**' "K N? Division of Agricultural Sciences UNIVERSITY OF CALIFORNIA tf or&l*: Barn Mow Haydrying F R Dciici iiUuiiiy ndy : = --;..:- : ?- : -- : :•■:- CALIFORNIA AGRICULTURAL Experiment Station Extension Service CIRCULAR 454 finishes drying hay that has been partially dried in the field by forcing air through it. The system offers these advantages: • Harvesting depends less on the weather. • Better quality hay can be produced by removing it from the field at the most advantageous time. • Safer storage is achieved by mechanical removal of the remaining moisture. Barn mow haydrying does not replace sun-drying; it com- pletes the process at greater convenience to you and less risk to your crop. Mold growth or spoilage by bacterial action will not develop if you follow sound harvesting and storage procedures. This circular describes the system and discusses its fea- tures. You will find here suggested layouts, instructions for installation, and construction details, as well as rec- ommended practices for making quality chopped hay. This publication replaces Circular 149. THE AUTHORS: John B. Dobie is Associate Specialist in Agricultural Engineer- ing, Davis. Ralph R. Parks is Agriculturist in the Agricultural Extension Service, Davis. MAY, 1956 7^0 System What it is and how it works; How it reduces problems of harvesting, storage, and nutrition; The importance of moisture content. X he barn mow haydrier has become an accepted part of the equipment necessary to produce top-quality chopped hay in California. Although originally expected to be most needed in the damp, coastal areas of the state, its widest acceptance has been in the dry, irrigated Central Valley areas where hundreds of such driers are now in use, particularly with dairies and beef feedlots producing their own hay. The advantages of chopped hay for feeding and handling are increased when the quality of good hay is preserved through the use of a barn drier. Forced air dries hay progressively A barn mow haydrier consists of a sys- tem of channels or ducts through which air is distributed to the hay by a fan. Hay is piled on the ducts so that the moving air passes through and dries it. Driers are usually located in the barn mow, but similar units are used for open stacks where rainfall is low. Drying by this method is progressive, taking place first in a thin layer near the ducts and then advancing in a drying layer toward the outside of the hay mass. This layer moves outward slowly, at the rate of % to 2 feet per day, depending on the volume, temperature, and humidity of the air and on the initial moisture con- tent of the hay. A mow of hay will dry to a safe storage level (16 per cent for chopped hay) in three to ten days, de- pending on the above factors, the depth of wet hay, and the rate of loading. Hay may be long, chopped, or baled Barn haydrying (sometimes called "hay finishing") can be used to advan- tage with long, chopped, or baled hay. Early experiments with long hay proved very successful, and where hay is stored in this form, barn drying can be used to advantage. Hay baled for use on the farm where it is raised can also be dried satis- factorily. Shrinkage of the hay during drying causes the bale ties to loosen, so artificially dried bales cannot be satisfac- torily handled as commercial hay. In California, barn drying has been used mainly for chopped hay, which has certain advantages for the livestockman : 1. It can be handled mechanically and with less labor than either baled or loose hay. 2. Feed loss is reduced and less labor is required in feeding. 3. Maximum capacity of storage can be obtained. To permit deep storage, the vertical-flue drier is used in most instal- lations in California. Much of the information in this circu- lar is basic to successful haydrying any- where; certain specific recommendations, however, are designed for conditions in the interior of the state. For the revisions necessary in coastal areas, see page 18. [3] Moisture content must be reduced Chopped hay also has its disadvan- tages. It packs tight in storage and, placed in storage at a moisture content of 16 per cent or more, may heat spontane- ously. This may result in hay of reduced feeding value ("tobacco hay" is the re- sult of excessive heating and is low- quality feed) or complete loss of feed, barn, and perhaps livestock, due to fires caused by spontaneous combustion. The reduction of moisture content by field curing alone to a safe level for stor- age is often difficult, particularly with first cutting. Field curing for normal IF YOU HAVE HOT HAY . . . Hay may heat spontaneously for several reasons, but usually the cause is excessive