MUSHKOOM CASING SOIL IN KELATION TO YIELD 7 



cium carbonate) was found to be just as effective in neutralizing the 

 soil as hydrated lime, and there seemed to be practically no danger of 

 injuring the crop from adding an excess. 2 



At the present time many growers neutralize the soil with hydrated 

 lime, and after the crop comes into bearing some of them fill the holes 

 on the bed with a mixture of one-tenth hydrated lime to nine-tenths 

 soil, They also water the beds occasionally with limewater. In the 

 opinion of the writers it is just as effective, and safer practice, to add 

 from 2 to 5 percent of limestone (high in calcium carbonate) to the 

 original casing soil and to the soil used for filling holes in the bed. 

 The custom of using hydrated lime instead of limestone seems to be 

 based on an erroneous opinion which is prevalent among growers, 

 that limestone must be added to casing soil several months before 

 using. In the experience of the writers, powdered limestone neu- 

 tralized the soil sufficiently for practical purposes overnight. Thus 

 the slower action of the limestone is more of a theoretical objection 

 than a practical one. Furthermore, an excess of limestone may be 

 safely added, and the continued buffering effect of the residual lime- 

 stone is beneficial in that it neutralizes the organic acid produced by 

 the mushroom mycelium. 



TEXTURE OF SOIL 



In the initial experiment to determine the effect of the texture of 

 the soil on yield, soils of four different textures were used: Clay loam, 

 loam, sandy loam, and sand. Each soil was limed to approximate 

 neutrality. As apparent from table 7, there was an unmistakable 

 tendency for the heavier textured soils to support better yields of 

 mushrooms than the light soils. The clay loam yielded twice as 

 much as the sand. 



Table 7. — Relation of the texture of casing soil to the yield of cultivated mushrooms 



[Tests made in winter of 1934-3"] 



Texture and source of soil 



Bed 



No. 



Yield 



per 10 



square 



feet 



Mean 

 yield 

 per 



square 

 foot i 



Keyport clay loam, Arlington, Va. 



Keyport loam, Beltsville, Md. 



Sandy loam, Arlington, Va. 



Sand, Arlington, Va. 



Ounces 

 35G 

 208 

 344 

 325 

 401 

 303 

 331 

 357 

 238 

 206 

 229 

 250 

 230 

 254 

 142 

 267 

 214 

 114 



Pounds 



2.0 



2.0 



1 Standard error of the mean yield of 5 plots is 0.09 pound per square foot. 



2 This statement refers only to limestone high in calcium carbonate. Both hydrated lime and limestone 

 are frequently high in magnesium. The effect of an excess of magnesium in the soil has not been systemati- 

 cally investigated, but it has the reputation among commercial growers of being harmful. 



