496 Agricultural Gazette of i\.S.W. [July 2, 1920. 



The addition of either of these fertilisers has resulted in an averacre diminished 



yield of two or three bushels per acre. Even were an increased yiidd obtained 



from their use it is doubtful whether it would be profitable owing to the high 



cost of the element nitrogen in fertilisers, and owing to the comparatively 



cheap and easy method of supplying the soil with nitrogen from the air !>y 



leguminous crops as explained in previous articles. Some idea of the amount 



of fertiliser to apply will be given by the following results of tests carried out 



with different quantities of superphosphate on the coast : — 



•2 cwt. Superphospluite 3 cwt. Superphosphate 

 per acre. per acre. 



bus. lb. bus. lb. 



Average of four tests ... 6G 51 64 1.3 



There seems to be no advantage, therefore, in a dressing of inore than 2 



cwt. of superphosphate per acre for maize on the coast. From the figures 



previously given it will be seen that 2 cwt. of superphosphate per acre will 



supply about as much phosphorus as is required for a 50-bushel crop, and it 



is reasonable to suppose that for heavier crops the balance of this element 



can be easily supplied by the fertility existing in the alluvial soils on which 



these tests are mostly conducted. The following results, however, definitely 



sho^v the superiority of 2 cwt. superphosphate per acre over 1 cwt. per 



acre : — 



1 cwt. Superphosphate 2 cwt. Superphosphate 

 per acre. per acre. 



bus. lb. bus. lb. 



Average of forty-two tests 55 55 59 36 



This means an increase of nearly four bushels of maize (at an additional 

 ccst of 5s. 6d. per acre) for the extra cwt. of superphosphate — a profitable 

 transaction. There is some indication, however, that on soils where heavy 

 5'ields of maize cannot be expected, it does not pay to use heavy dressings of 

 artificial fertilisers. The following results, obtained on the coast from plots 

 where the yield was less than 40 bushels per acre, are in favour of the appli- 

 cation of 1 cwt. superphosphate per acre on these soils : — 



1 cwt. Superphosphate '2 cwt. Superphosphate 

 per acre. per acre. 



Average of five tests, on bus. lb. bus. lb. 



soils yielding less than 

 40 bushels per acre... 37 1 35 31 



Further results confirmatory of this theory will be awaited with interest, 

 as thii number of tests so far made is insufficient to definitely establish it. 

 There appears, however, to be some ground for this opinion, for still smaller 

 quantities of fertiliser give the most profitable results on the tablelands, 

 where the average yields are about 25 bushels per acre. In any case the 

 gross returns from maize are not sufiiciently great to justify expensive 

 quantities of fertiliser such as are profitable witla potatoes and market- 

 garden crops. 



Of all the fertiliser mixtures tried on the coast in the Department's experi- 

 ments, none has given such large and i^mfitable increases in the maize 

 crop for grain as 2 cwt. per acre of the mixture known departmentally 



I 



