266 THE ESSENTIALS OF AGRICULTURE 



prevent sunscald of the trees and fruit and to decrease the dan- 

 ger of injury from frosts by retarding the opening of the fruit 

 buds in the spring. In comparatively level districts, orchards 

 should be located on the higher ridges. 



344. Air drainage. In some localities air drainage is as 

 important as water drainage. Cold air is heavier than warm 



FIG. 128. Shading delicate plants 



A Cuban grove, in which coffee (in flower) and tobacco are grown in the shade 

 of orange and palm trees 



air, and it drains to the lowest level just as water flows to the 

 lowest level. Frosts are more common in low places, because 

 the heavier, cold air has settled there. Consequently, orchards 

 should not be planted in low, frosty places. In hilly regions 

 the bleakest points may expose the orchard to winds that are 

 too severe, and in such localities the sheltered slopes and valleys 

 are preferable, especially if a still lower ravine or river bed is 

 adjacent to drain off the cold air on frosty nights. The depth 



