44 ILLINOIS STATE DAIRYMEN'S ASSOCIATION 



Then you see those two elements ought not to be mentioned 

 in the same breath for use on ordinary soils. Phosphorus is 

 rare and potassium an abundant element. There are thousands 

 of acres in Illinois that contain more potash in the soil, ton for 

 ton, than common commercial fertilizer. It may not be in as 

 readily available form, and it is not, of course, but there is a way 

 in which it could be made available. Turn into the soil organic 

 matter, allow it to be decomposed, and it will liberate potassium. 



So I say there are three materials necessary to build up 

 soils, organic matter or manurial products, phosphorus and lime- 

 stone. Rarely we find a soil that contains a good supply K)f 

 phosphorus, Dut orchnary soils are poor in that element, and 

 contain only about half as much phosphorus as the average of 

 average, than the earth's crust. Also we find often but 30,000 

 pounds of potassium instead of 50,000, which should be found 

 the earth's crust. Most soils contain about 1,200 pounds in* 

 stead of 2,000. The soil has been leached, and is poorer, as an 

 in the earth's crust. The normal soils of the state are rich in 

 potassium and rather deficient in phosphorus. 



So we must add phosphorus. We must also add nitrogen, 

 but we get that from the air with the legume crops to be turned 

 back into the soil, either directly or in manure. 



In the last few years in the agricultural press there have ap- 

 peared articles on the possible importance of sulphur as an ele- 

 ment of plant food. It has been stated by someone in a position 

 of rather high authority that it is just as necessary to add sul- 

 phur to the soil as nitrogen or phosphorus. But that is based; 

 on laboratory investigations, upon analysis of the soil and an- 

 alysis of the crop pretty largely. But there are other factors 

 that were not clearly in hand when these investigations were 

 made, and I might say the final test of all theories drawn from 

 laboratory investigations is a field test; and every scientist and 

 student must be pretty careful about drawing conclusions from 

 laboratory work solely for direct application in the field without 

 testing it out in the field. It so happens that there falls upon 

 an acre of land during the year 17 to 18 pounds of the element 

 sulphur coming down from the air in the form of rain and that 



