FERTILIZER 



2156 



FERTILIZER 



FERTILIZER, fer'tilyzer, any substance 

 that will increase crop yields. Plants require 

 certain foods, and in order to get the best pos- 

 sible returns from the land it is necessary that 

 the ground be supplied with the requisite food 

 to convey to the growing plants. As a general 

 rule, it may be taken for- granted that soil 

 that has not been called upon to produce crops 

 needs little or no fertilizer when first culti- 

 vated. When land has been long cultivated 

 the properties necessary to promote growth are 

 largely taken out of it, and the land needs 

 fertilizers to restore the proper balance of 

 properties. It is always well to bear in mind 

 that different crops exhaust different food ele- 

 ments in the soil, and that the starvation of 

 land due to constant reproduction of one kind 

 of crop can be prevented by a change of crop, 

 commonly referred to as rotation of crops, as 

 well as by an artificial supply of fertilizer. In 

 dealing with fertilizers here it is only intended 

 to consider commercial fertilizers, as distinct 

 from natural manures, which are dealt with 

 elsewhere in these volumes. 



Requirements of Plants. Plant life requires 

 ten essential food substances; if these elements 

 are not all present in proper proportions nat- 

 urally, which is very seldom the case, they 

 must be supplied. These substances are oxy- 

 gen, hydrogen, nitrogen, carbon, sulphur, phos- 

 phorus, potassium, calcium, magnesium and 

 iron. Iron, magnesium and sulphur are gen- 

 erally present in the soil, and it is only in 

 exceptional cases that they have to be supplied. 

 Hydrogen and oxygen are supplied in water. 

 Carbon is received from carbon dioxide in the 

 air. The four almost universally needed plant 

 food substances are calcium, nitrogen, phos- 

 phorus and potassium. 



The first step of the farmer towards finding 

 out what his soil needs should be to have a 

 sample or samples from different parts of his 

 farm analyzed at the agricultural college of his 

 state or province. This analysis, conducted by 

 experts, will help him in selecting the food 

 substances he must use. If his soil is found to 

 be wanting in calcium, or lime, it can be added 

 to the soil in the form of ground limestone, 

 burned lime such as is used for plastering, 

 hydrated lime, air-slacked lime or wood ashes, 

 which usually contain about one-third lime and 

 some phosphorus and potassium. The amount 

 of lime or any other fertilizer or mixture of 

 fertilizers t be added per acre of ground 

 cannot be definitely stated until an analysis 

 of the soil has been taken, or experimental 



crops raised, and even then will vary according 

 to the seed to be planted. 



Nitrogen is best added to the soil in farm 

 manures, but the most generally used nitrog- 

 enous fertilizer is nitrate of soda. This salt 

 is mined in Chile, and is shipped all over 

 the world; it usually costs from $50 to $60 

 per ton, and contains about fifteen per cent of 

 nitrogen. A soil that is well supplied with 

 lime and decaying organic matter may gain 

 in nitrogen, which is also indirectly received 

 from the air, while the plowing in of clover 

 and alfalfa greatly increases the supply of nitro- 

 gen. Another source of the necessary nitrogen 

 is ammonium sulphate, a by-product from the 

 manufacture of coke, which is similar to am- 

 monia combined with sulphuric acid, containing 

 about twenty per cent of nitrogen. Bone meal 

 and dried blood are also used as fertilizers, 

 but they are valuable as feed for hogs and 

 costly as fertilizers. 



Soils that are deficient in phosphorus are 

 generally those that are lacking in lime. The 

 phosphorus for fertilizers is mostly mined in 

 the form of phosphate rock in North Carolina, 

 South Carolina, Tennessee and Florida. It is 

 ground to a fine powder and then used as a 

 fertilizer. It usually contains about twenty-five 

 or thirty per cent of phosphoric acid. Most 

 of the phosphorus fertilizer used, however, 

 is obtained by treating the phosphate rock 

 with sulphuric acid, which, although making 

 it more costly, makes it more readily soluble. 

 The phosphate" rock derives its phosphorus 

 from the bones of marine animals; in fact, 

 nearly all phosphorus comes from the bones 

 of animals. When bone meal is used as a 

 fertilizer the phosphorus is directly given to 

 the soil. 



The potash mines of Germany are the chief 

 sources of the potassium required as plant food. 

 During the War of the Nations, beginning in 

 1914, this supply was cut off, entailing a 

 scarcity of the product. Kainit, a natural salt 

 mined in large quantities near Stassfurt, Ger- 

 many, is shipped just as it is when mined and 

 contains about twelve per cent of potash. 

 When treated with acid, however, it usually 

 contains fifty per cent of potash. 



Mixed fertilizers as commonly sold contain 

 nitrogen, phosphorus and potassium. When a 

 large quantity of fertilizer is needed it is more 

 economical and satisfactory for the farmer 

 to buy the materials separately and mix them 

 himself. He can thus see exactly what he is 

 using and that the food elements are present 