moisture or pressure, or mechanical damage. Such heating, if it does not exceed 130° F, is not dan- gerous. Many farmers even consider it desirable. However, there is rather a fine line between the temperature at which hay "sweats" and the point of spontaneous heating and combustion. Generally speaking, when hay reaches a temperature of 170° F it enters the danger zone. Between 170° and 200° F it should be cooled or removed from the barn. Hay above 200° F should be removed from the barn, and emer- gency fire-fighting equipment should be in readiness at all times. Don't take chances with rising tem- peratures. Check the conditions of your hay at regular intervals, and check temperatures at different loca- tions in the stack. Do not get on top of a stack that is suspected of serious heating. To check temperatures from the top of the stack, rest a plank across it, and do not step off the plank. Three methods are commonly used to check interior haystack tempera- tures : 1. Push a %- or l/^-inch iron rod into the haystack and leave it there for five minutes. As it is removed, feel the rod. If it is too hot to hold, the hay is too hot and will probably get hotter. 2. Drive a V^inch pipe downward into the stack. Lower a thermometer on a string down into the pipe and leave it there for 2 to 3 minutes. Re- move the thermometer quickly to get the maximum reading. 3. If possible, obtain a hay tempera- ture probe (your local Farm Advisor may have one that you can use). In- stantaneous readings permit rapid checking in several locations. If the stack is heating dangerously, follow one of these suggestions : 1. If the heating is localized, a trench dug through the problem area will sometimes cool it. 2. Spread the hay out. This usually requires removing part of it from the barn. 3. It is reported that up to about 200° F, hay can be cooled with a fan. To do this, dig a hole into the side of the stack and blow air into the hole. This is not recommended for stacks with a temperature above 200° F be- cause of the possibility of live embers somewhere within the stack. 4. If temperatures are above 200° F, remove the hay from the barn to safeguard the structure. The surface of the stack should be kept wet at all times, and water under pressure should be immediately available. Stack the removed hay away from buildings, as it may burn. [4 storage generally requires several days of good drying weather in the swath and windrow. If the field-curing period is too long, the new crop may grow up into hay being cured, and the new crop may be seriously damaged when the cured crop is removed. Also, the application of irri- gation water for the new crop is delayed. Slow field curing results in loss of qual- ity, and bad haying weather can cause complete loss of the cutting. Chopping at low moisture contents, unless done during periods of dew or high humidity, results in a considerable loss of leaves. Even then, the added mois- ture can be dangerous unless this excess is to be removed by some means such as barn mow haydrying. Barn curing reduces moisture content to a safe level With barn mow haydrying you can complete the drying of damp or partially field-cured hay in storage. Two or three days' field curing is enough to reduce the moisture content to 35 per cent or below. At this point it can be chopped and placed in storage. Here, air supplied by a fan and distributed through a tunnel under the hay dries it to a moisture con- tent safe for storage. Such a system eliminates the danger arising from spontaneous heating. Forced ventilation keeps the hay cool until all excess moisture has been removed. Leaf shatter can be minimized with this process. Tests indicate that even at 55 per cent moisture content, hay begins to shatter when handled during after- noons or when humidity is low. As the moisture content is reduced, leaf shatter increases until one fourth to one third of the hay may be lost in handling. Loss in protein content may be even more serious. A haydrier reduces these leaf losses in two ways: 1) it permits chopping at a higher moisture content; and 2) it makes practical the desirable practice of chop- ping for storage during periods of high humidity. Leaf losses can thus be kept to a minimum. 