We know that in the evolution of the creation of the earth that there 

 was deposited in the particles of rock, which through disintegration 

 have become the substance of the soil, such elements as potash, sulphur, 

 iron, lime, magnesia, sodium, etc. 



We also know that through some mysterious process, phosphorus was 

 formed and that in all soils which are regarded as agricultural lands, it 

 exists in varying quantities from the surface down through the under- 

 lying strata, which are called subsoils. 



We know that deep-rooting plants, such as the legumes and others, 

 through their roots, which reach many feet down into those subsoils, 

 carry with them water and air, and that when they decay, humus is 

 formed which combines with inorganic elements, and the compounds 

 thus formed are finally brought to the seed-bed, in a soluble form, by 

 capillary attraction. 



We know that the supply of potash is practically inexhaustible in most 

 soils, and that it can be made available by tillage methods and the appli- 

 cation of lime. If the supply of phosphorus or potash becomes exhausted 

 or originally was deficient, it can be supplied in a commercial form. 



Nature has in her storehouse, remote from our tillable lands, vast 

 beds of potash salts, and in regions of our own country there is appar- 

 ently an inexhaustible supply of phosphate rock containing a large per 

 cent of phosphorus which can be made available by using the right 

 methods. By guarding against unnecessary waste of both phosphorus 

 and potash, the supply will last until the end of time. 



Lime, a substance which is indispensable to all agricultural lands, is 

 found in abundance in nearly every section of our country at a cost 

 within the reach of all. Land which has been cropped for a long period 

 of years becomes sour and needs lime. 



Another source of supply of plant food is in the excreta from human 

 beings and animate creatures which have eaten the food. About 

 eighty per cent of the plant food elements required to make any of the 

 feeds can be returned to the soil in excrements. 



Again, the leaves and barks from trees and the decaying vegetation 

 in our swamps and forests which are formed into moulds, are all rich in 

 plant food elements. 



In the Oriental countries, where intensive farming methods have been 

 practiced for thousands of years, those substances are all utilized, and 

 through them, to a great extent, the fertility of the soil is maintained. 

 The sediment in pools, lakes, rivers and swamps is exceedingly rich in 

 plant food elements, and when necessity demands will be utilized to 

 enrich our tillable soils. 



Wastes 



We know the carelessness on the part of the farmers of the United 

 States is responsible for an enormous waste of fertility. Manure piles 



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