PRESIDENTIAL ADDRESS. 



377 



more important to endeavour to secure that the level reached at the period 

 of maximum productivity shall be maintained. 



Some information on this point is furnished by the three manuring-for- 

 muttoiii stations at Cockle Park, Sevington, and Cransley. At each of these 

 places a plot was dressed with 100 lb. of phosphoric acid derived from slag, 

 and for the fourth season thereafter the dressing was repeated, nothing more 

 being applied for the succeeding six years. At each of the stations there was 

 an immediate response ; at Cockle Park the repeated doee acted considerably 

 better than the first; at Cransley the effects of the two dressings were prac- 

 tically identical, only at Sevington was the effect of the first dressing con- 

 siderably better than that of the second.^" This subject can be followed for 

 twenty-one years at Cockle Park, where, since the end of the ninth year, 

 10 cwt. of slag per acre (200 lb. P.,0.) are applied every six years to Plot 3, as 

 contrasted with 5 cwt. (100 lb. P,0 ) every three years to Plot 4, another plot 

 receiving at the same time 100 lb. P.,0. in the form of 7 cwt. of superphosphate. 

 The information we want is as to whether these dressings of phosphates have 

 been able to maintain the high state of productiveness which we know was 

 secured by the initial doses of these substances. The figures bearing on this 

 point are brought together in the accompanying table. 



Average annual Live- Weight increase per acre for the same 6-year periods. 



It will be seen, in the first place, that the production of the unmanured plot 

 has manifestly declined from the earlier years, a result partly due to the lighter 

 stocking and partly to the shorter grazing season. Confining attention for the 

 moment to the upper section of the table, it may at once be said that the 

 high level of productivity induced by the second dressings both of slag (5 cwt.) 

 and superphosphate (7 cwt.) has not been maintained, the cause being probably 

 due, in large part, to a six-year interval occurring between the second and third 

 doses. But there is a distinct tendency for the live-weight increase to rise in the 

 later stages, and, on the whole, it may be said to be conclusively demonstrated 



" Supplement No. 5 to Journ. Board of Agric, 1911, p. 36. 



'• The 5 cwt. slag and 7 cwt. euper. were applied every 3rd year, except that 

 there was an interval of 6 years between the 2nd and 3rd doses. 



" The slag was applied every 6th year, except that there was an interval of 

 9 years between the let and 2nd doses. 



