FARM LANDS OF NEW SOUTH \\ mis. 



15 



This is, of course, largely to be attributed to the absence of water, which, in 

 more humid regions, carries away a considerable proportion of saline matter 

 into the subsoil. To show that these peculiarities are not abnormal, and 

 that they correspond with what has been observed elsewhere, I quote some 

 figures given by the late F. H. King, Professor of Agricultural Physics at 

 the University of Wisconsin, in his book on " The Soil," contrasting the 

 chemical nature of arid and humid soils. The figures are taken from 

 analyses of Hilgard : — 



COMPARISON of Soils from Humid and Arid Regions of the United States. 

 (From F. H. King, "The Soil.') 



Phosphoric 

 Acid. 



Soils from humid regions 

 Soils from arid regions ... 



•II 



■12 



In these figures it will be seen that the difference between the amounts of 

 mineral plant-food are even more strongly marked than is the case with the 

 figures dealing with our own soils. The explanation given by Professor King 

 is the same as I have suggested, namely, " that sufficient water falls for the 

 decomposition of the rock and the formation of alkalies and of zeolitic 

 mineral" (zeolites are soluble in hydrochloric acid), "but not enough to 

 remove these when formed, as is the case in humid regions." The fact that 

 these soils are richer in mineral plant-food is one of considerable importance 

 in relation to their fertility, though it must be remembered that richness in 

 plant-food is only one of the elements of fertility, and that this property 

 alone is not sufficient to render a soil fertile. 



Humus in American Soils. 



A much more striking difference between our soils and those of similar 

 soils in the United States, as examined by Hilgard, is the relatively large 

 amount of organic matter as compared with the " humus " shown in Hil- 

 gard's analyses. It must be explained that the organic or volatile matter in 

 our analyses is not strictly humus only, but includes unchanged vegetable 

 matter, small root-fibres, and so forth, which are sometimes present in these 

 soils in considerable quantities. It also includes water of combination and 

 carbonic acid. The true humus — that is, the decayed vegetable matter — is 

 certainly much smaller in amount, and the very striking peculiarity has been 

 pointed out by Hilgard that the humus in arid regions is very much richer in 

 nitrogen than is the case with the humus in moist regions. So much is this 

 the case that the nitrogen in the humus in arid regions rises as high as 15 

 per cent., or about three times the amount present in the humus of humid 

 regions, which is about 5 per cent. 



Powdery condition of the soil when dry. 

 A third striking characteristic of these soils, and one not shown in the 

 tables, is their peculiar powdery condition when dry. Everybody who has been 

 in the districts referred to is aware that the surface soil over large areas is 

 often carried away by the wind in the form of a fine dust, which is deposited 

 against outstanding obstacles, or, if unobstructed, is carried enormous dis- 

 tances, to be ultimately deposited when the wind subsides, or carried down in 

 the form of mud by a shower of rain This phenomenon is noticeable in all 



