B-l07l November 1967 Harvesting and Drying Selected Forage Crops a A&M UNIVERSITY ‘i ricultural Experiment Station unkel, Acting Director, College Station, Texas C 0 n tents Summary ........................................................................... -- 2 Introduction .................................................................... .- 4 Review of Literature .................................................... _- 4 Physical Properties of Forage Plants Related to Drying .................................................. .. 5 Field Drying Forage Crops .......................................... ._ 7 Effect of’ Harvest Method on Field-drying Time ........ ............................... .. 7 Flaming Alfalfa ...................................................... -- 9 Drying wtih Infrared Radiation ................................ -- 9 Forage Crop Absorption Wavelengths ...................... “l4 Effect of Treatments on Drying Characteristics of Forage Crops .......................... ..l5 Heat and Pressure Treatments ............................ _.l5 Freeze Treatments ................................................. ..l5 References ........................................................................ ._l6 Acknowledgments ........................................................... ..16 2 Summary Research on hay harvesting and ha ations was started at Texas AScM Univer This report summarizes procedures and r’ 1959-66. Studies were made to determine drying rates of selected forage crops. content of Kleingrass was reduced to 20 a shorter time than alfalfa, Coastal Bermi grass and perennial Sweet Sorgrass whi were cut at the optimum stage of matu had a faster drying rate than all cropsf Kleingrass reached the 20 percent level p of its lower initial moisture content. Kl a faster drying rate than Coastal Bermu, increased rate was not always great eno Kleingrass to reach a storable level I Coastal. This depended on the initial tents of the forages. Perennial Sweet the lowest drying rate and the highest ini content of the crops tested. 5 Tests were conducted to determin of harvesting method on field-drying y advantage was gained by using hay v.1 reduce the moisture content of alfalfa t However, when it was necessary to red _ ture to 25 percent, the crusher used in Q with the conventional method of maki 3 l4 hours drying time. The hay con nificantly reduced the field-drying time grass was dried to 50 and 25 percent mois“ oratory studies, crushed alfalfa reached ent moisture level in 7.8 hours, compared l- l9.3 hours, respectively, for the crimped iditioned alfalfa. When the material was ‘stead of crimped, a 26.4 percent time A lted. " was little difference in the time required i] ed and unflamed alfalfa to a moisture _r 25 percent. However, a saving of 20 hours _ field drying flamed, conditioned (crushed) l“ compared to unflamed, unconditioned . jor problem in using infrared radiant agricultural purposes is the lack of in- '41 concerning the absorption, transmission ion characteristics of agricultural products. i, a study was conducted on the use of diation to dry alfalfa hay. Four sources of radiation were used for these tests, each different spectral distribution of energy. ces were classified according to their maxi- iak wavelength and were 1.15, 2.3, 3.0 and , s. Three of these sources were electrical, , as gas-fired. ‘a hay having an initial moisture content ‘mately 63 percent, wet basis, was irradiated s from 0 to 240 seconds. Results of this A show that the higher the radiation in- l. the longer the exposure period for each i.- greater the rate of moisture removal. crement of time, the decrease in the hay content was always greater for the highest evel of each SOfllfiCfi of radiation. Scorching ' es was observed at several intensity levels. radiant energy source, the exposure time rching seemed to be related to the drying f, decrease in exposure time due to scorch- 4 a decrease in the total moisture removed i‘ of the intensity levels. Although the drying rates increased as the in- tensity level increased for each source, the drying rates for equal intensities varied among sources. The source which had its peak energy at 3.0 microns ap- peared to remove more moisture than the other sources at the same intensity level. Based on a moisture reduction of l0 percent, wet basis, the efficiencies of the sources of infrared energy ranged from 13.0 to 38.1 percent. The 1.15- micron source had the lowest efficiency, while the 5.0-micron source had the highest. Although the highest drying capacity was obtained with the 3.0- micron source, the capacity obtained was considered too low for practical use. Dryer capacity was in- creased by handling the forage three layers thick but was not increased sufficiently to warrant the use of infrared energy for drying forages. A spectrophotometer was used to obtain the infrared absorption characteristics of Iohnsongass and alfalfa. johnsongrass leaves absorbed more in- frared radiation in the 3.0—4.0-micron wavelength range than at any other wavelength. The major absorption bands for ground alfalfa occurred at wave- lengths of 2.9-3.0 microns and 6.1-6.3 microns. Studies were made to determine the effects of heat and pressure treatments on altering the drying characteristics of alfalfa. Drying rate curves plotted for each of the treatments in which samples were subjected to pressures ranging from —75 cm. Hg. to 150 psig. showed no increase in the drying rate when compared to control samples. There was no evidence of rupture of cell walls or damage to the cellular organization. Laboratory experiments were conducted to de- termine the effect of freeze treatments on the drying rate of unconditioned, crushed and chopped alfalfa hay. Liquid nitrogen was used to obtain a quick- freeze treatment. In these tests little or no advantage was gained by using a freeze treatment for drying alfalfa to a moisture content of 50 percent. How- ever, there was a significant decrease in drying time due to freezing when alfalfa was dried to a moisture content of 20 percent. A quick-freeze treatment applied to the standing crop or in the swath may be a fruitful approach to the problem of moisture release from drying forage, provided no serious effect. on nutritive value is found. Harvesting and Drying Selected Forage Crops j. W. SORENSON, JR. AND N. K. PERSON, ]R.