Food for niendable practice to use Nitrogen only, as it enables a use 

 Pl * nt> of soil constituents, which are of no service while in the soil. 

 ** The fear that such use of Nitrogen will result in an undue ex- 

 haustion of phosphoric acid and potash, which is sometimes 

 expressed, is not well founded, since, where an increase in crop 

 is caused by the use of Nitrogen only, the amounts of phos- 

 phoric acid and potash removed in the crop would not be rela- 

 tively greater than the amounts removed were some other 

 condition responsible for the increased yield. 



The chances of recovering, in the form of produce, the 

 minerals used in excess are greater than are the chances of 

 recovering all of the Nitrogen used in excess of the needs of 

 the plants, or even that used in moderate amounts, because 

 of the differences in the fixing power of soils for the different 

 elements when in a condition to feed plants. The Nitrogen, 

 when in its available form, the Nitrate, does not form again 

 any fixed compounds with the soil; hence, if the plant does 

 not take it up, it may be lost by virtue of further changes of 

 form, which results in its loss as a gas. This applies to the 

 Nitrogen in organic and ammonia forms, as well as to the 

 Nitrate. In the use of Nitrogen, the aim should be to feed 

 the plant ; in the case of the minerals, excessive quantities may 

 be used, as the accumulations are not liable to escape. 



In the next place, the best use of Nitrogen 

 Best Returns ^ attained when it is app n ed to soi i s in good 



e of condition, rather than to poor or worn-out 



ObSned Wh n S Us ' The Soi ! S t0 which hi g h 'g rade ferti ' 



, lizers are applied should possess good ab- 

 Applied to Good 



<N 1 W 11 P sorptive and retentive properties, in order 



' ~, that the materials applied may be retained 



pared for Crops. f f \ * \ \ i 



tor the use of the crop, and the physical 



character also should be such as to permit a ready penetra- 

 tion of heat and an easy circulation of water conditions 

 which are essential in order that the activities within the soil 

 may be unimpeded, thus making it possible for the plants to 

 easily obtain their needed food. In too many cases good 

 plant-food is wasted because applied to mixtures of sand, clay 

 and other materials, rather than to soils in the true sense, or 

 to soils that have not been thoroughly prepared^ the clods 

 and lumps preventing a proper distribution of the material, 

 as well as a ready absorption of moisture and free circula- 

 tion of the plant-food. 



