T. RiGG 401 



carbonate, 3-5 per cent. Its content of calcium carbonate distinguishes 

 it from the Oxford clay formation which in other details resembles the 

 gault clay formation very closely. The high percentage of clay on the 

 other hand cUstinguishes it from the boulder clay soil formation which 

 is also rich in calcium carbonate. 



The potash, iron and alumina percentages are both exceedingly 

 high while the phosphoric acid content is higher than any other pure 

 clay soil formation in this district. Determinations of the available 

 plant food by Dyer's method show that this soil formation has a potash 

 content above the average, but is somewhat poor in phosphoric acid. 



For spring sown crops superphosphate should be very suitable while 

 basic slag should be an efEective supplementary dressing for autumn 

 wheat and beans, considering the wet and heavy condition of the soil. 

 {b) The redland soil formation. 



This formation occurs as a narrow strip between the greensand and 

 pure gault clay formations. The formation is a little over a quarter 

 of a mile wide and runs right through from Gamlingay to Sutton. 



It possesses very characteristic properties which necessitate careful 

 handhng of the soil. It must not be ploughed or cultivated while wet 

 if it is likely to be caught in a hot sun. Should this happen it forms 

 hard steely lumps which remain in this condition until the frosts of 

 winter crumble them. 



For this reason, the redland formation is not suitable for market- 

 garden crops, although late potatoes and brussels sprouts are grown 

 to some extent. Mangels and kohlrabi do well on this soil, while oats, 

 wheat and barley are also extensively grown. A rotation of beans, 

 wheat, roots, barley is practised by more than one farmer. Tliis 

 formation gives fairly good yields if suitably manured. Thus wheat 

 averages 4-5 quarters, barley averages 5-6 quarters, mangels average 

 30 tons. 



Composition. The texture of the redland soil formation must 

 necessarily be somewhat uneven owing to a surface wash of greensand 

 which grades the redland soil off into the pure brown sand formation. 

 Sample 39 perhaps would represent the typical redland soil better than 

 any other, but an average of the three analyses given is sufficient to 

 give a fairly true picture of the mechanical composition and mineral 

 constituents of this soil formation. 



This formation is a coarse sandy loam deficient in calcium carbonate. 

 The potash content -52 per cent, and phosphoric acid -2 per cent, lie 

 between the percentages found in the greensand and gault soils. 

 Journ. of Agrio. Sci. vn 27 



