EDITORIAL. 105 



reaching importance to agriculture, and the application to this end 

 of nitrogen assimilation from the air by certain plants. '• We have 

 many instances of attempts made to improve soils or to maintain 

 their fertility by the introduction of leguminous crops, which have 

 proved disastrous rather than helpful in promoting plant growth 

 or of iDermanently increasing fertility in this respect. Furthermore, 

 we have no definite knowledge as yet as to the conditions which are 

 necessary in order that the plants shall appropriate nitrogen from 

 the air rather than from the soil, nor have we any definite informa- 

 tion as to how^ large a proportion of the nitrogen so gathered is re- 

 tained in the soil for the use of cereal and other crops which depend 

 entirely upon soil sources for their nitrogen." 



The supi^lying of fertilizing elements other tnan nitrogen is also 

 a question for the near future, in view of the present heavy demands 

 upon the known supplies of these materials, ll^iile there is suffi- 

 cient supi^ly of these in the soil to last for certain kinds of crops for 

 centuries, under conservative management, it is pointed out that 

 there is a class of crops- — such as vegetables, fruits, berries, etc., the 

 demand for which is rajjidly increasing — which "can not be grown 

 to perfection and in such quantities as to meet the demands of a 

 modem civilization without the stimulating effect of immediately 

 available plant food." The increasing demand for these fertilizing 

 elements, the speaker held, could not be supplied by natural means, 

 including the use of homemade manures, and hence the source of 

 supply of phosiDhate and of potash salts furnishes a broad field for 

 study. 



Another problem, economic in character, lias to do with the trans- 

 fer of the plant food elements from one place to another, and their 

 loss in so far as our own country is concerned. " There is no doubt 

 but that by careful adjustments of trade conditions it will be possible 

 to obtain quite as much money for our surplus products as is obtained 

 at the present time without having the practice result in so great an 

 annual loss of our plant-food constituents." 



.It will be seen that in a large measure these two addresses dealt 

 with the same great agricultural problem, but from somewhat differ- 

 ent i)()iiits of view — the one enforcing the need of checking the rapid 

 depletion of soils in fertility, in view of the fundamental importance 

 of the soil to all industry and the rapidly increasing jiopulation; 

 the other by analyzing the sul)ject and suggesting lines of research 

 upon which to base methods for greater conservation of this fertil- 

 ity and increased agricultural production. In conclusion Doctor 

 Voorheos emphasized the importance of a broad and detailed study 

 of the whole question of soil fertility, and his belief that " there is no 

 field of investigation more promising of fruitful results for the in- 

 vestigator and the country at large." 