* -moisture content is reduced to 60 percent, RESERVATION OF FORAGE QUALITY is an ' consideration in the development of l’ forage harvesting and handling systems. l obstacle to a quality product is the initial content of most forage crops at the stage of f“ for highest quality. The moisture content I, at this optimum stage is usually 75 percent . s’ In high-moisture forages, 7,000 pounds must be removed from SO-pelrcent-moisture l produce 1 ton of hay at l0 percent moistu initial moisture content is 60 percent, f pounds of water must be removed to prod of 10-percent-moisture hay. A total of 4 of 80-percent-moisture forage are required l the same amount of dry matter provided b" of hay at 10 percent moisture. When I pounds of forage are required to provide t, of dry matter in 1 pound of the dry hay. The high energy requirements to Ill amounts of moisture from fresh-cut fora difficult to find economical artificial dryin The energy required to dry forage can r} considerably by allowing it to partially :5 field before the artificial drying operation. the drying rate of the cut forage should possible in the field to reduce exposure minimum and lessen chances for quality. A fast drying rate is even more important that is completely dried in the field. I Research on hay harvesting and hand tions was started at Texas AScM Universii The major objective of this research was? rapid and economical methods of removi , from forages with a minimum loss in qu, report summarizes procedures used and- tained during 1959-66. Two approache’ lowed: (1) studies to determine the rela certain physical properties of forage time required for drying and (2) deve' methods for rapidly removing excess moi, field. REVIEW or LITERATURE: Mechanical dewatering studies made man(l)1 and others at the Florida Everglp ment Station showed that the higher x moisture content of a crop, the greater A of water removed by mechanical pressing. in pressure from 40 to 60 psi increased r‘ of moisture extracted; however, the incre also increased the dry matter expressed wi The small increase in moisture extra higher pressure plus the undesirable in of dry matter probably would prohibit A use of the higher pressure. It was foun_ *Respectively, professor and assistant professor, l‘, Agricultural Engineering. a. ‘Numbers in parenthesesreferito appended refe trient changes associated with maturity p forage were reflected in the pressed expressed juices. Mechanical dewatering ‘al in the production of grass silage and good grass silage can be made, without om forages grown in the Everglades. w system involving the harvesting and dry- fa leaves in an effort to reduce harvest i losses was studied by Whitney and , is new concept involves the stripping '5 om standing alfalfa plants and leaving regenerate new leaves for future harvest. ‘d leaves and minor stems are then dried ent moisture content using fluidization fciples. The dried leaves are pelletized handled in bulk, much as the current ;handling grain. This concept has not etely defined and explored. and others(3) found that packaging hay ,ture content during the dry part of the only a 4 percent loss in yield, compared i‘ ent loss when the hay was raked too dry. as both raked and packaged dry yielded less than hay that was handled properly. e a loss of protein was somewhat greater eld loss, indicating that the reduction in f edominantly leaves. (4) found that during the drying of alfalfa i shows a directional preference. Per unit i‘? area, water leaves the stem through a section at approximately 3.5 times the igitudinal section. By exposing large areas rior of the stems, the drying rate was "nsiderably beyond that of leafy material "a the stems. p- d(5) found a relationship between field yield when flail mower-conditioners were ialfa. For yields above l ton dry matter 7' average loss was 9 percent. Below a {the field loss average was 17 percent. Fand others(6) stated that mechanical treat- alfa to increase its drying rate is of limited ‘use little damage is done to the cellular n. They found that killing the plant 'th steam markedly increased the drying ifying the permeability of the cuticle or ane. V rd(7) reported that electric tubular quartz ips and gas-fired infrared generators dried about equal ability. Conditioning the hay ared exposuredid not effect its drying ‘pping slightlyf improved the rate of dry- p treatment. Agitation was required after of exposure to prevent scorching. iiearly work on hay harvesting and handling A conducted by the Texas Agricultural Ex- tation has been published (8, 9 and l0). PHYSICAL PROPERTIES OF FORAGE PLANTS RELATED TO DRYING Since the maintenance of quality is closely re- 1a ted to the time required for drying, initial moisture content of forage and drying rate are important in selecting a forage crop and/or improving quality within varieties. In developing a variety with re- duced field drying time, either or both factors may be considered; in selecting forage crops to be planted for feeding purposes, both factors must be considered. Alfalfa and Coastal Bermuda were selected for a study of relative drying rates because of their im- portance; Kleingrass, for its potential; and perennial Sweet Sorgrass, because of its difficulty to cure. Each crop was harvested at the optimum stage of maturity and placed on metal trays in a controlled environment room. Tray and forage sample weights were taken at the beginning of the test and peri- odically thereafter. These weight data were used to calculate the percent of moisture in the samples throughout the test. The initial moisture contents for the four crops were 77.5, 68.1, 66.1 and 86.8 percent for alfalfa, Coastal Bermuda, Kleingrass and Sweet Sorgrass, respectively. The moisture contents, wet basis, at various hours during the drying period are given in Figures l-4. These graphs also show the relative humidity and dry bulb temperatures at which each crop was dried. Table l gives the time required to dry each crop to 5O and 20 percent moisture contents. Alfalfa, Coastal Bermuda and Kleingrass dried to 5O percent moisture in an average of 3.7 hours. Kleingrass reached 20 percent moisture in a shorter period than the other crops: 21.6 percent faster than Coastal Bermuda and 17.5 percent faster than alfalfa. Even O O BG|:-||v|||vvvvv|||||fi'r TEMPERATURE T S i-mgim ix.