

1909] SCHREINER & REED— OXIDIZING POWER OF ROOTS 



373 



laboratory 30 has shown that this ameliorating action is due to the 

 removal of deleterious organic substances. Extracts were treated 

 with carbon black or ferric hydrate. The absorbing agent was 

 shaken with the soil extract and filtered off at the expiration of a half- 

 hour, in the same manner as the distilled water used in the experi- 

 ments was prepared. The relative effects of this treatment upon 

 growth and the oxidizing power of the plants is shown in Table VI, 

 where the effect in the untreated soil extract is in each case taken as 



100. 



TABLE VI 



Effect of treatment with carbon black and ferric hydrate upon growth and oxi- 

 dizing power of plants grown in extracts of various soils. Growth expressed in terms 

 of relative transpiration. 



3 



4 



5 

 6 



7 

 8 



9 



10 



11 



12 



*3 



*4 



No. 



Soil extract 



Arlington clay loam* 



" " " carbon black treated 



Takoma lawn soil* 



" " " carbon black treated 



Alio way clay* 



" " carbon black treated 



Dunkirk sandy loam* 



" " " carbon black treated 



Miami silt loam* 



" " " ferric hydrate treated 



Marshall clav loamf 



" " " carbon black treated 



Clarksville silt loamt 



carbon black treated 



Elkton silt loamf 



<< 



u 



.. 



carbon black treated 



Cecil fine sandy loamf 



a 



a 



:. 



" carbon black treated 



Hagerstown loamf 



• • 



u 



Cecil sandv loamt 



mi 



<< 



u 



u 



Dutchess silt loamf 



■ • 



<< 



>» 



Poor sandy loamf 

 Garden loamf 



- . 



a 



carbon black treated 

 carbon black treated 

 carbon black treated 

 ferric hydrate treated 

 ferric hydrate treated 



+ 11 e . nolp hthalin used in estimating oxidation. 

 TAloin used in estimating oxidation. 



Relative 

 growth 



IOO 

 124 

 IOO 



137 

 IOO 



116 



IOO 

 112 

 IOO 

 171 

 IOO 

 2l6 

 IOO 



450 



IOO 



179 



100 



112 



100 



230 



100 



193 



100 

 no 



TOO 

 I70 

 IOO 

 I36 



Relative 

 oxidation 



IOO 

 265 



IOO 

 IOO 

 IOO 



117 



IOO 



280 



IOO 



198 



IOO 



130 



IOO 



227 



IOO 



3'7 



:oo 



200 



IOO 



500 



TOO 

 241 



IOO 



373 



IOO 



534 



IOO 



313 



ft will be noted that in all but one of the soil extracts the effects 

 of the treatment with an absorbing agent strongly increased the 



t 30 Bur. Soils, U.S. Dept.Agric. Bulls. 28 36,40. Jour. Amer. Chem. Soc. 30: 

 I2 95- 1908. 



