CIRCULAR No. 3. 



United States Departent of Agriculture, 



DIVISION OF SOILS. 



THE SOILS OF THE PECOS VALLEY, NEW MEXICO. 



In March, 1899, a party was sent by the Secretary of Agriculture, 

 under the direction of the Chief of the Division of Soils, to map the 

 soils of the irrigated districts of the Pecos Valley, New Mexico, with 

 particular reference to the extent of and damage from ' ' alkali " and 

 seepage waters, and to investigate methods for the prevention of 

 further damage and for the reclamation of lands already abandoned 

 from these causes. Three months were spent in a thorough and 

 detailed examination of the Carlsbad and Roswell areas, with a 

 reconnoissance around Hagerman, N. Mex., and Barstow, Tex. The 

 following brief review of the results of this work is presented, pend- 

 ing the completion of a more detailed report : 



THE CLIMATE. 



The climate of New Mexico is distinctly arid. The average yearly 

 rainfall at Carlsbad is, according to a four years' record, 12 inches, 

 with a larger proportion of rain falling during the summer and fall, 

 from May to October, inclusive. There are occasional heavy local 

 rains during the summer, which cause great floods in the Pecos; 

 these floods generally commence in May while crops are yet tender, 

 and it is upon them that the large storage reservoirs at Carlsbad are 

 mainly dependent for the supply to the irrigation lands of that 

 district. 



The normal evaporation is said to be about 10 feet at Carlsbad 

 from a water surface, and, as the reservoirs when full average only 

 about 20 feet deep, it will be seen that this evaporation is an impor- 

 tant factor both in the matter of the available water supply and its 

 condition when long stored in the reservoir, owing to the increased 

 salt content due to the concentration through evaporation. During 

 the spring of 1899 the regular spring floods did not come down, the 

 first reaching the reservoir late in June. Previous to this the evapo- 

 ration in the reservoir exceeded the inflow from the Pecos River, 

 and the condition of the water was perhaps at its worst. 



THE DRAINAGE AREA. 



The Pecos River drains nearly all of the southeastern third of 

 New Mexico. Rising in the Santa Fe Range, the stream flows 

 through the inclined rocks of the mountains as a typical mountain 



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