Feb. 25, 1918 Influence of Carbonates on Soil Bacteria 



483 



From the results which are given in Table VII and from figure 9 it 

 will be seen that both magnesium and calcium carbonate increased the 

 number of bacteria in Miami silt loam soil. Here, again, the increase 

 was much greater with magnesium carbonate than with calcium carbo- 

 nate. The greatest increase was obtained two weeks after treatment. 

 In all cases, the heavier applications increased the number of bacteria 

 more than did the smaller ones. 



^ 3 4 5 6 7 

 tu/ceh 



Z i ^ 5 6 7 Q 9 /O II 



2 U/eeAi 



2 i 4 5 b 7 & 1 10 ti 

 3 U/iseAs 



Fig. 9. — Diagram showing the influence of calcium carbonate, magnesium carbonate, dibasic magnesium 

 phosphate, and monocalcium phosphate on the number of bacteria in Miami silt loam. 



1= no treatment. 



2= one-half calcium carbonate. 



3= full calcium carbonate. 



4= one-half magnesium carbonate. 



S=full magnesimn carbonate. 



6=0.1 per cent monocalcium phosphate. 



7=0.1 per cent dibasic magnesium phosphate. 



8=0.1 per cent monocalcimn phosphate+fuU calcium carbonate. 



9=0.1 per cent dibasic magnesium phosphate-hfuU calcium carbonate. 

 10= O.I per cent monocalcium phosphate -l-full magnesium carbonate. 

 11=0.1 per cent dibasic magnesimn phosphate+full magnesium carbonate. 



The results differentiate themselves from those obtained with acid 

 Colby silt loam soil since the phosphates increased the number of bacteria 

 in the neutral Miami silt loam. It was expected that these phosphates 

 would have a more beneficial effect in neutral than in acid soil, since it 

 is probable that the phosphate was hydrolyzed, thus adding more acid 

 to the soil. In every test magnesium phosphate gave a larger increase 

 in number of bacteria than was obtained by the use of calcium phos- 



