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1935

Artificial curing of forage cropsHarold Thomas Barr

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Recommended CitationBarr, Harold Thomas, "Artificial curing of forage crops" (1935). LSU Agricultural Experiment Station Reports. 522.http://digitalcommons.lsu.edu/agexp/522

r 36 7

MAY. 1935 LOUISIANA BULLETIN No. 261

Artificial Curing of Forage Crops

By

Harold T. Barr

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LOUISIANA STATE UNIVERSITY

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AGRICULTURAL AND MECHANICAL COLLEGE

AGRICULTURAL EXPERIMENT STATIONS

C. T. Dowell, Director

Artificial Curing of Forage CropsBy

HAROLD T. BARR

The drying of some agricultural crops by the use of artificial heat has received

increasing attention during the past few years. However, it is not a new process.

The first reference to artificial drying seems to be that recounted in "Horse-

Hoeing Husbandry," by Jethro Tull, published in 1829.1

Artifiicial heat was used in

this case in order to reduce the moisture content in wheat, so as to store it for long

periods of time, in order to sell when the price was high. One of the earliest at-

tempts at artificial drying in the United States was for drying prunes about 1880,

and then a few years later for the drying of walnuts.

The first10 work in artificial curing of forage crops was carried on by the United

States Department of Agriculture from 1910 through 1912, at Hayti, Missouri. In

1911, Arthur J. Mason built an experimental drier at West Point, Mississippi. Hemoved to the vicinity of Chicago three years later, where he continued his work.

The Bayley Blower Company of Milwaukee, Wisconsin, in 1915, built a dehydrator

for the McCracken Land Company of Houston, Texas.

The Louisville Drying Machinery Company, of Louisville, Kentucky, started

experimental work about 1915. From 1915 to 1925, there seemed to be little interest

along this line, with about the only work going forward being that of Mason and the

Louisville Company, each of whom was making improvements on his dryers.

During 1925, the interest in artificial drying gained momentum, and has been get-

ting greater each year. The United States Department of Agriculture, state agri-

cultural experiment stations, commercial companies, and various individuals have

each put forth considerable sums of money, time, and effort in bringing about this

development.

The importance of the hay crop in the United States is best shown by referring

to the yearbook of the United States Department of Agriculture for 1934. A total of

all crops harvested for 1933 is 327,324,000 acres, with 66,144,000 acres, or 20.20 per

cent, devoted to hays. In Louisiana, in 1933, the total hay acreage was 202,000

with a farm value of $1,577,000. In the humid area of the Gulf States, the average

monthly rainfall for the summer months is 4.56 inches. With this heavy rainfall,

the production of the best quality of hay is an uncommon occurrence. It is not

uncommon to have the quality of from 30 to 60 per cent of the hays in the Gulf

States lowered one or two grades, or completely lost from rain damage.

Throughout the Gulf States there are large acreages which will produce heavy

crops of hays, but they have only been partially developed because of the difficulty

encountered in producing hay of good quality.

Artificial drying gives a better color, a more uniform product, higher protein

content, and slightly higher percentage of leaves.3

Artificially cured

Field cured

Color %67

60

Leaves %52

48

Protein %20.4

19.5

2

The leaf loss and lower protein content are doubtless due to mechanical losses in

the process of field curing. With alfalfa hay, Kisselback and Anderson4 found that

from 68 to 75 per cent of the total protein was contained in the leaves, varying some

according to the stage of maturity, while work at the Louisiana Agricultural Experi-

ment Station on soybean hays, carefully cured, shows the leaves to make up 59.7

per cent of the plant and the stems, 40.3 per cent of the plant. The leaves at the

same time contained 4.78 times more crude protein than the stems.

With clear hot weather alfalfa or soybeans dried in the swath to a moisture

content satisfactory for barn storage were badly bleached. In this condition, few

leaves were lost if picked up by hand forks and loaded onto wagons; when raked

into windrows, the ground in several cases was covered with leaves and fine stems.

