248 GEOLOGY AND CHEMISTRY OF SOILS. 



prevented from decomposition. In some cases a bed of sev- 

 eral feet in thickness is almost pure vegetable matter, and 

 becomes hardened into peat fit for fuel ; in others, the tex- 

 ture is loose and spongy. 



Properties. The properties of peat soils vary according 

 to the character of the surrounding soils ; where the earthy 

 materials are clay they make a compact soil, retentive of wa- 

 ter, and capable of being made very productive ; when the 

 earth is silica, they are more light and spongy, and permit the 

 water to pass off. When mixed with calcareous matter they 

 are reduced to a fine black mould ; if the surrounding rocks 

 contain pyrites they often become acid ; if near the ocean, 

 they become mixed with sea-salt. They sometimes contain 

 bitumen. The properties therefore depend upon their tex- 

 ture, the earths with which they are combined, and the salts 

 which they contain. Analysis is the only sure means of 

 showing their exact composition. 



Mode of improvement. Peat swamps must first be drained, 

 to carry off the water, which renders them soft and spongy ; 

 they will then become hard. Siliceous and aluminous earth 

 may then be spread upon them ; yard-manure and lime or 

 ashes will also improve their properties by decomposing the 

 vegetable matters. Some recommend paring the surface 

 and burning it ; then by scattering the ashes over the soil, all 

 the acid properties will be neutralized. The peat itself makes 

 an excellent compost manure for the uplands, and should be 

 carried into the barn-yard and mixed with yard and stable 

 manures. 



Degree of Jertility. Peat soils are, or can be made very 

 fertile ; the want of fertility is not owing to any deficiency of 

 vegetable matter, but to their texture and to the want of 

 this matter in a soluble state, so as to nourish plants. When 

 this is converted into vegetable food and the texture im- 

 proved by draining and mixture of other earths, they are 

 the most profitable of all soils ; especially is this the case 



