3i6 P. G. JARVIS 



SOIL CHARACTERISTICS 



All the soils were obtained from a fragment of sessile oakwoocl (Padley 

 wood, Grindleford) on the Millstone grit to the west of Sheffield (Pigott, 

 1956). 



With the exception of soil SH, the soils were obtained from over the 

 gritstone ; SH was from a nearby area of shales, with which the grit is 

 inter-bedded. The soil in the SH area was a good brown earth with active 

 htter incorporation. It had a high clay content as compared with the 



10 20 30 AG 50 60 100 200 300 400 500 



Soil moisture content as a % of dry weight 



600 



Fig. 2. The relation between soil moisture tension (in atmospheres) and soil moisture 

 content (as percentage of dry weight), for the five soils. Soils D and H are plotted on 

 the larger scale for moisture content. Values determined in an experiment in which 

 seedlings of sessile oak, growing on the soils in sealed cans containing plaster resistance 

 blocks for SMT determinations, dried out the soil (Jarvis, P.G., i960). 



sandy gritstone soils. It also supported a richer flora and better growth of 

 oak trees. 



The relation between soil water content and soil moisture tension for the 

 five soils is shown in Fig. 2. Large differences exist in the absolute amounts 

 of water removed from the difTerent soils for equal changes in SMT. If 

 the soil water content is recalculated on a volume basis, these differences 

 remain large (Table 3). 



RESULTS 



Representative seedhngs from each treatment are shown in Plate I. On all 

 the soils, except BL, the roots were found to occur throughout the whole 



