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 
ehief value of crimson clover, rye, or other catch 
crop in the orehard 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, 
