INVESTIGATIONS AT ARDMORE, S. DAK. 3 



SOIL CONDITIONS 



The soil at the Ardmore station is a heavy clay loam that remains 

 fairly uniform to a depth of about 15 inches. Below that depth there 

 is a zone of lime carbonate accumulation that extends to a depth of 

 about 2 feet. Below that depth the soil remains fairly uniform clay 

 or gravelly clay until the undecomposed shale is reached, except 

 where sand or gravel deposits occur. The crop-rotation field is 

 underlain with a layer of sand and gravel that generally lies at a 

 depth of between 4 and 5 feet but comes closer to the surface in a 

 few places. Where the layer of sand is within 2 feet of the surface, 

 the producing capacity of the soil is drastically lowered. The color 

 and profile correspond closely to that of the Rosebud series as 

 mapped by the Bureau of Soils, and so far as essential character- 

 istics are concerned it can be designated the Rosebud clay loam. 

 The experimental plots are located on an upland terrace on which 

 the soil material had accumulated by deposition from river water. 

 The terrace is more than 100 feet above the level of Hat Creek. 

 There is no ground water. The plots do not receive run-off from 

 adjoining areas, and the nearly level surface does not especially 

 favor run-off. 



The surface soil is tenacious when wet, and when wet or dry, 

 requires considerable power for cultural operations. The expense of 

 working the soil makes it necessary to restrict the number of field 

 operations as much as possible without sacrificing the crop. 



CLIMATIC CONDITIONS 



The average annual precipitation at Ardmore during the period 

 covered by these investigations was 15.90 inches (table 1). Of this 

 amount, 9.81 inches fell during the 4 months April-July and 12.44 

 inches during the 6 months April-September. 



Table 1.- 



—Precipitation 1 at 



the Ardmore station for 



the 21 years, 



1912-32 



Year 



>> 



3 



a 



c3 



>> 



3 



<B 

 ft 



si 

 2 





>> 



<s> 

 a 



3 



>> 



3 



1 



< 



a 



a 



CO 



X2 

 O 



o 

 O 



1 



> 

 O 



a- 



1 



c© 



51 



1 

 a 



< 



1912 



In. 



1.12 

 .03 

 .02 

 .50 

 .25 

 .47 

 .48 

 T 

 .15 



1.15 

 .55 

 .05 

 .02 

 .29 

 .69 

 .22 

 .28 

 .09 

 .36 

 .02 

 .39 



In. 

 0.30 

 .40 

 .45 

 .64 

 .35 

 .09 

 .29 

 .76 

 .55 

 .18 

 .14 

 .30 

 .75 

 .45 

 .12 

 .34 

 .28 

 .17 

 .18 

 .36 

 .07 



In. 



1.35 

 .50 

 .28 

 .86 

 .54 



1.02 

 .60 

 .93 

 .92 

 .07 

 T 

 .40 

 .70 

 .42 

 .40 



1.14 

 .49 



1.31 

 .37 

 .73 

 .71 



In. 

 2.15 

 1.52 

 3.27 

 4.26 

 1.04 

 2.74 

 2.85 

 2.52 

 3.78 



.52 

 3.23 



.98 



.69 

 1.34 



.49 

 4.06 



.27 

 1.41 

 L93 



.19 

 4.17 



In. 

 0.80 

 2.04 

 1.24 

 3.40 

 3.61 

 5.34 

 5.99 

 2.65 

 5.20 

 2,41 

 2.56 

 3.80 

 .75 

 2.02 

 2.53 

 3.26 

 1.52 

 2.18 

 2.89 

 1.13 

 2.73 



In. 

 1.87 

 1.59 

 3.24 

 6.67 

 2.58 

 1.71 

 1.75 

 1.50 

 3.10 

 4. 54 

 2.59 

 5.93 

 1.95 

 4.02 

 1.80 

 3.28 

 3.67 

 2.21 

 1.24 

 1.89 

 .69 



In. 

 1.97 

 1.78 



.49 

 6.01 

 1.80 



.47 

 3.49 

 3.05 



.77 

 1.26 

 4.07 



.67 

 2.61 

 2.55 

 3.55 

 3.33 

 3.63 

 2.90 



.70 



.79 

 1.01 



In. 



0.83 



1.23 



1.79 



1.37 



1.90 



1.99 



.44 



.47 



1.59 



.55 



.78 



3.09 



.23 



.72 



2.94 



2.25 



.76 



1.49 



3.01 



1.34 



2.63 



In. 



1.68 



1.50 



. 75 



4.70 



.02 



.43 



3.01 



.38 



.29 



.46 



.15 



1.52 



1.24 



.7,0 



1.09 



1.01 



.30 



2.71 



1.10 



.44 



.19 



In. 



0.55 



1.59 



1.51 



.81 



.85 



.67 



.45 



2.10 



1.48 



.66 



.83 



1.48 



1.79 



2.45 



1.26 



1.16 



.55 



.74 



3.58 



1.71 



.95 



In. 



0.27 

 .15 

 T 

 .11 

 .39 

 .18 

 .25 

 .78 

 .29 

 .68 



2.19 

 .13 

 .57 

 .32 



1.70 

 .75 

 .14 

 .20 

 .34 

 .31 

 .09 



In. 

 T 



0.90 

 .43 



1.08 

 .20 

 .70 

 .66 

 .14 

 .31 

 .30 

 .41 

 .25 

 .44 

 .65 

 .09 

 .27 

 .16 

 .05 

 .01 

 .33 

 .14 



In. 



9.30 



9.66 

 10.78 

 26.41 

 10.95 

 12.68 

 17.53 

 10.57 

 14.73 



9.74 

 13.38 

 15.99 



7.47 

 11.35 

 12.40 

 17.19 

 10.15 

 12.90 

 10.87 



5.78 

 11.42 



In. 

 12.89 



1913 



13.23 



1914. 



13.47 



1915 



30.41 



1916 . 



13.53 



1917 



15.81 



1918 



20.26 



1919 



15.28 



1920 



18.43 



1921 



1922 



12.78 

 17.50 



1923 



18.60 



1924 



1925 



11.74 

 15.93 



1926 



16.66 



1927 



21.07 



1928 



12.05 



1929 



15.46 



1930 



15.71 



1931 



9.24 



1932.... 



13.77 



Average 



.34 



.34 



.66 



2.07 



2.76 



2.75 



2.23 



1.50 



1.13 



1.29 



.47 



.36 



12.44 



15.90 



» T=trace. 



