708 Ground Mineral Phosphates as Manures. [Nov., 



very little experimental work was "done with mineral phos- 

 phates. Quotations for most grades of basic slag are now about 

 2s. 5d. per unit of phosphate of lime at the farmer's nearest 

 station, whereas in the north of England finely ground North 

 African phosphates, containing 60 per cent, of phosphate of 

 lime, and guaranteed that 80 per cent, will pass through a 

 No. 120 sieve (14,400 holes to the square inch) are now offered 

 at about Is. 4d. a unit at the farmer's nearest station. The 

 great alteration in the relative commercial values of these two 

 phosphatic manures makes the late Dr. Aitken's results now 

 of great interest and value, and especial attention should be 

 given to his advice, repeatedly and emphatically made, that 

 mineral phosphates applied to the land are of use as manures 

 only when they are ground to the finest flour. 



Trials at Cockle Park, 1911-14. — Trials of various phosphatic 



manures for three years' seeds hay were made at Cockle Park 

 in the three years, 1911-1913, 10 cwt. per acre of high-grade 

 basic slag, or an equivalent amount of phosphates in other 

 dressings, being applied when the corn crop was harvested. 

 On the average of the three following vears the amounts of 

 hay produced per acre were: — untreated plot, 33} cwt.; basic 

 slag plots, 38} cwt. to 41} cwt.; bone meal, 40} cwt.; Tunisian 

 rock phosphate, 37 J cwt. ; and Belgian rock phosphate, 40} cwt. 



Similar trials were made for the three years, 1912-14, when 

 the average crops of hay per acre for the three years were : — 

 No dressing, 33} cwt. ; basic slag plots, 39 J to 41 cwt. ; bone 

 meal, 37 cwt. ; Tunisian phosphate, 89 cwt. ; and Belgian rock 

 phosphate, 40 cwt. (See Guide to Cockle Park, 1917.) 



These and other trials showed that ground mineral phos- 

 phates gave results practically equivalent to basic slag. 



Trials at Wylam-on-Tyne, 1914. — Trials of mineral phos- 

 phates on the park at Close House, Wylam-on-Tyne, were 

 commenced in March, 1914, when basic slag, Belgian phos- 

 phate and Algerian phosphate were applied to different areas of 

 the park, 200 lb. an acre of phosphoric acid being applied in 

 each case. A careful inspection 2 J years later showed on all 

 the treated areas a marked improvement due to these manures. 

 The pasture on the untreated area was valued at 25s. an acre 

 and that on the remaining areas at 45s. an acre. The results 

 showed that when mineral phosphates are as finely ground as 

 basic slag the phosphates they contain may be about equally 

 effective. 



