i9io.] The Scouring Lands of Somerset. 



537 



in the field. A mechanical analysis gives the proportion of 

 the particles of various sizes existing in the soil, but takes 

 no account of the state of aggregation of those particles ; and 

 it is on this that the texture (or physical condition) depends. 

 That is to say, in a soil containing a large proportion of 

 the finest grades of particles, the amount of aeration, the tex- 

 ture, &c, will depend almost entirely on whether these par- 

 ticles are aggregated into larger units or not. There are 

 many factors which may exert an influence on the physical 

 condition of a soil. Among others, the presence of abund- 

 ance of organic matter or of calcium carbonate in a fine state 

 of division causes the finest clay particles to adhere 

 and form larger aggregates, and this will result in a looser 

 texture and better aeration. The physical condition of a soil 

 can therefore, to some extent, be altered and controlled by 

 various means ; but the mechanical composition cannot 

 be changed except by actually adding sand or clay. 



Table I. 





Edgar ley. 



Westhay. 



Kingsdon. 





Sound 



Teart 

 2. 



Sound 

 5- 



Teart 

 6. 



Sound 

 11. 



Teart 

 12. 



Gravel (3 mm. to 1 mm. diam.) 

 Coarse sand (1 mm. to C2 mm.) 

 Fine sand (o - 2 mm. to 0*05 mm.) ... 



Silt (0*05 mm. to o'Oi mm.) 



Fine silt (croi mm. to 0*005 mm.) ... 



Clay (below 0*005 mm.) 



Moisture 



Loss on ignition (organic matter) 

 Calcium carbonate 



o'57 

 4"33 

 11-23 



28-68 

 2378 



9"34 

 19-84 

 0-17 



o'5 

 8-4 

 138 

 26-46 

 24-96 

 878 

 H'53 



0"22 



0-07 

 i -06 

 2*64 



5-79 

 19-14 



I5-39 

 12-78 

 40-97 

 0-28 



i -06- 



6 "02 



8-45 

 11*16 



27-35 

 20-66 



6-53 

 I5-59 



2'02 



0*79 

 5-26 



9-37 

 29-68 



27^5 



7-00 

 19-00 

 0-05 



1- 6i 

 6-27 



10-35 

 25-96 

 29-31 

 5-94 



I7"TI 



2- 4 I 





97-94 



97^5 



98-12 



98-84 



98-6 



98-96 



No. 1.—" Blackacre " — "moor " land of open texture — good pasture for dairy cows. 

 t, 2. — Stiff clay land — poor weedy growth — very " teart." 



A ditch or " rhyne" separates fields 1 and 2. 

 )> 5- — Very peaty loose texture " moor" land — quite black — good mild pasture 

 6. — Stiff clay land — good growth of herbage — very " teart." 



One field separates 5 and 6. 

 it. — Top 4 or 5 inches of soil of loose open texture — below this, clay — quite sound- 

 12. — Same as 6. 



Two fields separate 11 and 12. 



In Table I. are given the figures for the mechanical 

 analyses of the surface soil of three " teart " fields, each com- 

 pared with soil from an adjoining sound field situated on 



