofing. ‘y urred. After the second year, air distribution istems were installed in most 0f the bins t0 c001 e grain by aeration. Air flow rates of 0.2, 0.6, i and 1.3 cubic feet per minute (cfm) per 100 unds of grain (0.12, 0.33, 0.50 and 0.75 cfm hr bushel) were used. ,YING Tests were conducted with unheated and fated air. Unheated air is normal atmospheric A without the addition of heat. Heated air re- , ,ves large amounts of moisture from the grain. ated air is used for fast drying and unheated a. is used for slow drying. Unheated Air A bin dryer was used for the unheated air . ing tests. A bin dryer is one in which grain idried in the same bin in which it is to be stored. sts were conducted with small-scale and full- : bins. Initial moisture content of the grain i: 14.2 to 20.0 percent, wet basis. Grain depths ire 6 to 10 feet. Small-scale bins were used to TiiI-‘igure 5. This 56.000-pound capacity glass-lined steel, light bin was used to store high-moisture grain. store dry grain. A. A Z x 4-inch framework was constructed over this Inset shows the cover in place after the bin was filled with grain. fThis BLOOD-pound capacity round bin was erected on a tamped earth fill foundation. The grain was peaked at the center determine minimum air flow requirements for drying with unheated air. Air flow rates of 1.8, 2.7, 3.6, 4.5, 5.4 and 7.2 cfm per 100 pounds of grain (1.0, 1.5, 2.5, 3.0, and 4.0 cfm per bushel) were used. With Heated Air Heated air drying tests were conducted with bin dryers and batch-type dryers. A portable batch dryer, as shown in Figure 29, was used in these studies. Results of tests conducted in 1947 with a column-type-batch dryer (1)1 are summar- ized in this report. In the bin drying tests, grain was dried with air temperatures of 119° to 135° F. Initial mois- ture content of the grain was 15.4 to 23.0 percent, wet basis. Grain depths were 1.25 to 6.25 feet. A batch dryer is one which dries a fixed quantity of grain at one time, with additional batches dried on a repeating basis. Usually grain ‘Numbers in parentheses refer to the references. Figure 6. Underground pits were used to determine the practicability oi this type of storage in South Texas. is dried in layers 6 to 18 inches deep. A dryer 0f this type requires large volumes of heated air and is used when high drying capacities are de- sired. Grain dried by this method usually is transferred t0 another bin for storage. Air temperatures of 125 to 230° were used in the batch drying tests. Initial moisture content of the grain was 13.4 to 26.3 percent, Wet basis. Grain depths were 10 to 18 inches. Air volumes were 70 to 107 cfm per square foot of grain sur- face exposed to the air. QUALITY DETERMINATIONS Temperature observations were made at reg- ular intervals during the drying and storage pe- riod. Samples for moisture content, grade, fat acidity, germination, fungal infestation and in- sect counts were taken as the grain was stored and at intervals during the storage period. The fat acidity value was used as a measure of the quality of grain. It is defined as the num- ber of milligrams of potassium hydroxide requir- ed to neutralize the free fatty acids in 100 grams of dry grain. Tests made by the U. S. Depart- ment of Agriculture (2) indicate that freshly har- vested grain sorghum of unquestionable sound- ness usually has fat acidity values less than 25. In these experiments, 157 samples of freshly har- vested grain of the 1952, 1953, 1954 and 1955 crops Were analyzed. Fat acidity values for these samples were 13 to 37, With an average of 23. INSTRUMENTS A portable potentiometer and copper-constan- tan thermocouples Were used to determine tem- peratures at various locations in the grain. Stand- ard moisture testing equipment was used for mois- ture determinations. A deep bin probe _was used tomobtain samples of grain from the bins. Re- cording instruments Were used to obtain cont1n- Figure 7. A tight structure was necessary to prevent leakage oi outside moisture. Moisture leakage caused high insect infestation and heating which resulted in considerable spoilage oigrain. 8 uous records of atmospheric temperatures an relative humidities. Manometers were used w measure air pressures. f GRAIN - Approximately 4,500,000 pounds of Marti and 170,000 pounds of Texioca 54 were used dur; ing the 7-year test period. Initial moisture con; tents were 10.4 to 26.3 percentfwet basis. FOR SAFE STORAGE OF GRAIN High moisture and excessive trash (stem- leaves and grass seed) lead to insect, mold an heat damage, and are the basis for most of th troubles encountered in storing grain. High moi ture may result from the leakage of outside moi ture through bin walls or from the placing o, high-moisture grain in storage. BIN CONSTRUCTION Properly constructed conventional Wood 0 steel buildings and bins and a cement-plaster b' painted With Water-proofing paint and providl with adequate ventilation at the grain surfac, were satisfactory for storing sorghum grain. Wooden bins with single walls were not tigi; enough to exclude moisture or prevent loss ~- fumigants. Single-Wall bins can bemade tig by lining the Walls with roofing felt, but repa‘ Esually are necessary before each filling of ti 1n. e i Moisture leaked through the bin walls ‘ some of the steel bins where Wall joints and b heads Were poorly sealed, causing heating s. high insect infestation. Moisture leakage W prevented by caulking all joints and sealing: bolt heads properly. i In some cases, moisture leaked through t floor-wall joint in round steel bins. It was fou that bins should be located on well-drained arf and the floor elevated enough so that Water cf not collect and leak through the floor-Wall jo‘. A tamped earth fill encircled by a concrete bl retaining Wall, as shown in Figure 8, was a sa 7 factory foundation for round steel bins. were anchored to “dead men” buried in the gro ’ to prevent the possibility of Windstorm dam when the bins were empty. a Grain stored in temporary-type bins kept isfactorily, but the temporary use of the st tures did not justify the cost of construction s. the periodic maintenance required. Grain with a_ moisture content of 15 toi- percent was stored in an air-tight bin for as l, at 4 1/2 months without loss in market value w the grain Was transferred to another bin for r ing at the end of the storage period. Ger _ i tion dropped to zero after 3 months’ air-t’, storage. Some difficulty was experienced in loading since the grain would not flow re, Grain with an average moisture content of entpwas stored in 1953 in this air-tight bin was used satisfactorily in a 112-day feeding lat the Beeville station (3). A Underground storage was found to be unde- ,ble when storing grain for market purposes. was almost impossible to prevent soil from mix- with the grain during the loading and unload- operations. There was no satisfactory way control insects and rodents. Even if grain is ‘red for feed on the farm, the expense involved constructing bulkheads to hold the grain and ‘protect it from the weather during the feeding period is as great, if not more, than above- storage. ISTUHE CONTENT OF GRAIN The purpose for which grain is to be used a factor which determines the maximum mois- re for safe storage. For example, if it is de- ed to maintain germination of seed or to pre- ,nt a serious increase in fat acidity value, the ‘isture content must be lower than for grain ywhich maintenance of market grade is the ole consideration. If the grain is trashy or con- fns a large percentage of cracked and broken nels, a lower moisture content usually will be uired than if the grain is clean and sound. ain aerated during storage can be held at a her moisture content than when no provision fmade for aeration. Grain was stored at the following moisture intents to determine the maximum moisture for fe storage in South Texas: below 11 percent, to 12 percent, 12 to 13 percent, 13 to 14 per- §nt and 14 to 15 percent. Moistures within these g'es represent the maximum moisture in the p and not the average moisture content of the ain. Length of storage was 8 to 33 months. , The maximum moisture content for safe stor- e of sorghum grain in South Texas was found ,be 12 percent. This recommendation is based . storing grain to maintain market value for a gle season Without