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tity of water requisite to produce those juices, the addition of 

 manure will be useless. Manure is ineffectual towards 

 vegetation, until it become soluble in water ; and it would 

 remain useless in a state of solution, if it so abounded as 

 utterly to exclude air ; for in that case, the fibres or mouths 

 of plants would be unable to perform their functions, and 

 they would soon drop off by decay. 



The temperature of soils, which few planters take into 

 their consideration, is singularly improved by their being pul- 

 verized. Earths, as Griesenthwaite remarks, are among the 

 worst conductors of heat which we know ; consequently, it 

 would require a considerable time, ere the gradually increas- 

 ing temperature of spring could communicate its genial 

 warmth to the roots of plants, if their lower parts were not 

 heated by other means. To remove this defect, which al- 

 ways belongs to a close or dense soil, it is essentially neces- 

 sary to have the land open, so that there may be a free in- 

 gress to the genial air, and tepid rains of spring. 



Water, moreover, is known to be a condenser and solvent 

 of carbonic acid gas, which, when the ground is open, can 

 be carried immediately to the roots of vegetables, and prob- 

 ably contributes to their growth. But if the land be close, 

 and the water lie on, or near the surface, then the carbonic 

 acid gas, which always exists in the atmosphere, and is 

 carried down by the rains, will soon be dissipated. Let it be 

 observed also, that an open soil, besides being favourable to 

 the transmission of nutriment to the roots of plants, is like- 

 wise favourable to their extension, and thereby enlarges the 

 field whence nutriment is derived. Nor are these the only 

 benefits resulting from a friable soil : for, in addition to its 

 being the best adapted to supply the vegetables with food, it 

 is always most suitable for effecting those changes in the 

 manure itself, which are equally necessary to the prepara- 

 tion of such food ; and animal and vegetable substances, ex- 

 posed to the alternate action of heat, moisture, light and air, 



