14. DEPARTMENT BULLETIN 1425, U. S. DEPT. OF AGRICULTURE 
The relation of drainage to effective air seasoning is seldom fully 
recognized. It is the one natural influence subject to absolute control 
in existing yards and should receive more attention than is usually 
accorded it. 
YARD LAYOUT 
Economy or yard space is, of course, a consideration in laying out 
the drying yard. It is of greatest importance where land values are 
high or the area available is actually limited in extent. But economy 
in this respect 1s generally questionable if serious seasoning defects 
result. ‘The most rapid drying consistent with the least depreciation 
of stock is a primary objective of air seasoning. 
The layout of the drying yard should therefore depend in a large 
measure upon the climatic conditions to be encountered. If tem- 
perature, humidity, and wind movement are of such character that 
slow drying may be expected, the yard should be laid out in a much 
more open manner than would be necessary with rapid drying. In 
the fog belt of the Dougias fir region, for example, congestion in the 
drying yard is a more serious difficulty than in the San Joaquin 
Valley of California. 
MAIN ALLEYS 
In planning the drying yard the direction and width of the main 
alleys should first be decided. ‘These alleys must accommodate all 
the transportation and handling of lumber in the yard, of course, 
but, if seasoning is to be properly done, they must also function as 
well-defined channels of air circulation in the yard and of sunlight to 
the front of the lumber piles. The operating functions must be con- 
sidered, but it is the drying functions that are of major importance. 
Only too often convenience in handling is given undue weight in the 
yard plans. 
Of the three things that may influence the layout of the main 
alleys, slope may be of special importance because it affects con- 
siderably the transportation system, particularly that of the gravity 
type. But direction of prevailing winds and the desirability of 
maximum direct sunlight against the piles and on the alley floor 
bear directly on the seasoning problem and should be of chief 
concern. 
The desirability of admitting heat from the sun’s rays to as much 
of the pile as possible has been emphasized. ‘This can best be accom- 
plished by a north-to-south arrangement, for it permits the direct 
rays of the sun to strike farther down on the pile, front and back, 
for a longer period of the day than will an east-to-west arrangement. 
The transmission of more heat to the sides of the pile in an east-to- 
west arrangement does not equalize this advantage, because of the 
narrow spacing inevitable between piles on the same alley. The 
benefit in north-south alleys is most pronounced in the cooler and 
wetter months, when it is most needed. 
The main alleys offer the best channels for the movement of air 
currents in the yard. Thus it is apparent that their alignment 
parallel to the direction of the prevailing winds would be favorable 
to yard circulation. But in spite of this advantage their location 
from north to south, irrespective of prevailing wind direction, will 
probably give the best drying conditions. 
