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



a large niimbor of experiments are cited, among which are to be 

 found cases of injui'v, ineffectiveness, and stimulation by FeS04 

 to crop plants. Very few experiments appear to have been 

 reported on the effect on plant growth of FeSO^ or other iron 

 compounds in solution cultures. Those that are given indicate 

 the uniformly toxic nature of iron to the higher plants under 

 the conditions noted. For evidence on this point, the reader 

 is referred to the investigations of Boiret and Paturel,'^ Gile,'^^ 

 Ruprecht,^^ Thompson,"'* and Knop.'" No case has as yet come 

 to our notice of the stimulating effects of iron salts to plants in 

 solution cultures. 



In soil cultures the picture is an entirely different one, and 

 it is under those conditions that we observe the contradictory 

 results mentioned above. Distinct cases of injury by FeSO^ to 

 plants in soil cultures have been reported. In illustration of 

 these, may be mentioned statements of Voelcker,''* Steglich," 

 Nessler,'* Halsted,^'-^ and others. As showing FeSO^ to be with- 

 out effect on plants grown in soils, may be mentioned the experi- 

 ments of Scovell and Peter,^*^ A. Mayer,^^ Boiret and Paturel,*- 

 Petit,*^ Larbaletrier and Malpeaux,** and others. In other 

 words, some of the investigators just mentioned, as well as Coste- 

 Floret,^^ Brooks,-*^ Griffiths,*'^ Treboux,^^ and a number of others. 



71 Ann. Agron., 18, p. 417; E. S. E., 4, p. 435. 



■^2 Jour. Agr. Ees., 3, no. 3, p. 



'3 Mass. Agi-. Exp. Sta., Bull. 161. 



'■i Jahresber. Agr. Cliem. N. F., 36, p. 106. 



"5 Landw. Versuchs. Stat., 2, p. 73. 



■is Jour. Eoy. Agr. Soc. Eng., 2d ser., 1, p. 113. 



77 Ztschr. Pflanzenkrank, 11, p. 31; see also Jahresber. Agr. Chem., 43, 



p. 352. 



78 Centbl. Agr. Cliem., 2, p. 125. 



70 N. J. Sta., Ann. Eept., p. 321, 1890. 



80 Ky. Agr. Exp. Sta., Bull. 17. 



81 Jour, fiir Landw., 40, p. 19. 



82 Ann. Agron., 18, p. 417. 



83 Compt. Eend., etc., 117, p. 1105. 



84 Ann. Agron., 22, p. 20. 



85 Prog. Agr. et Vit., 26, pp. 434, 463, 496. 



86 Mass. Agr. Exp. Sta., Ann. Sept., p. 42, 1896. 



87 Chem. News., 50, p. 167. 



88 Flora, 92, p. 59. 



