ioi6 



Notes on Manures. 



[JAN., 



potash manure salt were applied equally to plots 2 to 1 1 at the 

 rate of J cwt. of each per acre. An equivalent amount of phosphoric 

 acid, approximately 50 lb. per acre, was given to each of plots 2 to 

 II. In plots 8 to 1 1 one-third of the phosphoric acid was from super- 

 phosphate, and two-thirds from the other phosphatic manures. 



In these cases the mineral phosphate has proved nearly 

 equal to slag. The difference, though only small, may, however, 

 l)e real, in view of the large number of experiments involved. 



At Cockle Park, Tunisian rock phosphate and Belgian rock 

 phosphate both proved less effective than basic slag, though 

 the difference was not very great. The fertilisers were used 

 at the rate of 200 lb. of phosphoric acid per acre, corresponding 

 to nearly 10 cwt. of 41 per cent, basic slag. The results of the 

 third test carried on from 191 3-1 5 were as follows : — 



Cockle Park : 3 Years Grass Ley. Yield of Hay in Cwt, per Acre. 





ist Year, 

 1913. 



2nd Year, 

 1914. 



3rd Year, 

 1915. 



Average. 



Unmanured 



33^ 



37i 



22 



31 





44i 



48i 



27i 



40 



Tunisian rock phosphate 



35 



4ii 



3oi 



36 



Belgian rock phosphate 



41 



39i 



29 



36 



The-^e figures bring out an interesting property of the mineral 

 phosphates — that they are less useful than superphosphate or 

 basic slag in the early days of the plant growth. Thus they 

 gave a lower yield than slag in the first and second years at 

 Cockle Park ; further, it was noticed in Scotland that the 

 braird of arable crops was considerably below that obtained 

 w^ith superphosphate or slag. It has been suggested that the 

 difficulty can be overcome by adding a certain proportion of 

 superphosphate which can be used by the seedling, leaving 

 the mineral phosphate for the older plant. 



Experiments in North Wales also indicate that rock phosphate 

 is distinctly effective. At six centres the yields of swedes 

 were : — 



Tons cwt. 



No phosphate . . . . . . . . . . . • 12 18J 



*Gafsa phosphate (333 lb.) .. .. 21 I3i 



♦Superphosphate (539 lb.) . . . . . . . . 22 10 



* Both contained 200 lb. of total phosphate. 



Broadly speaking, these different results indicate that finely- 

 ground mineral phosphates are worth trial in England west 

 of the line from Durham to Southampton, but that no farmer 

 should rely upon them until a proper comparison has first 

 teen made with basic slag and superphosphate. There are 

 liiany cases in which superphosphate proves invaluable in 



