1917] Lipman-Gericke : Smelter Wastes and Barley Growth 555 



the tailings, and, in the case of the land which is already affected, 

 the use of organic matter. The indications of our experiments 

 are that a year or two of fallowing will usuall}^ correct the 

 difficult}". 



We are therefore obliged to reaffirm the position taken by 

 Lipman and Wilson^-'^ to the effect that there seems to be little 

 danger in store for our agricultural lands in the metallic resi- 

 dues which are deposited bj' smelters in their vicinity and from 

 their ultimate solution in small degree in potential irrigation 

 water-supplies which may be subsequently transported to farm 

 lands. On the contrary, we give evidence above that so far 

 from being toxic to barley plants, small amounts of the metals 

 studied may be distinctly stimulating to them. "While this is 

 more strictly true in the case of some metals than of others, it 

 appears none the less to be so. Moreover, in cases in which 

 toxicity is effected by the application of any of the metallic sul- 

 fates named, it is usually very slight, even when large quantities 

 of the salts are employed. Wliile we have experimented in this 

 series of investigations only with barley, evidences given bj' 

 ourselves and by others who are above cited, indicate that a 

 number of other plants behave similarly to barley, if not exactly 

 like it. From the practical standpoint, therefore, we cannot see 

 that any other conclusion can be reached than that we may 

 virtually ignore any deleterious effects which may be urged 

 against the metals of smelter wastes which are here discussed. 

 We use the word "practical" here advisedly, because if solution 

 instead of soil cultures were taken as a criterion, our standard 

 of judgment would not be practical. Whatever may be said 

 about soil cultures, one must admit that they approximate most 

 closely of any greenhouse or laboratory methods the natural con- 

 ditions under which crops grow. We cannot see that any other 

 culture than one which at least offers a solid substratum to the 

 plant may be regarded as valid in the determination of whether 

 or not salts like those here under consideration are, under the 

 conditions of the smelter and its vicinity, a menace to plant 

 growth. 



123 Bot. Gaz.. 55. no. 6. p. 409. June. 1913. 



