Soils 



well known that where soil is baked over a fire, or exposed to great heat, it 

 becomes to a certain extent dead, and not as useful for plant growth as virgin 

 soil. It has been claimed by some that exposing the soils to high temperature 

 destroys the nitrifying bacteria which are said to be necessary to plant growth. 

 It is possible that this may be true where temperatures are carried too high or 

 the soil remains superheated for too long a period. If the temperature is 



Soil Sterilizer in operation — Sterilizing soil on the bench 



raised not higher than 195 to 212 degrees, and if the steam is not carried 

 in the soil for more than twenty to thirty minutes, it may be possible that 

 the beneficial bacteria will not be destroyed ; whereas, if this temperature 

 should be carried for a number of hours these bacteria might sufifer. Possibly 

 a perceptible loss of nitrogen may occur from evaporation where a high degree 

 of heat is maintained for an extended period. 



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