“ . 1o -\ 5 m ID O O TEMPERATURE-°F. 6O l l Lug-in m} f RELATIVE HUMIDITY " 3c y/MOISTURE CONTENT 2O -X MOISTURE CONTENT AND RELATIVE HUMIDITY- PERCENT b Ul 0 O v . - % - . v L l lcllllllllllllllllllllllll J 4 l2 l6 2O 24 2B 32 TIME — HOURS Figure 1. Moisture content of alfalfa and air conditions at various hours during the drying period. - UUIIITIITIIIIIIIIIIIIIIIIIIOO / . M/\*ZTTM—T<~TEMPERATuRE _ 7O 6O \ 8O 5O 4O 90 MOISTURE CONTENT AND RELATIVE HUMIOITY- PERCENT I I I I TEMPERATURE-‘F RELATIVE HUMIDITY II 11 3O g g _. MOISTURE >\ _ conrewr \ _ 2o |c l I I I I l I I I L I I I I L I I I I I I I I 4 a |2 l6 2o 24 2a a TIME -HOURS Figure 2. Moisture content of Coastal Bermuda and air con- ditions at various hours during the drying period. though these are relative values under somewhat ideal drying conditions, the decrease in time can be important in maintaining quality during the field- drying period. Alfalfa had a faster drying rate than all crops tested, Figure 5, but Kleingrass reached the 20 percent level first because of its lower initial moisture content. There was a 11.4 percentage point difference in the initial moisture levels between alfalfa and Kleingrass, but after 16 hours this difference was only 5.0 per- cent because of the higher drying rate of alfalfa. Kleingrass had a faster drying rate than Coastal Bermuda, but this increased rate was not always great enough to allow Kleingrass to reach a storable level faster than Coastal. This depended upon the initial moisture content of the forages. Perennial Sweet Sorgrass had the lowest drying rate and the highest initial moisture content of the crops tested. Compared to Bufflegrass, the drying rate of the Kleingrass seems to be more important than its moisture content. In drying rate studies, Kleingrass dried to 25 percent moisture content in 79.6 percent of the time necessary t0 dry Bufflegrass at the same TABLE l. HOURS REQUIRED TO REDUCE MOISTURE CONTENT OF SEVERAL FORAGE CROPS TO 5O AND 2O PERCENT (WET BASIS) I Forage Initial moisture Hours required to reduce crop content, percent moisture content to: 50 percent 20 percent Alfalfa 77.5” i 4.6 19.4 Coastal Bermuda 68.1 3.4 20.4 Kleingrass 66.1 3.1 16.0 Perennial Sweet Sorgrass 86.8 55.5 1 1T est was discontinued after 85 hours at which time moisture content was 41 percent. 6 7c II IIIII' IIITII §<~/\/~~/§ 0% O TEMPE K 1 \/ K i\ ' l‘ “RELATIVE nu i N O _ MOISTURE >\ __ courzur‘ \ MOISTURE CONTENT AND RELATIVE HUMIDITY- PERCENT 6 nllllllllllllllllll ‘\ ¢ l2 l6 20 24 TIME - HOURS Figure 3. Moisture content of Kleingrass and airi various hours during the drying period. initial moisture content. This was due i‘ drying rate of Kleingrass. Tests conducted on the drying rate: Bermuda indicate that this forage cro distinct drying periods, each having a A, ing rate. The faster rate occurred duri drying period and was maintained to a i the 50 percent level, wet basis. The ,8 occurred in the last of the four drying and started at a moisture content sli‘ 30 percent, wet basis. From the standpoint of energy g for removing moisture from forages, it? to have as low an initial moisture conten when the forage is at the stage of mat highest quality. Examples of forage have this low initial moisture content I are Kleingrass and Coastal Bermuda. A‘ 9G||||]|I]II|II]lI]TI|II ._ Li’? wii‘ " so _ \ ~\\ TEMPE"_l1 7O 6O 5O F I m uoisrua: e g X N‘ -\ \ i i 4C RELATIVE I MOISTURE CONTENY AND RELATIVE HUMIDITY - PERCENT QOIIIIIIIIIIIIIIIIIIII O IO 2O 3O 4O 5O GO TIME- HOUR$ Figure 4. Moisture content of perennial Sweet I conditions at various hours during the drying _ ALFALFA ,- , _ S’ 4,m_zm GRASS _ / __,,____. / f/"l , . I’ _ Xx _ ” “COASTAL BERMUDA _ ‘M PERENNIAL swear soRenAss _ Ellllllllllllllllllllll 3 I2 l6 2O 24 2B 32 36 TIME - HOURS i; oisture loss of the forage crops tested at various 'g the drying period. initial moisture content and a fast drying ptremely desirable from the standpoint of energy requirements for removing moisture : providing rapid methods of field drying. 1 is one example of such a crop. i: LD DRYING FORAGE CROPS V‘ Harvest Method on Field-drying Time I were conducted near College Station in getermine the effects of different hay-making T d equipment on the time required to field- ‘a and Sudangrass. inventional mower, side-delivery rake, flail y and two types of hay conditioners were these tests. One of the hay conditioners the material between steel and hard rubber j- the other crimped the material by passing n corrugated steel rolls. The former is re- e. as a hay crusher and the latter as a hay _ METHODS USED TO FIELD-DRY ALFALFA (ANGRASS f~< fa Sudangrass Mow—dry in swath Mow—crimp—dry in swath ' in swath 11 immediately- ‘windrow , in swath to 50 percent ~ content-windrow- windrow h—dry in swath =. —windr0w immedi- i- in windrow _j~ h—dry to 50 percent ~ ' content—windrow— windrow drow immediately- ‘ry in windrow Mow—crush—dry in swath Cut with flail harvester- dry in swath Alfalfa and Sudangrass were cut three consecu- tive mornings and arranged in treatments as outlined in Table 2. The initial moisture contents ranged from 75.9 to 81.2 percent for alfalfa and from 79.5 to 84.8 percent for Sudangrass. Forages used in these treatments were dried on hardware cloth trays. After the samples were placed on the trays, they were weighed periodically to determine the drying rate of each field-drying method. When the samples were considered dry, they were collected and placed in an oven to determine their dry matter weights. These weights were used to determine the moisture contents of the samples during the field-drying period. Field-harvesting efficiency tests were also con- ducted. Four harvesting methods were used: (1) mow, dry in swath and rake; (2) mow, crush, dry in swath and rake; (3) mow, crimp, dry in swath and rake; and (4) cut with a flail harvester, dry in swath and rake. After the hay had dried to a safe moisture level, it was picked up over a measured area with a forage harvester and weighed. This forage harvester had a pickup reel similar to that of a hay baler. Samples were taken from each method to determine the total dry matter content which was harvested. These values were compared to a check method which consisted of mowing and immediately picking up by hand. Results of the different field-drying methods listed in Table 2 are given in Table 3. Alfalfa which TABLE s. HOURS REQUIRED TO FIELD-DRY ALFALFA AND SUDANGRASS TO MOISTURE CONTENT or 50 AND 25 PERCENT (WET BASIS)1 Hours required to reduce moisture content to: Treatments 50 percent 25 percent (wet basis) (wet basis) Alfalfa Sudangrass Alfalfa Sudangrass Mow—dry in swath 5.5 50.0 39.5 54+’ Mow-windrow immedi- ately-dry in windrow 23.3 50.7 Mow—dry in swath to 50 percent—windr0w—dry in windrow 40.8 Mow-crush-dry in swath 3.7 5.9 25.2 28.7 Mow—crush-—windr0w immediately—dry in windrow 6.6 37.9 Mow-crush-dry to 50 percent—windrow—dry in windrow 35.8 Mow-windrow immedi- ately-crush-dry in windrow 5.7 25.7 Mow-crimp-dry in swath 6.6 28.3 Cut with flail harvester- dry in swath 24.4 31.0 lAlfalfa and Sudangrass were harvested during May and June, respectively. “T est was ended after sample was in field 54 hours. Moisture content after 54 hours was 45 percent. 