HORTICULTURAL RESEARCH 289 



11 worked " fruit-tree at this depth in the soil. Quite the contrary. 

 The beneficial effects observed were due entirely to the fact that 

 these paradise stocks were capable of throwing out new roots 

 from their stems, whereas the stems of ordinary apple-trees have 

 in most cases no such power, so that if buried in the way 

 described, the original roots would die off as in the case of the 

 paradise stock but no fresh root-system would be formed in 

 substitution. Even when crab stocks were used in place of 

 paradise stocks, the results were found to be unfavourable, for 

 the crab stocks do not throw out roots as easily as do the 

 paradise stocks. It may be noticed, too, that the behaviour of 

 the individual paradise stocks varies considerably, one of the six 

 shown in Fig. 7 having made very little growth, because the stem, 

 for some reason or other, was incapable of producing new roots. 



It is evident from these results that there is a particular depth 

 below the surface which is the most favourable for root-forma- 

 tion. This must vary with the nature of the soil and with the 

 habit of the plant but will generally be from 6 to 12 inches 

 below the level of the soil. This, as a rule, will be the best 

 depth at which to plant a young tree ; but small variations of, 

 for instance, 4 inches in either direction have been found to be 

 quite immaterial, for in such cases the new roots that are formed 

 have no difficulty in making their way to the level at which they 

 flourish best. 



High planting, in another sense, is sometimes adopted, the 

 roots being placed at the ground-level but covered up with earth 

 in the form of a mound 6 inches or more high. This is advan- 

 tageous if planting has to be done in a w T et locality. At present 

 we are investigating its effect as a means of minimising attacks 

 of canker : so far the practice seems to have led to good results 

 from this point of view but it would be premature to draw any 

 definite conclusions yet. As to its effect on the general behaviour 

 of the tree, this varies with the season, being, as might be 

 expected, good in a wet season and bad in a dry one. No one, 

 of course, would think of planting a tree in this way in a light 

 sandy soil. 



Aeration of the Soil 



The depth at which roots will flourish best is dependent, no 

 doubt, on the conditions prevailing in the soil with respect to air 

 and moisture. Aeration is necessary for the oxidation of organic 

 matter in the soil and of that thrown off from the roots, the 



