T. RiOxa 409 



to be low, particularly on the Stanford-Broom plateau. Sample GG 

 from the Ouse brown gravels contains very high percentages of 

 available potash and phosphoric acid. This has probably largely 

 been added in manures, for if the available content in samples .57 and 

 65 be subtracted from the total content of these ingredients, identical 

 percentages for phosphoric acid and potash are obtained in both 

 cases. 



(b) Heavy brown soil formation. 



This formation was laid down about the same time as the old brown 

 formation, but differs from it in containing nearly 10 per cent, more 

 of the two finer fractions, clay and fine silt. It is situated on the 

 western edge of the old brown formation and runs from a little north 

 of Southill to Upper Caldecote. 



The crops associated with this formation are early potatoes, late 

 potatoes, peas, spring cabbages, mangel seed, onions, cauliflowers, 

 brussels sprouts and cereals. Mangel seed, peas and spring cabbages 

 seem to be particularly suited to this soil. The farming practice on 

 this formation is very similar to that used on the old brown formation 

 and therefore need not be repeated. 



Composition. Chemical analysis shows that this soil formation 

 contains a much higher percentage of mineral salts and calcium 

 carbonate than the old brown formation. The only exception to this 

 is phosphoric acid which is rather low. 



(c) New dark soil formation. 



This soil formation is characterized by its dark colour and a more 

 loamy texture than the old brown soil formation. It is more recent 

 in age and the underlying gravels do not come so near to the surface. 

 This formation has probably resulted from the mixture of material 

 brought down by the tributaries of the Ivel, which join the main stream 

 in the vicinity of Langford. The following analyses show the com- 

 position of sludges taken from the river bed of the Hiz and the main 

 river. 