systematic turning or aera- _n, or for longer than 1 year with regularly eduled aeration practices. Storage for longer in 1 year without turning or aeration requires iting the moisture to 11 percent or less. Grain 12 to 14 percent moisture, aerated or turned ring storage, was stored safely for 9 months. with a moisture content higher than 14 per- fl t did not store satisfactorily. .4 f, ow ll Percent p, At initial moistures of 9.7 to 11 percent, one l; of 1949 grain was stored, without turning or ration, for 2 years and then fed out to beef cat- over anaadditional 6 months. It did not heat develop ain abnormal odor during storage. An rease of cracked kernels and trash from 2.8 A 5.3 percent caused a change in grade from ;mber 1 to Number 2. There was no change attest weight during the 2 years. Average mois- eincreased from 10.5 to 11.2 percent. Nine other lots were stored without aeration or turning for 9 to 17 months. There was no loss in grade except in one lot where a slight increase in percentage of cracked kernels caused a change in grade from Number 1 to Number 2. Changes in test weight varied from no change to a reduc- tion of 5 pounds per bushel. No significant loss in germination occurred during 9 months storage, but germination usually decreased gradually in lots stored longer. _ l1 to 12 Percent Out of 14 lots stored 9 to 10 months, no change in grade occurred in five aerated and three unaerated bins. Grade changed from Number 1 to Number 2 in four aerated bins and from Num- ber 1 to Number 3 in one aerated bin. The reduc- tion in grade of all five lots was caused by an in- crease in percentage of cracked kernels and trash. One of the lots was high in trash content and became heavily infested with insects. Frequent aeration was necessary during the fall and winter to reduce high temperature areas and resulted in considerable reduction in moisture content of both the grain and the trash. This bin graded Sample, Sour, after 9 months storage. One lot of grain stored in 1951 and aerated during storage did not change in grade for 26 months, but became musty and graded Sample after 32 months storage. Reduction in grade was due to heating and heavy insect infestation re- sulting from leakage of outside moisture. Aver- age moisture decreased about 0.5 percent during the 32 months. Germination decreased consider- ably after 8 months storage. Test weight per bushel decreased less than 1 pound. Another lot of grain dried with unheated air in 1955 was held in aerated storage for 2 years and then fed out to beef cattle over an additional 3 months. Germination dropped from 90 percent at the start of storage to 72 percent after 24 months. There was no lossin grade during the 2 years. Average moisture decreased about 0.5 p Figure 8. Foundations made by setting a ring of concrete blocks _ctnd filling the inside with well-tamped earth were used for most oi the round steel bins. 9 percent. Test weight” changed from 58.5 to 57.5 pounds per bushel. Fat acidity values increased from 18 t0 28 during the first year, and to 41 at the end 0f the second year. ~ Aerated grain in this moisture range, which was relatively free of trash and insects, was stor- ed for 9 months without loss in germination. Fat acidity values of 16 to 30 at the start were in- creased to 26 to 45 during the same period. There was little change in average moistures of grain stored without aeration but moistures decreased in aerated lots from 0.3 to 1.7 percent, with an average 1.1 percent. l2 to l3 Percent As in the lower moisture ranges, the amount of trash in the grain and the degree of insect in- festation were the most important factors in maintaining high quality grain. Extremely trashy grain, together with high insect infestations, caus- ed heating in two unaerated bins and resulted in Sample Grade grain, Sour, at the end of 9 months storage. Seven lots free of trash and low in insect ac- tivity were not reduced more than one grade dur- ing 9 months storage in four aerated and three unaerated bins. Changes in test weight were not great enough in any of the lots to cause a reduc- tion in grade. There was no loss in germination during 9 months storage in the aerated bins, but a significant loss occurred in all of the grain stor- ed without aeration. Average moistures decreased 0.3 to 1.1 percent in the aerated bins, but changed very little in bins that were not aerated. A con- siderable increase in fat acidity value occurred, except in one aerated lot that remained free of insects throughout the storage period. Figure 9. An example oi how trash rolls down into pockets as the bins are-filled.‘ This material causes air to channel and results in musty and heat-damaged grain. Proper adjustment of combines at the time oi harvest will reduce the amount of trash. l0 13 to l4 Percent Five lots of grain in this moisture ran started to heat after a few weeks storage. Sin none of the bins was equipped for aeration, gra in four bins was turned‘ from one bin to anoth to reduce hot spots. None of the lots was r duced more than one grade during 9 months sto, age, but there was a significant-doss in germin tion in all four lots.‘ Changesk in test weig ranged from 1.5 pounds per bushel increase to 2i pounds decrease. The fifth lot, held in stora without turning or aeration, decreased in gra from Number 2 to Sample, Sour, during 9 mont storage. .1 u‘ These tests showed that grain in this moi ture range can be stored without significant loss in commercial grade when facilities are availab for turning the grain. This is expensive and ti consuming and is not practical for farm storag however, turning could have been eliminated .0 provision been made for aeration. Even the good management practices are required to pr vent losses from heating and insects. i 14 to 15 Percent At initial moistures of 14 to 15 percent, t ~* lots of grain started to heat a few days after sto age. One lot of 1949 grain was held in stora for 9 months without aeration. Grade was r duced from Number 3 to Sample Grade duri this period. Test weight per bushel decreas from 58.0 to 56.5 pounds per fbushel. Germin tion dropped from 85 percent to zero during t first 3 months storage. a High temperatures developed in a lot of 19 grain a few days after storage. To prevent cessive losses, unheated air was used for 8 da to reduce the moisture to below 11 percent. ., further heating occurred during 9 months sto age, but an increase in percentage of cracked ke nels and trash caused a reduction in grade fri Number 2 to Number 4 during the same peri Test weight per bushel changed from 55.0 to 54“ pounds. Germination decreased from 86 to percent and fat acidity value increased from l to 50. CRACKED GRAIN AND TRASH The amount of cracked grain and broken ke nels is an important factor in grain storage. concentrations of these materials provide favl able conditions for insects known as flour beetl or bran bugs. These insects feed primarily i broken kernels or on grain damaged by other i sects. The activities of large numbers of the insects may causeheating and increase the moi ture content of the grain. It also is extremely df ficult to obtain effective fumigation in gra which has a high percentage of cracked grad and broken kernels. a Excessive trash caused heating in some bii even though the moisture content of the gra was below 12 percent. Stems and leaves of if m plants usually are higher in moisture than grain at the time 0f harvest. Since this ma- a1 is lighter than the grain, it accumulates in yfkets as the grain is loaded into the bin. This h-moisture material will soon start to heat A,» also make favorable conditions for the de- pment of insects, which in turn liberate more isture and cause the grain to heat. This con- ion, if allowed to continue, will spread through- the bin and may result in excessive spoilage pm’ insects and mold fungi. Control by aeration v fumigation usually is satisfactory under these , ditions. However, in extreme cases, it may be ‘essary to turn the grain to break up and re- ribute trashy areas. ERATURE ‘The temperature of low-moisture grain Was ‘food indication of its condition. Dry, clean, in- ltd-free grain did not heat when it was held in satisfactory storage structure. Any increase Ytemperature indicates an increase in moisture to trash, insects