16 THE FUTURE OF ARID LANDS 
great nutritive value of the semi-arid and arid vegetation has 
attracted stockmen to these areas and probably from the begin- 
ning of man’s use has had a part in pushing back the vegetation 
which had by tremendous adjustments established itself in this 
arid area. 
In the field of crop production most of the plants used by primi- 
tive man were dependent on well-watered land. He brought into 
cultivation all the principal crops now used. At the edge of the 
arid zone he showed marked ingenuity in the profitable use of 
arid land for the production of seed crops. In the Sahara and other 
Asian and African desert areas he made great use of the ‘‘ashab”’ 
or temporary growth of lush weedy drought escaping plants. He 
also seeded short-lived barley, a very well-adapted plant, to pro- 
duce a catch crop following a temporary summer rain. Every 
advantage was taken of flood water. Sorghum was planted close 
to the receding water edge and the planting was continued until 
the water had disappeared. This resulted in a field in which the 
plants were younger toward the center of the area. 
In the Southwest of the United States the Pimas relied chiefly 
upon flood water and irrigation to produce their crops. They also 
made great use of wild plants. These include about 22 varieties 
of plants of which they used stems, leaves, or flowers, 4 that fur- 
nish bulbs, 24 seeds or nuts, and 15 fruits or berries. This may 
indicate why primitive man so far excelled modern man in the 
domestication of plants and animals. Mesquite beans were collected 
and the fruit of the saguaro was made into dried sweetmeats, 
jams, and jellies. All suitable fruits of cacti were used. The 
fields were prepared and planted to cotton, maize, squash, water- 
melons, beans, and devils claw. The Papagoes practiced dry 
farming with or without flood water. Maize, wheat, barley, beans, 
and cotton were the principal crops. 
The Hopi are outstanding as successful crop producers under 
arid conditions. With a very low rainfall, they developed irrigation 
and dry farming to a degree hardly reached by modern agriculture 
even with the aid of such powerful weapons as soil physics, soil 
chemistry, plant physiology, and plant genetics. Hopi maize 
grown in fields of varying sizes and shapes presents an interesting 
