164 The Principles of Fruit-growing. 



which has accumulated during the winter and spring; 

 it is capable of putting the soil in fine mechanical 

 condition, and this condition is as important as fer- 

 tility ; it warms up the soil and sets the plants 

 quickly to work ; it turns under the herbage when 

 that herbage is soft and moist and when there is 

 moisture in the soil, so that the herbage soon breaks 

 down and decays. All catch crops on the orchard 

 should be plowed under just as soon as the ground 

 is dry enough in the spring, for these crops soon 

 pump the water from the soil and cause it to bake 

 and cement together, and the longer they remain the 

 more difficult it is to cause them to rot when turned 

 under. Hard and woody herbage, plowed under late 

 in the season, may remain as a foreign body in 

 the soil all summer, breaking the connection be- 

 tween the upper and the lower soil, and thereby 

 preventing the upward movement of the water and 

 causing the top soil to completely dry out. The 

 chief value of crimson clover, rye, or other catch 

 crop in the orchard lies in its fall growth and 

 its protection of the soil in winter, not in its 

 growth in spring. 



Few people are aware that the season of growth 

 in most woody plants extends scarcely to midsum- 

 mer. It is worthy of note that most, if not all- 

 native trees and shrubs cease growing very early in 

 the season. This is no doubt one reason why they 

 are able to endure the winter. Plants which cease 

 growing early, and which mature their wood well, 

 are often said to be determinate in their growth, 