Where hay is grown as a cash crop or commercial enterprise, a suggestion by

Hurst and Kisselback7

is that the value of the hay should be determined by com-

parison with the actual prices paid for the various grades at the terminal markets.

They found that "a greater part of the alfalfa hay sold on the Kansas City market

falls within No. 2 and No. 3 grades." In 1927 and 1928 the average price of

U. S. No. 1 Extra Leafy Alfalfa was $8.01 higher than U. S. No. 2 on the Kansas

City market. For the period of 1922-1932, according to the United States Depart-

ment of Agriculture yearbook of 1933, the average price of U. S. No. 1 alfalfa

was $4.12 higher than U. S. No. 2 at the Kansas City market.

With reasonable care, and allowing from two to four hours wilting in the swath

before delivery to the drier, the hay from an artificial drier will grade U. S. No. 1,

Extra Leafy.

Workers at other stations have found artificially cured hays to have several

times as much vitamin A and vitamin E as similar hays cured in the sun. Vitamin

D is lowered somewhat, perhaps due to the shorter period of exposure to the sun

after cutting. In order to test out the effect of the curing process alone on the feed-

ing value of soybean hay, two adjacent "cuts" of Biloxi soybeans of the same

age and stage of maturity were cut. One-half was dried in the field, and the other

half put through the artificial drier.

In order to be able to answer the questions as to the feeding value of the

artificially dried hay, the Animal Industry Department8of the Louisiana Agricultural

Experiment Station made a very careful study. "Four lots of calves were used in

the test. Lot I was fed long soybean hay as it is normally fed. Lot II was fed

field cured soybean hay cut or chopped the same as it is chopped for artificial drying.

Lot III was fed the same amount of artificially dried hay as Lot II. Lot IV was

fed artificially dried hay just as the calves would consume it." Their results were

as follows: "1. One hundred pounds of artificially dried soybean hay was equivalent

to 162 pounds of uncut field cured soybean hay in producing gains on calves.

2. Artificially dried soybean hay produced from 10 to 11 per cent more gains on

calves and steers than cut or chopped field cured soybean hay. Two years' results

showed artificially dried hay to be from 10 to 15 per cent more efficient in producing

gains than field cured chopped soybean hay of the same quality. 3. Cutting or

chopping reduced the waste of soybean hay about 40 per cent, probably because

the steers eating the long hay consumed more leaves and refused more stems.

4. Artificially dried hay was more palatable than field cured hay."

During five years' work in artificial drying, most of the experimenting was

with soybeans, as this has proved the hardest crop to cure successfully, and is a

widely used hay crop throughout the Southern States. Other hay crops and pos-

sible hay crops were cured artificially, and their relative feeding values given in Fig. I.

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The principal hay crops are relatively high in moisture content when ready for

cutting, and if brought direct to the drying plant necessitate the hauling of large

amounts of moisture and at the drying plant reduce the total amount of dry hay

that may be produced per hour. Each pound of water in the hay requires a definite

amount of heat to raise its temperature from the temperature as delivered to the drier

up to 212 degrees, and then evaporate this moisture. Each drier is built with a

furnace capable of delivering a predetermined quantity of heat at maximum capacity.

Hence, the dried hay capacity of the drier is normally this maximum heat, divided by

the amount required to raise the temperature of, and evaporate, the moisture in green

hay above that of the dried hay.

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hours; then the rate of moisture loss slows up, as shown in Fig. II. Jones and Palmer9

found similar results on Johnson grass and soybeans, but on alfalfa they found that

the rapid loss continued from 7 to 8 hours. In curing a 250-pound sample (in the sun)

of soybeans, it was necessary to leave the beans in the field four and one-half days

in order to reduce the moisture content from 82 per cent to 17 per cent, with an

average daily temperature of 88° F. by 10:30 a. m. With analyses from five

years' work, the initial moisture content of green soybeans cut for hay ranged from

