SOILS. 29 



or common sand did not gain a pound; calcareous sand 

 gained 2 Ibs. ; loamy soil, 21 Ibs. ; clay loam, 25 Ibs. ; such 

 as were rich in vegetable mold, still more ; while peat ab- 

 sorbed a much larger per cent, than either. 



Davy also found, that the same quantity of very fertile 

 and perfectly dry soil, on exposure, gained 1 S Ibs. in one 

 hour ; a good sandy soil, under the same circumstances, ab- 

 sorbed 1 1 pounds ; a coarse, inferior sand, 8 Ibs., and an 

 almost worthless heath, (gravelly soil), gained but 3 pounds 



The capacity of soils for retaining water, is somewhat 

 proportionate to that of absorbing it : 



Of its own weight. 



Quartz sand is saturated when it contains 24 per cent. 

 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 we 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 rnat- 

 ters in solution, injurious to vegetation ; and finally, when the 

 subsoil is in the proper condition to facilitate the free admis- 

 sion and escape of moisture and air, and the extension of 

 the roots in every direction it is only when 'all these con- 

 ditions -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 their 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 a soil can be relied on for 

 such constant results, only when it has been so ameliorated 

 as to approximate towards the character of loams. 



