114 THE ART OF CULTURE. 



to the loss of humus ; it is the mere consequence of the exhaus- 

 tion of alkalies, and of other essential ingredients. 



Let us consider the condition of the country around Naples, 

 which is famed for its fruitful corn-land ; the farms and villages 

 are situated from eighteen to twenty-four miles distant from one 

 another, and between them there are no rqads, and consequently 

 no transportation of manure. Now corn has been cultivated on 

 this land for thousands of years, without any part of that which 

 is annually removed from the soil being artificially restored to it. 

 How can any influence be ascribed to humus under such cir- 

 cumstances, when it is not even known whether humus was ever 

 contained in the soil ? 



The method of culture in that district completely explains the 

 permanent fertility. It appears very bad in the eyes of our 

 agriculturists, but there it is the best plan that could be adopt- 

 ed. A field is ploughed once every three years, and is in the 

 intervals allowed to serve as a sparing pasture for cattle. The 

 soil experiences no change in the two years during which it lies 

 fallow, further than that it is exposed to the influence of the 

 weather, by which a fresh portion of its alkalies is again set 

 free or rendered soluble. The animals fed on these fields yield 

 nothing to them which they did not formerly possess. The weeds 

 upon which the cattle live spring from the soil, and the materials 

 returned to it in the form of excrements must always be less in 

 quantity than those removed as food. The fields, therefore, can 

 have gained nothing from the mere feeding of cattle upon them ; 

 on the contrary, the soil must have lost some of its constituents. 



Experience has shown in agriculture that wheat should not be 

 cultivated after wheat on the same soil, for it, as well as tobacco, 

 is of the class of plants which exhaust a soil. But if the humus 

 of a soil gives it the power of producing corn, how happens it 

 that wheat does not thrive in many parts of Brazil, where the 

 soils are particularly rich in this substance, or in our own climate, 

 in soils formed of mouldered wood ; that its stalk under these 

 circumstances attains no strength, and droops prematurely ? The 

 cause is this, that the strength of the stalk is due to silicate of 

 potash, and that the corn requires certain phosphates, and these 

 substances a soil of humus cannot afford, since it does not contain 



