i8 



RAPIDITY OF NITRIFICATION. 



Under favourable circumstances, where all the necessary 

 conditions are fulfilled, nitrification goes on with great 

 rapidity. Thus, in two experiments, Schlcesing obtained 

 the following results. In each case the figures show the 

 actual quantity of ammonia and nitric acid respectively 

 present in 500 grams of soil, at the beginning and end of 

 the experiment. 



TABLE VI. 



In each experiment a large proportion of the ammonia 

 present on June 13 was evidently nitrified from 88 to 90 

 per cent, of it having disappeared by the end of the ex- 

 periment and in its place a large amount of nitric acid 

 was produced. It will be noticed that the change was 

 remarkably rapid ; the whole time occupied by the experi- 

 ments being only eighteen days. In a natural soil nitrifi- 

 cation will seldom be as rapid as this ; but even in ordinary 

 cultivated land, it will often take place very quickly. For in- 

 stance, the following results were obtained in an experiment 

 on light land on the farm of the French Institute Agrono- 

 mique in 1888. The amounts of ammonia and of nitric 

 acid in the soil were ascertained on the dates mentioned 

 on two plots, one receiving no nitrogenous manure, and 

 the other manured at the rate of 462 Ibs. cf sulphate of 

 ammonia per acre. The results are stated per 100,000 

 parts of the dry soil. 



TABLE VII. 



As in the preceding instance the ammonia gradually 

 disappeared from the plot manured with sulphate of 

 ammonia, until the quantity was the same as in that 

 receiving no nitrogenous manure, and nitric acid took 

 its place. That the amount of nitric acid was not 



