SOIL AND SURFACE CONDITIONS 125 



No greater fallacy was ever propounded than the theory 

 that forest trees can dispense with soil fertility. It is, of 

 course, quite true that surfaces will produce fine timber 

 vdiich cannot yield a profitable agricultural crop. The latter 

 may fail merely from sterility in the first few inches, or, 

 as is more often the case, through the rough, uneven, or 

 stony character of the surface preventing cultivation or 

 close grazing. But the fertility existing in the soil within 

 three or four feet of the surface, in the form of phosphates, 

 nitrates, potash, and water-holding capacity, will, if care- 

 fully examined, be found somewhat on a par with that of 

 ordinary agricultural or grazing land. The great difference 

 between forest trees and agricultural crops lies in the fact 

 that the former have a wider and deeper root range, while 

 trees can be established without that complete cultivation 

 of the surface which is necessary for the latter. Under a 

 forest canopy, again, moisture is preserved near the surface, 

 the physical condition of the soil is improved, and the 

 finer soil particles are not washed away, or soluble nutri- 

 tive material washed out so readily. These differences in 

 rooting, and requisite surface conditions between forest 

 and agricultural crops account in a large measure for 

 the apparent, rather than actual, power which forest 

 trees possess of growing under comparatively sterile soil 

 conditions. Grow seedlings on sterilised soil, or young 

 trees successively in poor, unmanured ground, and the 

 results are little better than would be the case with 

 ordinary farm or garden crops. Agricultural chemists 

 have shown that the quantities of ash constituents 

 removed by a crop of commercial timber are far less 

 than those removed in crops of oats, barley, or wheat 

 calculated per ton of raw material in each case. But 

 the fact appears to be overlooked that the soil under 

 the latter crops is artificially stimulated, or encouraged by 

 cultivation and manuring to yield up its soluble food- 



