Oct. 29, 1921 Absorption of Copper from the Soil by Potato Plants 285 



Tabl^ II. — Copper found in soil 



SPRAYS APPLrED TO SOIL NEAR PLANT ROOTS 



SPRAYS APPLIED TO VINES IN COMMERCIAL PRACTICE 



July 16 



Aug. 31 



Samples taken before any 

 sprayings were made in 

 1917. 



Samples taken after last 

 sprayings were made in 

 1917. 



Control 



Pickering "C" formula. 



Bordeaux 5-5-50 



Pickering "A" formula 



Control 



Pickering "C" formula 



Bordeaux 5-5-50 



Pickering "A" formula 



DISCUSSION OF RESULTS 



VINES AND TUBBRS 



The leaves, stems, and roots of the plants from the soil receiving 

 the Pickering spray showed an increased copper content with each 

 successive analysis (Table I). The largest percentage of the copper was 

 held by the leaves. The roots held an appreciable part of the copper, 

 the amount increasing from o in the first sample to 0.0160 per cent in 

 the sample taken on September 3. The tubers contained only minute 

 amounts of copper. 



The plants from the Bordeaux treated soil showed irregularities, 

 particularly with respect to the copper content of the roots and stems. 

 The leaves and stems contained more copper than those of the plants 

 from the Pickering treated soil, while the roots contained less copper 

 than the roots of the plants from the Pickering treated soil. The 

 amounts of copper found in the tubers were small. 



The vines grown in the soil treated with a solution of copper sulphate 

 showed a marked progressive increase in copper content of the roots 

 with each succeeding analysis. The leaves contained somewhat larger 



