498 Agricultural Gazette of N.S.W. [July2, 1920. 



a dry season, one may be sure that little or none of the fertiliser will be lost 

 from the soil, and that the residual effect will help to swell the yield in the 

 following season. 



Northern Tableland. 



An instance of how the fertiliser requirements for maize on the Northern 

 Tableland differ from those of the coast may be seen from the results 

 obtained from P7 mixture. Here (on the Northern Tableland) compared 

 with those from superphosphate, the yields from P7 have fallen short by 3 

 bushels per aci^e, each fertiliser being applied at the rate of 1 cwt per acre. 

 As regards potash, the tests made so far indicate that the fertiliser is not 

 required for maize on the tableland soils, an average decrease of 1 to 3 

 bushels being obtained from the addition of 14 to 28- lb. sulphate of potash 

 to superphosphate. There is, however, something to be said in favour of 

 soluble nitrogenous fertilisers like nitrate of soda or sulphate of ammonia. 

 In these cold districts, the conversion of nitrogen compounds into nitrates 

 which can be used by plants is much slower than on the coast, and soluble 

 nitrogenous fertilisers supply this lack in eai'ly spring with some benefit. 



An SLverage increase of 4:| bushels per acre has been obtained by the 

 addition of 56 lb. sulphate of ammonia to superphosphate — an increased 

 production valued at 18s., at a cost of 13s. per acre for fertiliser, represent- 

 ing a profit of 5s. per acre from its use. There is no reason why nitrate of 

 soda should not give a similar profit here. 



Tests made to compare the comparative values of 1 cwt. superphosphate 

 and 2 cwt. superphosphate on the tablelands, do not show any further 

 increase in yield from the larger quantity. The following average results 

 were obtained from 56 lb. superphosphate as compared with 1 cwt. per acre : — 



On these figures, 56 lb. superphosphate is the most pi'ofitable application, 

 and shows a profit of about 16s. per acre. These results are borne out by 

 experiments in Rhodesia,* where, on light volcanic soils, in a climate similar 

 to our Northern Tableland, 1 cwt. mixed fertiliser was found to give better 

 yields of maize, and a greater profit per acre, than 1-^-or 2 cwt. 



From the foregoing it therefore ajapears that a fertiliser mixture consisting 

 of equal parts of sui^erphosphate and sulphate of ammonia or, nitrate of soda, 

 at a cost of about 16s. per acre, may be expected to give an increased yield of 

 S or 9 bushels per acre. Owing to the. tendency of soluble nitrogenous 

 fertilisers to delay the maturity of the crop, and of superphosphate app)lied 

 alone to hasten it, it is recommended that 56 lb. superphosphate alone be 

 used per acre when the crop is sown later than usual, or when a somewhat 

 late or risky variety for this district is planted. 



There is need for further experiments with fertilisers containing nitrogen 

 to be carried cut on the tablelands. 



Jihodesia A<jri. Jour., Aug., 1916. 



