408 EUROPEAN AGRICULTURE. 



their roots torn asunder, by the violent disruption of the clods. 

 On the other hand, soils may be too fine, powdery, and friable, 

 being subject to be blown by the winds, being too little retentive 

 of moisture, and therefore liable to be severely affected by 

 drought, and failing to furnish a sufficiently strong hold for the 

 roots of those plants which spread themselves upon the surface. 

 A soil neither excessively consistent and close, nor excessively 

 friable, is undoubtedly to be preferred. All pent-up or stagnant 

 water, either on the surface or within the ground, is unquestion 

 ably prejudicial to a healthy vegetation ; and a freedom or porosity 

 of soil, so as to admit the free access of the air, is an important and 

 valuable feature. It seems to be a well-established fact, that a 

 newly turned up surface attracts moisture from the atmosphere : 

 and the more friable a soil is, the more surface it exposes to the 

 external air. In condensing the aqueous particles floating near the 

 surface, it thus procures for the plants growing upon it some of the 

 most important elements of vegetation. This is undoubtedly the 

 secret of the success in forwarding vegetation by frequent stirring 

 of the earth around plants even in time of drought, especially 

 plants with broad leaves, such as cabbages and lettuces, which, 

 by means of their expansive foliage, protect the earth underneath 

 them from the direct rays of the sun. 



4. TEMPERATURE OF SOILS. It is not my intention to give a 

 treatise on this subject, nor to extend my remarks beyond such 

 notices as will best explain the great improvements in cultiva 

 tion, or the management of soils, which have been undertaken 

 and accomplished here, and which may properly be said to con 

 stitute the glory of English husbandry. I proceed, then, to ob 

 serve, that another important property of soils may be said to be 

 their temperature. This is a matter of great importance in respect 

 to vegetation. Heat, as well as moisture, are both equally essential 

 to vegetable life and growth. The temperature of a soil would 

 seem to be very little under human control ; yet undoubtedly 

 much may be done in some ways for this object. At certain 

 seasons of the year, on the approach of frost, vegetation is arrested, 

 and at all seasons, in certain altitudes, cultivation is hopeless. In 

 Great Britain, this limit is reckoned at fifteen hundred feet above 

 the level of the sea; but the cultivation of wheat cannot be rec 

 ommended above six hundred feet. The main source of heat to 



