Feb. as, 1918 



Influence of Carbonates on Soil Bacteria 



485 



number of bacteria, since it gave no increase except when used in combi- 

 nation with calcium carbonate, and then the increase was no greater 

 than that obtained with calcium carbonate alone. 



TablB VIII. — Influence of calcium carbonate, magnesium carbonate, limestone, and 

 monocakium phosphate on the number of bacteria in Colby silt loam 



Treatment. 



Number of bacteria in i gm. of dry soil. 



After 

 2 months. 



Rela- 

 tive. 



After 

 3 months. 



Rela- 

 tive. 



None 



One-fourth calcium carbonate 



One-half calcium carbonate 



Full calcium carbonate 



One-fourth limestone 



One-half limestone 



Full limestone 



One-fourth magnesium carbonate 



One-half magnesium carbonate 



Full magnesium carbonate 



0.1 per cent monocalcium phosphate 



0.1 per cent monocalcium phosphate -1- one- 

 fourth calcium carbonate 



0.1 per cent monocalcium phosphate -1- full 

 calcium carbonate 



10, 700, 000 

 13,400,000 

 17,000,000 

 14, 800, 000 

 17,600,000 

 II, 200,000 

 14, 300, 000 

 11,900,000 

 25, 700,000 

 43 > 700, 000 

 10, 700, 000 



10,800,000 



13,600,000 



100 



158 

 138 

 164 

 104 

 133 

 III 

 240 



lOI 



127 



8, 000, 000 



8,800,000 



7, 100,000 



8, 700,000 



10, 300, 000 



8, 700, 000 



10, 700,000 



10, 900, 000 



13, 200,000 



33,500,000 



8,300,000 



7, 600, 000 



10.300,000 



100 

 no 

 83 

 108 

 128 

 loS 

 133 

 136 

 i6s 

 418 

 103 



95 



128 



The data in Table IX are in agreement with those obtained with Colby 

 silt loam — that is, magnesium carbonate increased the number of bac- 

 teria in Plainfield sand to a considerable extent beyond that produced 

 by calcium carbonate or Umestone. The effect of the magnesium car- 

 bonate on the number of bacteria was most noticeable one month after 

 the treatment was applied. In general, limestone proved inferior to 

 calcium carbonate in stimulating the number of bacteria in Plainfield 

 sand, except that in one case the monocalcium phosphate when applied 

 alone did not increase the number of bacteria. 



Table IX. — Influence of calcium carbonate, magnesium carbonate, limestone, and 

 monocalcium phosphate on the number of bacteria in Plainfield sand 



Treatment. 



Number of bacteria in i gm. of dry soil. 



After 

 3 months. 



Rela- 

 tive. 



None 



One-fourth calcium carbonate 



One-half calcium carbonate 



Full calcium carbonate 



One-fourth limestone 



One-half limestone 



Full limestone 



One-fourth magnesium carbonate 



One-hall magnesium carbonate 



Full magnesium carbonate 



0.1 per cent monocalcium phosphate 



0.1 per cent monocalcium phosphate-l-one-fourth 

 calcium carbonate 



0.1 per cent monocalcium phosphate-1-full cal- 

 cium carbonate 



2, 100,000 

 2,450,000 

 3, 200,000 

 2,900,000 

 I, 780, 000 

 2,550.000 

 2,550,000 

 3,000,000 

 5,000,000 

 4, 800, 000 

 2, 340, 000 



3,230,000 



2, 700,000 



100 

 116 

 152 

 138 

 84 

 121 

 121 

 133 

 238 

 238 

 III 



154 

 128 



