72 SOILS 



the soil, when both full and average and meager yields 

 were secured. 



Naturally, it was concluded that when the full crop 

 was obtained, all elements of food were, of course, pres- 

 ent, and therefore every requirement of the plant was 

 available and provided ; that where light yields were 

 obtained, some element or elements was present insuffi- 

 ciently for the fullest development of the plant. Conse- 

 quently, if you would overcome this difficulty, you had 

 only to take a sample of the backward soil that its anal- 

 ysis might be secured and then the truant element would 

 be discovered. With this done, its duties might be pro- 

 vided through the addition of the element in some other 

 way by chemical manures, most likely. 



What was later revealed. Some surprise followed the 

 analysis of soils, for high productive soils often showed 

 no greater plant-food content than the most miserable 

 producing ones. And this was just the same when a like 

 crop was seeded on similar soil types. 



This naturally caused surprise and further investiga- 

 tion. All sorts of soils were then analyzed and all sorts of 

 plants. The same results were obtained ; as a rule, how- 

 ever, the best producing soils contained a large quantity 

 of plant food, the low producing soils a smaller quantity. 

 When calculations were made, it soon was discovered 

 that great quantities of plant food, even in the most un- 

 productive soils, were present; quantities so great that 

 in but a few inches of surface soil, enough plant food was 

 there at hand to make maximum yields, and these yields 

 for hundreds of years. When these same soils were 

 seeded to crops, however, light yields invariably resulted, 

 despite the fact that chemical analysis showed that every 

 kind of plant food was there and it was there abundantly 

 an hundred times as much as the plant required. 



