Journal of Agricultural Research 
It will be observed that guanidin carbonate very markedly inhibited nitrifica- 
tion during the first three to five weeks, depending upon the rate of application- 
Later the nitrification was quite rapid and nearly complete. At the last period 
of analysis the percentage nitrification was 83.4, 91.2, and 48.7 for the 5, 10, and 
mgm. of nitrogen added. Undoubtedly, if the experiment had been continued 
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-Diagram showing the comparative rates of nitrification of varying amounts of guanidin carbon¬ 
ate and ammonium sulphate 
longer the largest rate of application would have shown a percentage nitrification 
comparable with the other rates. 
The nitrification of ammonium sulphate took place fairly rapidly and was nearly 
complete at the end of the experiment. In fact, with the smaller rates of applica¬ 
tion the figures show slightly more than 100 per cent nitrification. This was 
probably due to a slight stimulation of nitrification of the soil organic matter. 