or leakage of outside mois- e. When hot spots occur, steps should be taken eliminate the cause of heating. p Low temperatures are desirable in any area prevent loss in germination and serious in- ase in fat acidity value. They also are desir- ale in South Texas to reduce insect activity. ration was effective in maintaining relatively 5w temperature during the winter, but it was f» practical to attempt to reduce temperatures uch below 90° during the summer. p Typical temperatures of grain stored in 18- yt diameter bins are shown in Figure 11. In j he aerated and unaerated bins, average grain mperatures were not reduced much below 90° ‘ring July and August, but they dropped below a is level during September when there was a cor- ponding drop in atmospheric temperature. In eunaerated bins, average temperatures grad- lly decreased to 65 to 70° by February, and re- ined at that level for the remainder of the stor- period. Average grain temperatures in the irated bins were reduced quickly below 80° dur- l: September and reached 60 to 65° by Novem- fr. Continued aeration during the winter re- iced average temperatures below 60° bv Jan- ry. They remained below this level until the p; of April when they started to increase with a a esponding increase in atmospheric tempera- res. ect of Structure and Bin Wall lor on Temperatures A Table 1 shows variations in the temperature fair above; the grain and at the west bin wall for a eral types 6f bins. This information was com- ed for different seasons of the year and at dif- rent times of the day during 1951-53, with the ception of the double-wall bin in the 32 bv 60- t steel building. ‘Temperatures in this build- i: are for the 1951-52 storage year only. Air temperatures above the grain and bin wall temperatures were considerably higher in un- painted round steel bins than in painted steel bins and buildings and in a cement plaster bin. The greatest temperature difference occurred during the summer. Air temperatures above the grain at 2:00 p.m. during August were as much as 10° lower in white-painted round steel bins than in unpainted round steel bins. In no case were the grain temperature differences enough to have an important effect on commercial grade. However, the lower temperatures are desirable for storing planting seed and for effective insect control. ‘INSECTS Infestation of stored grain usually takes place after the grain is placed in storage; how- ever, in many areas of the State, grain is infested frequently in the field with rice weevils and An- goumois grain moths. Some of the grain receiv- ed for these studies had a light initial infestation of insects originating during the handling from the grower to the storage site. Conditions are very favorable for insect de- velopment in South Texas and stored-grain in- sects invade the bins as soon as they are filled. Even when the grain is fumigated in late» July or August, it often will become reinfested within a month or two. Insect activity is greatly reduc- ed after temperatures of 60° or less are reached; therefore, the movement of insects into bins is at a minimum during the winter, and those in the surface layers remain inactive. However, insects already established deep in the bin will continue to flourish, because the grain temperatures usu- ally remain in the 70’s unless the grain is cooled by aeration. Activity is resumed in the spring as the temperatures rise. The rate of insect de- velopment is greater in high-moisture than in low-moisture grain. Fourteen species of stored-grain insects were found in samples taken from the experimental Figure 10. When grain was aerated by pulling air down through it, a reasonably accurate average grain temperature was determined by placing a good quality thermometer in the duct between the fan and grain close to the bin wall, as shown here. ll bins between December‘1952 and April 1955. The most prevalent species were the flour beetle, flat grain beetle, lesser grain borer, rice Weevil and a complex of the Indian-meal, rice and almond moths. The moth larvae infested the surface layers of grain, and the other species were scat- tered throughout the bins. Tests were conducted in the 1952-53, 1953- 54 and 1954-55 seasons on protective-treatment insecticidal formulations applied as dust or sprays directly to the grain as it Was placed in the bin. Dusts containing pyrethrum, which are recom- mended for use on stored wheat, gave only fair protection from the time of binning until cold weather and did not prevent moth infestations in the surface layers. An experimental protective I IU IOO 9O 8O 7O MAXIMUM GRAIN TEMPERATURES 6O 5O 4O IOO 9O 8O \ 7O AVERAGE GRAIN TEMPERATURES 6O DEGREES F. 5O 4O IOO 9O so \ I MINIMUM GRAIN TEMPERATURES TEMPERATURE 7 6O 5O 4O IOO 9O 8O s X AIR TEMPERATURE I ---- MAXIMUM . AVERAGE 1 --—MINIMUM 7O 6O 5O 4O 2I 3| IO 2O 3O 9 I9 29 9 I9 29 8 I8 28 I DEC. JULY AUG-. SEPT. OCT. I NOV. a I828? I727 e Iezsazazsv n21 dust containing ryania gave excellent protecti for 9 months, but it cannot be recommended u til a tolerance for residues of this material h been established. I Since the infestations first appeared in I surface layers of grain, studies were made to evv uate surface applications that might prevent Ij festations from becoming establish-ed. A refin_ light mineral oil applied as a spray‘ to the surfa layer at a rate of 2 quarts per 100 square feet‘ August and again in October gave excellent pr tection through February against infestation v moths. Ryania dust also gave excellent prot tion when applied in August and December. rethrum dusts were not effective at dosages w, 0.9 to 2.7 ppm of pyrethrins, but recent tes ----- AERATED 1"- UNAERATED V I JAN. I FEB. ‘MAR. IAPRIL. Figure ll. Typical temperatures of grain stored in 18-foot diameter steel bins from Iuly 1954 to April 1955. Air tempera! ~ during the same period are shown in the bottom graph. 12 where 0n other grains at higher concentra- 3 s are promising. Tolerances for residues 've been established for mineral oil and for py- ,hrum, but not for ryania. Various liquid fumigants were effective in trolling insect populations after infestation eloped. These were the standard liquid grain e-and carbon bisulfide in an 80-20 ratio by vol- ihe; carbon tetrachloride, ethylene dichloride and ylene dibromide in the 60-35-5 ratio; ethylene hloride, carbon tetrachloride, ethylene dibro- ALE 1. COMPARISONCF ABOVE GRAIN AND BIN WALL PERATURES IN VARIOUS TYPES OF BINS AT DIFFER- Y ENT TIMES DURING THE DAY ’espherie temperature‘ Average temperature. degrees F‘ °i bin and time °I daY August September December fospheric temperature o=oo a.m. a4 7o so 2=oo p.m. 97 91 s5 yiioot diameter steel bin. ,'""nted aluminum 0'8 vbove grain ’1'8:00 a.m. 85 80 51 '_ 12:00 p.m. 103 98 70 ;West bin wall a=oo a.m. as a1 s2 2:00 p.m. 105 100 72 loot diameter steel bin. _'nted white {Above grain ~. 8:00'a.m. 84 78 53 f 2:00 p.m. 100 91 69 fWest bin wall 8:00 a.m. 82 76 53 c: _ 2:00 p.m. 104 95 70 foot diameter steel bin. ‘ 1: ~- painted {Above grain 8:00 a.m. 89 83 54 .. 2:00 p.m. 110 100 69 iwest bin wall _ a=oo a.m. a7 so s9 f‘- _2:00 p.m. - — 70 '_ foot diameter cement aster bin Above grain it 8:00 a.m. 78 74 49 .J 2:00 p.m. 95. 89 62 fWest bin wall . If 8:00 a.m. 80 75 52 I‘ 2:00 p.m. 94 I 88 63 huble-wall bin in y ‘x 60 foot steel y» "lding. painted cream , Above grain _ 8:00 a.m. 85‘ 78 54 . 