56 CHEMICAL FERTILIZERS; AND LIME 



It will be seen that in chemical composition these soils are practically 

 identical, and yet one grows good alfalfa and one does not. 



This shows that the chemical composition is not always the deciding 

 factor in fertility. As a matter of fact, it is rarely the deciding factor. 

 A soil that showed higher amounts of plant-food than in the cases cited 

 above gave very low yields. A good system of tile drains was put in 

 this field, and three years later the crops were very large. The drain- 

 ing produced no differences in the chemical content, but it brought 

 success. Failure may be due in other cases to poor tilth, acidity, bad 

 rotations, and various physical causes. 



Chemical analyses of soils are valuable mainly to assist in con- 

 ducting investigations of a scientific character. With the present 

 methods they are of little use as a means of deciding what fertilizer 

 should be applied. The farmer should experiment with different fer- 

 tilizers, and not depend on a chemical examination of his soil, unless 

 he has reason to think that he has a very special problem. The wide- 

 spread notion that chemical analyses of soil and of plant will tell what 

 fertilizers to add and what crops to grow is erroneous. 



Field tests to determine fertilizer needs may be made as follows : 



The field should be plowed before the plats are laid out. Then 

 use substantial stakes at the corners of the plats and mark them 

 well. It would be well to leave a space of 4 feet between each two 

 plats, to be sure that the plants on one plat cannot feed on the fer- 

 tilizer each side of it. 



Do not lay out the plats on land that has been manured within one 

 year. If you made fertilizer experiments last year, do not use the same 

 set of plats again this season. 



The following diagram shows the arrangement of the plats, with 

 the spaces between, each plat containing aV of an acre : 



1. Plat K. 15 lb. Muriate 



100 lb. lime 



P tash on this half 



2. Plat N. 15 lb. nitrate soda TtWs half 



3. Plat P. 30 lb. super phosphate JJtfcb hSf 