64 to 83 per cent, with an average of 74 per cent moisture. With a moisture con-

tent of 83 per cent, it is necessary to evaporate 8,353 pounds of water to leave one

ton of 12 per cent hay, or requires hauling 10,353 pounds of green hay from field

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to drier. With 74 per cent initial moisture, 4,769 pounds of water must be driven

off, and 6,769 pounds of green hay is needed. While with 64 per cent initial mois-

ture, 2,888 pounds of water must be driven off, and 4,888 pounds of green hay is

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By leaving the soybeans in the field from two to four hours after cutting, the

moisture was reduced from 60-45 per cent, depending upon the time left in the sun and

the stage of maturity. This is the practice as recommended for use in artificial dry-

ing of forage crops.

In order to remove artificially the excess moisture in the forage, heat must be

supplied in rather large quantities. To evaporate one pound of water from 80° F.

(temperature of hay delivered to drier) into steam at 212° F. requires 1,102 British

Thermal Units. With forage in which there is an initial moisture content of 74

per cent, there is a necessary removal of 4,769 pounds of water to produce one ton

of 12 per cent hay. This would require 4,769 X 1,102, or 5,255,438 British Thermal

Units. With forage of 64 per cent initial moisture content, and the necessary re-

moval of 2,888 pounds of water to produce one ton of 12 per cent hay, this would

require 2,888 X 1,102, or 3,182,576 British Thermal Units.

With fuel oil containing 19,000 British Thermal Units per pound, and coal

containing 14,000 British Thermal Units per pound and a theoretical efficiency of 100

per cent, the first case would require 276.6 pounds of oil, or 375.3 pounds of coal,

while the second would require 167.5 pounds of oil or 227.3 pounds of coal to pro-

duce one ton of dried hay. Fourteen tests made on artificial driers in operation

gave fuel efficiencies varying from 28 to 78 per cent. Leaving out two extremely

low tests and one extremely high test, the average efficiency obtained was 63 per

cent (Fig. IV).

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In 1927, work was started at this station by Messrs. C. L. Osterberger and J. J.

Munson on artificial drying. Upon Mr. Munson's resignation, Mr. Carl Nadler worked

for one year on the problem. Mr. Osterberger and Mr. Nadler resigned in 1929,

and Mr. William Whipple and Harold T. Barr filled their places. The first drier

was essentially a rectangular box, four by eight by forty feet high, on a framework

of angle irons. The green material was chopped and blown to the top of the tower,

where a set of baffles distributed it evenly over the top, allowing the material to

fall off by gravity through a rising stream of hot furnace gases which entered the

tower near the bottom. A given batch of hay was recirculated until the moisture

was lowered sufficiently. Considerable trouble was encountered when the hay

reached moisture contents just above the desired condition. It was hard to get the

hay to travel against the stream of gases. Very low fuel efficiencies were also

obtained.

In 192S. a single rotary drum drier three feet in diameter by twenty-eight feet

long was tested out with very good results, but lacked capacity. From these results,

a large drier was built in 1929.

The present drier which has been used successfully for three seasons is shown

in Fig. V. The green forage is delivered to the ensilage cutter, chopped into short

lengths (cutter set for 3/16-inch cut), elevated into the cyclone feeder, and fed by

gravity into the high temperature end of the revolving drum. At this point, the

green material comes in direct contact with furnace gases at a temperature of from

1600° F. to 1800° F.

An exhaust fan draws out the gases after they have been cooled by furnishing

heat for the evaporation of the excess moisture at a temperature of 225° F. and main-

tained in the drum a current of air (400 F. P. M.) sufficient to carry out of the

high temperature zone the particles of low density and therefore low moisture con-

tent. Repeated tests have been run which show the best temperature at the furnace

end to be from 1600° F. to 1800° F., with an exhaust temperature of from 225° F. to

240° F. As soon as the drier is thoroughly warmed up the oil burners are set to give

a heat of from 1600° F. to 1800° F. with complete combustion of the fuel.