2:00 p.m. 98 92 70 est bin wall 58:00 a.m. 83 79 - 54 v 2:00 p.m. 98 91 - 68 erage temperatures during 1951-53 with the exception of double-wall bin in the 32~ x 60 foot steel building. Tem- atures in this building are for the 1951-52 storage year .5‘ Y. .5’ l a igant mixtures containing carbon tetrachlo- mide and sulfur dioxide in a 70-24-3-3 ratio; and a formulation containing carbon tetrachloride, ethylene dichloride, ethylene dibromide and car- bon bisulfide. A dosage rate of 6 gallons per 1,000 bushels Was considered an absolute minimum for use in circular metal bins. Partial failures occurred with this dosage rate in small bins (less than 600 bush- els), in bins: Where the fumigant Was applied when the temperatures in the headspace Were well above 100°, when there was a 12 to 15 mph Wind when the fumigant was being applied and Where the bins were not tight. I No deterioration of the quality of the grain occurred from repeated fumigations with these mixtures. Germination and fat acidity remained at nearly the same level after the fifth fumiga- tion of one lot of grain. These tests demonstrated that proper fumi- gation Will destroy the current infestation, but Will not prevent reinfestation from outside sources. Fumigants were recirculated through the grain mass in storages Where aeration systems were installed. A duct was attached to the blower discharge to direct the fumigant back to the head- space, as shown in Figure 13. Fumigants Were distributed more effectively and the dosage rate reduced considerably with this method. Methyl bromide Which will not penetrate bulk grain well by gravity diffusion was distributed uniformly through the grain mass by recircula- ting it for 15 minutes after the gas was intro- duced. A dosage rate of 4 pounds per 1,000 cubic feet killed test insects implanted in all parts of Figure 12. A good clean-up campaign was necessary for effective insect control. After the clean-up. a 2.5 percent methoxychlor spray. was applied. to the point of runoff. to the inside walls. as shown here. A DDT spray was applied to the outside ewalls and to the soil near the bin. but was not used where it might contact the stored grain. 13 Figure l3. A return duct installed on a steel building to recirculate iumigants. the bin. A 60-35-5 mixture of carbon tetrachlo- ride, ethylene dichloride and ethylene dibromide was distributed evenly by recirculating the vapors for 30 minutes after the mixture had been spray- ed uniformly over the surface of the grain. An application rate of 4 gallons per 1,000 bushels killed test insects implanted in all parts of the bin. A 3-gallon rate killed all but five of the hundreds of test insects. (Some fixed bromide residue accrues from each fumigation with methyl bromide, so that repeated fumigations will result in a residue in excess of the tolerance of 50 ppm. Users of methyl bromide are cautioned not to fumigate sorghum grain more than three times, unless chemical analysis for already incurred bro- mide residue is first made to assure adequate mar- gin for another fumigation.) Other tests were made with the recirculation method in a round metal bin which was com- pletely covered with a polyethylene sheet, as shown in Figure 14. The aeration fan pulled air down through the grain and discharged it out- side the bin but beneath the cover, where it was pushed back to the surface of the grain. A dos- Figure 14. A circular steel bin covered with a poly- ethylene sheet to aid in recirculating fumigants. l4 age rate of 4 pounds of methyl bromide per 1,000 cubic feet killed test insects implanted in all parts of the bin, as did an application of 3 gallons per 1,000 bushels of the ‘60-35-5 fumigant mixture. A 3-gallon rate of the 60-35-5 mixture was appliedn in the same polyethylene-covered bin, without the recirculation, as a check. In this test the vapors were allowed to disperse by gravity diffusion. This resulted in only partial gmbrtality of test in- sects in the middle and lowerilevels in thebin. This was considered an apt demonstration of the unequal distribution resulting from natural dif- fusion of the fumigant vapors. It also showedj why dosage rates of 6 gallons per 1,000 bushels? or greater, are needed when fumigants are ap- plied in this manner. RODENTS Rats and mice were difficult to control and probably were responsible for considerable losses.‘ Effective control was obtained through ap- proved rodent control procedures. Areas sur- rounding bins were kept free from rat-harboring places. Outside openings in aeration ducts were. sealed tightly when not in use to prevent the en-1 trance of rats and mice. Sprinkling DDT powders between double walls was effective in controlling, a mice, but it should be spread when the bins are. empty to protect the grain from the DDT. ' MOLD DEVELOPMENT Fungi that infect grain in the field before harvest do not seem to be associated with cdete-g? rioration of sorghum seed during storage. Chri’ tensen (4) designated the fungal genera that in- vade seed as field and storage fungi. Field fun‘ invade the seed while it is still on the plant. Stor‘ age fungi develop on and within the seed during. storage. Some fungi designated as storage fun were present on the grain in these tests at har- vest, but generally in low percentage. The percentage fungal infestation at harves it and the beginning of storage apparently dependi on the maturity of the grain and the climatic con i ditions during the latter part of the growing se; son. Grain harvested at 14 to 15 percent moi“; ture in 1954 was infested 98 percent with specie of Alternaria while grain harvested at 18 to 2 percent moisture was infested with 70 percen’ Alternaria. There was considerable year-to-yea, variation in the percentage of overall infestatio: as the seed were harvested. Ninety-three peil". cent of the seed were invaded by fungi in 1951i 35 percent in 1952, 64 percent in 1953 and 88 per; cent in 1954. The year-to-year spread of infestf tion by specific-genera of fungi was just as grea Twenty-seven genera of fungi were noted. Sixty. one percent of the seed were infested with specie; of Alternaria in 1951, 73 percent in 1952 and percent in 1953. Twenty-four percent were i, fested with species of Hormodendron in 1951,; trace in 1952 and 4 percent in 1953. Species _ the black molds, Alternaria, Curvularia, Helmi thosporium, Hormodendron and Nigrospor '1 ade up 95 percent of the infestation at the be- inning of storage. , In general, fungi found infesting seed at the l e 0f harvest decreased sharply during the first q_ months of storage and continued to decrease Ytadually during the remainder of the storage riod. Sixty-four percent of the seed harvested l, 1953 were infested with fungi at the beginning storage, 25 percent after 3 months and 12 per- ntafter 6 months storage. .In one bin of 1951 ‘in, only 12 percent of the seed were infested 5- 1 year storage. This was reduced to 5 per- it after 2 years and to 3 percent after 32 “nths storage. 7. Species of storage molds, Aspergillus and i? icillium, developed on seed stored under high isture conditions and in high-moisture areas ulting from leakage of outside moisture. n ples taken in 1951 from one lot of grain that , an average moisture content of 15.8 percent Qthe beginning of storage were infested 100 per- t by Aspergillus versicolor, and the germina- j dropped to zero at the end of 3 months stor- A The grain was transferred to another bin é dried to a moisture content of 12 percent or . After 3 months additional storage at this er moisture content, the infestation by Asper- - versicolor was reduced to 32 percent. f’ An increase in infestation of the grain by ies of Aspergillus and Penicillium was asso- with deteriorating seed quality. This em- fizes the importance of storing grain in a filler-tight structure and at a low enough mois- content to prevent development of these Mold development during storage was not yblem in South Texas when grain was stored " moisture content of 12 percent or less. TION Aeration was practical and economical in "ng grain during storage. These tests show Y:' it is desirable to aerate grain as soon as ‘bleafter the bin is filled until the temper- in the grain are reduced to 90° or less; ,f_,~ for operating the fan 2 to 3 hours once a fl to change the air in the bin, further aera- lis not necessary during the summer unless 11g occurs; and grain should be aerated dur- he winter until temperatures are reduced to " less. j ffective cooling was obtained with air flow fas low as 0.25 cfm per 100 pounds (about ’ m per bushel). However, with such a low _w rate, more time was required to cool the . For example, during the 1954-55 storage ithe fan operated a total of 306 hours when as suppliedlat a rate of 0.25 cfm per 100 s, compared with 181 hours with an air ‘bf 0.60 cfm per 100 pounds (1/3. cfm per l). Grain in these tests was aerated as soon ‘sible after the bins were filled. Fans were “ted during the nights only until grain tem- peratures were reduced to 90° or less. Aeration fans were not operated again until September when atmospheric temperatures started to drop. Fans were operated during the fall and winter as often as necessary to reduce grain temperatures to 60° or