330 JoURIfAL of THE DePAIrTMENT OF AGRICULTURE. 



" Nitvofjeuous Manures. — The most striking and fundamental 

 difference between the nianurial practice of Europe and that of 

 Australia is that, in the Old World, nitrogenous manures are all 

 important, whilst in Australia they are generally unnecessary and 

 unprofitable. In European agriculture, the controlling factor for 

 successful cropping is the amount of available nitrogen present in the 

 soil. In Australia, assuming the rainfall be sufficient, the limiting 

 factor in crop production is the amount of available phosphoric acid. 

 The conditions of soil and climate, and mode of cropping in our wheat 

 areas, are conducive to rapid nitrification of the organic matter, 

 resulting in the formation of a sufficiency of available nitrates for 

 all demands of the ceieal crop. Most of the wheat sown in tliis State 

 is on fallowed land, and during the progress of fallowing nitrifica- 

 tion proceeds at a very rapid rate. 



" From this table [one dealing with nitrates in fallowed or 

 ' braak ' and non-fallowed land at Longerenong, Victoria] it will be 

 seen that the amount of nitrate in the fallowed land gradually rose 

 from 59^ lb. in December "to 118.3 lb. in the first week in February 

 (and 105 lb. at the end of March), to 91.87 lb. in May, and 89.6 lb. 

 in August, as contrasted with 21 lb. in the non-fallowed portion. 

 As a 15-bushel wheat crop removes in its grain and straw about 21 

 lb. of nitrogen per acre, it will be observed that there was four and 

 a half times more available nitrogen in the fallowed [or braak] portion 

 at seed-time than was required for a 15-bushel crop. On the other 

 hand, in the non-fallowed portion there was barely enough nitrogen 

 to supply the requirements of one such crop even assuming that every 

 particle of nitrate-nitrogen in the first 5 feet could have been used by 

 the crop." 



It is evident, in the opinion of the writer, that nitrification proceeds at a rapid rate in 

 the Western Province soils during the summer and early autumn months on "braak" 

 lands, and it is recommended to farmers, either by " braaking " or by summer ploughing of 

 tlieir stubble lands, to prepare their grain lands ready for seeding with the first rains, in order 

 to lessen the risk of loss of nitrates by leaching if heavy rains occur in April and May. It is 

 admitted that the stubble lands are sometimes too hard to plough in summer unless power 

 traction is available, but if a one-way disc plough be run over the stubble lands to a depth of 

 three or four inches during the summer, subsequent ploughing will be possible. It is 

 recognized also that early seeding maj^ result in rank growth, but this may be obviated or 

 remedied by (methods discussed earlier in this article. The rapid nitrification during the 

 summer, with possibility of loss by leaching, furnishes a warning against excessive summer 

 cultivation of " braaked " lands. 



PhospJiatic Manures. — " It is sufficient to note that practical 

 experience and experimental work throughout the wheat belt of 

 .iustralia has conclusively demonstrated the value and necessity of 

 phosphates in cereal culture. In many of the wheat areas the \ise of 

 soluble phosphates is absolutely essential to secure a crop." 



Superphosphate. — " This is deservedly the most popular and 

 profitable artificial manure used in the wheat areas of Australia a^ 

 the present time. There are very few soils in the wheat areas proper 

 which will not favourably and profitably respond to applications of 

 super, and in dry seasons many soils fail altogether to produce a crop 

 without soluble phosphates. The reason for the efficacy of the super 

 may probably be accounted for by the fact that when it is applied to 

 the soil, the soluble phosphate is dissolved by the soil water or by the 

 rains, and it immediately becomes thoroughly and intimately diffused 

 through the soil. 



