58 THE FUTURE OF ARID LANDS 
aid under this enactment are already highly productive, especially 
in assessing the merits and costs of producing fresh water from 
saline supplies. The Saline Water Program is due to end in July 
1957, but I am sure we hope that it may be extended beyond that 
date. 
Soils 
Soil, the base on which food production on a scale to satisfy 
world needs rests, must now be considered. It is not proposed to 
go into any detail about arid soils, because Kellogg can write 
books about them. Suffice it to call attention to a few character- 
istics such as their low content of organic matter and so of nitro- 
gen, the fact that they are more usually alkaline than acid and 
so may develop permeability problems with irrigation, and their 
sometimes rather high content of soluble salts. Despite these 
characteristics, with suitable fertilizer treatments crop yields 
under irrigation can be remarkably high and large scale prosperous 
communities may be established, as witness the position in the 
United States and in Australia. 
I cannot do better than quote Kellogg’s summary to his intro- 
ductory paper at the Jerusalem Desert Research Symposium 
(1) as follows: 
Several important areas of needed soil research are the following: 
1. Morphological study of the soils of relatively unexplored regions 
and their classification as a basis for preliminary reconnaissance mapping 
and appraisal. Previous soil experience has been highly concentrated on 
alluvial soils and especially in areas easily reached by existing transport. 
Soil scientists have had inadequate opportunities to make detailed 
studies of arid soils remote from present population centres. Even in 
places where water is scarce, principles of great fundamental value to 
our knowledge of the formation and development of arid soils can be 
learned—principles important generally and to the stabilization and use 
of arid soils for grazing even though they cannot be irrigated. 
2. Relation of soil permeability to drainage and salt removal. We 
need to know more precisely the lower limit of permeability, especially 
in subsoils and substrata, for satisfactory management with different 
kinds and amounts of irrigation water, the factors that control the per- 
meability, and how permeability may be modified by chemical treat- 
ments, growing plants, and water management. 
