16 FOR BETTER CROPS IN THE SOUTH 



The Ten Essential Plant Food Elements — There are ten 

 different elements of plant food, each of which is absolutely 

 essential to agricultural plants. These elements are carbon, 

 hydrogen, oxygen, nitrogen, phosphorus, potassium, calcium, 

 magnesium, iron, and sulphur. 



Carbon, hydrogen, and oxygen, which constitute more than 

 90 per cent of most agricultural plants, are contained in air and 

 water, the supply being unlimited. The two elements, iron and 

 sulphur, although absolutely essential to plant growth, are 

 required in very small amounts, while they are provided by 

 nature in practically inexhaustible quantities. 



On the other hand, the five elements, nitrogen, phosphorus, 

 potassium, calcium, and magnesium, are required by plants in 

 very considerable amounts, and soils are frequently found which 

 are so deficient in one or more of these five elements as to limit 



The old inefficient way of spreading manure 



the yields of crops. It should be understood that soils are never 

 found which are entirely devoid of these elements. Even the 

 poorest and most unproductive soils still contain at least some 

 small supply of each of these elements, and as a general rule 

 such so-called exhausted soils contain at least one and frequently 

 two or three of these valuable elements in large amount, the 

 low productive capacity being due to the deficiency of one or 

 two elements only. 



Sometimes the element which the plant fails to obtain in 

 sufficient quantity for its normal growth, the element which 

 positively limits the yield of the crop, is actually present in the 

 soil in a very large amount. In such cases the practice should 

 not be to add to the soil more of this plant food element, but 

 to adopt methods of soil treatment and management by which 

 we can liberate a sufficient amount of this element for maximum 

 profitable crop yields. This point will be further discussed in 

 the pages following. 



