Depletion of Nursery Lands. 179 



When the crop is removed, even the roots are 

 taken out of the soil. For four or five years, the 

 land receives practically no vegetation which can rot 

 and pass into humus ; and then, the trees are dug 

 in the fall, often when the soil is in unfit condition, 

 and this fall digging amounts to a fall plowing. The 

 soil, deeply broken and robbed of its humus, runs 

 together and cements itself before the following sum- 

 mer ; and it then requires three or four years of 

 "rest" in clover or other herbage crop to bring it 

 back into its rightful condition. This resting 

 period allows nature if man grants her the privi- 

 legeto replace the fiber in the soil, and to make it 

 once more so open and warm and kindly that 

 plants can find a congenial root -hold in it. 



The following synoptical sketch of the causes of 

 the so-called wearing -out of nursery lands will 

 serve to bring the question of productivity of lands 

 into its proper relationships and perspectives:* 



a. The fertility of the noil. There are two analytical means 

 of determining the fertility of the land. One method deter- 

 mines the chemical constitution, and the other the mechani- 

 cal or physical condition. 



Chemistry determines the amount and kind of plant-food 

 in the soil, but it cannot tell just how useful this food may 

 be to the plant. This depends upon the physical condition 

 of the land, or upon the relation of the soil to warmth, 

 moisture, air and mechanical constitution. The plant is not 

 simply a passive agent, taking in the food which is pre- 

 sented to it, but it is actively engaged in searching for and 

 appropriating food. 



* L. H. Bailey, before American Association of Nurserymen, at Chicago, as 

 reported in Garden and Forest, June 24, 189B. 