Then the exhaust temperature is maintained or varied by the amount of green

material (or moisture to be evaporated) fed into the high temperature end of the

drum. This gives a very simple and practical method of controlling the moisture

in the dried hay. The velocity of the flue gases carries the lighter portions through

the drum in a few seconds while the heavier stems are picked up and dropped

through the path of the hot gases until they lose their moisture. The entire drum is

under a vacuum of about H" static water pressure maintained by the exhaust fan

which helps to keep down the maximum temperature of the material as well as to

reduce the amount of heat required for evaporation. At the entrance to the drum the

chopped hay receives considerable heat by radiation from the flame and the in-

candescent brick work, so that the temperature of the material would be higher than

the wet bulb temperature of the flue gases, and the rate of vaporization is increased

above what it would be if shielded from direct radiation. The heat which must be

supplied to the drying material can enter only through the surface, and cutting the

hay into short lengths increases the ratio of dry to wetted surface and thus speeds

up the rate of drying by exposing a greater possible surface to the hot gases. The

high velocity of the gases past the wet surface of the material and the high mean

temperature difference between the hot gases and green forage tends to speed up

the drying process and give high evaporative capacity to this type of drier.

8

The drier as shown in Fig. V gave an average capacity of evaporating of 3,800

pounds of water per hour for two seasons. One test run of two hours evaporated

4,110 pounds of water per hour and a second test of one hour gave 4,400 pounds

of water per hour.

The dried hay leaves the drier at an average temperature of 168° F., with

exhaust gas temperatures of 230° F. with 10,030 pounds of dried hay in sacks

stacked in a storage building the temperature in the hay reduced from 168° F. to

85° F. in twenty-four hours, with an outside temperature of 83° F. in the shade at

the same time the final temperature reading was made in the hay. As the hay is

discharged from the drier it can be sacked, baled, blown into a storage building,

or conveyed direct to the mixer and the necessary molasses or other ingredients

added to make a mixed feed.

With an average evaporating capacity of 3,800 pounds of water per hour an

average efficiency of 55 per cent was obtained. This in turn required 41 gallons of

fuel oil.

In producing one ton of dry hay from 74 per cent or freshly cut hay with a

required evaporation of 4,769 pounds of water, 51.5 gallons of fuel oil was required

and 134 hours to produce 1 ton of dry hay. When hay is left in the swath from

three to five hours and is reduced to 64 per cent moisture and a required evaporation

of 2,888 pounds of water, only 31.16 gallons of fuel oil are required and 1.3 tons of

dry hay are produced per hour.

The amount of labor required to operate the drier will depend upon whether

the hay is baled, sacked, or blown into a storage building. Successful operation

has been obtained with three common and one semi-skilled laborers, when produc-

ing and sacking one ton of dry hay per hour.

The power required to operate the drier is distributed as follows: 10 horse-

power to drive the ensilage cutter, 5 horsepower on the burner fan, 2 horsepower to

revolve the drum, 1 horsepower on the oil pump, 1 horsepower for the conveyor

screw, and 5 horsepower on the exhaust fan. If an elevating fan is used to store

the dry hay, an additional 5 horsepower will be needed. For experimental work,

individual electric motors were used, but for a permanent installation, a line shaft

running lengthwise of the drum would be preferable, and one 30 horsepower electric

motor, a 35 horsepower engine, or a tractor with 35 horsepower on the belt should

be used.

A standard 16-inch ensilage cutter was used, but in order to secure a cut shorter

than y2 ", an increased capacity, and a lower horsepower requirement, the following

changes were made: To obtain a shorter cut (3/16-inch) a jack shaft was installed

between the counter shaft and the lower feed roller shaft. Then for each 3/16-inch

advance of the feed table, one knife passes the shear bar. To compensate for the

slow feed table travel, the cutter was speeded up to 650 r.p.m. from a recommended

500 r.p.m. This increased speed gave a large increase in horsepower required, and

to reduce this, 3 of the 6 fans were removed. The cutter thus modified was operated

by a 10 horsepower motor and handled the material easily, as the maximum eleva-

tion is 12 feet.

