396 Market-Garden Soils tnol Cropx 



The Oxford clay soil to the west of Northill and Southill is rafhor 

 better drained, and a slightly better type of farming is possible. Much 

 of the land, however, is in comparatively ])()()r pasture and woodland. 

 Where the land is cultivated, the cr()])s previously mentioned are grown. 

 Usually wheat, oats and clover do fairly well, but the yield of wheat 

 and oats is disappointing on thrashing. Mangel seed seems to be the 

 most profitable crop for this heavy land. 



Composition. Mechanical and chemical analysis reveal that this 

 soil contains a very high percentage of the clay fraction — the highest 

 of all the clay formations occurring in the district — and a great poverty 

 of calcium carbonate and phosphoric acid. The potash and the iron and 

 alumina content are both very high as one would expect in such a heavy 

 clay soil. 



The available plant food as determined by Dyer's 1 per cent, citric 

 acid method shows a sufficiency of potash but a great deficiency in 

 phosphoric acid. A phosphatic manure such as basic slag should be 

 particularly valuable in the iin])rovoment of poor pasture and foi- all 

 crops grown on these heavy soils. 



(h) Ulay loam formation. 



As previously explained this formation has probably originated 

 from an intermixture of alluvial wash with the underlying clay. It is 

 considerably lighter in texture than the formation just considered, 

 but it shares with it a dark brown colour and a somewhat shaley appear- 

 ance. This formation is remarkably uniform throughout both areas 

 mapped which are widely separated by the Ivel gravels. 



Tliis formation is almost entirely under cultivation, and when well 

 manured grows good mangels, mangel seed, wheat, oats and horse beans. 

 Brussels sprouts, late ])otatoes, onions, parsley and small seeds are also 

 grown, but this formation is not very suitable for market-garden crops 

 as the soil is somewhat heavy, and it is raflicr difficult of access for 

 carting dung or produce. 



Composition. This formation contains 9 per cent, less clay than 

 the pure clay formation, with a correspoiuling increase in the sand 

 fractions. The phosphoric acid is slightl}' higher, while the potash is 

 a good deal lower than in the case of the pure clay formation. The 

 phosphoric acid content at first sight ajipears to vary rather widely 

 in the three samples taken from this formation. One sample, however, 

 has been heavily manured and contains -051 per cent, available 

 phosphoric acid. Probably -045 per cent, of this has been added in 

 manures and the total content for purposes of comparison should be 



