\g CIRCULAR 443, U. S. DEPARTMENT OF AGRICULTURE 



7. It is very important that the forage be thoroughly dried down 

 to its safekeeping moisture content, which for practical purposes 

 should approximate 12 percent. Too often the inexperienced operator 

 attempts to increase the output of the drier beyond its capacity or 

 without due regard to the heat input. The result is a partially dried 

 product that may mold or may heat sufficiently to cause spontaneous 

 combustion. Whole field-cured hay usually can be stored with a 

 moisture content of from 15 to 25 percent, depending upon locality, 

 without danger of heating. Experience indicates that artificially 

 dried hay, especially when chopped, should have a lower moisture 

 content. Such material, when conveyed directly to a mow from the 

 drier, has a higher temperature than that of the atmosphere and there 

 is likely to be some variation in the moisture content of the particles. 



The cost of operating a drier (power, labor, and fuel) depends in 

 part upon the thermal efficiency of the drier; the initial moisture 

 content of the forage; the unit costs of power, labor, and fuel; and the 

 kind of forage to be dried. However, results of tests made by the 

 Department of Agriculture in Louisiana on several commercial and 

 experimental driers shown in table 3 will give an indication of what 

 may be expected in this connection. The labor was computed at 

 20 cents per man hour, fuel oil at 3.5 cents per gallon, and electric 

 current at 4.7 cents per kilowatt-hour. 



Barr 2 shows from 20 to 29 kilowatt-hours, 16 to 26 gallons of oil, 

 and from 0.97 to 4 man-hours per 1,000 pounds of water evaporated 

 in various types of driers. With the same unit costs for power, labor, 

 and fuel as shown in table 3 the cost per 1,000 pounds of water evapo- 

 rated ranged from $1.69 to $3.07. ^ 



Clyde 3 gives as the cost of drying per ton of dry hay (2,400 pounds 

 water evaporated at an over-all thermal efficiency of 65 percent for 

 the drier) the following items exclusive of overhead charges: 



Fuel, 29H gallons oil at 7 cents $2. 07 



Labor, 3 men, 1.35 hours at 40 cents, 30 cents, and 30 cents 1. 35 



Power, 20.4 kilowatt-hours at 3 cents . 61 



Repairs, estimated . 17 



4. 20 



In using the same unit costs for power, labor, and fuel as previously 

 indicated the cost would approximate $1.23 per 1,000 pounds of water 

 evaporated. 



At the Lewisburg, Tenn., station of the Bureau of Dairy Industry, 

 approximately 170 tons of hay were dried artificially with a commercial 

 rotary -drum drier during the 1935 season, as shown in table 4. The 

 total cost of drying the hay, including the harvesting in the field and 

 mowing in the barn , but not including interest or depreciation on the 

 equipment, was $11.77 per ton of dry hay. Repairs (labor and parts) 

 accounted for $3.20 of the above cost, the major portion of which was 

 spent on the upkeep and repairs on field-harvesting machinery. 

 Much of this expense appears to be due to the fact that this equipment 

 was manufactured for handling dry hay and was not strong enough to 

 handle the heavier green material. 



2 Barr, H. T. artificial curing of forage crops. La. Agr. Expt. Sta. Bull. 261, 14 pp., illus. 1935. 



3 Clyde, A. W. new developments in hay driers. Agr. Engin. 14: 127-129, illus. 1933. 



