MANGELS 



13 



Thus, towards the end of October, the plots receiving the excess of 

 nitrogen present a very unhealthy appearance ; a large proportion of the 

 plants seem scorched and withered as regards the outer leaves, and only 

 show a cluster of small dark green active leaves at the heart. 



WITH COMPLETE MINERALS. 



(Plots 4). 



WITH DUNG. 

 (Plots 1). 



Series 



Fig. 3. — Mangel Wurzel. Effect of increasing amounts of Nitrogen. Average 

 Produce of Roots per acre, 1876-1902. 



O = No Nitrogenous Manure. I N = 86 lb. Nitrogen as Nitrate of Soda. 



A = 86 lb. Nitrogen as Ammonium-salts. | C = 98 lb. Nitrogen as Rape Cake. 

 AC = 98 lb. Nitrogen as Rape Cake, and 86 lb. Nitrogen as Ammonium-salts. 



Effect of Mineral Manures 



The effect of the different mineral constituents of a manure upon the 

 mangel crop can be seen by an examination of Plots 4, 5, and 6. 



The great increase of crop comes as a rule when potash is added to 

 the superphosphate, and is to be correlated with the fact that the mangel is 

 essentially a sugar-producing plant, and that large supplies of potash seem 

 to be essential to the processes in the plant which result in the formation 

 of sugar and similar carbohydrates. 



• The effect of potash and of the other saline manures is plainly visible 

 in the appearance of the plants themselves. On the plots receiving potash 

 the plant begins to ripen early, the leaves turn yellow and become flaccid, 

 so that in October these plots may be seen outlined from the rest by their 

 lighter tint. 