7 I'llIVIIIIIIIVIIIIITI-IIII III IIIIII-I III I — flu-CRUSIFCXRE TO 5O PEnCENT-WIIIDRx-CURE IN WINDROI '9 ' Ila-CURE III $WITN IO 5O PERCENT -“N$OW-CURE IN Wluwo“ I-Iwl-CIIUSH-WINDROIWURE III IINDIIUW DQIIED LINE REFRESENIS NIGIIT 8 s_e /% / i N I fi \ \ \ t l MOISTURE CONTENT - PERCENT- (WET BASIS) I IllIIIIIIIIIIIIILIIIIIIIII O E I E I6 2O 24 28 32 36 4 D I I I I I I I I I I T F I I’ I I I I I I I I I I F I I I I I '*HOW'CURE III SIIIITH Q-IIOW-CRUSN-CUNEINSWITH 4‘ “IOVFWINDROW-CHJSIFCLIIE IN WINDRQW DOTTED LINE REPRESENIS NIGHT I 7L7 In B0 < m '_ - _ u 5 s II- z - __ .--— / _ u _- -- _ ,* u \__- _ ' n. X ,’ | L’ \ /’ '2 I \ IE 2O \ 1 M? O U ,- _ III a: a I- ‘L’ O I L I I I I I I l l_ l I I I l I L l L I l l L I I l I O 8 I2 l5 20 24 2B 32 36 4O TIIE AFTER CUTTING-HOURS I I I I ‘I I I I I I I I I I I I I I I I I I I I I I IO _ ,_ DRY BULB T.MPERATUR - IL _ mu so \ / \ mu I (95 _ _. ILI m , _ T; _ _ ‘i’: so \ 3Q _ - _ t: g/ , <3 — nzumvs nummTv - II '3'“, ' I 52 I-‘Z _ _ _l In _ _ 51E m 2o _ E _ o L I I I I I I I I l I I I I I I I I I I I I I I I I I 0 8 I2 I6 2O 24 2B 32 36 4O TIME AFTER CUTTING -NOURS Figure 6. Alromparison of the diying time of several methods of field-drying alfalfa. was mowed and dried in the swath required 39.5 hours to reach a 25 percent moisture. When a crusher was used with this method, l4 hours were saved. The moisture content of alfalfa which was mowed, crushed and then dried in the swath was reduced to 25 percent in 25.2 hours compared to 25.7 hours when alfalfa was mowed, windrowed immediately, crushed and then dried in the windrow. The latter method shows considerable promise because there is less chance of quality loss due to leaf shattering and bleaching from the sun. A comparis ‘A dyring time of several methods of field-dryii is given in Figure 6. I When Sudangrass was mowed and a! remain in the swath, 54 hours were rel reduce the moisture content to 45 percent, The time necessary to dry to 25 percent, content was estimated to be-‘labout 192 hou' a hay crusher and crimper were used, the fi time required to reduce the moisture c 25 percent was 28.7 and 28.3 hours, r Figure 7. A flail-type harvester reduced the fi; time on Sudangrass. As a result of using this; it required 31 hours to reduce the moist to 25 percent. This drying rate compared with the crushing and crimping methods. results from field-harvesting efficiency tes that this is not feasible because of excessive losses when this machine is used. Results of tests conducted to determine? encountered with the different methods of _h are given in Table 4. The flail harves” higher percentage field loss than the 0th? methods. The loss while harvesting Sudan“ I I I I I I X I I I I I I I I I I I I I I l e mow-cue: m swnu + NOW-CRIMP-CURE m swnn . mow-cRusn-cufl: m swnu a cuY vuTn rum HARVESTER-CURE m swnn I00 — oonso use nsmzszurs ruem G O O O — \\t;:iiil"e\ KT” \\ I U, \\ \\ \\\ \\\\\ \\ ‘\ \\ \\\ MOISTURE CONTENT - PERCENT-(WET BASIS) 2 \, g G l I l l I I l l I I I I I I I I I l L O B l5 24 32 4O 4C TIME AFTER CUTTING -HOUR$ I I I I I I I I I I I I I I I I I I I I I lo _ nav aura rzuvznnrun: w = B“ “fry j “ I: o — v o m _ u w \ \ a n. _ J1 >' ec \ o: v; _ ~°- 9 I \/ 4 2 5 = ‘ a I 40 5 I; - ncumvz numunv v- ; - m 4 _ _1 _| 3 w 20 In c: _ >- g _ 0- I I I I l I I I I l I I l I I I I I O IZ I5 2O 24 2B TIME AFTER CUTTING -HOURS Figure 7. A comparison of the drying time of s I of field-drying Sudangrass. ~1- :"4. FIELD HARVESTING EFFICIENCY TESTS, 1960 *1 Percent moisture at ' time hay was picked Yield per acre, Percent loss compared up, wet basis pounds dry weight with check Alfalfa Sudangrass Alfalfa Sudangrass Alfalfa Sudangrass up immediately by 70.1 77.1 1,398.3 2,935.9 jji(check treatment) f in swath—rake——pick up 21.8 50.5 1,158.7 2,865.8 17.1 19.4 rage harvester h—dry in swath—rake-— 15.5 26.1 1,097.7 2,400.2 21.5 18.2 with forage harvester ' p-dry in swath—rake— ‘ 18.0 25.1 1,267.6 2,880.5 9.8 20.6 with forage harvester _ r1511 harvester-dry in swath— 16.8 27.4 288.1 1,254.5 79.8 8 57.8 ‘Tick up with forage harvester l’ harvester was 57.3 percent compared to an of 19.4 percent for the other methods. ‘ing losses for alfalfa were 79.8 percent with “fl harvester compared to an average of 16.0 for the other methods. en artificial drying is used in conjunction A ld-drying, the time the forage is in the field tting is greatly reduced, since it is necessary "I ve only a portion of the moisture in the field. these conditions, the value of using a hay ner for alfalfa is questionable. Alfalfa which iywed and dried in the swath required 5.5 ;to reach a moisture content of 50 percent. fa crusher was used, the moisture content was y to 50 percent in 3.7 hours, a saving of only s. However, the crusher may be justified e moisture content is reduced to 20 percent the reduction in drying time may mean the ce between the crop remaining in the field \<_; uncouomoueo _ \\\ i cnususu/k’\\éimpzo — lllLlllllllllll 4 3 |2 l6 2O 24 28 3? TIME-—HOURS Comparison of moisture content at various hours ‘he drying period for different methods of conditioning overnight or not, Figure 8. In comparative drying tests under controlled conditions, crushed alfalfa reached the 20 percent moisture level in 7.8 hours, compared with 10.6 and 19.3 hours, respectively, for the crimped and unconditioned alfalfa. When the material was crushed instead of crimped, a 26.4 percent time saving