Section III.— SOIL RECLAMATION AND 

 IMPROVEMENT 



Barrenness. — Very large numbers of soils are not 

 producing anything approaching to their maximum crop, 

 although one cannot definitely classify them as being under 

 the well-recognized types of land difficrdt of cultivation. 

 These lands are only partially barren, from improper treat- 

 ment due frequently to economic causes. 



The supply of plant food in the soil is sometimes the 

 chief cause for the difference between productive and 

 unproductive land. Table i6 shows the amount of plant 

 food in productive and unproductive types of soil. 



Table i6. — Composition of Soils. 

 Parts per Two Million or Pounds per Acre to a Depth of Seven Inches. 



A very common cause of unproductiveness in a soil is the 

 lack of proper plant food. There are many other causes, 

 but there are few of them quite so common as the question 

 of the supply of proper mineral plant food in the soil. That 

 the supply of plant food in the soil is a verj^ fundamental 

 question is illustrated in Table 17, which shows the relative 

 supply and demand of the most important elements of plant 

 food, and it will be noted on purely fundamental grounds 



