Feb. 25. 1918 Influence of Carbonates on Soil Bacteria 465 



acid. Lime was added in amounts varying from o.i to i.o per cent, 

 while calcium carbonate was added in amounts of i.o per cent only. 

 Besides the total number of bacteria, these investigators determined the 

 nitrate and ammonia nitrogen of the soils subjected to this treatment. 

 The results of the experiments showed that in all of the soils, liming 

 increased the number of bacteria. At first the heavier applications of 

 lime retarded and later stimulated the reproduction of microorganisms. 

 The acid soil required more lime to retard the growth of bacteria than 

 the nonacid soils. As a result of liming, ammonification and nitrifica- 

 tion in all of the soils was increased. The authors concluded that differ- 

 ent soils varied in relation to the amount of lime needed to effect partial 

 sterilization. They assumed that each soil absorbed a certain amount 

 before the antiseptic action began. 



Miller (57) carried out a rather intensive study of the effect of lime 

 and calcium carbonate in both calcium-rich and calcium-poor soils, and 

 also in soils low and high in organic matter. His results were in accord- 

 ance with those obtained by many other investigators — namely, that 

 lime in small amounts increased the number of bacteria, while larger 

 application, decreased at first and later increased the number. To this 

 investigator it appeared that lime was a direct stimulant to the soil 

 flora. The same general increase was obtained with soil low and soil 

 high in calcium content, and also in soils low and high in organic matter. 

 Unlike lime, calcium carbonate brought about only a slight increase in 

 the number of bacteria. 



Beckwith, Vass, and Robinson (5) applied lime at the rate of 2 tons 

 per acre to both acid and nonacid soils. Only the soils with an acid 

 reaction or where large amounts of organic matter were added showed 

 an increase in the number of bacteria from the lime treatment. Under 

 the same conditions ammonification and nitrification responded in a 

 like manner. 



Soil was treated with lime, magnesium oxid, and magnesium car- 

 bonate by Lemmermann and Fischer (34). They found that mag- 

 nesium oxid caused a greater increase in the number of bacteria than 

 did either lime or magnesium carbonate. 



Engberding (13) treated clay soil with o.i per cent of lime and with 

 0.5 per cent of magnesium oxid. Both treatments increased the number 

 of bacteria, although the lime seemed to give better results. 



Jenkins and Britton {26) showed that by using heavy applications of 

 lime with raw-bone meal, the latter was decomposed more rapidly. 



Fabricius and Van Feilitzen (14) noted an increase in the number of 

 bacteria in moor soils treated with lime. 



Lemmermann, Fischer, Kappen, and Blanck (55) reported a gain in 

 the number of bacteria in cultivated and noncultivated moor soils and 

 in clay soils when lime or calcium carbonate was added. However, an 

 increase in the number of bacteria was not shown in a sandy clay soil 

 or in a sandy soil. 



