78 SUCCESS WITH small fruits. 



tain limits, of course), as the difference of temperature be- 

 tween winter and spring is the exciting cause of the ascent 

 of the sap." In other words, too much water in the soil 

 may cause no marked difference between the underground 

 climate of winter and spring. 



Dr. Madden shows, moreover, that excess of water keeps 

 out the air essential not only in promoting chemical changes 

 in the soil itself and required by the plants, but also the air 

 which is directly needed by the roots. Sir H. Davy and 

 others have proved that oxygen and carbonic acid are ab- 

 sorbed by the roots as v/ell as by the foliage, and these 

 gases can be brought to them by the air only. 



Again, drainage alters the currents which occur in wet 

 soil. In undrained land, evaporation is constantly bringing 

 up to the roots the sour, exhausted water of the subsoil, 

 which is an injury rather than a benefit. On the other 

 hand, the rain just fallen passes freely through a drained 

 soil, carrying directly to the roots fresh air and stimulating 

 gases. 



Wet land also produces conditions which disable the foli- 

 age of plants from absorbing carbonic acid, thus greatly 

 decreasing its atmospheric supply of food. Other reasons 

 might be given, but the reader who is not satisfied had 

 better set out an acre of strawberries on water- logged land. 

 His empty pocket will out-argue all the books. 



The construction of drains may be essential, for three 

 causes : ist. Land that is dry enough naturally may lie so 

 as to collect and hold surface water, which, accumulating 

 with every rain and snow storm, at last renders the soil sour 

 and unproductive. 2d. Comparatively level land, and even 

 steep hillsides, may be so full of springs as to render drains 

 at short intervals necessary. 3d. Streams, flowing perhaps 

 from distant sources, may find tlieir natural channel across 



