July 2, 1920.] Agricultural Gazette of N.S.W. 497 



as P7 ; this consists of equal parts of superphosphate and bonedust. 

 It had given good results in maize in 8outh Africa, and was suggested by 

 Professor Watt (Chair of Agriculture, University of .Sydney), to the writer 

 who, in turn, suggested its trial to the Department. In comparison with 

 superphosphate, its superiority was at once seen, and that it has been main- 

 tained will be seen from the following averages, extending over several 



years :— 



2 cwt. P7 2 cwt. Superphosphate 



per acre. per acre. 



bus. lb. bus. lb. 



Average of thii'ty-two tests 58 "19 56 46 



This superiority of P7 over superphosphate shows up more on the South 

 Coast and on the North Coast tablelands (Dorrigo and Comboyne), where an 

 average increase of 3 J bushels per acre is recorded in favour of P7. 



Reference has previously been made to potash as a fertiliser for maize. 

 Although some increases' are recorded from sulphate of potash, it was stated 

 that ovv'ing to the high prices for potash fertilisers, and to the fact that 

 farmers can render themselves independent of the need for supplying potash 

 by maintaining the supply of organic matter, no application of potash 

 fertilisers was advisable for the maize crop for grain, except in those 

 instances where experiments have shown their need and the profitableness 

 of their application under these conditions. That we have in P7 an efficient 

 and protitable fertiliser for maize for gi-ain on the coast without rushing after 

 potash fertiliser at the present time will be seen from the following com- 

 parison with P5 mixture — the only mixture containing potash which has 

 been tried on maize in New South Wales. These mixtures are about 

 equivalent in price at the present time (1920) : — 



2 cwt. P7 U cwt. P5 



per acre. per acre. 



bus. lb. bus. lb. 



Average of twelve tests ... 66 1 62 29 



Finally, the profitableness of the Department's recommendation for maize 



on the coast will be seen from the following : — 



2 cwt. P7 

 No manure. per acre. 



bus. lb. bus. lb. 



Average of thirty-seven tests 52 28 61 16 



At a cost of 15s. per acre, P7 mixture has given an increase of nearly 9 

 bushels per acre (with an average value of 36s.) ; thus showing a profit of 

 21s. per acre. On the North Coast tablelands (Dorrigo and Comboyne) the 

 average increase per acre has been 13^ bushels. 



No maize grower on the coast can afford to ignore this method of increasing 

 the profits from his maize crop. In addition to increased and highly profit- 

 able yields from P7 mixture during the season of application, there is little 

 doubt that this mixture (containing bonedust) will have more residual value 

 than most other fertilisers. The best results have been obtained from it in 

 seasons of good rainfall, and if the results do not come up to expectation in 



