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9 



ately ploughed in, and in the caurfe of cultivation is 

 well mixed with the foil, will produce feveral good 

 crops — more or fewer according to the quantity ap* 

 plied, and the nature of the foil. Twenty loads of 

 winter-made dung, of neat cattle, in which there is 

 commonly very little flraw or other litter, each load 

 filling the body of a cart drawn from the dung-heap 

 to the field, by one pair of good oxen, would be con- 

 fidered as a pretty good allowance of manure for an 

 acre ; yet, if evenly and clofely fpread, it would form 

 a cover but a little more than a quarter of an inch 

 thick. Were this thin cover to remain on the fur- 

 face, expofed to the fun and air, I fhould doubt 

 whether its efFecls would be vifible much beyond 

 the crop of the year : although if ploughed in as foon 

 as applied, the crops of four or five years would be 

 manifeftly improved. I am induced to think the 

 fpreading of dung on grafs land, the mofl wafteful 

 way in which it can be ufed. Only one exception 

 occurs to me : v/here a meadow well laid down in 

 good grafs lies fo low, and is fo moift, as to render it 

 improper to break it up. 



I take the opinion to be general, that manure 

 when ploughed in cannot be kept two near the fur- 

 face; on the common idea that its effence will be 

 difTolved and carried down by rains below the reach 

 of cultivated plants : but if the above theory be cor- 

 reel:, this notion is w^holly unfounded. 



So extremely minute are the mouths and vefTels 

 of plants, that the nourifhing parts of manure can 

 enter them only in a flate of dilTolution by water. 

 This element, fuppiied by rain, or otherwiie, to the 

 earth, during the feafon of vegetation, is, in a regular 

 courfe, afcending. The ellence of manures alcends 

 with it, and the portion not intercepted by the roots 

 ©f plants, efcapes into the air. 



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