Feb. as, 1918 



Influence of Carbonates on Soil Bacteria 



487 



With an increase of calcium carbonate there was a decrease in ammonia 

 production. This decrease was shown with all carbonates, magnesitun 

 carbonate causing the greatest decrease. 



After three months the same order was held by these compounds in 

 stimulating ammonia formation. At this time the full limestone had a 

 greater effect than the smaller limestone applications; the effect was 

 almost as great as that due to the phosphate treatment. It is evident 

 from the results obtained in both Colby silt loam and Plainfield sand, 

 that the greatest accumulation of ammonia (six days' incubation) does 

 not occur where the largest increase in the number of bacteria was 

 obtained. Where the greatest number of bacteria developed, it seems 

 probable that the greatest amount of ammonia should be formed. Since 

 the substances which gave the highest number of bacteria also neutral- 

 ized the soil acids, it is probable that the ammonia partly escaped through 

 volatilization. Because of the open texture of the Plainfield sand, more 

 ammonia escaped from this soil than from the Colby silt loam. 



Table XI. — Influence of calcium carbonate, magnesium carbonate, limestone, andm,ono- 

 calcium phosphate on nitrate accu7nulation in Colby silt loam and Plainfield sand 



Treatment. 



None 



One-fourth calcium car- 

 bonate 



One-half calcium carbo- 

 nate , 



Full calcium carbonate. . , 



One-fourth limestone 



One-half limestone 



Full limestone 



One-fourth magnesium 

 carbonate 



One-half magnesium car- 

 bonate 



Full magnesiinn carbon- 

 ate 



0.1 per cent monocal- 

 cium phosphate 



0.1 per cent monocal- 

 cium phosphate -t- one- 

 fourth calcium carbon- 

 ate 



0.1 per cent monocal- 

 cium phosphate 4- full 

 calcium carbonate 



Nitrate nitrogen accumulated in 100 gm. of dry soil. 



Colby silt loam. 



Mgm. 

 S-86 



7-23 



6. 10 

 6.25 

 5- S3 

 S-86 

 6.51 



6.58 



8.13 



13-28 



S-63 



6. 10 

 6.73 



Mgm. 



•24 

 •37 



— -33 

 .00 

 •6S 



•72 



2. 27 



7.42 



— -23 



.24 



.87 



•^ o 



Mgm. 

 6.05 



6-94 



7-s6 

 8.18 

 6.0s 

 6. 40 

 6. 42 



6.75 



8.44 



13.00 



6.05 



6. 42 



Mgm. 



0.89 



I- SI 

 2. 13 

 .00 

 •35 

 •37 



.70 



2-39 



6.9s 



.00 



•37 

 2-13 





Mgm. 

 6.62 



8.36 



9^37 

 12.00 



7.2s 

 7-25 

 8.56 



9-43 

 12.00 

 IS- 00 



7-2S 



Mgm. 



1.94 



2^7S 

 5^38 

 •63 

 •63 

 •94 



2.81 



S-38 



8.38 



.63 



2-75 

 4-63 



Plainfield sand. 



a 5 



Mgm. 

 1.74 



2.42 



2.3s 

 2. 20 

 a. 20 

 1.87 

 1.97 



a. 10 



2. 20 

 2^34 

 2. 12 



Mgm.. 



.61 

 .46 

 .46 

 •13 

 •23 



•36 



.46 



.60 



•38 



.61 

 .06 



^a 



Mgm. 

 1.S8 



i.8s 



2.31 

 2. 22 

 1.80 

 1.67 

 1.87 



1.24 



2.78 

 1.85 



Mgm.. 



•73 

 .64 

 . 22 

 .09 

 •29 



■ -34 



.64 



I. 20 



•27 



^a 



Mgm 

 ^•33 



1.67 



3-55 

 2.92 

 1-73 



2. 00 

 3.80 



1. SO 



2. 70 

 4.62 



3-oS 



Mgm. 



0.34 



1.23 

 i^S9 

 .40 

 .67 

 1.47 



•17 



^•37 



3- 29 



I- 75 



•87 

 I-7S 



ACCUMULATION OP NITRATES 



From the data presented in Table XI it will be seen that nitrates 

 accumulated faster in both the treated Colby silt loam and Plainfield 

 sand than in the untreated. In both soils the magnesium carbonate 

 benefited nitrification more than did the other carbonates. Next in 

 order to magnesium carbonate was calcium carbonate, and lastly, lime- 



