536 SOILS: PROPERTIES AND MANAGEMENT 



phorus arising from the presence of carbonate. Neither 

 did the availability of iron or aluminium phosphate 

 appear to be influenced by calcium carbonate. 



These and recent experiments by Simmermacher l and 

 others tend to discredit the earlier conclusions as quoted 

 above and as set forth by Deherain 2 regarding the favor- 

 able influence of lime on the availability of phosphorus. 

 However, the preponderating evidence is still with the 

 earlier experimenters. The principles that underlie the 

 effect of lime on availability of phosphorus are discussed 

 in paragraphs 259 and 260. 



456. Influence of lime on the formation of nitrates in 

 soil. — It has already been remarked that nitrification 

 proceeds very slowly in acid soils. A soluble base 

 must be present with which the nitric acid may com- 

 bine, otherwise the process will be inhibited by the toxic 

 effect of the acid on the bacteria concerned in the forma- 

 tion of the acid. The addition of lime is the most 

 economical method of providing the base. This is 

 often a matter of great moment for crops that respond 

 readily to nitrate nitrogen, and is one of the important 

 reasons for applying lime to sour soils. The fact that 

 some plants grow better in some soils than in strongly 

 basic ones is also an indication that such plants absorb 

 a considerable part of their nitrogen in forms other than 

 nitrates. 



Many investigators have found that the presence of 

 calcium carbonate promotes the ammonifying and nitrify- 

 ing process. The addition of calcium carbonate to a 



1 Simmermacher, W. Einwirkung der Kohlensauren Kalkes 

 bei der Dungung von Haferkulturen rait Mono- und Dicalrium 

 Phosphat. Laridw. Vers. Stat., Band 77, Seite 441-471. 1912. 



2 Deherain, P. P. Traite de Chemie Agricole, p. 525. 1892. 