resulted. A comparison between crushing and no conditioning showed a saving of 59.6 percent in drying time. Flaming Alfalfa Field tests were conducted to determine the effects on drying time of flaming alfalfa with a conventional flame cultivator. There was little dif- ference in the time required to dry flamed and unflamed alfalfa to a moisture content of 25 percent. However, a saving of 20 hours resulted in field-drying flamed, conditioned (crushed) alfalfa as compared to unflamed, unconditioned alfalfa. DRYING WITH INFRARED RADIATION Research was conducted to determine the effec- tiveness of using infrared energy to dry alfalfa hay. The objectives were to determine (l) the effects of exposure time, intensity of radiation and wavelength distribution on the rate of moisture removal, (2) the penetrating characteristics of different infrared sources and (3) the capacity and efficiency of drying with different sources of infrared radiation. Four sources of infrared energy were used, each having a different spectral distribution of energy. Three of these sources were electrical, and one was gas-fired. All sources were assumed to emit energy which follows the laws of radiation for black bodies and were classified according to their maximum or peak wavelength. These maximum wavelengths were designated by the respective manufacturers and were 1.15, 2.3, 3.0 and 5.0 microns. To achieve radiation of the desired intensity levels, small individual units were combined to make a sin le source. The construction of these sources is g 9 shown in Figure 9. All sources except the 5.0-micron source radiated from an overall surface area of ap- proximately 640 square inches. The radiating area of this source was about 740 square inches. To study the effects of the various factors listed in the objectives, it was necessary to irradiate hay at the same relative intensity levels of radiation for each source. Some means had to be provided to determine these intensity levels, regardless of wave- length distribution. For this purpose, a thermopile was constructed of thin copper plates with thermo- couples attached underneath, Figure l0. A dull, black paint was used on top of each plate so that the ab- sorption would be approximately the same for all wavelengths used. The relative amount of energy from each source at different heights above the hay was obtained with the thermopile, Figure ll. k» ~ ~4- »,>~» 0on1. w - -»-, Figure 10. Thermopile used to determine relative amount of energy from each source at different heights above the hay. l0 Figure 9. Sources of l radiation used in this Assuming that the absorption the black paint did not vary significantly wavelength range used, then equal tem would closely approximate equal rates of ' O HEIGHT OF SOURCE FROM THERMOPILES-INCHES -‘ N) HUGHT OF SOURCE FROM THERMOPlLES-INCHES AVERAGE TEMPERATURE HEIGHT or souRcs mom THERMOPILES-lucngs '8 HEIGHT or souncs mo» THERMOPlLES-INCHES IO 2O 3O 4O 5O S0 70 8O 90000 I50 AVERAGE Tsmwsnznuns RISE-DEGREES F AYEMGE TWPEMTW! Figure 11. Calibration curves of source height ture rise of the thermopile. Apparatus used t0 determine the rate at which removed from irradiated hay. Sample on hardware placed on frame under infrared source. Frame from scale at top so that weight loss readings at intervals during test period. Consequently, to irradiate hay at the same level it was necessary only to select an temperature rise on the thermopile and de- from the graphs the corresponding heights source. and uncrimped hay were transported field to the nearby test area. Only enough Twas cut at one time to test completely one l.| 5 MICRON SOURCE LEAVES STARTED TO SCORCH V SIS) m O MOISTURE LOSS-PERCENT (WET 8A 5 IOO I2O I40 I60 I80 EXPOSURE TIME - SECONDS 3.0 MICRON SOURCE V LEAVES STARTED TO SCORCH MOISTURE LOSS-PERCENT (WET BASIS) IOO I20 I40 BO E XPOSURE TIME - SECONDS ZOO 2O 4O 6O E XPOSURE TIME — SECONDS "SQ '80 200 20 40 6O source; therefore, the moisture content of the hay was approximately the same througho-ut each test. After the material was brought into the test facility, it was divided into QOO-gram samples and placed in single layers on hardware cloth trays. These trays were then placed under the radiation sources using an apparatus with a frame suspended from a scale so that a weight loss reading could be recorded for any interval of time, Figure l2. At the end of each test, the samples were dried in an oven to- de- termine the dry matter content. To determine the penetrating characteristics of the sources, three similar layers of hay were placed on top of each other and irradiated. Each layer was separated from the other by hardware cloth. After the combined sample was irradiated for a given time, the individual layers were weighed to determine their total weight loss. Single layers of hay were placed on hardware cloth trays and exposed to energy from each source. Enough hay was used in each test so that maximum radiation from each source would be intercepted by the sample. The exposure time needed to reduce theinitial moisture content by 1O percent, wet basis, was determined. This was used to determine the efficiency. The drying capacities were calculated by correcting sample weights to a 20 percent moisture basis. Alfalfa hay having an initial moisture content of approximately 63 percent, wet basis, was irradiated in these tests. The irradiation periods ranged from 0 to 240 seconds, depending upon the time at which the leaves started to scorch. Results show, Figure l8, that the higher the radiation intensity and the longer the exposure 2. 