ICir. 124— A] 



AGRICULTURE ON THE YUMA RECLAMATION PROJECT/ 



By Carl S. Scofield. Agriculturist in Charge of Western Irrigation Agriculture. 



THE SOIL AND TOPOGRAPHY. 



The agricultural area of the Yuma Reclamation Project includes 

 about 130,000 acres lying on both sides of the Colorado River in 

 Arizona and California immediately north of the boundary between 

 the United States and Mexico. Of this about 90,000 acres are valley 

 land, formerly subject to overflow by the river, and 40,000 acres are 

 on a bench or mesa directly south of Yuma. This mesa land is about 

 100 feet above the river and is irrigable by pumping. The valley 

 soil is composed of silt deposited by the river during the annual 

 floods, and much of it is of very recent deposition. The character 

 of the soil with respect to fineness is extremely variable, depending 

 upon the velocity of the water where it was laid down. The irrigable 

 area lies in a narrow strip along the river between low blufl"s of gravel 

 which mark the edge of the mesa. Since 1906 the valley lands have 

 been protected from overflows by levees on either side of the river. 

 Prior to that time agricultural operations on the valley land had been 

 precarious, because of the annual floods. 



The subsoil underlying the valley is easily pervious to water, and, 

 since it all lies close to the river channel, the ground water is not far 

 below the surface. The height of the underground water fluctuates 

 with the height of the water in the river. 



In topography the valley lands are nearly level, ^\^th a gentle 

 slope to the south of about 1 foot to the mile. However, there are 

 numerous old sloughs and stream channels left by the river as well 

 as hummocks and sand hills formed from drifting soil. These must 

 be leveled before the land can be irrigated to advantage. This leveling 

 is often expensive, sometimes costing as much as $80 to SI 00 per 

 acre, though the average cost is probably not over $30 per acre. In its 

 natural condition the valley land was covered with a heavy growth 

 of timber and underbrush. The timber consisted chiefly of cotton- 

 wood, willow, and mesquite. The underbrush was arrow weed and 

 a large saltbush. The clearing of the land of timber and under- 

 brash has been expensive, costing from $5 to $25 per acre. 



1 Issued May 3, 1913. 

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