EFFECT OF EXCESS OF MTL'OCKX lo:} 



Uromi/ces heta>, and to a Tonila, wliicli is abundantly developed 

 on tlie mangels on the plots receiving an excess of nitrogen 

 but is not present elsewhere in the field. 



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. 



The above appearances are not confined to the phjts 

 receiving very large amounts of nitrogen ; it is rather a 

 question of the relative excess of nitrogen as compared with 

 the quantity of available alkalies, especially of potash. Thus 

 the plants on Plot 1 AC are particularly bad, as they receive 

 the maximum amount of active nitrogen in addition to the 

 dung, whereas the plants on Plot 2 AC, which receive the 

 same nitrogen but also sulphate of potash, arc comparatively 

 healthy. The plants receiving nitrate of soda as a source of 

 nitrogen show less damage than those receiving an equivalent 

 amount of nitrogen in the shape of ammonium-salts. Super- 

 phosphate, in the absence of alkaline salts, seems to increase 

 rather than diminish the injurious effects. 



B. Effect of Mineral Manures. The effect of the difierent 

 mineral constituents of a manure upon the mangel crop can be 

 seen by an examination of the results yielded by Plots 4, 5, 

 and 6. Plots 5 receive superphosphate only at the rate of 

 392 lb. per acre. Plots 6 receive 500 lb. per acre of sulphate 

 of potash in addition to the superphosphate, while on IMots 4 

 the other alkalies which are taken up by the plant are added 

 in the shape of 200 lb. of sulphate of magnesia and 200 lb. of 

 common salt per acre. In the cross-dressings of nitrogenous 

 manures it should be noticed tliat all the plots in Series N 

 receive soda through the use of nitrate of soda, whereas the 

 other nitrogenous dressings, being either ammonium-salts or 

 rape cake, provide no appreciable amount of alkaline sidts. 



The following diagram (15) shows the results given in 

 Table XL., but set out in a graphic form, for Plots 8, 5, 6, and 



