86 



NITROGENOUS MANURES 



[chap. 



tinctly seen in a prolongation of growth far into the 

 autumn ; on the plots receiving little or no nitrogen 

 the leaves turn yellow and begin to fall in early October, 

 when the mangolds on the high nitrogen plots are still 

 putting out fresh growths of green leaves and showing 

 no signs of entering into a resting period. It is hardly 

 possible to illustrate this effect by figures, but analysis 

 of the mangolds from these plots demonstrate the 

 preponderance in the roots grown with excess of 

 nitrogen of such unclaborated materials as the nitrates, 

 amides, and reducing sugars, associated also with a 

 higher proportion of water. 



Table XXV. — Composition of Barn Field Mangolds, 1902. 



In November the roots grown with excess of 

 nitrogen approximate in composition to normally 

 manured roots taken in August, when still growing 

 vigorously. 



One of the most important effects upon plants of 

 an excess of nitrogen is their increased susceptibility 

 to fungoid attacks of all kinds; for example, rust is 

 always much more abundant upon wheat which has 

 been heavily manured with nitrop-en, just as it appears 



