CROPPING SYSTEMS FOR THE BLACK LANDS OF TEXAS. 7 



ill the Southwest is not as efficient in ero]) production as the same 

 amount in the Central West or in the Eastern States, owing to the 

 greater evaporation in the Southwest. 



ins, 



KmfrTTlfcunTf^^ I4t1-Hl i7\Jt\1\ 



Fig. 4.— Graphical representation of tlie distribution of the average precipitation during the several 

 months of th(>, year in the Southwest at selected areas extending westward from the eastern to the 

 western limits of the black-land region. The line of diagrams at the top of the figure shows the dis- 

 triVjution over the territory extending west from the vicinity of Memphis, Tenn., through Little Rock, 

 Ark., the vicinity of Oklahoma City, Okla., Amarillo, Tex., to Santa Fe, N. Mex. The middle line 

 of diagrams shows the distribution over the territory extending west from the vicinity of Vicksbiirg, 

 MLss., through Shrcvcport, La., and Fort Worth, Blanco, and El Paso, Tex. The bottom line of dia- 

 grams shows the distribution over the territory along the Gulf coast extending from the vicinity of 

 New Orleans, La., through Galveston and Corpus Christi to Brownsville, Tex. (Data compiled by 

 the L'nited Slates Weather Bureau.) 



The foll(nving dates show^ing the extreme and average occurrence 

 of kilhng frosts (first in autumn and hist in spring) in this region are 

 com])iled from the records of the United States Weather Bureau: 



Table I. — Extreme and average dates of killing frosts in the black-land region of Texas, 



Station and relative location in the region. 



Paris (northern part) 



Dallas (farther southwest) 



Waco (central part) 



San Antonio (southwestern part) . 



[Cir. 84] 



Average date. 



First in 

 autumn. 



Nov. 15 



..do 



Nov. 10 

 Nov. 30 



Last in 

 spring. 



Mar. 28 

 Mar. 26 

 Mar. 16 

 Feb. 25 



Extreme date. 



First in 

 autumn. 



Nov. 3 



..do 



...do 



Nov. 9 



Last in 

 spring. 



Apr. 12 



May 1 



Apr. 5 



Mar. 19 



