William Wkik 



251 



case the amount was the same and in two cases the amount was less 

 but on both these occasions the crop (mustard) failed on one soil. 



Table VIII. Nitrogen in soils and crops. 



Durini; the winter of 1914-1915 additional quantities of the same 

 two soils were extracted and used in vegetation experiments in precisely 

 the same way as in the previous sets. In this instance th(! acid and 

 alkali treatment removed a somewhat smaller amount of the soluble 

 humu.s matter from both soils. 



Table IX. 



Total Nitrogen in Untreated Allotment Soil, per cent. ■.'!2(! 



,, ,, in E.xtracted ,, ,, ,, ■2()() 



,, „ removed, per cent. ... ... ... ■120 



Percentage reduction ... ... ... ... ... 'MyS 



Total Nitrogen in Untreated Field Soil, per cent. ... -177 



„ „ in Extracted ,, „ „ ... -107 



„ „ removed, per cent. ... -070 



Percentage reduction ... ... ... ... ... 39-5 



In the case of the Allotment Soil, wheat was sown in the pots on 

 November 12th, 1914. The plants in the untreated soil grew and 

 tillered better than the others but in both sets the crops were good. 

 They were cut when nearly in full ear on 2.3rd June, 1915. 



Wheat was not sown in the Harpenden soils till 25th March, 1915, 

 so that the growing period was much the same as for the wheat crops 

 of the previous season. It was cut on 23rd June, 1915, when the ears 

 were beginning to come out. 



The yields were comparatively poor but during the whole time the 

 plants in the extracted soil were greener in the leaves and did better 

 than those in the untreated. The following figures were obtained for 

 the four soils on cutting and drying : 



