CHAPTER 11. 



UNFAVORABLE PHYSICAL CONSTITUTION OF THE SOIL. 



I. LIMITED SOIL MASS. 



Root Curvature. 



For practical agricultural and forestry purposes, the question as to the 

 limitation of space in the soil plays a subordinate role when there is no 

 scarcity of food stuffs, since disturbances in nutrition, arising from the 

 overgrowth and rubbing of roots pressed tightly against one another, or by 

 their growth in crevices of rocks, have no agricultural significance. The 

 matter is quite different, however, in gardening and the cultivation of house- 

 plants by the plant lover. 



In these circles, however, opinions as to the influence of too small soil 

 space on the spreading of the roots are divided. Predominant and also 

 clearly expressed on the part of many agricultural chemists is the opinion 

 that the mechancial effect on roots, closely pressed on one another and 

 tangled by repeated curvature, has no influence on the thriving of the plants. 

 They think that in limited soil space only a scarcity of food may ever be 

 involved which would make itself felt very quickly and could be corrected 

 advantageously by fertilizing. The best proof should lie in the cultivation 

 of the so-called "market varieties" by commercial grow-ers in large cities, 

 who, conforming to public taste, grow very vigorous specimens of all blos- 

 soming plants (Fuchsias, Pelargoniums, Begonias, etc.) in relatively very 

 small pots. 



The fact is correct, the explanation, however, inconclusive. 



The restriction of a large root mass in a small space results first in the 

 increased production of lateral roots. This may be observed easily in water 

 cultures. If one of the large roots reaches the bottom of the glass container 

 and its tip is forced to bend around, new lateral roots are produced im- 

 mediately. NolP has given special study to this. He found that on the 

 bent portions of the main root, the lateral roots were formed only on the con- 



1 Noll, F., Ucljer den bestimmenden Einfluss der Wurzelkriimmungen auf 

 Enststehung und Anordnuiig: der Seitenwurzcln. Landwirtsch, Jahrbiicher XXIX 

 (1900). p. 361. 



