E. J. KUSSELL AND A. Al'I'LEVAKD 



27 



be got into a tilth for the seeding and it speedily becomes compact and 

 less favourable to gaseous diffusion. 



During the current year the top half of Broadbalk field has been 

 fallowed and a comparison was made between the fallow and the 



JuiieJuly Aug.Sept.Oct. Nov. Dec. Jan. Feb. .Mar. .\pr. Maj- June July Aug.Sepf. 

 Fig. 11. Curves showing percentage of CO, in air of Hoos wheat and fallow plots. 



cropped portions of the dunged plot. Here the conditions are different 

 from those in Hoos field; the soil contains considerably more organic 

 matter and does not become very compact: the difference in physical 

 condition between the cropped and fallow portions therefore is not 

 nearly so marked (although it still exists) and a stricter comparison is 

 possible. Moreover the crop (which was fairly dense) did not apparently 

 affect the temperature of the soil, and from May to July practically 

 no differences were observed i. The moisture content, however, was 

 affected, the percentage of water being: 



Fallow portion 

 Cropped portion 



June 12 July 7 I July 27 



18 

 19 



20 

 17 



12 

 9 



per cent, of water 



