28 THE POTATO CROP. 



ford and lias) in Oxfordshire, Wiltshire, Gloucestershire, 

 and Worcestershire are those least suited to its growth, 

 and consequently potatoes are rarely seen as a field crop 

 in those places. The numerous varieties of the potato, 

 however, give it a great advantage over most of our culti- 

 vated plants, as it offers a selection of sorts suitable, more 

 or less, for every class of soils, some of which, indeed 

 the Yam, Irish Cup, Stafford Hall, for instance prefer 

 the stronger to the medium, and will give very productive 

 returns in the soils even of our clay formations. 



Within the last few years, our clay lands have undergone 

 a great mechanical change; thorough draining, subsoil 

 ploughing, and deep tillage have quite changed their 

 agricultural characters, and have reduced the difficulties 

 of their cultivation to about what the ordinary loams 

 presented some twenty or thirty years ago. For the gene- 

 ral cultivation, however, of the potato, the lighter class of 

 loams form the best soils the produce being of superior 

 quality, and generally equal in quantity to that from any 

 other description of soils. Calcareous soils are not 

 generally very productive potato soils ; they are usually 

 shallow, and, from the nature of the composition, dry, 

 while their geographical position in this country has 

 placed them also in a dry climate. The potato in this 

 respect some what resembles the oat (p. 144,voL i.); it requires 

 a considerable amount of moisture to support its natural 

 functions in a healthy condition. In order to secure this 

 moisture, therefore, which must be either obtained from 

 the soil or from the atmosphere, it is desirable that, if the 

 climate of the district in which it is cultivated be dry, the 

 soil selected for the crop should be of such a retentive 

 character as to supply sufficient moisture during its growth; 

 if, on the contrary, the climate be comparatively moist, 

 as we see on our western coast, then the soil apportioned 

 to the crop should be of a drier nature, as the leaf surface 



