E. J. Russell and A. Appleyard 



405 



Our results are : 



Field 

 Broadbalk, fallow 

 dunged ... 



Broadbalk, fallow 

 unmanured 



Great Harpenden . 



Nitrate 



before 



ploughing* 



] 18 



j 27 



) 12 



) 14 



Date of 



ploughing, 



1915 



May 12 



July 26 



May 17 

 July 26 



Sept. 10 



Nitrate after ploughing 



June 10 

 Aug. 6 



June 10 

 Aug. 6 



Oct. 1 



20 

 28 



14 



12 



10 



July 14 

 Aug. 17 



July 14 

 Aug, 17 



Oct. 29 



28 

 32 



10 

 12 



13 



Sept. 6 

 Sept. 3 



33 



12 



* N as nitrate, parts per million, mean of surface and subsoil contents. 



Toulaikoffi working on the black earths of Samara in the semi-arid 

 region of Russia has obtained a much sharper connection between 

 nitrate accumnlation and ploughing. His results are : 



Nitric Nitrogen in different Fallows : parts of N per 

 million of dry soil. {Five years'' averages.) 



The black fallow had been ploughed in autumn, while the April, 

 May and June fallows were ploughed about the 20th of their respective 

 months. It will be observed that the nitrates show little sign of change 

 till after the ploughing but they then rise rapidly. 



It is interesting to note that ToulaikofE's figures are of the same 

 order as ours but lower : in his case, however, the addition of dung 

 did not raise the nitrates while in ours it causes a great increase. 



1 Toulaikoff, N. M. (Director. Besentchuck Agricultural Experimental Station), in 

 Selskoye Khosiaistvo Liesovodstvo, 1915, 247, 35-65 (abstract in Bull. Int. Inst. Rome, 

 1915, 6, 797). Toulaikoff's figures are given as mgms. N2O5 per kg. of dry soil, but we 

 have converted them to parts of N per million. 



Journ. of Agric. Sci vni 



27 



