174 MOZAMBIQI^E 



literature on the subject of dry farming,* points 

 out that, while it is usual to suppose that the 

 compactness of the subsoil facilitates the upward 

 lift by surface tension of water from the perma- 

 nent water-table, it would seem equally rational 

 to suppose that the compact subsoil retards the 

 percolation of the water. In other words, hinders 

 drainage. 



Another article of belief held by dry farmers is 

 that by keeping the surface stirred while the crop 

 is growing a soil-mulch is created which checks 

 evaporation. But, as Mr. Russel again states, 

 the function of this loose top layer is not settled. 

 ''It is commonly regarded as a break in the 

 structure of the soil leading to a rupture of the 

 capillary films of water. It may equally be a 

 nonconducting layer, shielding the mass of the 

 soil from the sun's heat, and therefore lessening 

 evaporation." A protest should be entered against 

 the principle of frequent hoeing being claimed as 

 a dry farming monopoly. A loose surface layer 

 enables the air to penetrate the soil, supplying 

 oxygen to the bacteria of nitrification, whose 

 activities are thereby increased, and by keeping 



* " Transvaal Agricultural Journal," vol. viii, 1910 ; " Agri- 

 cultural Journal of the Cape of Good Hope," vol. xxxi, 1910; 

 " Water Requirements of Crops in India," by J. W. Leather 

 (Memoirs of the Department of Agriculture in India). 



