DEPENDENT UPON NlTKOdFAOlS MAMIM'.s <.'.» 



A. Ejfect of Nitro(h'n()ii.< Munun.^. Tlic nianu'fl wm/fl, 

 being a plant with a large leaf development, was at one time 

 to a certain extent regarded as one of the restorative crops, 

 capable, with its large area of leaf, of drawing npon the 

 atmospheric nitrogen and thus rendering itself independent of 

 nitrogenous manures. Though it was obvious that nitrogenous 

 manm-es had a powerful effect even upon leafy crops, it was 

 urged that the benefit consisted in starting the crops, which, 

 as soon as they had attained their proper development of leaf, 

 would continue to feed themselves by drawing upon the 

 nitrogen of the atmosphere. It was with the view of testing 

 the truth of this opinion that the manuring on Plots 7 was 

 arranged. They receive superphosphate and sulphate of 

 potash as mineral manures, together with a small quantity of 

 nitrogen, 36! lb. per acre of ammonium-salts conUiining 7'8 lb. 

 of nitrogen per acre, i.e., about one-eleventh of the amount 

 applied to the plots in Series A. 



On the hypothesis indicated above, the small quantity of 

 nitrogen would act as a starter, and establish the plant, which 

 should then be able to maintain itself upon atmospheric 

 nitrogen. 



The results, however, yielded by Plots 7 as compared with 

 Plot 6 show this opinion to be mistaken, the small addition of 

 7'8 lb. of nitrogen per acre produces an increase of crop of 1'4 

 ton per acre only, whereas a further 86 lb. of nitrogen raises 

 the crop by 87 tons per acre. 



Thus the opinion may be dismissed that the mangel plant 

 when once started can become independent of the nitrogen in 

 the soil and manure. 



AVe may next pass on to a consideration of the effects of 

 the varying forms and amcjunts of nitrogen when use<l with- 

 out any mineral manuring, l.r., on Plots 8, where no standard 

 manures are applied. The entirely unmaiunvd plot (8 ()) 

 has produced an average crop of :) !) tons of roots only, 

 which is increased by the application of 86 H). nitrogen in th.- 

 ammonium-salts to T)!* tons, and l)y 08 lb. of nitrogen in tlie 



