314 



Rain Falling at Rothamsted 



Fig. 2, however, brings out the interesting point that the ammonia 

 content of the rain is highest during May, June, July and August, 

 and lowest during January, February, March and April. 



The significance of this close relationship between rainfall and 

 ammonia content is discussed later. 



Bainfall in inches 



Nitrogen lljs. per acre 



asNHa 



as NoOs 



-1 1 \ 



3-5 



30 



25 



20 



V5 



1 



"1 r 



"1 r 



'V as_NiUate 



J L 



J L 



0-3 



0-2 



StPT OCT NOV DEC JAN FEB. MARCH APRIL MAY OUI 



Fig. 2. Monthly fluctuations in amounts of ammoniaeal and nitric nitrogen in rainwater, 

 Segt. 1, 1888-Aug. 31, 1916. 



The amount of nitrate in the rain. 



The quantity of nitrate in the rain is shown in Tables 2, 3 and 5 

 (pp. 332-4) ; over the whole period it is half that of ammonia and amounts 

 on an average to about one-tenth of a pound per acre per month 

 (O-ll lb. per acre to be exact), but it varies less than the ammonia. In 

 the Southern Hemisphere the proportions are reversed: at Lincoln, 

 New Zealand, the ammonia is much smaller in amount than the nitrate^, 

 and at Melbourne the nitrate is high in amount and fluctuates^; in the 

 Tropics also there is a considerable excess of nitrate over ammonia^. 



^ G. 'iray, Proc. Avslral. Assoc Sydney, 1888. 



' V. V,. Anderson, Journ. Boy. Meleorol. See, 1915, 41, 99. 



' J. 15. Harrison and J. Williams, Journ. Amer. Chem. Soc, 1897, 19, 1. 



