EFFECT OF SOIL TYPE ON RATE OF AMMONIFICATION 41 



Exercise 7 

 Effect of Soil Type on Rate of Ammonification 



1. Weigh out four 5o-gram portions of garden soil, 

 field soil, and acid soil into clean, dry tumblers. 



2. Mix thoroughly i per cent, of ground clover or 

 powdered casein with each soil. 



3. Determine at once the ammonia nitrogen in duplicate 

 tumblers of the various soils. 



4. Add water to the soil of the s^x remaining tumblers 

 until it is two- thirds saturated. After standing for one 

 hour stir with a spatula. 



5. Cover with Petri dishes and incubate for six days or 

 longer. If casein is used, the time of incubation may be 

 shortened to two or three days. In the case of clover 

 no definite date need be followed, one week or longer will 

 not seriously change the results. 



6. Determine the amount of ammonia nitrogen. 



7. Arrange the data in a table. 



TABLE 12. Effect of Soil Type on Rate of Ammonification 



