Inter-Planted Crops 117 



the fertility of the soil. If need be, he should fertilize the 

 land accordingly. Otherwise, the growing of the filler-crop 

 can only be to the material disadvantage of the fruit-trees. 



COVER-, GREEN-MANURE, AND SHADE-CROPS 



Because of the close similarity of these groups of crops 

 and the objects for which they are used in orchards, they may 

 well be considered together in the present discussion. The 

 distinction between them, when it exists, has been pointed 

 out in another place (pages 112-113). 



Though clean tillage for peach orchards during the first 

 part of the season or until some time in July is the general 

 practice, the use of cover- and green-manure crops is of 

 fundamental importance and in many cases even of neces- 

 sity if the orchards are well maintained. 



Doubtless the relation of these crops to the physical 

 condition of the soil through the addition of humus repre- 

 sents their most important function. This interrelation of 

 the humus-content of the soil to its physical condition, and 

 in turn its physical condition to its fertility through the 

 chemical and biological activities that are either promoted 

 or retarded by this condition, are too well recognized, even 

 though they may not be fully understood, to require ex- 

 tended comment here. It will suffice to establish the fact 

 that peach orchards often need the ameliorating effects on 

 the soil of cover- and green-manure crops and not infre- 

 quently suffer because of their lack. 



It will help the reader who has to meet the problems 

 incident to the use of these crops to have in mind rather 

 definitely their more important effects on the soil and the 

 part they play in successfully maintaining or improving its 



