132 TILLAGE MOVEMENTS OF SOIL WATER [chap. 



are afforded by the Rothamsted plots ; samples of 

 soil from the wheat land were taken on 13th September 

 1904, on the previous day 0-262 inch of rain had 

 fallen, but for nine days before there had been little 

 or no rain. The portions of the plots from which 

 the samples were drawn had been fallowed through 

 the summer, so that the drying effect of the crop 

 is eliminated. Samples were also taken from the 

 barley plots on 3rd October of the same year ; 0-456 

 inch of rain had fallen on the 30th September, before 

 which there had been fifteen days of fine weather. 

 The following table shows the water in the soil of the 

 unmanured and the continuously dunged plots respec- 

 tively, as percentages of the fine earth from which the 

 stones had been sifted : 



Percentages of Water in Rothamsted Soils. 



It is thus seen that in both cases the dunged soil, 

 rich in humus, had retained more of the comparatively 

 recent rainfall near the surface, so that the top soil was 

 moister while the subsoil was drier. The difference 

 in favour of the surface soil was about 3-5 per cent, which 

 on that soil would amount to about 30 tons per acre, 

 or approximately 0-3 inch of rain. It is thus seen 

 that the surface soil of the dunged plot had retained 

 practically the whole of the preceding rainfall; and 

 the greater dryness of the subsoil was due to the way 



