72 The Principles of Fruit-groioing 



in three gave almost as good results as cultivation and 

 cover-crop yearly." 



These results of experiments are confirmed by the 

 extensive apple-orchard surveys made by Warren in New 

 York, in> which the actual experiences of growers are 

 tabulated and compared. 



Allowable use of sod. 



Notwithstanding these authoritative findings, sod may 

 hold a very important part in the present management of 

 an orchard of apples or pears. In many cases, it is impos- 

 sible to secure the time and labor to keep all the orchards 

 in a state of good tilth, and it may be better to till one part 

 thoroughly and then seed it down for a short time than 

 to try to till the whole area indifferently. This is partic- 

 ularly true in clay lands, in which the period of useful 

 plowing in the spring is very short. In this way, one may 

 practise a rotation of tillage in different parts of the plan- 

 tation; but care must be taken that no part remains in sod 

 so long that the trees become weakened or injured. In 

 other cases, it is necessary to hold the orchard in sod 

 to prevent serious washing on steep slopes. In hillside 

 orchards, strips of sod may be left across the slope alter- 

 nating with tilled areas, and the areas may rotate from 

 year to year. Some orchard areas are so steep or so stony 

 (Fig. 8) that tillage is impossible; in this case, the stones 

 provide the smiace mulch. 



The results with sod depend largely on the other 

 treatment that the orchard receives. The trees should have 

 at least as good care in pruning, grubbing, spraying, and 

 otherwise as they receive in tilled lands. The grass should 

 not be cut for hay; it may be mown and allowed to he as 

 a mulch; or the area may be pastiu-ed with hogs or sheep. 



