236 The Spraying of Plants. 



tigation has shown these fears to be groundless, as it has so 

 many other doubts formerly entertained. The following ex- 

 tracts should prove sufficiently convincing even to the most 

 skeptical : x 



" Former analyses of unsprayed top soils of the station farm 

 have shown no trace of copper in their composition. Recent 

 analyses of top soils taken from an old potato field which has 

 received many applications of Paris green (an aceto-arsenite of 

 copper), show from three ten-thousandths to three and one-third 

 ten-thousandths of one per cent of metallic copper. Analyses of 

 top soils from a portion of the same field to which Bordeaux 

 mixture was applied last season for the potato blight show 

 four ten-thousandths of one per cent of metallic copper, equal 

 to about sixteen ten-thousandths of one per cent in the form of 

 copper sulphate. English writers frequently speak of using 

 from 22 to 32 pounds of copper sulphate per acre in one season's 

 application of Bordeaux mixture for potato blight. To impreg- 

 nate such soil as that which was used in the above analysis to 

 the depth of one foot with one per cent of copper sulphate would 

 require about 32,625 pounds of the sulphate, which, if applied 

 at the rate of 30 pounds a year, would require in its application 

 nearly 1100 years, provided that none of it escaped in drainage." 



Some experiments conducted by Bailey in 1895 indicate that 

 practically no danger is to be feared from very heavy applica- 

 tions of arsenites to soil. His conclusion is as follows : " The 

 arsenic which falls upon the soil seems to become or to remain 

 in an insoluble condition, and passes downward, if at all, to a 

 very little distance, and then only by the mechanical action of 

 water in carrying it through spaces in the soil." 2 



The results obtained by a careful European investigation 8 

 are also inserted here, that the subject may be viewed from 

 different standpoints. The only conclusion to be drawn from 

 these extracts is that proper applications of insecticides and 

 fungicides will apparently never cause any appreciable injury 

 either to the roots of plants or to the soil : 



" 1. Soluble copper salts are injurious to plants ; the injurious 



1 Beach, Country Gentleman, 1892, 68. 



2 Cornell Agric. Exp. Sta. 1895, Bull. 101, 502. 



3 Haselhoff, "Injurious action of solutions of the sulphate and the nitrate of 

 copper upon soil and plants," Landwirthschaftliche Jdhrbucher, 1892, 272-276. 



