The Law of the Minimum 



which are the same as those of the manure, but in 

 another form, are dearer than those in the manure. 

 This means converting a product of higher value 

 into one of lower value without counting the losses 

 which arise in the process of transformation. 



Improvements. 



All modifications applied to the soil, whether 

 physical, physiological or chemical, are classed as 

 improvements, which, without being regarded as 

 manures, help to ameliorate and correct the soil 

 from an agricultural point of view. These improve- 

 ments are practically as necessary as the manures. 



Thus certain soils, poor in fertilising elements, 

 have gradually lost their humus as well, because of an 

 insufficient supply of farmyard manure. Cultural 

 operations, aided by bacteriological influence, and 

 natural oxydisation stimulated in most cases by 

 the use of lime, have impoverished the soil in 

 humus to such a degree that chemical manures alone 

 cannot make it fertile. Humus is of great import- 

 ance. Indeed, it is of such absolute necessity to 

 the soil that it must be considered as seriously as 

 manures. It does not constitute a manure in itself, 

 but soil in which it is lacking is practically sterile, and 

 it is chiefly in these soils that green manures are of 

 the greatest service. 



The Law of the Minimum. 



The importation of manure is regulated by the 

 Law of the Minimum. In point of fact, the crops 

 are proportionate — all conditions being equal — to 

 the amount of manure that the soil contains in the 



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