2 CIRCULAR 4 43, IT. S. DEPARTMENT OF AGRICULTURE 



areas. Overdrying, leaf shattering, and discoloration by rain and 

 dew reduce the returns to the grower regardless of whether the hay 

 is used on the farm or is sold. At times unfavorable conditions result 

 in virtually a total loss of the crop. 



The use of green, leafy alfalfa hay and of alfalfa meal as a source 

 of vitamin A has also stimulated interest in artificial drying. When 

 the crop is cut at the proper stage and dried artificially, hay or hay 

 products equivalent to U. S. No. 1 Extra Green, Extra Leafy alfalfa 

 may be obtained. The carotene content, source of vitamin A activity, 

 usually is higher in artificially dried hay than in sun-cured hay of the 

 same grade. Artificial drying also tends to preserve the protein and 

 mineral elements of hay by eliminating the possibilities of leaf shat- 

 tering in handling and of leaching caused by weathering in the field. 



TYPES OF DRIERS 



The artificial drying of forage crops has been practiced to a limited 

 extent in some localities in the United States for many years. Avail- 

 able information does not indicate the exact date the first hay drier 

 was used in this country, but about 1909 an experimental drier was 

 constructed and used in Missouri for alfalfa, and a machine was con- 

 structed for drying native grasses in Louisiana as early as 1910. Since 

 that date a number of types and designs of driers have been developed. 



The design of many of the early machines indicated a radical de- 

 parture from established practices in the utilization of heat to evap- 

 orate moisture from damp or wet materials. In other cases equipment 

 typical of that used for drying materials other than hay was slightly 

 altered or changed in design. The most common types were those 

 generally known as apron-conveyor and revolving-drum driers. An 

 apron-conveyor drier of the type commonly used for hay is diagram- 

 matically illustrated in figure 1, and drum driers in figures 2 and 3. 



Air from fan I mixed 

 with not gases from furnace I 



Discharge 



c 



Air+o 

 fan'l ■> 



Air return Air from fan 2 mixed 



to fan 2 with hot gases from furnace 2 



i-i H- 



Feed 



.J 



Figure 1. — Apron-conveyor type of forage drier. 



Feed 



Figure 2.— Revolving-drum type of forage drier, single-drum design. 



