554 SOILS: PROPERTIES AND MANAGEMENT 



FIG. 62. Curve showing the increased growth of oats under the in- 

 fluence of constantly increasing amounts of phosphorus, that ele- 

 ment being in the minimum. 



The formula as proposed by Mitscherlich has been 

 questioned by several investigators, 1 who have shown 

 that a number of conditions, such as light, heat, and 



1 Pfeiffer, Th., Blanck, E., and Flugel, M. Wasser und Licht 

 als Vegetationsfaktoren und ihre Beziekungen zum Gesetze vom 

 Minimum. Landw. Ver. Stat., Band 76, Seite 211-223. 1912. 



Also, Maze, P. Reckerckes sur les Relations de la Plante 



