2 FUNDAMENTALS OF AGRICULTURE. 



seed to allow the latter to absorb this moisture, it 

 must not be water-logged nor so closely packed around 

 the seed as to exclude air, otherwise the seed will rot 

 and fail to germinate. It is true that seeds can germi- 

 nate entirely soaked in water, but this happens in case 

 of water which has had an opportunity to absorb oxy- 

 gen from the air, while water that remains stagnant 

 in the soil for some time is robbed of its oxygen and 

 is unfit for the germination of seed. 



A POOR CROP, DUE TO LACK OF THE ESSENTIAL ELEMENTS. 



The Essential Elements. Under proper conditions 

 of moisture and temperature seed will germinate and 

 continue to grow for some time. Sooner or later, 

 however, growth will cease unless certain chemical 

 elements, usually spoken of as the essential elements, 

 are available. These are nitrogen, phosphorus, sul- 

 phur, potassium, calcium, magnesium, and iron, and in 

 addition hydrogen and oxygen of the water. These 

 elements are absorbed by the plant from the soil in the 

 form of salts which are soluble in the water. The 

 salts are formed in the soil as the result of chemical 

 processes which we will refer to later. Of these ele- 