less. Fan and air distribution systems used for drying grain supplied air at a higher rate, but also were satisfactory for aeration. With the high air flow rates used for drying, grain was cooled in about one-third the time required to cool grain with air supplied at a rate of 0.25 cfm per 100 pounds. For this reason, close supervision is required when high air flow rates are used to prevent large losses in weight caused by exces- sive reduction in the moisture content of the grain. Air was pushed up and pulled down through grain. These methods seemed equally effective for cooling grain. Pulling air down avoids con- densation in the winter. The humid air leaving the grain does not come in contact with cool sur- face grain or the cool bin roof. Condensation was not a problem, however, when aeration was start- ed early in the season. Pulling air gives an op- portunity to smell the air coming out of the bin to detect any off odor which may have developed. As shown in Table 1, air temperatures in the top of the bin were high during the summer. Under these conditions, it was best to push air to pre- vent pulling hot air through the grain. In bin drying, grain is dried by pushing air up. There- fore, when bins are equipped with drying sys- tems, it would be an advantage to push air for aeration since it would be unnecessary to reverse the fan to change the direction of air flow. Grain was cooled during the summer by op- erating the fans at night. There usually was enough difference in grain temperatures and at- mospheric temperatures to operate fans during clear nights without danger of increasing the moisture content of the grain. During cool weather, fans were operated any time the atmos- pheric temperature was 10° or more below the average grain temperature, except during rain or fog. WEIGHT LOSSES IN STORAGE Records were kept on the weight of grain loaded into bins at the beginning of storage and at the end of storage. Losses occurring over the 7-year period are shown in Table 2. Total loss in weight for 9 to 10 months storage during 1949-55 averaged 1.8 percent. A large part of this loss was due to a reduction in moisture during aera- tion. Weight losses during a scheduled drying operation were not considered a storage loss. Since losses occurring under experimental conditions are probably greater than losses under actual farm storage conditions, a loss of 1 to 1.5 percent is probably more representative for a normal op- eration. 15 TABLE 2. LOSSES IN WEIGHT DURING STORAGE 1955-55 Item 1949-50 1950-51 1951-52 1952-53 1953-54 1954-55 Length oi storage. months 9 9 9_5 9 10 1Q 3 A Amount oi new grainyreceived. pounds 926.300 676.030 741.385 554.320 753.965 621,625 313.550 Calculated amount carried over from previous year's test. pounds 263.710 90.000 190.867 ' 94.457 Y Calculated moisture loss in drying, pounds 5.701 17.190 6.098 5.440 15.419 25.159 20.218 ‘ Total amount of dry grain stored. pounds 920.599 922.550 825.287 739.747 843.003 596.466 293.3327. Weight at end oi storage. pounds 907.425 904.945 808.407 725.117 825.720 588.100 290.060 *5 Total weight loss from sampling. decrease in ' a moisture. rodents. insects and handling. pounds 13.174 17.605 16.880 14.630 17.283 i: 8.366 3.272 Percentage loss during storagel 1.43 1.90 2.04 1.98 2.05 ‘Average for 1949-55. inclusive—1.8 percent. HANDLING IN AND GUT OF STORAGE A 21-foot auger loader operated by a S-horse- power electric motor was used for loading and un- loading bins. The loader handled an average of 41,000 pounds per hour in moving grain from trucks to storage bins. This capacity was ob- tained by using a grain tow board, as shown in Figure 15. Records were kept on different methods of unloading bins. Steel bins 18 feet in diameter and 14 by 16-foot wooden bins were unloaded by shoveling grain into a flight and a screw convey- or. Three men unloaded 23,000 pounds of grain per hour with a flight conveyor and 28,000 pounds of grain per hour through an "unloading spout in the wall of an 18-foot diameter bin. With a screw conveyor installed in the bin floor of a 14-foot diameter bin, 32,000 pounds of grain were unloaded per hour. In all cases, the grain was allowed to flow by gravity as long as possible. DRYING HIGH-MOISTURE GRAIN The moisture content of grain harvested in South Texas usually is too high for safe storage. For this reason, it is necessary to provide some method of drying to reduce the moisture content to a safe storage level. WITH UNHEATED AIR Bin Drying Bin drying with unheated air offers some ad- vantages as well as disadvantages in comparison Figure 15. An auger loader and grain tow board were used for handling grain in and out oi storage. 16 1.40 y 1.11 f with bin drying with heated air. Unheated air drying requires less investment in equipment,-rp duces fire hazards and usually results in more“. uniform drying. There are, however, certain spe- cific limitations. One is the uncontrollable Weath- er factor, since the rate of drying with unheated air depends on weather conditions. If the grain is to be sold soon after harvest, the comparatively long time required for drying with unheated air. is a disadvantage. In this case, some other meth- od of drying should be used. If the grain is fedj on the farm or is held in storage for a period longer than is required for drying with unheated air, the time element is not so important. Con- siderable supervision over a long period of time; is required when unheated air is used as the dry-o I ing agent. . In South Texas, grain sorghum usually is, harvested during late June or early July. Weath- er records in the Corpus Christi area, Tables 3% and 4, indicate a considerable period of time dur-f ing a July day when conditions are favorable for y unheated air drying, Figure 17. However, the air temperatures occurring at this time are extreme- ly favorable for mold growth. Therefore, for un-j heated air drying to be successful, the grain mois- ture content should be reduced below the levelj favorable for mold development in as short a time: as possible. Drying Equipment. ed for bin drying with unheated air consists of. a structure for holding the grain, an air dIStITI-fr; Figure 16. The portable auger. shown inside the bif was used to unload grain from storage bins. It was driveti by a flexible shaft connected to an electric motor. i? The equipment requir-j lTABLE 3. AVERAGE MONTHLY ATMOSPHERIC TEMPERATURE DURING THE DAY FOR CORPUS CHRISTI, 1949-55 Temperature. degrees F. Ah Midnight 3:00 a.m. 6:00 a.m. 9:00 a.m. Noon 3:00 p.m. 6:00 p.m. 9:00 p.m. 56.3 54.9 54.2 58.6 66.4 67.9 61.9 58.5 58.0 56.4 55.5 60.6 67.7 69.4 63.8 60.0 63.0 61.6 61.2 66.6 72.3 72.9 68.2 64.5 67.4 66.6 66.1 72.8 77.4 77.9 73.0 69.8 73.6 73.9 71.8 78.7 82.9 83.7 79.4 74.7 78.6 77.1 - 77.1 84.4 88.6 88.8 83.1 80.2 76.1 78.0 77.2 86.2 90.6 91.1 86.4 _ 81.6 -@ st 80.0 .78.0 76.8 86.0 90.7 91.3 86.4 ‘ 81.7 ytember 77.6 75.5 74.4 82.3 88.1 88.1 83.6 79.8 ber 70.3 68.1 67.5 76.2 81.6 82.0 76.6 72.6 ember 60.9 58.4 57.5 64.1 71.3 72.4 66.6 62.9 Q ember 57.1 55.4 54.3" 58.6 66.1 68.1 62.3 58.9 udes 1956 records. _ ion system and a fan driven by an electric tor 0r gasoline engine. Both steel and wood s and steel buildings were satisfactory storage i ctures for drying grain. The main consider- 'on is to provide a tight structure to prevent fkagfilff air and moisture through the bin floor w Wa s. I An air distribution system should be selected ~: will provide adequate distribution of air ,oughout the bin. Types of air distribution stems used in these tests were designated as: l) false floor, (b) main duct and laterals and ) center duct. These are shown in Figure 18. in duct and lateral systems are satisfactory tr both round and rectangular bins and build- ‘s. False floors are better suited for round bins A for larger storage structures. A type of nstruction for a false floor is shown in Figure c} A center duct is limited to use in a narrow ilding (a width of 16 feet was used in these ts) and requires a building with ppenings in wall to permit uniform distribution of the air jough the grain. A main duct and lateral sys- jL. or a false floor is recommended for farm dry- 5;: installations. _ Centrifugal and axial-flow fans, as shown in fgure 20, are suitable for bin drying grain. "Cen- ffugal fans ordinarily