54 



SOIL BACTERIOLOGY 



Exercise 18 

 Effect of Limestone on Nitrification 



1. Prepare ten tumblers of soil, 100 grams in each. 

 Two types of soil may be used, neutral and acid. 



2. Arrange each soil type as follows: 



(a) i and 2, untreated. 



(&) 3 and 4, 30 mgm. of nitrogen as ammonium sulphate. 



(c) 5 and 6, 30 mgm. of nitrogen as ammonium sulphate plus i gram 



CaC0 3 . 



(d) 7 and 8, 30 mgm. of nitrogen as gelatin. 



(e) 9 and 10, 30 mgm. of nitrogen as gelatin plus i gram CaCOs. 



3. Stir in the chemicals thoroughly by means of a sterile 

 spatula. 



4. Add water and incubate for ten to twenty days at 

 room temperature. From time to time replace the water 

 lost by evaporation. 



5. At the end of the period of incubation analyze for 

 nitrates. 



TABLE 23. Effect of Limestone on Nitrification 



