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should be heaped about the base of the trees, 

 and the manure should be spread early 

 enough in the fall to assist them in ripening 

 their fruit and preparing the bloom of the 

 succeeding year, or late enough in the spring 

 to avoid the accidents of frost. The Greeks 

 do not make use of manure, except when 

 chance conducts a flock of sheep to the foot 

 of an Olive , which immediately becomes 

 conspicuous by a richer vegetation. 



When substances proper for manure can- 

 not be obtained in the requisite abundance, 

 the deficiency may be supplied by sowing 

 grasses or cereal plants, and ploughing in 

 the green herb. The intelligent cultivator is 

 aware that he thus not only renders back 

 what was extracted from the earth, but, as 

 vegetables imbibe nourishment from the at- 

 mosphere , and as their roots arrest nutri- 

 tious particles which would have escaped by 

 filtration or evaporation, that he enriches the 

 soil by an accession of new matter. 



Vegetable chemistry has probably impor- 

 tant secrets to reveal in this part of practical 

 agriculture. As a soil may be exhausted by the 

 continued growth of the same plants while it 



