COMPARATIVE FERTILITY. 37 



soil on the River Parrott, stretching along the 

 sea-board. It is in permanent pasture, and is 

 let for grazing at 4. to $ of rent an acre. 

 Some of the marsh-lands of Sussex and Kent 

 are of equal fertility. And on certain limestone 

 lands, not alluvial, in various parts of the 

 country, both east and west, feeding pastures 

 of great fertility are met with. Such lands, as 

 they require neither labour nor manure, yield 

 the largest rents to their owners. The profit 

 to the stock-feeder beyond the rent paid to the 

 landowner depends on the skill with which he 

 conducts his business. The minimum of fer- 

 tility may be exemplified by a bleak mountain 

 pasture, where ten acres will barely maintain a 

 small sheep. 



The artificial maximum and minimum of and of an 



average 



fertility which result from the treatment of soils soil un- 



manured, 



of the same quality is more instructive, and and 



specially 



may be clearly exemplified by taking two of manured, 

 the experiments which have been carried on 

 by Mr. Lawes of Rothamsted, in Hertford- 

 shire, for the last thirty years. Confining the 

 comparison to the average of the last twelve 



