kellerman: effect of boron on vegetation 485 



significant size were found in these samples, although, with the 

 rather high content of the white alkali salts in these spots, it is 

 difficult to determine the relative importance of borax and the 

 other salts in the alkali injury. Somewhat similar conditions 

 exist in regard to Lake Elsinore, in Riverside County. The 

 water of Lake Elsinore shows an appreciable percentage of borax 

 and this suggests the possibility that the destructive injury fol- 

 lowing the use of Lake Elsinore water in irrigation may be 

 partly due to borax poisoning, as well as to injury from other 

 alkali salts. In this connection it is worthy of note that the 

 lakes of the Southwest, famous for the remarkable clearness of 

 the water, in many cases at least are more or less strongly im- 

 pregnated with borax. It is true that the salt content in Lake 

 Elsinore is high in relation to the percentage of borax; in the 

 case of Clear Lake, Owens Lake, and Mono Lake, the com- 

 parison with the other salts is much higher. I am inclined to sug- 

 gest, therefore, that wherever there are lakes in which the tem- 

 perature of the water is sufficient for satisfactory development 

 of aquatic plants but which remain free of vegetation, they should 

 be prospected for the possible occurrence of borax. 



Plant physiologists have frequently included boron compounds 

 in determining the toxicity of various compounds upon plants, 

 both in water cultures and in sand and in soil. As is the case 

 with the very scattered literature dealing with field applications 

 of borax to crop plants, there are some contradictions and differ- 

 ences of opinion regarding the toxic action both of borax and 

 other boron compounds. A fairly complete review of this lit- 

 erature up to 1 9 14 has been published by Dr. Brenchley, of the 

 Rothamsted station. Following this review Dr. Brenchley con- 

 cludes that boric acid seems to be less harmful to the higher plants 

 than compounds of copper, zinc, and arsenic; and, further, that 

 below a certain amount of concentration boron compounds exert 

 a favorable influence upon plant growth. 



From a review of much of the literature reported upon, I am 

 inclined to doubt the validity of this last opinion, considering 



