58 Fertilizers 



conditions, since the usefulness of the different forms are 

 also dependent upon such other conditions as the char- 

 acter of soil, kind of crop season and the object of the 

 application. 



The character of soil is an important factor. The 

 mechanical composition of a soil is a dependable guide as 

 to the rapidity of leaching of the soluble forms of nitrogen. 

 A loose light soil permits more rapid percolation of water 

 through it to the lower layers below the reach of plant- 

 roots and nitrogen is more readily leached away than in 

 heavier soils possessing finer particles. Furthermore, 

 some soils naturally possess conditions favorable to 

 nitrification, some possess similar conditions through the 

 efforts of man, and still others possess conditions unfavor- 

 able to nitrification. Soils sufficiently open and porous 

 to permit easy cultivation and proper circulation of air 

 and moisture, and well supplied with lime and organic 

 matter possess those characteristics favorable to the 

 spread and development of bacteria which bring about 

 a more rapid change of the form of nitrogen. Again, 

 the previous treatment of a soil is an important considera- 

 tion. Liberal applications of manure, and the production 

 and use of leguminous crops for manurial purposes tend 

 to build up the content of organic nitrogen in a soil so 

 that less might be used at planting time. 



The kind of crop is an important factor, since certain 

 crops grow and develop quickly, while others grow for 

 a comparatively long period. Some require greater 

 quantities of food in a usable form and others feed more 

 slowly. It is the object in some instances to produce 

 succulence, in others to produce grain. The season, 

 likewise, because the changes from organic forms to 

 ammonia, or nitrate, only take place when the tempera- 



