CROPS AND SOIL IMPROVEMENT 



distinct value, and especially to one lacking ex- 

 perience with his soil. The mapping of soils by 

 national and state authorities has given pretty ac- 

 curate knowledge of hundreds of soil types, their 

 location and characteristics, and when a soil 

 expert obtains a sample of soil and the history of 

 its past treatment, he can assign it to its type and 

 give to its owner dependable advice regarding 

 its crop-adaptation and probable fertilizer re- 

 quirements. 



The Use of Nitrogen. There is no fully satis- 

 factory way of determining the kind and amount 

 of fertilizer that should be used at any particular 

 time for any one crop. Perfection in this respect 

 is no easier in attainment than in other matters. 

 There are, however, means of arriving at con- 

 clusions that are a valuable guide. 



In a general way, nitrogen is in scant supply in 

 all worn soils. Wherever the cropping has been 

 hard, and manure has not gone back to the land, 

 the growth in stalk and leaves of the plant is 

 deficient. The color is light. Inability of a soil 

 to produce a strong growth of corn, a large amount 

 of straw, or a heavy hay crop, is indicative of lack 

 of nitrogen in nearly every instance. 



The legumes, such as clover, and the stable 

 [164] 



