T. RiGG 405 



for market-gardeu crops. Oiiious, parsley, parsnips, briissels sprouts 

 and late potatoes are the principal market-garden crops, but mangel 

 seed, horse beans, cereals and clover are also grown. 



The treatment adopted by the market-gardeners for this soil is very 

 similar to that in practice on the brick earths soil formation. Twenty 

 tons of dung are used for potatoes or brussels sprouts and during the 

 following two years soot and malt dust are used for parsnips and 

 onions. The average yield of crops is very similar to the yields oa the 

 brick earths soil formation. 



Corn-position. This formation contains a higher percentage of 

 stones and coarser particles than the pure clay formation just considered. 

 The soil is well suppUed with calcium carbonate and the available plant 

 food, particularly phosphates, is very much higher than that of the pure 

 boulder clay soils. 



(c) Sandy loam soil formation {boulder day on greensand). 



This formation occurs in the district only in two small areas but 

 its characteristics are so different from true boulder clay that it must 

 be designated as a distinct soil formation. This formation only occurs 

 where the boulder clay covering the greensand forms a thin capping 

 which intermixed \vith the sand residts in a loamy soil. The texture 

 of this soil formation varies even on the small areas mapped, owing to 

 varying thickness in the capping of boulder clay. It resembles the 

 redland soil formation in its characteristics and possesses the same 

 property of going steely if caught wet with a hot sun. 



This soil formation is mainly used for mixed farming but a small 

 area of market-garden crops is grown. Brussels sprouts and late 

 potatoes are the most important of these crops. Mangels, kohlrabi, 

 barley and oats all do fairly well on this soil formation. 



Composition. The only sample taken was from the more sandy part 

 of this formation, since it was only on the more sandy parts that market- 

 garden crops were grown. The sample is obviously a mixture of boulder 

 clay and greensand and its properties are intermediate. The calcium 

 carbonate is, however, very low, resembling the brown sand soil forma- 

 tion closely in this respect. 



7. Valley Gravel Series. 



(a) Old brown soil formation. 



This soil formation derives its name from the extensive valley 

 gravel deposits at higher levels on either side of the Ivel, in the neigh- 

 bourhood of Biggleswade and Stanford. These gravels were evidently 



