CHAPTER XVI. 

 CONSERVATION OF SOIL MOISTURE. 



Fig trees are peculiarly susceptible to variations 

 of moisture, an inadequate supply affecting their 

 growth very quickly, while they respond to the 

 addition of normal quantities of water and recuper- 

 ate from drought quite readily. Trees that receive 

 no tillage often drop both leaves and fruit at least 

 once every summer, unless rain is frequent, and it 

 is not rare to find them dormant as many as four 

 times in one season. Their nature is to make rapid 

 growth, and the cellular tissue being coarse and 

 soft sap moves quickly, if given sufficient water, 

 making at least ten times the weight of wood that 

 the peach, pear or plum does in the same length of 

 time. Each pound of fiber requires about five hun- 

 dred pounds of water as a medium of transmission. 

 Water is the solvent of plant food in the soil and 

 the conveyer of that solution to different parts of 

 the trees, where, in new chemical combinations, it 

 changes to protoplasm, fiber, fruit or oil. Air and 

 sun extract it through the bark in containing evap- 

 oration while leaves exhale it from every point in 

 remarkable quantities. So important is the func- 

 tion of water that its conservation is one of the 

 primary objects of tillage. 



Illustrations of water movement in plants are 