In order to arrive at the cost of operation per ton of dry hay, the moisture in

the green hay will be considered at the average for freshly cut hay. And thus the

fuel required will be at the upper limit. With careful management and field wilting

for 3 to 5 hours the fuel and power can each be lowered somewhat below the follow-

ing figures. With any expensive piece of machinery in order to reduce the over-

9

head cost per hour or ton of material, sufficient work must be available before buy-

ing the equipment. The following table is based on 500 tons of dry hay per season:

Drier depreciation, $3,500— 10 -years.. - - - -$ 350.00

Interest, $3,500—$350 @ 6 per cent 94.50

2

Fuel, 51 gal. per ton @ 2J^c X 500 637.50

Power, 22 K.W. @ 2c X 500 220.00

Labor—3 common @ 10c 150.00

1 semi-skilled @ 25c 125.00

Repairs 2 per cent of original investment 70.00

Total cost of drying 500 tons '.. $1,647.00

Total cost per ton of dry hay...._ 3.29

FIELD OPERATIONS:To get the complete cost of artificially cured soybean hay, records were kept

for two years on all operations. An upright-growing Biloxi soybean has proven the

best bean to grow for the drier in this locality. Drilling in rows 42 inches and 22

inches apart were each tried. The yield in each case was about equal; but the 22-

inch rows gave smaller main stems and thus a slightly better grade hay. The average

yield of dry hay was two tons per acre. Part of the field was operated with mule

power and the remainder with tractor power as shown in the following table:

FIELD LABOR AND POWER SUMMARYFig. VI

Disking Planting Cultivating Mowing Loading Hauling Unloading

T M T Mule M T Mule M T Mule M Mule Men **

2-Mule .35 .38 1.24 .68 3.4 1.87 1.80 1.0 6.3 12.6 9.5 4.75 3.78 1.90

.35 .38 3.1 1.70

General Purpose 35 .38 .72 .79

.50 1.10* .70 .77 .63 12.6 9.5 4.75 3.78 1.90

Tractor 35 .38 .435 .48

Cutting with a power-driven corn binder increased the tractor work .30 hours

per acre, and decreased the man hours 3.15 in loading and unloading. The bundled

beans also decreased the labor in feeding the cutter; however, the bundled beans do

not wilt down evenly, and the increased amount of fuel to evaporate this increased

moisture will more than offset the gain from using the binder. Dump wagons or

slings for unloading at the drier are recommended time savers.

TYPES OF DRIERS:Driers in general may be classified briefly as follows:

1. Rotary drum (Louisiana State University, Ardrier)

2. Conveyor (Mason, Bayley, Fulmer)

3. Multiple Fan (Koon)

4. Tray driers

5. Tower driers

6. Stack driers

The first two types have proven the most successful with installations of each

type scattered in various parts of the United States.

'Two men with 4-row 22-inch planter.

**Hauling 1 miles and returning to field.

10

12

The Ardrier (Fig. VI) employs the same general principles as the Louisiana

State drier, of air flotation, parallel passage of material and hot gases. The one

difference is that it has three drums, one inside the other, which allows for a some-

what more compact unit. The characteristics of this type drier have already been

covered in this bulletin.

Conveyor Driers: The first drier of any record in the United States was a

conveyor drier, built and tried for three seasons, 1910 to 1912, at Hayti, Missouri.

Later conveyor driers were built by Arthur J. Mason, Bayley Blower Company,

and J. H. Fulmer. These driers consisted in the main of an endless apron for con-

veying the material to be dried through a tunnel where the green material is sub-

jected to the hot drying gases. In this drier, the driest hay comes in contact with

the hottest gases. They produce an excellent quality product, require a rather high

horsepower, cost of drier is relatively high, and because of slow speed of conveyor,

are difficult to adjust. If the material is drying too much or not enough, it is dif-

ficult to adjust quickly.