3 MICRON SOURCE Figure 13. The rate at which moisture was removed from al- falfa hay irradiated for different exposure times under the 1.15, 2.3, 3.0 and 5.0-micron sources. IOO I20 I40 I60 I80 200 5.0 MICRON SOURCE IOO I20 I40 I60 I80 ZDQ EXPOSURE TIME - SECONDS l1 EXPOSURE Tl ME- 3O SEC. MOISTURE LOSS-PERCENT (WET BASIS} I 2 3 4 5 6 MAXIMUM WAVELENGTH - MICRONS Figure 14. Moisture loss after 30 seconds exposure time plotted against the maximum wavelength of each source of radiation. period for each source, the greater the rate of mois- ture removal. Intensity level l in the graphs repre- sents the lowest intensity used in these tests and intensity level 4 the highest. The first portion of each curve indicates a variable rate of drying, but after 20-60 seconds of exposure, the water was removed at a constant rate. The time necessary to obtain this constant rate varied with the level of intensity and wavelength distribution. After a constant rate was obtained, each intensity level resulted in a different rate of moisture removal, indicated by a different slope for each curve. For any increment of time, the decrease in the hay moisture content was always greater for the highest intensity level of each source of radiation. For example, hay which was irradiated for 6O seconds by the 1.15-micron source lost 0.9, 1.4, 2.8 and 5.4 percent moisture for intensity levels l through 4, respectively. Moisture lost from hay irradiated with the other sources in- creased progressively with intensity levels similar to those resulting from the 1.15-micron source. The drying rate at the. higher intensities as compared to the lower intensity levels increased as the exposure time increased. This is shown by the increasing distance between the curves with an in- crease in exposure time. The difference in moisture loss between intensity level 4 and intensity level 1 after 60 seconds exposure from the 1.15-micron source was 4.5 percent. This difference at 120 seconds in- creased to 10.8 percent. Scorching of the leaves was observed at several intensity levels. This was one of the major problems encountered during this research because additional exposure burned the leaves. For each radiant energy source, the exposure time before scorching occurred seemed to be related to the drying rate. The higher the intensity level the faster the hay started to scorch; consequently, the exposure time for the high intensity levels was extremely short. There also ap- peared to be some relationship between time before 12 q scorching and initial moisture content. Hay high initial moisture contents (70-80 percent) scorch as fast as hay having a lower moisture c, The 3.0-micron source scorched the leav p a shorter exposure time than the other sourc, intensity level 3 the leaves started to scorc 60 seconds exposure. The same condition after 15 seconds at intensity level 4. Each dec exposure time due to leaf scoriching caused a in the total moisture removed regardless of tensity levels. For example, radiation from micron source at intensity level 4 removed 2.4 moisture before scorching, while 7.3 percei removed at intensity level 3. Although the drying rates increased as tensity level increased for each source, the rates for equal intensities varied among sourcej was due to the spectral response characte the hay. An approximation of the hay ab rate at different wavelengths was made by the moisture loss against the peak wavel I: each source, Figure 14. The source which peak energy at 3.0 microns appeared to remo moisture than the other sources at the same level. This was more apparent as the intensi increased. At the highest intensity used, micron source removed 5.1 percent moisturi? seconds compared to 2.25 percent for the sour had its energy peak at 1.15 microns. This i increase in the moisture removal rate of abo"? percent for a 30-second exposure. ‘ An infrared energy source which has wavelength between 3.0 and 5.0 microns may? increase the drying rate without increasing: tensity. The energy distribution of the fouf‘ was plotted so that the total energy was for each curve, Figure 15. The shaded area 15 represents the portion of energy radiate: 3.0-micron source only. Since this source if a faster drying rate, the increase was the resufj energy distributed in the shaded portion of .0 us MIC on sounc: / O ENERGY AT MAXIMUM WAVELENGTH O Ch fizz mscnou sounce o, l ,l,s.o mcnon souncc P? ' // 475.0 mcwou souncs G2 r.*\\\ L _ _ 1 2 3 4 5 s 7 a 9 no n :2 as 14 15 l5 WAVELENGTH~MICRONS RATIO OF ENERGY AT WAVELENGTH T Figure 15. Energy distribution from sources of inf tion showing the portion of energy radiated only h micron source. » Y LEVEL- 1 EXPOSURE TlME- 240 SEC. QKMPLE T11R_EE LAYERs r111c1< i BOTTOM LAYER [[[|] “ MIDDLE LAYER VIA I "roe LAYER — comemso SAMPLE E ‘ SINGLE LAYER sA£L_E_ - _1 Figure 16. Moisture removed .. from each layer of hay which - was three layers thick as com- Y pared t0 a single layer. depth which infrared radiation will pene- ‘faterial largely determines the quantity that dried by a given size source. In order to I the amount of hay under the radiation fused, additional layers were placed on top p; other, and the moisture loss was recorded l layer, Figure 16. At intensity level 1, the layer of hay did not lose more than 2 percent while the top layer lost as much as 13.5 Moisture loss from the combined samples, c l? layers being considered as one, ranged from l_ .6 percent. The layer closer to the source tion always lost more moisture than the other ggSome radiant energy was transmitted through ,1 layer to the middle and bottom layers, de- i‘ upon the absorption characteristics of the p portion of the radiant energy did not come ct with the top layer, since this layer did not solid mass. Therefore, a small amount of Iwas received directly from the source by the o layers. _e capacity of a dryer which handles three layers has a higher capacity than one handling layers, assuming equal decrease in moisture j In such a dryer the 3.0-micron source, 116, will remove 5.2 percent moisture in 240 lfwith a capacity of 1.70 pounds (based on 20 l moisture content) per hour per square foot a The capacity of a dryer handling a single fuld be 1.11 pounds per hour per square foot. ling the depth of hay to increase the dryer is not recommended because of the wide f“ in moisture contents Within the hay. Also, eased capacity is not sufficient to Warrant l of infrared energy for drying forages. lbecame evident that the top layer was drying than previous single layers under the same conditions. This proved to be the result of an additional heating effect caused by the other layers of hay when different types of trays were used to hold the hay under the radiation sources. All the energy which was not intercepted by the hay was either transmitted, absorbed and/or reflected by the supporting tray. In the case of the hardware cloth tray, this energy was lost because there was no medium to absorb it. A solid sheet of aluminum was painted dull black and used as a tray. The results showed, Figure 17, that most of the energy lost with the hardware cloth could be used. After a 160-second exposure, the black tray increased the moisture loss 89.25 percent over the hardware cloth tray because most of the remaining energy was absorbed by the black tray. This energy was converted into heat and transferred to the hay pri- marily by conduction. Since there was a time lag needed to heat the tray and transfer this heat to the INTENSITY LEVEL-2 3-0 MICRON SOURCE 24 1 I 1 1 1 r 1 1 1 1 1 a 1 1 1 1 1 1 1 1 1 1 1/11 1 1 1 b- —4 l —1 SOLID sorrow TRAY _ PAINTED BLACK “\ 2’ / / s ,/ ‘l // HARDWARE CLOTH TRflY /Z Z N o 1 - PERCENT (WET BASIS) v MOIST URE LOSS \ 0% 1111111111 111111111 l l 1 1 2O 4O 6O BO ‘IOO I20 I40 I60 180 ZOO EXPOSURE TIME - SECONDS Figure 17. Effect of a solid tray painted dull black on the moisture removal rate of hay irradited by 3.0-micron source. 