Feb. 25, 191S 



lyifluence of Carbonates on Soil Bacteria 



475 



Unlike calcium carbonate and limestone, full applications of magne- 

 sium carbonate increased the number of bacteria far beyond the increase 

 obtained with the one-half and one-fourth treatments. From the 

 figures in this table it will be seen that the effect of the application of 

 magnesium carbonate to Colby soil invariably increased the reproduction 

 of the soil bacteria, especially during the first, second, and third week. 



i Z d 4 

 iUTeek 



/ £ 3 4 

 ZU/eehs 



I Z 3 4 



ZWeeh 



6U/eeh 



I z 3 4 



"PJO, 5. — ^Diagram showing the influence of magnesium carbonate on the number of bacteria in Colby silt 



loam. 



i=no treatment. 



a = one-fourth magnesium carbonate. 



3 = one-half magnesium carbonate. 

 4= full magnesium carbonate. 



Figure 5 shows very conclusively the marked effect of magnesium car- 

 bonate on the number of soil bacteria. For instance, the increase with 

 full magnesium-carbonate treatment was more than six times as great 

 as that of the control. The absolute numbers varied with the time of 

 the count, but the ratio of numbers between the different quantities of 

 magnesium carbonate remained almost the same throughout the entire 



