40 University of California Publications in Agricultural Sciences [Vol. 1 



In this connection the "lime-magnesia ratio" has become a 

 matter of general interest and is being extensively investigated 

 at the present time. Some recent experiments by Lemmermann^ 

 and others seem to indicate that a wide variation in this ratio is 

 of no consequence to plants. It is well known, however, that the 

 effects produced by natural limes and limestones are not always 

 equal. In certain instances dolomitic limes are known to produce 

 less favorable results than non-magnesian limes. During recent 

 years additional light on the action of lime in soils has been 

 found in the fact that calcium carbonate enhances certain bio- 

 logical activities through supplying an active base by means of 

 which the essential neutral condition is maintained. In this con- 

 nection the question of the effects on bacterial activity brought 

 about by different sources of lime and limestone naturalh^ sug- 

 gests itself. 



In regard to physiologically balanced solutions for bacteria. 

 Dr. C. B. Lipman* has shown that the ammonification of peptone 

 b}' pure cultures of B. subtilis is favored on the one hand by a 

 certain ratio of calcium to potassium, magnesium to sodium and 

 potassium to sodium ; while on the other hand, he failed to observe 

 any antagonism between calcium and magnesium or calcium and 

 sodium. In his investigations Lipman found that a certain con- 

 centration of magnesium chloride proved toxic to the development 

 and activity of B. subtilis and at the same time the addition of 

 certain amounts of calcium chloride failed to overcome this tox- 

 icity. Likewise, magnesium or sodium was ineffective in over- 

 coming the toxicity of calcium. While it is probably true that 

 calcium is not necessarj^ for the normal development of bacteria, 

 the importance of these observations, if found to apply in soils, is 

 at once obvious. 



From a study of the effects of various carbonates on the 

 nitrification of ammonium sulphate in solutions, Owen^ in 1908 

 concluded that magnesium carbonate is better suited to the stimu- 

 lation and growth of nitrifying organisms than calcium, potas- 



sLandw. Jahrb., 40 (1911), pp. 173-254; Also see Gile, Porto Eico Sta. 

 Ann. Kept., 1911. 



4Bot. Gaz., 48 (1908), pp. 10.5-125; 49 (1909), pp. 41-50. 

 r. Ga. Sta. Bui. 81 (Teclmical Series Xo. 1), 1908. 



