106 The Control of the Soil [ft. ii 



of weeds was therefore reduced; still later rotations were 

 gradually introduced; liming and chalking were more 

 carefully done; drainage was attended to; in the middle 

 of the 19th century artificial manures were introduced 



WHEAT SOILS 



] Fine Gravel, larger than 1 mm. 5;.--S^v'^ ^''t, 04 to 01 mm. 



Coarse Sand, 1 to 02 mm. W^^^I^M Fine .Silt, 01 to 002 mm. 



HIHH Clav, smaller tliAn 002 mm. 



Fine Sand, 0-2 to 004 nim. 



Fig. 28 o. Mechanical composition of soils well adapted for 

 certain crop.s. 



and tillages were improved ; still more recently improved 

 varieties and better seed have been available so that 

 now 40 bushels are readily obtained by good farmers*. 



1 Mr Alfred Amos obtained 96 bushels per acre in 1918. See Journ. Bd. 

 Agric. 1919, xxv. 1161. 



