THIRTY-SEVENTH ANNUAL CONVENTION. Ill 



have in the soil before we can grow a crop, and if the soil lacks 

 in any one of these elements nothing will grow. These elements 

 are: Oxygen, carbon, hydrogen, nitrogen, phosphorus, potas- 

 sium, iron, calcium, magnesium and sulphur. Iron for ex- 

 ample, is an essential element but there is enough iron in Illinois 

 soil to last thousands of years. But without, iron in the soil 

 no plants will grow. It is the chlorophyll that makes the plan: 

 green, and without iron, chlorophyll canno: be made. I might, 

 go on mentioning other seemingly unimportant cements of 

 plant food, but I think it better for me to confine my remarks to 

 the three most important elements or those which must con- 

 cern the farmer, namely, nitrogen, phosphorus and potassium. 

 These words may seem hard to some of you who have not 

 heard them before. My only reply is, if they seem unreasonable 

 why don't we have them taught in our public schools, they are 

 no moie difficult to learn than scores of the terms we learn in 

 arnnmetic and never use outside the school house. For ex- 

 ample, the least common multiple, greatest cbunroi divisor, etc. 

 I ivili leave it to you what words are the most important for the 

 farmers' sons to know. 



I will consider briefly the elements, nitrogen phosphorus 

 and potassium. 



Nitrogen forms about four-fifths of the air or rbout 12 

 pounds is resting upon every square inch of soil. Since it is one 

 of the necessary elements of plant food which must be con- 

 sidered by the farmer, the question is, how can it be incorpor- 

 ated into the soil in sufficient amounts for growing crops? It 

 has been found by scientists that the legume family of plants 

 have bacteria growing upon their roots which form nodules 

 and gather nitrogen from the air. In a practical vay the 

 farmer has discovered that the growing of clover enriches his 

 land, that is, if properly handled. In brief one may say that 

 the nitrogen supply of the soil may be kept up through growing 

 clover, alfalfa, etc. 



Phosphorus is lacking, on the whole, in Illinois soils. The 

 only way to get phosphorus into the soil is to purchase it and 



