226 



The Ohio Journal of Science [Vol. XIX, No. 4, 



of the Katmai ash, wiU miUtate strongly against the revegeta- 

 tion of the areas affected. Ferrous sulphate in the presence 

 of water hydrolyzes, giving ferrous hydroxide and sulphuric 

 acid. Nitrifying bacteria do not thrive well in a strongly 

 acid medium. The presence of 1.35% FeO (FeS04 calculated 

 as FeO) kills all nitrifying bacteria, while 0.3%, according to 

 Storer\ is very injurious. Voelcker found that 0.5% FeS04 

 did much harm to plants, while 1.0% killed entirely. 



TABLE I. 

 Water Soluble Ferrous Iron Content and Acidity of Katmai Volcanic xVsh. 



The toxic effects of Samples No. 1 and No. 6 are no doubt 

 attributable to the ferrous iron content, while Sample No. 5 is 

 probably a poor soil for the growth of most plants. In fact, the 

 seedling grass observed on it was far from healthy and strong. 

 A low nitrogen content, of course, would prevent any rank 

 growth, and this Sample No. 5 also possesses. The Katmai 

 Mud Flow does not possess sufficient ferrous sulphate to injure 

 plant development and consequently, as Dr. Griggs found, wheat 

 would germinate and grow when the ash was brought into 

 proper physical condition by the addition of coarse sand. 



The soluble sulphate content of the samples analyzed is not 

 sufficient to combine with all the iron present. There was a 

 certain amount of chloride present in the samples, but a quanti- 

 tative estimation of this acid radical was not made. The 

 ratio of sulphate to iron in the two samples analyzed is 

 practically the same. 



The presence of water soluble ferrous iron in the above 

 samples is probably directly attributable to the volcanic origin, 

 of the ash. Ferrous iron in marshland and moors is attributed 

 to the reducing action of algae upon sulphates, but here, although 

 the soil was wet, algas were not in evidence to any extent, and 

 surface water conditions could hardly be considered as stagnant. 



^Storer, F. H. Agriculture in Some of its Relations to Chemistry. Vol. 2, 

 page 209. 1906. 



