64 CHYMISTRY APPLIED TO AGRICULTURE. 



plants, the agriculturist will find his account in prevent- 

 ing the dissemination of their seeds, which, by propagat- 

 ing in the fields, deprive the crops of the nourishment of 

 the soil. The turf, that borders fields and highways, may 

 be made to answer the same purpose, by cutting it up with 

 all the roots and the earth adhering to them, rotting the 

 whole in a heap, and afterwards carrying the mass upon 

 the fields, or what is still better, by burning it, and dress- 

 ing the land with the products of the combustion. 



If straw did not serve as beds for animals, and did not 

 contribute, at the same time, to their health and cleanliness, 

 it would be better to cut the ears of corn and leave the 

 stalks in the fields ; since they serve only as absorbents of 

 the true manures. 



It is always said that barn-yard manure, besides its nu- 

 tritive virtues, possesses the advantage of softening hard 

 lands, and rendering them permeable by air and water. I 

 do not deny the truth of this ; I even acknowledge that it 

 owes this property almost entirely to the straw which it con- 

 tains ; but the same effect would be produced by burying 

 the straw upon the spot. 



Besides the characteristic of providing plants with food, 

 the various kinds of dung possess other qualities, which 

 add to their fertilizing powers. Dung, as it is applied to 

 the ground, is never so much decomposed as to have ceased 

 fermenting; and from the moment it is mixed with the 

 soil it produces in it a degree of warmth favorable to vege- 

 tation, and serving to guard the young plants against the 

 effects of those sudden returns of cold in the atmospheric 

 temperature, which are so often experienced. On account 

 of the viscous fluids which it contains, dung is not easily 

 dried, unless it be in contact with the air. It therefore 

 preserves the roots of the plants in a state of moisture; 

 and supports vegetation at those periods, when, without it, 

 plants would perish from drought. It likewise contains 

 many salts which are transmitted by water to plants, serv- 

 ing to animate and excite their functions. The various 

 kinds of dung, mixed with earth, may be considered in 

 the light of amendments to the soil ; and in this view they 

 ought to vary according to the nature of the earth to be 

 improved. Compact soils require to be separated and 

 warmed ; they require, then, those manufes which have 

 been but slightly fermented, and that are the richest in 

 salts. Calcareous and light earths require oily manures, 



