Sept. 15, 1925 
The Ammonia Content of Soil 
553 
SUMMARY 
A study was made of the relation between the ammonia content 
of soils, total nitrogen, nitrate content, and soil reaction. No corre¬ 
lation could be made when the ammonia content of a large number 
of soils was compared with the total nitrogen content, the accumula¬ 
tion of nitrates, or the soil reaction. 
The ammonia content of a soil is evidently in equilibrium with 
the products of protein hydrolysis and nitrification, just as the 
nitrate content is in equilibrium with the ammonia content of the 
soil and the plants and microorganisms. 
The ammonia content of most field soils does not exceed 20 parts 
per million, and the majority of soils contain less than 10 parts per 
million. Occasionally the ammonia content of some soils may be 
as high as 60 or 70 parts per million. This may be due to conditions 
being unfavorable for nitrification or to vigorous ammonification, or it 
may be the result of both of these factors operating simultaneously. 
LITERATURE CITED 
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(7) - 
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( 8 ) - 
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