CHAPTER VI 



FERTILITY 



Natural Productiveness. Fertility and infertility, as 

 ordinarily applied to soils, are essentially relative terms. 

 Soils are never absolutely barren unless rendered so by 

 climatic conditions, the presence of injurious substances, 

 or 'other accidental circumstances. Of soils which have 

 been reclaimed and improved by mechanical treatment, 

 i.e., draining, tilling, etc., some are naturally much more 

 productive than others, and are said to be more fertile. 



The natural productiveness may be greatly increased 

 or it may be diminished by systematic cultivation. In 

 some cases, especially when land is scarce or dear, it is 

 profitable to increase the productive capacity and to main- 

 tain it at a point far above the natural fertility of the soil. 

 When land is fairly cheap and naturally of a high degree 

 of fertility, it may be more profitable to rely upon the 

 natural resources of the soil. 



When the fertility of a soil has been diminished by re- 

 moval of available plant foods, the soil is said to be 

 exhausted. This may mean merely that the productive- 

 ness has been reduced below the level at which it is 

 normally maintained, and to which it may have been arti- 

 ficially raised ; or it may mean that it has been reduced 

 to a point below the natural capacity of the soil. In 

 ordinary language, the soil may be said to be completely 

 exhausted when the fertility has been so reduced that it 

 ceases to give a profitable return for the labour employed 



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