112 



During the eight years, the western boundary of profitable wheat-growing (see 

 Coghlan's solid line, 1904 map) has moved further westward, and it is pointed out that 

 the line will never wholly coincide with the 10 inch isohyet, since success depends not 

 so much on the total rainfall as on the incidence of it. (Compare 1905, Coghlan.) 



(Beference may also be made to " The Climatic Control of Australian Production " 

 by Griffith Taylor, Bulletin No. 11, Commonwealth Bureau of Meteorology, 1920, p. 20). 



The article "Wheat-breeding in Australia "by A. E. V. Richardson, in Joum. 

 Agric. Vict., Nov., 1914, p. 644, has a clear map of Australia, showing isohyets, obtained 

 from the Commonwealth Meteorologist. The map shows — 



1. The high rainfall belt (20 inches and over), coloured green in Mr. Richardson's 



map. 



2. The intermediate belt (over 10 inches and under 20 inches), coloured yellow. 



3. The low rainfall belt (under 10 inches) coloured grey. 



In South Australia, the margin of cultivation of wheat has already been extended 

 to the 10 inch isohyet, and profitable wheat-growing is now carried on in districts with 

 an annual rainfall of under 10 inches. 



The latest publication on the subject is by Mr. H. A. Smith, entitled " Wheat- 

 growing in New South Wales " (Memorandum by the Government Statistician regarding 

 the area of the State within which experience has shown that wheat for grain can be 

 grown profitably). Laid before the Legislative Assembly, September, 1923. 



He shows a map with lines drawn across it representing : — 



(a) The eastern limit of wheat-growing in 1922, in blue. 



(b) The western limit of wheat-growing in 1922, in blue. 



(c) The western limit of wheat-growing in 1912, in green. 



(d) The western limit of wheat-growing in 1904, in brown. 



(e) The western limit of 10-inch rainfall in the growing season — average from 



April to October, inclusive, in scarlet. 



Mr. Smith then details " The Western Wheat Line of 1922," and says it " along 

 its entire length passes through the edge of the great Western Plains, where the natural 

 features of the country are uniform. Its trend is decided principally by rainfall and the 

 nature of the soils." He then proceeds to describe the line geographically, and goes 

 south to north. Starting from the Queensland border, near Yetman, it successively 

 goes near Pilliga, Pallamallawa, Wee Waa, Coonamble, Gulargambone, Collie, Warren. 

 Nevertire, Fifield, Condobolin, Cargellico, Rankin's Springs, Hillston, Murrumbidgee 

 Irrigation Areas, Darlington Point, Moulamein, Balranald, Barham (most westerly 

 point). 



"The Eastern Wheat Line of 1922" is similarly treated. It "is determined 

 partly by the contour of the country and partly by the rainfall. Very little wheat is 

 grown at an altitude of more than 2,000 feet." 