13 WAVENUMBER CM ' $000 4000 3000 2500 7000 I 500 I 400 I 300 I 200 I I00 I000 900 800 7 8 :_ _17.l: V_ I t PIIZHLI] l i v {>1 I 1:1|||u|.|[: II; i l] II] IIII _ ill l} L .1‘ _j. _:_ g’ too J ‘ ' i‘ "i '3 i l I l ' ' if” —.—.--'.:g'-;=:=_'-;=._Lh . . >1 a ;_'_.;_l?T71‘II§7‘_»-»* ' 90 . ._ .. .._ . _-.-.'.- -. I I f = _ ' » : a0 " "L; i" i1 ' ' -—’ i “"4 ‘fflpfg j.'f“:j:°"+ - *-- _ v 1 H ~ a~ 1- s??? . . _ . _ .._ >IL ~ ‘ .".._. .V.:_§"%‘£: 7° t _ if- i k ‘ _ - :: iIMFE £- ___ § w I l 1 k g . a , . -.= I“ v g l '_ :_':l “A 2. '33.; g ' , _; . l: 441:2.‘ w ' . ' -r 1,__ " " . -1"? .1 ‘l’ ’°;_ ~ * - ~ t. . E 5 . ..'~.. I T Q12"; _ T -» Ml T’ L I _ T"' ' . § ‘o n __ ‘ 5 .=;-1!“ 5” _.;_.. FBI" t _ i; 5 ~ ~_ 1»; fl-L L 30 — ——: W _W ' . _ g _ _ QEEE-Ezz-EE z: r a r <- - r -- - " -— — -‘-- a jg; 222% g w __ , 2O ji_ >;A ‘HI’ D 77-1 l V 1 1 *1 '7 5 ~5;;§; a r1514. ta + no __ - -* - __ ‘u; " _ _ a - - a l i Y._ 0V1‘ _ ’ o t ;;1-_§;;_ ‘TC -i-5_ ‘ . _ _ i; Kf~ - '1 3 S 6 7 8 9 IO II I? I3 I4 IS WAVELENGTH IN MICRONS Figure 18. Absorption characteristics of pelletized mixture of 2 Mg. of ground alfalfa leaves and stems having a moisture c f 8 percent, wet basis, mixed with 400 Mg. of Potassium-Bromide. hay, the longer the exposure time the greater the The efficiencies ranged from 13.0 to 38.1 increase in moisture removal up to some equilibrium while the capacities ranged from 1.69 to 3.17 point. per hour per square foot of hay area, Table 5. Efficiency and capacity are important in a drying installation. They are probably more important when drying hay than other crops because of the lower money value of hay. To determine the ef- ficiency and the capacity of drying with different sources of infrared radiation, single thickness samples of alfalfa were placed on hardware cloth trays and irradiated under each source. Each source was placed as close as possible to the hay, and sufficient sample areas were used so that all emitted energy was inter- cepted by the sample. percent. For purposes of comparison, the The LIB-micron source also had the lowest _ _ _ the 5.0-micron source. The efficiency and capacity of each source are presented in Table 5. These efficiencies represent the overall efficiency of the installation and were FORAGE CROP ABSORPTION WAVELE calculated by the following formula: A spectrophotometer was used to 0b Effigiency: infrared absorption characteristics of Joh (Lbs- Water TBmOWd) (BUYS t0 ¢VaP°Yat¢ 1 lb- Water) X 100 and alfalfa. Previous research showed the imf (Units of power or fuel) (Btu content per unit) The hay temperature was assumed to be constant in these tests; therefore, the Btu’s (British Thermal Units) required to evaporate l pound of water were held constant at 1,026. of being able to expose a forage crop to only g lengths which are most readily absorbed by Studies with Johnsongrass showed that absorbed more infrared radiation in the 3.04. wavelength range than at any other Wal An insignificant amount of energy was ab at, TRAYSI I microns to a level which may be consideredf; Efficiency Hay capacity, pounds per malQT absorption band- Source pmmmt hour p“ Squaw footz Finely ‘ground mixtures of alfalfa 1e l? L15 micron 1&0 L69 stems having an initial moisture content of 8i g3 micron 19,3 250 wet basis, were used to determine the inf" 3.0 micron 15.6 3.38 sorption characteristics of alfalfa. With 5.0 micron 38.1 3.17 an infrared spectrophotometer the samples one minor and two major absorption bands, F “Capacity in pounds of hay per hour per square foot of hay Th6 major bands Occurrfid at Wavelengths surface area. Weight of hay calculated on a basis of 20 percent and 6163 microns with an absorption 0f moisture content (wet basis). percent, respectively, of the total energy. 14 ‘Based on a moisture loss of l0 percent. data are based on a moisture reduction of of hay used to calculate the capacity were c to a common basis of 20 percent moisture (wet basis). The l.l5-micron source had th efficiency while the 5.0-micron source had the but the 3.0-micron source, rather than the the highest capacity. This was attributed inability of the 3.0-micron source to conve power into useable infrared energy as efficifi ; bed 79 percent of the total energy and was _;9.4-9.5 microns. _ OF TREATMENTS ON DRYING (I CTERISTICS OF FORAGE CROPS Pressure Treatments were made to determine the effects of ressure treatments on altering the drying ics of alfalfa in an attempt t0 increase its were subjected t0 temperatures ranging fto l,000° F. under chamber pressures of l)'75 cm. Hg. t0 150 psig. Samples were j e desired temperature and pressure for i; gths of time after which the pressure or is suddenly released. The treated samples ' placed in a controlled environment room p were allowed to dry t0 an equilibrium ntent of about 18 percent. _~ s of the alfalfa stern that had been sub- 21a pressure of 125 psig. and held at that ‘or l0 minutes before releasing were ex- r cellular damage. Both cross-sections and lal sections showed no rupture of cell walls e of damage to the cellular organization. i0 curves plotted for each of the treatments _ the samples were subjected to pressures 0m —75 cm. Hg. t0 150 psig. without the if supplemental heat showed no increase ' ing rate when compared to the control correlation was obtained from the tem- est data since it was concluded from these ts that the correlation depends upon in- temperature and not upon the measured Ape of the air surrounding the product. V‘ gh internal temperatures are a function 1 ounding