used for farm drying v.e either “forward-curved” blades or “back- rd-curved” blades. “Forward-curved” fans 'e lighter and less expensive than “backward- YrVed” fans. However, with the “forward- j ved” fan, there is a possibility of overloading 1 the motor if the fan operates against static pres- sures lower than those used in the design of the system. This is an undesirable characteristic for bin drying since grain depths vary during the time bins are being filled. A’ “backward-curved” blade fan offers the advantage of a self-limiting horsepower characteristic. This means that the maximum horsepower for a given speed and air density is reached in the usual operating range. The practical advantage is that it is unnecessary to provide excess motor capacity beyond that necessary to carry the normal load. Axial-flow fans used for farm drying are of vaneaxial and tubeaxial types. A vaneaxial fan consists of a fan wheel within a cylinder with a set of air guides either ahead or behind the fan wheel. It is designed to move air over a wide range of volumes and pressures. A tubeaxial fan consists of a fan wheel within a cylinder without air guide vanes, as shown in Figure 20. Its con- struction is similar to a vaneaxial fan. The tube- axial fan is designed to move air over a wide range of volumes at medium pressures. Axial-flow fans designed to operate against static pressures of 3 inches or more usually are suitable for bin drying. The initial cost of these fans is usually lower than the cost of centrifugal fans. Low initial cost, together with the small space required and the ease of installation, are advantages. Air Flow Requirements. The use of the proper air flow rate to dry grain with unheated air is of primary concern. Interrelated with the LE 4. AVERAGE MONTHLY ATMOSPHERIC RELATIVE HUMIDITY DURING THE DAY FOR CORPUS CHRISTI, 1949-55 i’ Relative humidity. percent nth Midnight 3:00 a.m. I 6:00 a.m. 9:00 a.m. Noon 3:00 p.m. 6:00 p.m. " 9:00 p.m. nary‘ 58.1 I 86.7 87.9 80.5 64.4 “ 62.1 73.9 . - '" 81.8 . 83.6 86.5 87.9 78.0 63.2 _ 60.5 ‘ 72.2 80.8 ,-- ch‘ 84.3 85.6 86.7 73.6 60.9 59.3 71.0 80.0 L ' ‘ 86.4 88.0 88.8 72.2 62.2 61.0 72.2 83.0 _ 88.6 90.5 91.6 75.6 65.2 62.2 70.6 83.2 He if, ~ 74.0 74.1 78.4 61.9 51.8 49.5 56.7 67.9 . 85.5 89.4 92.0 70.2 57.3 54.6 67.7 79.6 gust 84.6 88.7 91.2 72.4 56.5 54.1 62.2 79.0 _ tember 82.8 86.9 88.9 75.8 50.0 56.6 64.3 77.0 ' ber 81.9 85.2 87.3 76.4 58.7 56.2 65.5 85.5 vember 80.0 . 81.6 82.9 74.1 57.4 54.3 65.3 76.3 : ember 80.9 82.7 82.6 78.7 61.5 56.9 65.5 78.5 ludes 1956 records. l 17 - TEMPERATURE RELATIVE HIMIDITY AIR TEMPERATURE '- DEGREES F. RELATIVE HUMIDITY — PERCENT MIDNIGHT TIME —F HOURS MIDNIGHT _Figure l7. Air temperature and relative humidity for a typical Iuly day in the Corpus Christi area. air flow requirement are the initial moisture con-c tent and the basic drying rate 0f the grain. Air must be supplied at a rate t0 complete drying be- fore the grain is damaged by mold growth or other causes. For this reason, the drying rate in the wettest layer of grain provides the basis for selecting the required air flow rate rather than the average grain moisture observed during the drying operation. The purpose for which the grain will be used determines the air flow rate for drying with un- heated air. If the grain is sold on the market, grade is the only factor to consider. A recom- mended air flow rate of 4.5 cfm per 100 pounds (2.5 cfm per bushel) was indicated by these tests for drying sorghum grain Without loss in grade. This rate was based on a grain moisture content of 18 percent, which is near the maximum mois- ture of sorghum grain harvested in South Texas. The, minimum air flow used to dry sorghum grain at this moisture content, without loss in grade during the tests, was 3.5 cfm per 100 pounds (2.0 cfm per bushel). Grain with a moisture content of 16 percent or less was dried without loss in mar- ket value at air flow rates as low as 2.7 cfm per 100 pounds (1.5 cfm per bushel). p An air flow rate of at least 5.4 cfm per 100 pounds (3.0 cfm per bushel) was required to dry grain success‘. fully with moisture contents of 18 to 20 percen 1 q If the grain is to be used as seed for plan a ing, germination is the factor that determines th amount of air to use. There was no loss in ger mination of grain dried with an air flow rate 0 5.4 cfm per 100 pounds (3.0 cfm per bushel) This rate is based on a maximurnii-‘Iitial moistur content of 18 percent. ' As shown in Figure 23, there was a consider- able increase in fat acidity value in the top layel of grain at all air flow rates. To prevent su stantial increases in fat acidity value, tests indie. cated that an air flow of 9.0 cfm per 100 pound would be required for drying 18 to 19 percen moisture grain. c a Information required by drying equipment dealers and others who select fans for dryin grain are the total air volume and the static prep sure requirements. Static pressure is a measur of the resistance that the air distribution syste and grain offer to the flow of air. It is desig natedin inches of water. Static pressures agains which fans must operate to develop air flow rate of 3.5, 4.5 and 5.4 cfm per 100 pounds of grai are given in Table 5. Grain Depth. The recommended air flo rate of 4.5 cfm per 100 pounds limits the grai depth to a maximum of 8 feet for the most ec nomical drying. As stated previously, this ra i; is based on a maximum grain moisture content 0, 18 percent. Grain moisture content, as well a weather conditions, vary from year to year. It is important to provide drying equipment of suf: ficient capacity to insure drying grain witho p loss in grade under the different conditions elf countered. When the initial moisture content the grain is above or below 18 percent, the grai depth can be varied to increase or decrease th air flow rate as needed for the different moistu conditions. Grain depths for drying grain wit various initial moisture ranges are shown it Table 6. This is based on the selection of equi[ ment to provide an air flow rate of 4.5 cfm per 100 pounds at an 8-foot depth. Figure 18. Types oi air distribution systems used in the bin drying tests: A. false floor; B. main duct and laterals: C. center duct. é 18 Drying Time. These tests show the rela- tionship between the length of the drying period and mold development. Under similar Weather conditions, the time required to dry grain with unheated air depends on: (1) the rate of air flow, (2) the initial moisture content of the grain and (3) the uniformity of air flow through the grain. In these tests, the percentage of fungal in- festation was associated closely with the same three factors. For example, none of the differ- ent kinds of molds associated with grain dete- rioration, such as Aspergillus, was noted in grain dried with an air flow rate of 5.4 cfm per 100 pounds. There was agradual increase in in- festation with a decrease in air flow from 4.5 to 2.7 cfm, per 100 pounds. This increase was due to the longer time required to dry the grain to the desired moisture level with the lower air flow rates. Moisture is a major factor influencing the growth of molds. Even at the lowest air flow rate, samples taken at the bottom of the bins were free of harmful infestation, but increased in the upper layers where the grain remained higher in moisture for a longer time. m WALL l I 1, gx4_%vécens /-2-2xe a¢§ ‘ . . I- Iv "i 4x6 2'-o" sitoa if; é; .1»: ':. . ; e =.~. ~-: fifgb‘ \ v ' ‘r nus 2v ea. ROD '2 m x6 0° u/tsnaovs FOOTING GROSS sscpou SCALE 3/8"= I'—O GIRDERS RECESSED INTO CONCRETE FLUSH WITH TOP OF_ FOUNDATION |"x l" no. :2 GAUGE WITH l6 MESH SCREEN WIRE FLOOR PLAN Figure 19. A type oi construction for a false floor in c: round steel bin. WIRE MESH COVERED Mold development was observed on the grain when the moisture content was above 15 percent more than 6 to 8 days. A contributing factor to the rapid mold development was the high grain temperatures. The grain temperature at the time of loading the bins averaged 95 to 100°. Within 24 hours after the start of drying, the average grain temperature dropped to about 80°. As drying progressed, grain temperatures in- creased to a final average of 90 to 95°. In unheated air drying applications under South Texas conditions, the moisture in the wet- test layer of grain must be reduced to 15 percent in 8 days or less to prevent undesirable mold de- velopment. Further reduction in moisture to a safe storage level can be accomplished over a longer period of time, as long as 2 weeks in these tests, without serious mold development. Fan Operation Schedule. A primary consid- eration in the selection of a fan operating sched- ule is the provision for drying at a rate fast enough to prevent mold development. The dry- ing system should be simple to operate and re- 2"x 2 v2" 24 GAUGE ANGLE mow sass mus PLACED on ma: noon mo eouso TO am wnu. 2X4JOISTS |o'o.c. I6 d "A"- .