1919] SOILS — FERTILIZERS. 



717 



to rainfall, nnd Is very closely bound up with the season and abundance of the 



rain." 



The results of a study of the interaction between rainfall and man are em- 

 bodied in a "climograph" chart, which shows "at a glance how the seasonal 



changes in moisture affect the comfort and health of the i pie in the region 



concerned." By a similar graphical means, the " hythergraph," the distribu- 

 tion of plant life and conditions under which certain crops are likely to succeed, 

 are indicated. Australia is divided into 15 major rainfall regions, of which the 

 physiography and the origin, distribution, and effects of rains are diseased in 

 detail witli the aid of numerous maps and diagrams. 



Discussing generalized conditions for Australia as a whole, It is pointed out 

 that "the best known feature of Australian meteorology is the arid center and 

 its encircling belts of progressively wetter country. This arid area is, however, 

 eccentric— so much so that its western margin reaches the ocean at Shark's 

 Bay in western Australia. The arid region is, of course, due to presence of 

 constant southeast trade winds, which blow to the north of the belt of high 

 pressures. Where these blow from sea to land, as in the east, there is a fairly 

 uniform rainfall; where they blow from land to sea, as in the west, there is 

 practically a desert. The central region is also traversed by these southeasters, 

 and as the moisture has already been largely deposited on the eastern high- 

 lands, there is no supply for the center. Moreover, the wind has a southerly 

 component, and so is gradually approaching warmer regions, and this again 

 decreases the chances of rain. . . . 



"The absence of forests in northern Australia is seen to be associated with 

 the lack of uniform rain in that region, though the totals amount to very 

 considerable figures." 



Of the two main climatic factors, heat and moisture, the latter appears to be 

 dominant as regards vegetation in Australia. Classifying the vegetation areas 

 with respect to rainfall and temperature, it is found that "the agreement with 

 the former is extremely close, but the vegetation zones lie across the isotherms 

 nnd have little relation to them." Conditions under which wheat, rice, cotton, 

 tea, and coffee are likely to succeed are indicated by means of the 



" hythergraphs." 



The progressive desiccation of Africa: The cause and the remedy, E. H. L. 

 Schwarz (So. African Jour. Sci., 15 {19 IS), Wo. 3, pp. 139-190, figs. 8).— The 

 author explains the patent fact that Africa is drying up as due to the progres- 

 sive encroachment of the coastal streams upon the interior elevated drainage 

 area of the continent. The remedy proposed is to build a series of barrages 

 which will prevent the inland drainage waters from being carried away use- 

 lessly to the sea. The drainage systems involved and the practicability of the 

 protective measures proposed are discussed in detaiL 



SOILS— FERTILIZERS. 



Soil erosion in Iowa, E. E. Eastman and J. S. Glass {Toica Sta. Bui. 183 

 (1919), pp. 81,5-391, pi 1, figs. 32).— The nature of soil erosion, its causes, and 

 effects with respect to conditions in Iowa are discussed, and suggestions made 

 relative to the control and prevention of erosion with particular regard for 

 methods successfully employed in different parts of the State. 



It is stated that no one method of prevention or control can be recommended 

 for all conditions, and that preventive measures are better than remedial ones. 

 For medium-sized and large gullies a carefully constructed earth dam with 

 surface inlet known as the Christopher or Dickey dam is said to be the least 

 expensive method of control and also the most generally applicable to Iowa 



