60 THE FUTURE OF ARID LANDS 
It is dangerous to disturb the land surface more than neces- 
sary, even with good intent, because of the possibility of soil 
removal or seedling scarification by the sand-loaded winds which 
blow in the hot season. I have seen this in the Thal desert of 
Pakistan where we are making trials with a number of plants. 
It seems to me that the provision of some shelter from these 
searing winds is essential and this can begin around nursery 
areas and in strips suitably placed across the prevailing winds. 
The limitless horizons of the desert are very interesting to write 
about but they are no good for proper land care. 
I come from a land where it has been necessary to introduce 
and establish every kind of plant food for man and his animals, 
with the exception of the native grasses and top feed dry climate 
trees like the mulga (an Acacia). We have successfully introduced 
every kind of fruit and vegetable which can be grown anywhere 
and we are still testing many grasses and legumes. So has the 
United States, where I think trial introductions from all over the 
world total more than 65,000. Outstanding in Australia has been 
the success of the establishment of subterranean clover, which 
has meant untold millions to the sheep men of southern Australia. 
Phalaris tuberosa and rye grasses (Lolium spp.) in the south, 
Cenchrus spp. in the west, and Rhodes grass in Queensland are 
other illustrations. The United States and Australia use alfalfa, 
called by Australians lucerne. (The American name is nearer the 
Arabic which means the good plant.) I refer to this to illustrate 
the possibilities of plant exploration for grasses and legumes, 
particularly in old arid areas. Much must yet be done in this 
field, and it is good to hear from Whyte about the work which is 
in progress at the moment under his guidance in FAO (See p. 185). 
In the detailed studies that are essential with respect to any of 
these introductions there will be plenty of scope for selection and 
genetical studies of those that show promise of establishment. 
We have now, for example, a number of established strains of 
subclover, and it may be that Trifolium hirtum, native of Turkey 
and now established in California, will develop ecotypes. 
It is obviously necessary to learn what are the physiological 
factors which enable desert and near-desert plants to survive 
