FERTILIZERS IN FRUIT GROWING 119 



roots will be even, but perhaps not so extensive. If, on the 

 other hand, you use the same amount of fertilizer in a third 

 pot, but mix it with the 3 inches of soil next the bottom, 

 you will find this layer filled with fine rootlets, which are 

 the effective part of the root, while the root system is very 

 sparsely spread elsewhere in the pot. If the fertilizer is 

 mixed with the 3 inches of soil next the surface, or is put 

 in a section of soil on one side the result is the same. Just 

 so surely as a hungry cat follows the milk pan, the roots of 

 any plant follow after the plant-food in the soil, and when 

 they find it, the feeding roots go all through it, and stop 

 hunting elsewhere. 



The main roots of any perennial plant are, of course, 

 fixed and immovable in the soil from year to year. Such 

 roots have, for the most part, lost all power of taking up 

 plant - food. They are woody and covered with a dead 

 bark, somewhat like the trunk of the tree. The real work 

 of imbibing food and drink is done by the slender rootlets 

 and by the root hairs, and these are constantly making new 

 growth. Besides this, at certain times, whole new roots 

 start. Whenever clover, for instance, is cut, a sudden new 

 growth of roots takes place before any growth appears 

 above ground, and it is quite certain that^ with each renewal 

 of tree growth above ground, or before such growth, there 

 is a new growth of fibrous roots below ; that is, a fruit tree 

 occupies new tracts of soil as well as pushes fresh roots into 

 the old root pastures. These tender roots lay hold of par- 

 ticles of soil so strongly that they cannot be pulled apart, 

 the acid plant-juice can gnaw the rock fragments so as to 

 etch them where it has taken out plant-food, and all the 

 gathered material is passed on through the young sapwood 

 chiefly to the leaves, where it is used for building up the 

 plant, also for laying by a reserve of food in the stem or 

 root to be used for the early spring growth or for perfect- 

 ing fruit. Experiments have shown that a fruit tree may 

 lay up a reserve of food in its trunk and root, which may be 

 carried there for more than one season, to supply, perhaps, 

 the extra draft made on the tree in a great bearing year. 



Next we come to inquire how much plant-food, of the 

 sort supplied in fertilizers, a fruit tree or an acre of fruit 



