146 Fertilisers [pt. hi 



Even small dressings have produced marked all-romid 

 improvement on soil very deficient in phosphates. The 

 most striking examples are found in Austraha and have 

 been investigated at the Roseworthy Agricultural Col- 

 lege^; good instances also occur in Cardiganshire, 

 Striking effects are also produced in the Fens. 



Grain per Ac re, lb 



Phosphoric Acid 



and 



Potash. 



Straw per Acre, lb. 



Fig. 31. Effect al phosphates and of potash on the yield of barley. 

 (Hoosfield, Rothamsted.) (Average 60 years, 1852-191 1.) 



The columns represent total produce per acre while the figures in the 

 diamond spaces give bushels of grain and cwts. of straw per acre. 



Superphosphate is soluble in water but it is rapidly 

 precipitated in the soil and only very small quantities 



See especially 4<A Report, 1909-11. 



