THE EFFECTS OF CERTAIN ORGANIC 

 COMPOUNDS ON PLANT GROWTH 



By 



M. J. FuNCHESS, Associate Agriculturist. 



Introduction. 



The causes of fertility or infertility of soils are 

 usually explained by soil chemists and physicists in 

 terms of plant food, or i)hysical condition of soils. Un- 

 l)roductive soils are either deficient in some element, or 

 elements, needed for plant growth, or they are in a bad 

 pliysical condition, according to these old and rather 

 generally accepted views. Such unfavorable condi- 

 tions may be remedied by the application of manures 

 and fertilizers, thereby supplying the deficient ele- 

 ments; or through the amelioration of the soil by the 

 use of lime, by the nchhtion of organic matter, and by 

 thorough pulverization with tillage implements. 



In comparativel}^ recent years, a quite different view 

 of the causes of infertility has been developed in the 

 rnited States by the Bureau of Soils of the United 

 Slates Department of Agriculture. According to this 

 very advanced theory, infertility is frequently due to 

 the presence in soils of substances which are injurious 

 to plants, rather than to deficiencies of plant food. 

 These liarmful su])stances ore root excretions, or are 

 due to the i)roducts resulting from organic decomposi- 

 tion within the soil. To restore such soils to fertility, the 

 injurious compounds must in some way be removed or 

 rendered harmless. In supjiort of this position, quite a 

 large amount of experimental work has been rei)orted.* 

 The bulk of such experimental evidence, however, has 

 been obtained from solution cultures, using wheat seed- 

 lings as the plant indicator, the plants being allowed to 

 grow for only sliort periods. The methods used by the 

 Bureau of Soils are fully described in several of its 

 bulletins. 



Oi'.jECT OF The Experi:sients. 



The work herein reported was undertaken in order 

 to determine, if possible, whether the results obtained 



~ SFe~c.speciallv bulletins \o. 23. 28. 36, 40. 47, 53, 70. 77 

 and 87, of the Bur. of Soils, U. S. Dept. of Agr. 



