IMPROVEMENT OF THE SOIL. IIT 



sandy, or calcareous soils, which liave much depth; but 

 they are injurious to rich, compact, argillaceous soils ; for 

 in such the noxious plants of which I have just spoken, 

 readily establish themselves. 



To ascertain the most favorable times for irrigation, it 

 is necessary to consult the state of the soil, and of the 

 plants ; when the earth is deprived of moisture to such a 

 depth that the plants languish, and begin to lose their 

 leaves, the favorable moment has arrived for watering 

 them. If allowed to remain in this state too long, they 

 cease to grow, and hasten to terminate their vegetation by 

 the production of fruits and flowers ; but these are always 

 feeble, poor, and incomplete, when produced under such 

 circumstances. 



The custom of allowing lands to lie fallow after having 

 produced several harvests, has descended from the re- 

 motest antiquity, and is still followed in the greatest part 

 of Europe. It has been thought necessary, that land, after 

 having been exhausted by two or three successive crops, 

 should be allowed to rest, or to remain in fallow during 

 one or two years, in order that it might have time to re- 

 cover its strength, or productive virtue. The necessity 

 for rest, imposed by nature upon all animals after con- 

 tinued action, undoubtedly gave rise to this practice; and 

 though the supposed analogy between living bodies, and 

 those that are not so, has no rational foundation, yet it has 

 confirmed the custom of fallowing which arose from it. 



However, I am far from believing that this was the only 

 cause for the adoption of the method of which I am 

 speaking: I believe that it may be attributed to the want 

 of hands for performing the labor of constant cultivation, 

 or to the impossibility of nourishing a sufficient number of 

 animals to furnish the necessary manures. 



The extent to which the cultivation of lands should be 

 carried, ought always to be in proportion to the popula- 

 tion to be fed by its products. It is to be presumed, that 

 when the globe had fewer inhabitants, the settlements 

 were made in those spots where the soil was most fertile, 

 and that when these were exhausted, they removed else- 

 where ; but when property came to be divided and marked 

 out, each cultivator confined his labors to such a por- 

 tion of land as would supply his wants: so that when it 

 was sufficient for him to cultivate one quarter, or one 

 third of his territory, he allowed the rest to remain un- 

 tilled. 