'Multiple Fan: This type of drier was developed by A. W. Koon, of New

Orleans, Louisiana. It consists of a series of fans, pipes, cyclone separators, and

furnace. The green material and hot gases are mixed at the fan and blown up into

a cyclone separator. Six fan and cyclone separator circuits comprise the travel of

the hay. Most of the gases are recirculated through the furnace. Each drier has

been built differently from the former, and he now has a modified portable drier.

Tray, Tower, and Stack Driers: Each of these has been built with compara-

tively little success. The tray type is a batch process, having a relatively low

capacity, and high labor requirement. The tower driers have employed gravity or

conveyors to carry the material to be dried down through the drier over various

baffles or shelves. Low capacity, low fuel efficiency, and in some cases recirculation

to get the necessary moisture reduction have characterized this type drier. Stack

drying has been used where a portable furnace and fan have supplied heat for drying

material stacked around a central perforated pipe in the field. This type has given

moderate success where only a small amount of moisture is to be removed.

ACKNOWLEDGMENT

The author wishes to acknowledge the work of C. L. Osterberger, Carl Nadler

and J. J. Munson in beginning and carrying on the first two years of this work.

To William Whipple, for his valuable assistance during three years of active tests

as a co-worker, and to the Chemical Laboratory, Louisiana Agricultural Experiment

Station, for all chemical analyses, thanks are also due.

SUMMARY

Artificial drying of hay crops is an economical and practical operation in the

humid area.

Many acres now idle in the humid area can be used for hay crops by the use

of artificial curing.

By artificial curing, a hay may be produced which is uniform as to color, odor,

and food value, regardless of weather conditions.

Feeding trials with beef cattle gave faster gains on machine-dried soybean hay

as compared to chopped field cured soybean hay.

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Feeding trials have shown 2,000 pounds of artificially cured hay to be equivalent

to 3,237 pounds of long field cured soybean hay for beef cattle.

Dairy cattle gave favorable results on artificially cured hays for each of the

three years' tests.

REFERENCES

1. Artificial Drying of Agricultural Products, by R. B. Gray, W. M. Hurst and

E. D. Gordon. Agricultural Engineering, Vol. 13, No. 10. October, 1932.

2. The Nutritive Value of Mechanically Dried Hay as Affected by High Tempera-

tures in the Presence of Air. The Pennsylvania Agricultural Experiment Sta-

tion, 44th Annual Report. Bulletin 266. July, 1931.

3. The Artificial Curing of Alfalfa Hay, by H. B. McClure. United States Depart-

ment of Agriculture. Circular 116. March 8, 1913.

4. Quality of Alfalfa Hay in Relation to Curing Practices, by T. A. Kiesselbach

and Arthur Anderson. U. S. D. A. Technical Bulletin 235. April, 1931.

5. Chopping Hay for Livestock and Steaming or Pre-Digesting Foods, by G. Boh-

stedt, B. H. Roche, I. W. Rupel, J. G. Fuller and F. W. Duffee. Wisconsin

Agricultural Experiment Station, Research Bulletin 102. December, 1930.

6. Chemical Problems in Connection with Artificial Drying of Hay, by Henry

Atterson, Ph.D. Paper presented at annual joint meeting of American Asso-

ciation of Medical Milk Commissions and Certified Milk Producers' Association

of America. June 23, 1930.

7. Drying Alfalfa Hay by Forced Draft with Heated Air, by W. M. Hurst and

T. A. Kiesselbach. Transactions of the American Society of Agricultural En-

gineers, Vol. 23, pp. 19-21, 1929.

8. Machine Dried Soybean Hay for Fattening Calves, by M. G. Snell. Louisiana

Agricultural Experiment Station, Bulletin 257. August, 1934.

9. Hay Curing III: Relation of Engineering Principles and Physiological Factors,

by T. H. Jones and L. O. Palmer. Agricultural Engineering, Vol. 15, No. 6.

June, 1934.

10. Pasture Fertilizer Results, by R. H. Lush and J. L. Fletcher. Journal of Dairy

Science, Vol. 17, No. 11, pp. 733-735. November, 1934.

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