MUSHROOMS 425 



"The potash in the mushroom manure is relatively low, the 

 phosphoric acid high, as compared with horse manure. The mush- 

 rooms do use much more of potash than of phosphoric acid, but 

 their consumption is very small in proportion to the supply given. 

 One hundred cubic feet of manure, underlying 100 square feet of 

 the beds, would weigh, in the fresh state, and compacted, approxi- 

 mately 3,500 pounds, and would furnish about 77 pounds of nitrogen, 

 71 of potash and 47 of phosphoric acid. One hundred pounds of 

 mushrooms harvested from 100 square feet of beds contain only 

 0.58 pounds of nitrogen, 0.23 of potash and 0.07 of phosphoric acid. 



"The changes the horse manure undergoes, during its preparation 

 for and use in the mushroom beds, are little, if at all different, from 

 those which would attend its quite complete rotting under other con- 

 ditions, with the exception that all but samples Nos. 2 and 3 indicate 

 some loss by leaching away of the potash either during composting 

 or at some earlier time. The result is a relative depression of the 

 soluble potash and, in some measure, of nitrogen and a correspond- 

 ing increase in the proportion of the phosphoric acid, which is pres- 

 ent in forms not soluble in water. 



"All in all, the mushroom manures are somewhat richer in nitro- 

 gen and potash, and much richer in phosphoric acid than an equal 

 weight of fresh horse manure. It is probable, however, that their 

 values for agricultural use are like those of other well-rotted 

 manures, as distinguished from fresh manures holding the soluble 

 urinary constituents little changed." 