9,000 25 30 35 40 45 50 55 PER CENT MOISTURE CONTENT OF HAY This shows amount of water that must be removed from hay to make it safe for storage. Hay at 35 per cent moisture still has 616 pounds of water per ton to be removed. [5] Hay to be chopped for a barn drier seldom has to lie in the swath and wind- row more than three days, so the hay can be removed from the field quickly and water applied to speed up the next crop. The bulk of the moisture is lost during this period. Weather is seldom so bad that a crop is lost because of rain or fog. When wet weather prevents complete field curing, the hay can be dried in the mow to a safe moisture content for storage. What you will need — basic requirements and new equipment- Suggested layouts for satisfactory installation; Construction details for units you can build yourself. Basic requirements The hay mow should have: 1. An airtight floor. Ground-level hay mows are ideal. 2. A good roof to protect the hay once it is dry. For an open-sided barn, provide enough roof overhang or other protec- tion to keep driving rain from the sides of the stack. 3. Enough ventilation under the roof to carry away the damp air as it leaves the hay and prevent its recirculation to the fan. 4. For chopped hay, posts along the side of the hay mow, designed to with- stand the horizontal pressure of the hay as it settles. Wire or board formers should be placed outside these vertical supports. If you are building a new barn, the side posts or walls can be sloped in- ward at the top, 2 feet for 20-foot-high posts, to relieve pressure on them. 5. For long hay, a strong and well-sup- ported hay carrier and track to handle the added weight of the moist hay. Building the main duct The recommended size of the main air tunnel for a 5-hp unit is 4 x 4 feet or 4x5 feet. Such a tunnel is not costly to build. It is easy to maintain and does not take up much space in the storage area. Since a 5-hp fan delivers about 16,000 cubic feet of air per minute, a 4 x 4-foot tunnel with 16 square feet of cross sec- tion would give a maximum air velocity in the tunnel of 1,000 feet per minute, the maximum desirable. The larger area pro- vided by a 4 x 5-foot tunnel further re- duces this air speed and provides more space for the air to enter the hay, thus increasing efficiency. The tunnel is framed with 4 x 4-inch posts set about a foot in the ground and tied across the top with another 4x4. The posts should be not more than 4 feet apart. The sides of the tunnel can be built of a variety of materials — 1-inch lumber spaced 2 to 3 inches apart, snow fence, woven-wire fencing, or welded wire — fastened on the insides of the posts. One- inch boards spaced 1 inch apart and nailed to the underside of the cross- pieces are satisfactory for the top, pro- vided 2-inch planks are laid on top of the crosspieces to take part of the hay load. These 2-inch planks serve an addi- tional purpose by helping to keep the flue formers erect until some hay has been placed around them. Another method of constructing the top is to place 4 x 4-inch plates lengthwise of the tunnel on top of the posts and lay 2-inch planks across the top, leaving 1-inch cracks. The end of the tunnel opposite the fan end should be boarded up, with i/o-inch cracks between the boards, similar to the top. The first eight feet of the tunnel at the fan end should be airtight. A temporary tunnel can be formed with dry bales of hay or straw. Two rows of bales, 3 bales high, form the sides of the tunnels; they should be piled so as to leave as much open space as possible between the bales. The top is made by laying 2-inch lumber across the top of the bales, leaving 1-inch cracks between the boards. This system is not recom- mended for a permanent installation but is used mainly for small outdoor stacks or as an inexpensive temporary tunnel. Flue formers The flue former provides a path or flue to carry air to the upper part of a stack of hay more than 12 feet deep. The form- ers are spaced 8 feet apart. As they are pulled up, they leave 1-foot-square holes in the hay to carry air up to the bottom of the flue formers, where it is forced out through the hay. Flue formers are 1 foot square and 6 feet long, plugged at both ends. They are made by nailing four 1 x 12's together to form a box. A rope or wire handle is fastened on one end to aid in lifting the former, and a 1 x 2-inch stick is fastened to the side about 2 feet from the other end, as shown, to keep the former from sliding back down in the hole in case the hay is not packed tightly enough around it. Each former may be supported by a rope over a pulley hung from the framing above. This helps to keep the formers vertical and to locate them if they be- come covered with hay. Fans The purpose of the fan is to push air through the hay at a rate that will dry the hay. For chopped hay, 15 cubic feet per minute (cfm) should be provided for every square foot of hay mow. This fig- ure may be reduced to about 12 cfm for long hay and increased to 20 cfm for baled hay. The design figures used for static pressure of the system (the back pressure against which the fan must work in forcing air through the hay) are l 1 /^ inches of water for chopped or baled hay and 1 inch for long hay. The fan should (continued on page 12) A"xA" -i Air deflector door D D D D Z. Airtight walls 5hpfan v^~ ■ 4'x4'tunnel Door Longer barns, because of management problems in filling the storage area, should be laid out as shown above. The barn can then be filled in sections. Note that the tunnel from the fan to the main duct is airtight. A baffle door permits drying half the barn at a time. A barn 200 feet long would have two units such as this. [8] DUCT SYSTEM The effect of mow width — 40' to 50' maximum A single duct down the center will handle a storage area up to 28 feet wide. < Fan ^ 8' ^ r ° D D D D 4 x 4' tunnel CO CN O +- CN Maximum area 1,100 sq. ft. If storage space is wider than 28 feet, place on each side of the duct slatted floor equal to half the width in excess of 28 feet. For example, in a 36-foot-wide barn, use 4 feet of slatted floor on each side of the duct. If the barn is wider than 36 feet, divide it crosswise into a number of units 28 feet or less in width and treat each unit as an individual drier. Here is an arrangement of 5-hp units suitable for barns 36 feet wide or wider. Dividers are usually wire mesh to form sides of stacks but permit passage of air. Any length < a 1 4'x D 4' tunnel / Dividers D D D D . D a D a a a D D D ^ mm „^ 24' to 28' [9 5-hp blower Safety screen Main duct airl Use plywo [10] Wire mesh or snow fence Slatted top — 1" spacing t 4' x A' for 32' tunnel first 8 feet ?r boards lined with paper Plan of a vertical flue haydrier developed by the Department of Agricultural Engineering of the University of California. [ii] For chopped hay— If your barn is: sq. ft. up to 1,100 You need a hp 5 10 fan of: Del vering up cfm 16,500 24,000 34,000 to: At a static pressure of: inches of water VA VA VA 1,101 to 1,600 1,601 to 2,250 be non-overloading to operate satisfac- torily with variations in static pressure (sp) in the system. When selected for proper volume and pressure, centrifugal, propeller, vaneax- ial, and tubeaxial fans will all do a satis- factory drying job. The propeller type is most commonly used because it fulfills the above requirements and has the added advantages of ease of installation, portability, and low cost. You can use either of the two follow- ing methods to calculate your needs and select the proper fan: 1. If you plan a standard 5-hp installa- tion, each 5-hp fan can handle up to 1,100 square feet of mow area. 2. The hay-mow floor area may be multiplied by the correct cfm/sq. ft. fig- ure for the type of hay to be dried, and the fan size selected according to the re- sulting cfm figure and the recommended static pressure. For example : for chopped hay a 28 x 50-foot barn would require 28x50x15 = 21,000 cfm at 1% inches of water static pressure. This would re- quire a 7V2 _n P fan. Installation. The fan is located at the inlet end of the main duct, which is made airtight for the first 8 feet. Weather pro- tection for the fan and motor can be provided by mounting the fan 2 feet or more in from the end of the duct. If the fan is located inside the inlet duct, the air opening in the duct on the suction side of the fan should be twice as large as the fan inlet. A wire-mesh guard should be installed on the inlet side of the blades for safety. Power unit Wherever electricity is available, the fan may either be direct-connected at 1,750 rpm with an electric motor, or it Recommended Values for Figuring Haydrying Installations Long hay Chopped hay Baled hay Type of drier Vertical flue Vertical flue Slatted floor or single tunnel Amount of air (cfm per sq. ft. of mow area) 1 2 cfm 1 5 cfm 20 cfm Pressure at fan discharge 1" water VA" water VA" water Maximum depth of hay 25-30 ft. 25-30 ft. 7 bales Maximum moisture content of hay when placed on drier 50% 35% 35% Maximum width of mow without laterals. 32 ft. 28 ft. 25 ft. Storage space required per ton 450 cu. ft. 170 cu. ft. 200 cu. ft. * A tunnel may be formed with bales and bales stacked 5 or 6 deep around it. [12] may be belt-driven. Direct-driven units are usually preferred unless the motor is to be used for other jobs. Three-phase motors should be used where this type of power is available because of the low- er first cost and maintenance cost as compared with single-phase. The electric motor should be properly protected, both from electrical overload and from dirt and moisture. In selecting a magnetic controller, be sure to use heaters of the proper size. Some fans may overload the motor 10 to 15 per cent, requiring the size of the