- ¢'-‘j»',~.:_é. .”- ‘T;-;'.¢1;.-"--0¢.1' a .- .";- . _ ., D ' '- ""/'..'0'v' " _.a.0 '_ -, '. I .' . zf-é r 4-"f’."-. ‘tiff. GROUT PLACED AFTER BIN IS ERECTED BUT BEFORE FLOOR IS PLACED ‘SCALE 3"= |'- o" 19 Figure 20. Types of fans suitable for drying grain. The centrifugal fan (A) is designed to move air over a wide range of volumes and pressures. The tubeaxial fan (B) 1s designed to move cur through a wide range of volumes at medium pressures. quire minimum supervision. Other desirable fea- tures 1n a fan operating schedule are maximum drying efficiency with a m1n1mum air flow rate. The question of whether air should be pushed up or pulled down through the grain during dry- ing often arises. It is recommended that air be pushed up through the grain for the following reasons: (1) the wettest layer of grain is at the top where sampling is done easily, (2) heat from the motor and fan can be used in drying and (3) under farm conditions, the wettest grain fre- quently is the first loaded into the bin and the first to be dried. Based on the results of these tests the follow- ing fan operating schedule is recommended: Start the fan as soon as the air distribution system is covered uniformly with grain. Push air through the grain continuously until the mois- ture content of the top foot of grain is reduced to about 15 percent. After the moisture is reduced to this level, operate the fans only when the rela- tive humidity is less than 75 percent (usually dur- 22 V STARTED OPERATING FAN ONLY WHEN RELATIVE HUMIDITY WAS BELOW 75 PERCENT In) (D CIRCLED FIGURES INDICATE CFM PER I00 LB OF GRAIN L 8 ADDITIONAL DAYS 7 TO DRY TO l2 7i PERCENT 1~\ Tv- , I’! >Il I 3 .. ,1 /) ././ a 9/ \ \ O ' o E lit I 3/0/07! j I IU f" I “' / I I h I I I I ‘a o 2 4 a a IO |2 :4 no no 2o DRYING TIME - DAYS F6 PERCENT MOISTURE-WET BASIS TOP FOOT OF GRAIN / /. Figure 21. Time required to dry an 8-foot depth of sorghum grain with unheated air supplied at airflow rates of 2.7. 3.5. 4.5. 5.4 and 7.2 cfm per 100 pounds of grain. 20 ing daylight hours on clear, bright days). Con- j tinue this procedure until the moisture content of l; ‘the top foot of grain is reduced to 12 percent. Cut the fan off if it rains during the period of con- '. tinuous fan operation. When rainy periods last: longer than 24 hours, keep the grain cool by op- erating the fan 2 to 3 hours each day until the I weather clears. Inspection. for each level. Since low temperatures during drying do not, always indicate that the grain is in good condi-ot tion, the samples pulled for moisture content also should be checked for mold growth. zoo — stun or oavms sun or onvms 9O BO 7O PERCENT GERMINATION .,BOTTOM uoiogwru ,A_ 6O 5O 5.4 l‘ 4.5 3.6 gm FLQW RATE, CFM PER IOO POUNDS Figure 22. Effect of airflow rate on germination whe; sorghum grain with an initial moisture content of l8 to ~ percent was bin dried with unheated air. The percentag’! germination at the start and end of drying is given for Ih; bottom foot, a 12-inch layer at mid-depth and the top of grain for different air flow rates. r The moisture content of the P grain should be checked at least twice a week dur- a ing the drying operation. The grain should be a probed at 8 to 10-foot intervals over the surface j of the grain and samples drawn from the bottom, center and top foot. Grain from each level should i be mixed thoroughly and a moisture check made 5 if WITH HEATED AIR Bin Drying Bin drying with heated air has the following advantages and disadvantages. The chief ad- f5. vantages are the comparatively short drying per- ' iod and the fact that drying can be done regard- less of weather conditions. Disadvantages to us- ing heated air are the extreme variations in mois- ture occurring from the bottom to the top of the bin, the higher initial equipment costs, the close supervision required and the fire hazard. A structure for holding the grain, afan and an air distribution system, as described for bin dryers using unheated air, were satisfactory for q bin drying with heated air. In addition, a burner is required to heat the air to the desired temper- ~ ature. Automatic controls should be used to elim- 5 inate fire hazards caused by fan stoppage and ~_ flame failure. A simple installation is shown in Figure 26. In bin drying, grain usually is dried at depths - of 6 to 10 feet. The moisture content of the grain {next to the incoming air changes first, and the drying progresses in stages according to the direc- ' tion of air flow through the grain. There is _jmuch greater variation in moisture from the bot- tom to the top with heated air than with unheated .air. Higher air flow rates are required for dry- - {ing with heated air than with unheated air. . Tests with heated air were made in bins equipped with perforated false floors. Grain ranging in moisture of 15.4 to 23.0 percent was dried with air temperatures of 119 to 135°. Grain kdepths were 1.25 to 6.25 feet. Drying time var- llied from 4.5 to 92 hours. As shown in Table 7, r there was considerable variation in moisture for Iall depths above 1.25 feet. The moisture content §at various depths during the drying operation is _ shown for a 6-foot grain depth in Figure 27. - sun or navmc cm: or ammo ,- H, ‘~_.:.»,~»-"“.,‘ s’. . j, 4' FAY Aomrv-Wnmul .5 0P .7 -.~’<=_gl-'<§.; w‘, BOTT "- I..'.‘.1.°.°“'*L*_.ll j , , _ MlO-DEPYH T 0 91.129‘ fl§ A ggfilq i I 5| A Figure 23. Effect ofairflow rate on the fat acidity value hen sorghum grain with an initial moisture content oi 18 g l9 percent was bin dried with unheated air. The {at lfdity values shown at the start and end oi drying for each flow rate were determined from samples drawn from the ittom foot. a 12-inch layer at mid-depth and the top foot g gram. i is Al] [LOW RATE CFM FER I00 POUNDS 3v r‘ »I 5 TABLE 5. STA'I'IC PRESSURE-IS REQUIRED TO DEVELOP DIFFERENT AIR FLOW RATES THROUGH VARIOUS DEPTHS OF GRAIN Air flow rate . Static pressure. per 100 pounds. Gun? gtepth‘ inches water cfm e column‘ 3.5 8 2.3 10 3.0 4.5 8 2.8 10 3.4 5.4 6 2.9 8 3.7 ‘Includes an estimated 0.25-inch pressure drop in the duct system. Based on results of these tests, the use of heated air is not practical for bin drying grain. Tests with other grain show that less variation in moisture is obtained with supplemental heat when the temperature of the drying air does not exceed 10 to 15° above the outside air tempera- ture. However, weather conditions during the summer in South Texas usually are favorable for drying sorghum grainwith unheated air. For this reason, supplemental heat is not recommend- ed as a standard practice, but may be desirable for use on a stand-by basis in the event of pro- longed adverse weather conditions. Batch Drying Portable Batch Dryer. A portable batch dry- er, as shown in Figure 28, was used. This type is suitable for drying a small quantity of grain, but is not applicable Where a large amount of grain is to be dried. Four batches of grain, ranging in moisture from 17.7 to 18.4 percent, were dried with air temperatures of 175 and 190°. Grain was dried at 11, 12, 14 and 18-inch depths. The amount of air used wasthe maximum that could be obtained 2o __“°\ ‘L’ |a\ T‘ rep m \ ,e E‘: . \\ "U? 6v. Iv o- \ \( \ w l6 \7‘ \ 3 u; n \, :2 ‘* 3 l4 , ‘é g; \ \o \ e — \4 2 \ ‘is n2 --—~Q \ _, g Q}, \~,4_{—~"V—"' 8 ‘ g/ -Z v @1 5 no H‘ _ / o. o’)! a o a 4 e a 1o :2 I4 1o |e DRYING TIME -' DAYS Figure 24. In a bin dryer. the moisture content oi the grain next to the incoming air changes first. and the drying progresses in stages according to the direction of air flow through the grain. In this case. unheated air. supplied at a rate of 4.5 ctm per 100 pounds. was pushed up through an 8-toot depth of grain. It is recommended that air be pushed up through grain for bin drying since the wettest layer of grain is at the top where sampling is done easily. 