CIRCULAR 5 9, U. S. DEPARTMENT OF AGRICULTURE 



Table o. — Effect on the yield of cultivated mushrooms of adding excessive amounts 

 of hydrated lime to the casing soil 



[Tests made in 1933] 



Hydrated lime added 





Reaction at— 



Yield 



Bed 







per 10 







No. 



Time of 



End of 



square 

 feet 





spawning 



crop 









Ounces 



1 * 



pll 



pH 



f 234 

 237 

 241 



A 



> 6.9 



6.9 



i * 







311 



1 







287 



2 



\ :. 6 



_ _ 



261 



} 3 





287 



I 4 ■ 







261 



f 1 1 



1 





f 239 



2 

 i 4 



8.5 



8.3 



242 

 204 



I 5 



1 





312 



1 J 

 1 I 



1 





( 219 



2g.6 



2 8.6 



159 



149 



1 





230 



f 1 



1 





119 



! 



■ s, 



2 8.7 



142 

 123 



I 5 



J 





I i09 



Mean 



yield per 



square 



footi 



percent.. 

 0.1 percent. 



1 percent,. 



2 percent. . 

 4 percent. _ 



Pounds 



1.6 



1 Standard error of the mean yield of 4 plots is 0.20 pound per square foot. 



2 The actual pH value is no doubt higher than the values shown because of the limitations of the quinhy- 

 drone method when applied to material having a pH value above 8.3. 



Another series was made up to determine the effect of an excess of 

 hydrated lime (calcium hydroxide) in the casing soil. As shown in 

 table 5 there was a distinct tendency toward a reduction of yield as a 

 result of excessive liming with this material. 



The following fall a similar experiment was set up, using high- 

 calcium limestone in place of hydrated lime. In this experiment five 

 times more limestone was used than was necessary, yet there was no 

 statistically significant reduction in yield, as shown in table 6. 



Table 6. — Effect on the yield of cultivated, mushrooms of adding excessive amounts 

 of limestone to the casing soil 



[Tests made in winter of 1933-34] 



Limestone added 



percent. 



6 percent- 



Bed 

 No. 



Yield 



per 10 



square 



feet 



Ounces 

 263 

 214 

 273 

 122 

 244 

 285 

 ISO 

 196 



Mean 



yield 



per 



square 



foot 



Pounds 



Limestone addet 



12 percent - 



25 percent. 



Bed 

 Xo. 



Yield 



per 10 



square 



feet 



Ounces 

 228 

 246 

 207 

 201 

 205 

 215 

 152 

 179 



Mean 



yield 



per 



square 



foot 



Pounds 



I- 



The tests as a whole clearly indicated that soil approximately neu- 

 tral in reaction yielded better than acid soil or excessively alkaline 

 soil. Any pH value between pH 5.5 and pH 8.0 seemed suitable. 

 It is evident that hydrated lime may be injurious if added to the soil 

 in excess. On the other hand, limestone (more than 90 percent cal- 



