UNIVERSITY OF CALIFORNIA PUBLICATIONS 



IN 



AGRICULTURAL SCIENCES 



Vol. 1, No. 6, pp. 127-139 March 28, 1914 



THE EFFECT OF COPPER, ZINC, IRON AND 



LEAD SALTS ON AMMONIFICATION 



AND NITRIFICATION IN SOILS 



BY 

 C. B. LIPMAN AND P. S. BUEGESS 



In the course of investigations on the effect of smelter wastes 

 on crop growth one of the writers decided to test also the effects 

 of the salts of the heavy metals on the transformation of organic 

 nitrogen in the soil into ammonia and nitrates which serve as 

 the source of nitrogen for plants. This correlation between the 

 effects of external factors upon both the soil flora and the physio- 

 logical condition of plants was deemed eminently worth while, 

 for reasons which are at once obvious to the careful student of 

 soil fertility problems. Some of the results obtained with plants 

 have been published,^ and still fuller data dealing with the same 

 problem will soon find publication elsewhere. In view of the 

 foregoing the writers have carried out experiments dealing with 

 the toxic and stimulating effects of copper, zinc, iron and lead 

 on the ammonifying and nitrifying flora of a sandy soil. The 

 results, owing to their interesting nature and their cogency at 

 this time are here given apart from the results obtained with 

 plants. 



Methods of the Experiments 



The work here described was carried out by the direct soil- 

 culture method in a manner fully explained by one of us else- 

 where.- No attempt was made to modify the soil flora, but the 



ff^' 



1 Bot. Gaz., vol. 5.5, p. 409. 



2 Cent, fiir Bakt., 2*" Abt., vol. 32, p. 58, vol. 33, p. 305. 