21 TABLE 6. DEPTHS FOR DRYING GRAIN WITH VARIOUS - INITIAL MOISTURE CONTENTS Initial grain Maximum moisture con- depth oi grain tent. percent‘ at start. ieet Operating procedures When the top ioot oi grain is reduced to 15 percent moisture. more grain may be added to fill to the recommended depths shown below. When the top ioot is reduced to l5 percent moisture, grain 'with a moisture content oi l5 percent or less may be added to iill the bin to a depth oi l0 ieet. 18 to 20 6 l5 to 18 8 Below l5 l0 Maximum depth recommended. ‘A moisture content oi 20 percent is the maximum recom- mended ior drying with unheated air. with a 30-inch wheel diameter centrifugal fan and a 5-horsepower electric motor. Air volumes range from 70 cfm per square foot of floor area for an 18-inch depth of grain to 100 cfm per square foot of floor area for an 11-inch depth of grain. The fan operated against a static pres- sure of 3.60 inches water column. The moisture content of the grain at inter- vals during drying for the different grain depths is shown in Figure 29. When grain was dried with an air temperature of 175°, the highest dry- ing capacity was obtained at 12 and 14-inch grain depths. The capacity at these depths was about the same, or about 2,640 pounds of dry grain per hour. The capacity at an 18-inch depth was 2,340 pounds per hour. Operating costs per ton for propane fuel and electricity were 73 to 80 cents. There was a significant loss in germination at all depths. 22 \ \ \ v STARTED OPERATING rm 2° om_v WHEN RELATIVE uumomr Q GRAIN DEPTH — 2.3 FEET WAS BELOW 1s PERCENT m 4; GRAIN DEPTH — 5.6 FEET 2 ‘a / :e_RA_m DEPTH - a FEET________ u 3 \\\ 1L \ m lO \\\ 3 \ ‘ll-I __ ‘i \ \ -_ ‘s \\ Q x 2 '4 _____ \ \ \ \ \ F .- TQ \ Z g- __ \'\> m \ u U g Qf_-_———TOP l2 LAYER i‘) 12 ‘*1: LAYER-MID DEPTH m ‘aorrom 12" LAYER n. JUNE 21, 195s \ '0 so 10o 15o 20o 25o 30o 35o 40o 45o soo ‘ 1a oms | s oms I HOURS OF FAN OPERATION Figure 25. Faster drying was done by loading each bin to a depth oi 2 to 3 ieet in succession. Then. starting with the iirst bin. 2 to 3 ieet were added to each bin progressively until all the storage space was utilized. In this case. air was supplied at a rate oi 4.5 cim per 100 pounds. The moisture content oi all the grain in the bin was reduced to 15 percent in less than 4 days. which is desirable irom the standpoint oi preventing undesirable mold development. 22 .quired for loading and unloading when the drye fl Figure 26. This portable ian and heating unit was to dry grain in the same bin in which it was to be stored. An auger grain loader was used to fill thi drying bin to the desired depth. The dryer was unloaded with a heavy duty hydraulic wago I dump and with a grain tow board. Total time re-f was filled to a 12-inch depth was 37 minutes wit the hydraulic lift and 25 minutes with the grain tow board. Column-type Dryer. A dryer of the typ shown in Figure 30 is desirable when high dryj ing capacities are needed and large quantities o grain are to be dried. t Tests showed that sorghum grain can 6 dried successfully with a dryer of this type. Th E TABLE 7. BIN DRYING WITH HEATED AIR Item Test I Test 2 Test 3 ‘ Weight beiore drying. pounds 13.050 40.455 41.880 f Depth oi grain at start. ieet 1.25 3.3 6.0 Moisture content. wet basis. percent Beiore drying 15.8 15.210 17.0 15.2 to 1s _ End oi drying 11.4 9.0 1° 14.6 2.21011. Average air temperature. i deg. F. Plenum chamber I30 I33 118 Outside 83 86 83 Average relative humidity. ' percent Plenum chamber ' 21 l8 26 Outside i 75 67 79 Calculated air volume. cubic ieet per minute ~ Total . 7.680 8.800 5.400 Per square iootoi iloor area 40 35 35 5 Static pressure in plenum chamber. inches oi water 2.0 3.2 5.5 Drying time. hours ' 4.5 14.0 40 Cost per ton ior propane. and electricity. cents 77 71 73 ABOVE FLOOR on e"or GRAIN i FLOOR rroon I.O'ABOVE ‘ \ V DESIGNATES TIME BURNER TURNED OFF PERCENT MOISTURE" -WETT BAStS O 2 4 6 8 IO l2 l4 l6 l8 2022 2426 28 30323436 3840 DRYING TIME- HOURS _ Figure 27. A wide variation in moisture content occurred when sorghum grain. in a round steel bin. was dried with ated air. In this test. an air temperature of ll9°F. was used. fastest rate of drying and the lowest costs for ower and fuel Were obtained when thevelocity f the air through the grain column was 8O t0 feet per minute. The air temperatures found be most efficient for drying grain to 12 per- sent moisture Were 150° for grain with 14 to 16 j rcent moisture, 175° for grain with a moisture ontent of 17 to 20 percent and 200° for grain bove 20 percent moisture. The Wet milling characteristics of Martin 0nd Early Hegari, with initial moisture contents Figure 28. This portable batch dryer, used in the studies. 2J- isted of a drying bin 7 by 14 feet with walls 6 feet high. perforated steel floor separated the drying bin from the l‘ chamber. Grain was loaded to the desired depth on the floor and heated air was forced into the air chamber through the grain until the moisture content was reduced {a safe limit. The experimental farm crop dryer attached ‘lithe batch drying bin utilized LP gas" and electric power "ng operation. ‘ o l, ‘g’?! rQ-‘lg J 2O Q0 |9o°r.-|oo~cFM ~ '0 \0€ PER so FT.—Il"DEEP-» <~ \¢‘ (:0 | \ |2 I |1s° F. - 9s cm PER / sort. -|2' DEEP PERCENT MOISTURE-WET BASIS o so so 9o :20 15o |ao 21o TIME - MINUTES Figure 29. The moisture content of grain at intervals during drying for different depths of grain when dried in a portable batch dryer. of 14 to 26 percent, were not impaired by drying to 11 to 13 percent moisture With air tempera- tures of 125 to 200°. Figure 30. This column-type dryer was used to dry high-moisture grain. The drying -unit consisted of two vertical columns separated by an air chamber. Each column"was 6 feet high. 9 feet long and l0 inches thick. The holding capa- city of the dryer was about 4.500 pounds, dry basis. 23 State-wide Research .‘T> L‘: ‘if’ "k The Texas Agricultural Experiment Station“ is the public agricultural research agency of the State of Texas. and is one of ten parts of the Texas A&M College System Location of field research units of the Texas Agricultural Experiment Station and cooperating agencies IN THE MAIN STATION, with headquarters at College Station, are 16 subject-i matter departments, 2 service departments, 3 regulatory services and -_ ' administrative staff. Located out in the major agricultural areas of Texas at 21 substations and 9 field laboratories. In addition, there are 14- cooperatin stations owned by other agencies. Cooperating agencies include the Tex orest Service, Game and Fish Commission of Texas, Texas Prison Syste, U. S. Department of Agriculture, University of Texas, Texas Technologic 5 College, Texas College of Arts and Industries and the King Ranch. So t» experiments are conducted on farms and ranches and in rural homes. THE TEXAS STATION is conducting about 400 active research projects, group _ in 25 programs, which include all phases of agriculture in Texas. Amon these are: Conservation and improvement of soil Beef cattle Conservation and use of water Dairy cattle Grasses and legumes Sheep and goats Grain crops Swine . Cotton and other fiber crops Chickens and turkeys 0 P E R A T I o N Vegetable crops Animal diseases and parasites Citrus and other subtropical fruits Fish and game Fruits and nuts Farm and ranch engineering Oil seed crops Farm and ranch business Ornamental plants Marketing agricultural products ‘ Brush and weeds Rural home economics Insects Rural agricultural economics Plant diseases Two additional programs are maintenance and upkeep, and central servic, Research results are carried t0 Texas farmers, AGRICULTURAL RESEARCH seeks the WHATS- the WHYS. the WHENS, the WHERES and the HOWS of ranchmen and homemakers by county agents hundreds of problems which confront operators of farms and ranches. and the many industries depending on or serving agriculture. Workers of the Main Station and the field units of the Texas Agricultural Experiment _ _ Station seek diligently to find solutions to these tenszon Service preblems- a f] J ’ l? l. J1 3 ’ O a” £5 QJQCLPC J OIWlOPVOl/U 6 I"OgI”265 and specialists of the Texas Agricultural Ex-