26 AMERICAN AGRICULTURE. 



rich in vegetable mould still more, while peats absorbed a 

 much larger per cent, than either. 



Davy also found, that the same quantity of very fertile and 

 perfectly dry soil on exposure gained 18 Ibs in one hour ; a 

 good sandy soil under the same circumstances absorbed 11 

 pounds ; a coarse inferior sand, 8 Ibs, and an almost worthless 

 heath gained but 3 Ibs. 



The power of soils in retaining water, is somewhat pro- 

 portionate to their power of absorbing it : 



Of its own weight. 



Quartz sand is saturated when it contains 24 per ct. 

 Calcareous sand " " " 28 " 



Loamy soil " " " 38 " 



Clay loam " " " 47 " 



Peat (about) " " 80 " 



It is thus evident that perfection is not obtained in either 

 sandy, gravelly, clay or peat soils, as they are characterized 

 in the classification wo have assumed. It is only when they 

 have been improved by partial admixture with each other, 

 and charged with the proper quantity of vegetable manures, 

 and the salts which are requisite for their fertility ; when 

 they have been drained wherever necessary to free them 

 from stagnant water, whether upon or within the soil, or to 

 remove any noxious springs which sometimes contain mat- 

 ters in solution injurious to vegetation ; and finally when the 

 subsoil is in the proper condition to facilitate the free passage 

 of the roots in every direction it is only when all these 

 conditions exist, that the. fullest products from soils can be 

 realized. 



It is absolutely essential to profitable cultivation, that all 

 the earthy substances required by the crops should exist in the 

 soil in sufficient quantities, and in an accessible form to 

 supply its wants. The proportions may be various, one 

 sometimes greatly predominating over another, as is suffi- 

 ciently obvious in the equally productive powers of good 

 clays, sands and peats; yet in every instance it will be found, 

 unless owing to a heavy coating of manures, and a peculiarly 

 favorable season, that they can be relied on for such constant 

 results, only when they have been so ameliorated as to 

 approximate towards the character of loams. 



