Cultural Experiments 



189 



TABLE XXIV 

 Wheat Grown in Garden Plots Containing Cu as CuSO^ (1914) 



Sample 

 No. 



Cu added, 

 per cent 



5648a none 

 5649a .01 

 Toxic effects 



5650a .025 

 5651a .05 



5652a 



Dry 

 Condition matter, 



of leaves grams 



29 in. high; good 4.46 



29 in. high; good 3.16 



begin at about .02% Cu in soil. 

 25-27 in. high; affected 3.23 



23 in. high; severely af- 1.90 



fected 

 .10 20 in. high; very severely 1.33 



affected 



Cu 

 found, 

 grams 



.00012 

 .00190 



.00200 



Cu 

 p.p.m. 



in roots 



27.00 

 601.00 



.00260 805.00 



.00380 1737.00 



1504.00 



TABLE XXV 

 Wheat Grown in Pots to Check Plots Containing Cu as CuSOi (1914) 



Cu added, 

 per cent 



5672a .0025 



Sample 

 No. 



Condition 

 of leaves 



Green; 27 in. high 



Toxic effects begin at about .005% Cu in soil 



5673a 

 5674a 



5675a 



5676a 



.01 

 .025 



.05 



.10 



Yellowish; 23 in. high 

 Yellow and stunted; 17 



in. high 

 Yellow and stiinted; 12 



in. high 

 Yellow and stunted; 4-12 



in. 



high 



The corn series contains much smaller proportions of copper 

 in the roots than either of the wheat series, a fact explained in 

 part by the coarser roots of corn, which therefore have less ab- 

 sorptive surface in proportion to their weight. Wheat roots 

 grown in plots show much more copper than pot samples, 

 although the copper is much more toxic to the plants in pots 

 than in plots, a contradiction not easily understood unless it 

 be that other less favorable conditions of growth in pots were 

 responsible for the backward condition of the plants. 



Field Samples op Soils and Vegetation 



In order to relate, if possible, the experimental work detailed 



on previous pages to samples of field material, roots of barley, 



wheat, oats and corn, were collected in the district studied and 



the amounts of copper in them determined. The samples of bar- 



