CHEMICAL ANALYSES 



27 



or grit, but a consideraMe amount of fine sand and silt and a 

 large body of clay. In consequence, the soil has to be worked 

 with care, becoming very sticky and drvinL; to impracticable 

 clods if moved when w^et. It "runs together" if heavy i-ain 

 falls after a tilth has been established, and then dries with a 

 hard, unkindly surface, these difhculties being nuich exaggerated 

 on the plots which have been farmed for a long time without 

 any supply of organic matter in the manures. 



The chemical analysis of the Rothamsted soils differs very 

 much from plot to plot according to the long-continued manu- 

 rial treatment which has been given to each plot. But every- 

 thing points to the fact that the soil was of an ordinary type 

 when the experiments began, certainly no richer in dormant 

 plant food than the majority of fairly heavy soils in this country. 



The following table gives the results of analyses (made by 

 Dr B. Dyer as regards the mineral constituents) of samples 

 drawn from the Broadbalk wdieat soils in 1893 : — 



Table XIII. 



• Determined in the solution obtained by treating the Ignited soil with strong Uyilrochlorlc Acid, 

 t Determined in the unignited soil. 



The most notable feature in the Rothamsted soil is the 

 amount of calcium carbonate in the surface layer ; analyses of 



