12 CIRCULAR 2 51, U. S. DEPARTMENT OF AGRICULTURE 



manure with a moderate proportion of straw to droppings is piled 

 up from 4 to 6 feet high when first assembled. Manure containing 

 an excess of straw has a loose texture and will shrink to one-fourth 

 of its bulk during composting. Therefore manure of this type is 

 piled up 6 to 8 feet high when first assembled and should be 

 weighted down with a layer of soil or boards during the early stages 

 of fermentation. Some growers always spread a layer of soil over 

 the top of the rick to make it more compact and to help conserve 

 the moisture; others consider the soil unnecessary and regulate the 

 moisture entirely by watering during the composting. In either 

 case the height of the rick is allowed to recede as the manure 

 shrinks during composting until it is about 3 or 4 feet high at filling 

 time. 



The ricks are usually allowed to stand undisturbed for 10 days 

 after they are assembled before the first turning. The turning is 

 usually done by hand although a few growers use special machines. 

 During the first turning water is applied to the dry straw, the 

 caked manure is broken up, and the sides of the heap are turned 

 in to the center. This process is repeated at intervals of from a 

 week to 10 days until the compost is in proper condition to go into 

 the house. The object of the turning is to aerate the manure, break 

 it up, thoroughly mix it, and maintain a moderate moisture content 

 throughout the rick. Success or failure depends very largely on the 

 moisture content of the rick during fermentation. 



Excessive watering causes a "greasy" compost, sometimes called 

 "black butter," which favors the development of a disease called 

 " plaster mold " on the bed and may be difficult to dry out suffi- 

 ciently to enable mushroom mycelium to run. On the other hand, 

 too little water slows down the fermentation and may cause an 

 excessive drying out and burning. The average grower maintains 

 about 150 to 250 per cent water (on a dry-weight basis) in his heap, 

 although this differs with different seasons, different types of manure, 

 and different stages in the composting period. In general, the 

 manure may be said to be moist but not wet, and a larger water 

 content is allowable at the beginning of the composting period than 

 at the end. As a rule, heavy watering is confined to the first turnings. 

 The objective toward the end of the composting period is to obtain a 

 condition slightly more moist than the optimum for the growth of 

 mycelium, in order to allow for a small loss of water during the 

 final fermentation in the house. 



The grower's practical test for this moisture content is to squeeze a 

 ball of compost tightly in the hand. If the hand is not moistened 

 the compost is too dry ; if water oozes out freely between the fingers 

 the compost is too wet. Manure in a desirable condition contains 

 about 150 to 175 per cent water as compared to dry matter. Ex- 

 perienced growers know the great necessity of avoiding a soggy con- 

 dition toward the end of the composting period. Such a condition is 

 one of the most common causes of failure. Mushroom mycelium will 

 not run in wet manure and the compost will not heat properly in the 

 bed. During cloudy weather ricks often become more moist toward 

 the end of the composting period without any water being added. 

 Growers refer to this change as " taking up water." Probably the 

 apparent taking up of water is really a more rapid loss of dry matter 



