124 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 



" Table V. — Amount of the more important constituents of plant 

 food removed fr07n an acre of laud by the annual produce of 

 certain crops and trees. 



"(From Warington's Chemistry of the Farm, 15th ed., pp. 72-74-, except as to 

 the nitrogen in Scots pine, which is taken from Ebermayer's Physiolo- 

 gische Pflanzeuchemie, p. 67.) 



" Not only do trees require but little plant food, but they have 

 special powers of collecting even that little, inasmuch as their 

 root range is immensely greater than that of grass or of farm 

 crops. Thus it comes about that one may find a crop of timber 

 of maximum quantity and quality on land of a rental value of 

 a few pence per acre, and in support of this statement there is 

 abundant evidence in the volumes of the proceedings of the 

 various public inquiries which have been held. 



"Speaking generally, and with very few exceptions, the land 

 that it is suggested may with advantage be afforested is at 

 present grazed by mountain sheep. Even below the upper limit 

 of profitable tree-growth in this country — 1500 feet — it is 

 seldom that such land can support throughout the year more than 

 one sheep to two acres. The tangible produce that finds its 

 way to market is the four months' old lambs, minus such female 

 lambs as are necessary to maintain the flock at its numerical 

 strength, plus a proportion of the ewes — the "draft" or "cast" 

 ewes. In addition to this meat there is the yield of wool, of 

 which the annual supply for the class of sheep in question may 

 be put at 4 lbs. per head, or 2 lbs. per acre. 



"The Royal Commission that have recently reported went in 

 considerable detail into the relationship of afforestation to meat 