fuse to be increased propor- tionately. This is not objectionable be- cause of the cooling effect of the fan. Separate protection should be provided for each fan motor. Some power-take-off tractor-driven fans are used, usually where electric power is not readily available or where the added ease of portability is impor- tant. Take care to operate the fan at or near its rated speed for safe and efficient service. A suitable spark arrester should be installed on the engine exhaust for safety from fire. Auxiliary heat The addition of heat would speed the drying and help correct high humidity conditions often found in the coastal counties. In most other parts of Califor- nia it is not necessary to satisfactory barn drying. If auxiliary heat is used for drying a combustible product such as hay, a heat exchanger should be used to keep the products of combustion from entering the hay. A heat exchanger works like a stove or furnace to heat the air without the danger of sparks or smoke. A heat exchanger would add consider- ably to the cost of the installation as well as the cost of operation. Cost of drier On the basis of 1956 prices, the aver- age 5-hp haydrier will cost about as fol- lows. (These figures are rough estimates; wiring, in particular, may be less, or it may come to considerably more.) 5-hp fan $270 5-hp motor (three phase; add $150 for single-phase) 180 Motor starter 40 Lumber and materials for standard duct 100 Wiring 100 Total cost (less labor for construction) $690 Labor (40 hours at $1.25/hr.*) 50 Total cost $740 Normally, a 5-hp drier has a capacity of 120 tons or more, making the invest- ment per ton of capacity about $6.20. The cost of operating the fan is 25 to 50 cents per ton. The cost of mow-drying chopped al- falfa hay is shown in the table. The cost of the drier is amortized over a 10-year period and is based on a 5-hp unit, filled once a year with 120 tons of hay. * Farm labor is usually suitable for construc- tion of the haydrier tunnel. Cost of Barn-Drying Hay Depreciation: Motor, fan, starter, and wiring ($4.92 for 10 years*) $0.49 Ducts ($1.25 for 10 years) 13 Interest ($3.09 @ 5%) 15 Taxes, repairs, etc. (2% of $5.33) 12 Powert 44 Total cost per ton $1 .33 * Ten years is a conservative estimate of the life of a motor, fan, starter, and wiring. t Average based on 19 installations, Pacific Gas and Electric Co. survey, 1955. [13] 'Piactccet How to determine moisture content- Harvesting and storing recommendations for better quality hay. A general guide for determining mois- ture content is illustrated below. Since this test depends on individual human judgment and is therefore subject to con- siderable variation, an objective mois- ture test is also recommended — for the first year at least — to check the results. A more accurate method would be to dry a sample of hay in the oven of the kitchen range. Weighing the sample be- fore and after drying, then dividing the loss in weight by the wet weight of the sample only gives a reasonably accurate measure of moisture content. Oven-dry- ing requires a temperature of 275° for two hours, or until heating causes no further reduction in weight of the sample. When moisture content is between 25 and 45 per cent, the carbide method is sometimes used. This test requires some special equipment, such as sample cans and scales, but is relatively inexpensive. Another test uses the heat from the trac- tor exhaust to dry the sample. Instruc- tions for both these methods may be obtained from your local Farm Advisor. One of the simplest yet most accurate methods of testing is the so-called "French-fry" system. The sample is boiled in vegetable oil (ordinary cooking oil) for about 20 minutes and the loss in weight is recorded. If a 100-gram sample is used, the loss of weight in grams can then be read directly as moisture content. The oil may be recovered for further use. Commercial moisture testers are also available, ranging in price from about $50 to $125 or more. The less expensive units use electric heat, so 115-volt power must be available. These units require about 20 minutes per sample and are quite simple to operate, but the sample is small, so representative sampling is diffi- cult. Instantaneous-reading moisture test- ers, which measure the electrical resist- ance of the sample, may be used in the field, but these are expensive, and poor sampling can make the method inaccu- rate. Recommended practices for making quality chopped hay 1. Mow at y U) bloom, after the dew is off. Mow as much as can be chopped the third day. 2. Rake at 55 to 65 per cent moisture content — just before the leaves start to 80% Freshly cut 60% Wilted [14] TESTING FOR MOISTURE Juice can easily be squeezed from stems Hard to squeeze juice from stems Slightly tough 35% Sia» 25% # ## * / Safe for baling 18-23% ^h \ Usually safe for storage / =S 15-18% Your Farm Advisor can help you with these estimates — he has ways of determining moisture content by laboratory methods. [15] FIRST DAY 80 70 — 60 -I Z 50 O u LU Q£ co 40 O 3E H 35 Z UJ U 30 UJ Q_ DRYING PERIOD 8 A.M. TO 4 P.M. SECOND DAY 1^ NOON w THE HOURS . 