§ CIRCULAR 609, U. S. DEPARTMENT OF AGRICULTURE 
When considered from the point of view of yield of mushrooms per — 
ton of manure in the beds the indoor composting system compared very 
favorably with the old system. In the Arlington Farm experiments 
the manure was placed in the beds at a rate of slightly more than 200 
square feet per ton of fresh manure as received from thestables, whereas 
Figure 4.—Typical first break on beds prepared by indoor composting. 
commercial growers at the present time fill only 70 to 100 square 
feet with a ton of manure as received from the dealer. In the spring 
crop the check plots yielded at the rate of 1% pounds per square foot.” 
When considered on a basis of raw material the beds yielded at the rate 
of 300 to 400 pounds of mushrooms for every ton of fresh manure. 
INDOOR COMPOSTING AS AN IMPROVED METHOD 
FOR COMPARING SUPPLEMENTS ‘GR SUBSTITUTES 
FOR MANURE 
In making comparisons of manure supplements and synthetic com- 
posts the system of composting under controlled conditions may be 
used to advantage in small glass jars, in trays, or in sections of a bed. 
In practice it has been found desirable to run numerous exploratory 
tests in glass jars to determine the effect of various treatments and 
combinations of treatments on the suitability of the compost for 
mushroom mycelium. The materials showing the most promise are 
then tested further in small plots on the bed. Briefly, the tests in 
olass jars are made by holding jars of prepared compost between 125° 
and 130° F. for the required number of days and following this by 
inoculation with mushroom spawn and incubation at 70° F. If the 
material in the bottles is reduced to a fine texture; if moisture, tem- 
perature, and aeration are properly controlled; and if treatments are 
2 For comparison with commercial yields the figures shown in tables 1, 2, and 3 should be reduced about 
20 percent, as they include the stems and stubs. 