air temperature, there was not A time for the hay to reach equilibrium urning. n‘ HUHCIHS jatory experiments were conducted to de- pe effect of freeze treatments on the drying conditioned, crushed and chopped alfalfa ‘ tests included various treatment combina- 3i slow-freeze and quick-freeze processes. ye gram samples of alfalfa hay harvested pent bloom stage of maturity were used in ‘riments. l hay was cut into l-inch lengths for the samples. The crushing treatment was ap- assing the sample between two hard rubber iquid nitrogen was used to obtain a quick- tment. The samples were placed on screen 1 immersed in liquid nitrogen until frozen I. 15 seconds). The slow-freeze treatment ‘i ed by suspending the sample in a deep- TABLE 6. HOURS REQUIRED TO DRY LONG AND CHOPPED ALFALFA HAY TO MOISTURE CONTENT OF 5O PERCENT (WET BASIS) WITH SLOW-FREEZE AND QUICK-FREEZE PROCESSES Hay Treatment, hours condition Replication None Slow-freeze Quick-freeze Long, uncrushed A 22 21 17 B 26 15 12 C 21 13 12 (23.0) 1 (16.3) (13.7) Long, crushed (before A 14 11 10 freezing) B 14 9 8 C l0 8*’ 8 (12.7) (9.3) (8.3) Chopped A 10 8 7 B 10.5 8 6 C l0 8 6.5 (10.2) (8.0) (6.8) 1Fi ures in arentheses are avera es of three re lications. g P gEstimated. freeze unit for 24 hours. All the hay used for the tests was cut by hand from the same general location in the field. The samples for one replication were harvested and treated the same day. The treatments for three replications were applied on three consecu- tive days. Following each treatment, the samples were placed in a conditioned room held at 85° F. and 60 percent relative humidity. The drying rates were determined by periodically weighing the samples. After equilibrium was reached, the samples were oven-dried at 220° F. to determine dry matter weights. The time required for the samples to reach 50 and 20 percent moisture, wet basis, is presented in Tables 6 and 7. The data show that crushing after slow freezing has no additional effect on the rate TABLE 7. HOURS REQUIRED TO DRY LONG AND CHOPPED ALFALFA HAY TO MOISTURE CONTENT OF 20 PERCENT (WET BASIS) WITH SLOW-FREEZE AND QUICK-FREEZE PROCESSES Hay Treatment, hours Condition Replication None Slow-freeze Quick-freeze Long, uncrushed A 80 64 64 B 80 56 52 C 70 54 54 (76.7) 1 (58.0) (56.7) Long, crushed (before A 65 32 35 freezing) B 50 33 33 C 37 30’ 30 (56.7) (31.7) (32.7) Chopped A 35 24 24 B 34 25 23 C 35 26 24 (34.7) (25.0) (23.7) lNumluers in parentheses are averages of three replications. zEstimated. 15 30- /Long, Uncrushed 2O - ‘XLonqLCrushed (before freezing) 1O ' \ HOURS REQUIRED TO REDUCE MOISTURE CONTENT TO 5O PERCENT (WET BASIS) Chopped 0 l I I UNFROZ EN SLOW QUICK FROZEN FROZEN Figure 19. Effect of freeze treatments on the time required to reduce the moisture content of uncrushed, crushed and chopped alfalfa hay to 50 percent, wet basis. of drying and that crushing after quick freezing has about the same effect as crushing before quick freezing. The times given in Tables 6 and 7 do not include the 24-hour slow-freeze period. The average values from tables 6 and 7 are presented graphically in Figures l9 and 20. In these tests little or no advantage was gained by using a freeze treatment for drying alfalfa to a moisture content of 50 percent. However, when alfalfa was dried to a moisture content of 20 percent, there was a significant decrease in drying time due to freezing, with no significant difference between slow-freeze and quick-freeze treatments. Also, there was a significant difference between the uncrushed, crushed and chopped treatments for drying to 20 percent moisture. Chopped hay, frozen or unfrozen, showed the fastest drying rate, followed by crushed and uncrushed hay, in that order. How- 8O >- J a tr _ a 2 7O r /Long, Uncrushed (L) d) o 2 E so - w E o 3 Q *2- 50 - m m f,’ ‘Z Long, Crushed (before freezing) ° 5 4o - ' F- fl_ ' Q 0 U] N E 3O - 3 o 0 r- u.| .. ,2 ,0 _ \ g E Chopped z 2 e w - o I l l UNFROZEN SLOW QUICK FROZEN FROZEN Figure 20. Effect of freeze treatments on the time required to reduce the moisture content of uncrushed, crushed and chopped alfalfa hay to 20 percent, wet basis. l6 ever, the difference between crushed and chop! was not significant for drying to 50 percent mi A quick-freeze treatment applied to the s -. crop or in the swath may be a fruitful appri the problem of moisture release from drying ' provided no serious effect on nutritive value is _ ACKNOWLEDGMENTS The authors express their appreciation v, C. Holt, professor, Department of Soil an Sciences, Texas AScM University, for his in conducting these tests. - Appreciation is also expressed to the land Machine Company, Division of Sperry Corporation, New Holland, Pennsylvania f viding equipment for field studies. REFERENCES 1. Casselman, T. W., Green, V. E., Jr., Allen, R. J.,: Thomas, F. H. Mechanical Dewatering of F0 -;. " Technical Bulletin 694. Agricultural Experimen- University of Florida. August 1965. 2. Whitney, L. J. and Hall, C. W. Harvesting .|\(r Alfalfa Leaves. ASAE Transactions. 7: 3, 33. 343. 1964. 1' 3. Dobie, J. B., Goss, J. R., Kepner, R. A., Meyer, J Jones, L. G. Effect of Harvesting Procedures 7' Quality. ASAE Transactions. 6: 4, 301-303. 1 4. Singley, Mark and Mandich, P. A. The Effect of‘. Shape on the Drying Rate of Cut Alfalfa Stems. 9 graphed Paper. New Jersey Agricultural Expe '0 tion, Rutgers-The State University, New Brun: Jersey. November 1962. * 5. Kjelgaard, William L. Flail Mower-Conditionl Place in Forage Harvest. Agricultural Engine a 4, 202. April 1966. l 6. Byers, G. L., Routley, D. G. and Colburn, M. W. Release from Cut Alfalfa. Agricultural Experim y University of New Hampshire. March 1964. 7. Kjelgaard, William L. Hay Drying with Selectl Sources. ASAE Transactions. 6: 4, 324 and 327 8. Person, N. K., Jr. and Sorenson, J. W., Jr. A I of Different Methods of Field Curing Alfalfa grass. Progress Report 2185. Texas Agricultu ment Station. April 6, 1961. is 9. Person, N. K., Jr. and Sorenson, J. W., Jr., of Curing Rates of Several Forage Crops Dried _i trolled Conditions. Progress Report 2227. Te I tural Experiment Station. February 12, 1962.. l0. Person, N. K., Jr. and Sorenson, J. W., Jr. l1. with Infrared Radiation. Agricultural Engine 4, 204-207. April 1962. 4o 11. Hackforth, H. L. Infrared Radiation. McGraWfl Company. New York. 1960. .