7X ~ OF DARKNESS "* HAY PICKS UP MOISTURE FROM DEW »TJkJ ^M aP ■ : ' ■■■■■J iii^L MOWING starts about 8 a.m. and con- tinues throughout the day. RAKING starts early on the second day while the leaves are tough from dew. when leaves begin to shatter. Continue next morning if necessary. Chart is for averts On first and last cuttings, or under wet conditions, it may require as I [16] THIRD, FOURTH, OR EVEN FIFTH DAY NOON NOON CHOPPING FOR STORAGE WITH DRIER Below 35 per cent the hay can go into the barn for further drying. when leaves begin to shatter. when leaves begin to shatter. season cutting. 5 days to bring moisture content of hay down to 30-35 per cent. [17] shatter. If moisture content is below 55 per cent, rake during high humidity period, usually in the forenoon. 3. Allow to cure in the windrow one to two days, or until the moisture content is 35 per cent or less. 4. Chop during period of high humid- ity, or while dew is on, and place on the drier. 5. Cover the main tunnel the first day if possible. Build the pile of hay in uni- form layers, mounded over the main duct. Do not fork the hay around exces- sively. Spread it as much as possible with the conveyor, using the fork only to push off high piles or to loosen tight spots. Keep the vertical flues worked up near the top of the stack. Keep off the stack as much as possible until the hay has been dried, except for tramping around the flue formers and any upright posts within the hay-storage area that might cause air leakage. When hay is piled to the tops of the flue formers, tramp it down around each former and pull the former up about 4 feet. Hay may then be built up to the top of the former again. During drying, the top of the former should be even with the top of the stack. 6. Operate the fan continuously for a few days or until the hay seems to be dry. Hay 6 to 12 inches under the surface will dry last. When drying seems complete, turn off the fan for 24 to 48 hours. Then start the fan in the cool of the morning, and check the top of the stack for warm air or vapor. If any is found, let the fan run another 48 hours and repeat the test. Hay may be forked off any warm spots if the rest of the hay seems dry. Barn Drying for Coastal Conditions The basic requirements and man- agement practices recommended in this circular are for average condi- tions found in the interior valleys of California. They do not apply in coastal areas of high humidity. Barn drying is more difficult under the lat- ter conditions. Design requirements should be modified as follows: • Provide 20 cubic feet of air per minute (cfm) per square foot of mow area. • For any one cutting, allow 500 cfm per ton of hay to be dried. (A 5-hp fan, delivering 16,500 cfm, would , v . , 16,500 nn be limited to = 33 tons per cut- ting and a mow area of 825 square feet.) • Use a longer cut for chopping, preferably a 3- to 4-inch length (theo- retical length of cut). • Put up clean hay. Heavy weed stems and grass are harder to dry. • Reduce maximum drier width to 24 feet and use a 4 x 5-foot tunnel. • Operate the blower continuously during the first few days of storage. After that, turn the fan on only during good drying weather. In wet weather, operate the blower only often enough to keep hay cool. • Use supplemental heat if neces- sary or desirable. Provide an increase in temperature of about 5° to 10° F with a sparkless heat exchanger. Ex- tend the blowing period to all but the worst drying conditions, such as fog, steady rain, or humidity above 70 per cent. [18 ACKNOWLEDGMENTS The authors wish to acknowledge the assistance of J. V. Galindo, assistant architectural drafts- man in the Department of Agricultural Engineering, who made many of the drawings used in this publication. Co-operative Extension work in Agriculture and Home Economies, College of Agriculture, University of California, and United States Department of Agricult co-operating. Distributed in furtherance of the Acts of Congress of May 8, and June 30, 1911. George B. Alcorn, Director, California Agricultural Extension Sen 15m-5,'56(B5650)BEB , 41 <&$$»£;. [19 1 AND AGAIN . . . REMEMBER 100° IN STORAGE 300 AND CAN BURN . WITHOUT HAYDRYING MOIST HAY 200° GETS HOT 450° J/ Mli