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and pH values next appear in Table V, columns 3 and 4. By <br />using graphs found in Agriculture Handbook A'o. 60, U.S.D.A. (6), • <br />one can derive equivalent concentrations (meq./liter) of <br />dissolved salts in water, basis measured conductivity data. <br />Figures 5 and 6 are working graphs taken from pp. 10 and 12 <br />of landbook 60. Figure 5.is the more useful plot because <br />concentrations in meq./liter are presented as function of <br />conductivity for several dissolved salts commonly found in <br />surface water, soils and soil extracts. A few words of <br />explanation may help to clarify the use of the graph. For <br />example, consider extract solution ~F38. The corrected <br />electrical conductivity, in Table V, column 4, equals 0.186 mi11i- <br />mhos%cm at 25°C. According to the caorlcing graphs of Figure 5, <br />the concentration of dissolved salts in the extract solution <br />ranges betcaeen a minimum of 1.5 meq./liter and a maximum of <br />2.0 meq./liter, depending on the dissolved species of cations <br />and anions. The identity of the dissolved species must be <br />determined by additional chemical or instrumental analyses. <br />So much zor conversion of electrical conductivity data to • <br />equivalent salt concentrations. <br />Continuing our examination of data in Table V, it is <br />readily seen that none of the extract solutions have conductivities <br />exceeding 2 millimhos/cm; equivalent salt concentrations range <br />between 14 and 25 meq./liter. This means the extract solutions <br />are essentially nonsaline in character. The bar graphs of <br />Figure 7 shoca only three of the 19 samples, Nos. 33, 31 and 23, <br />have electrical conductivities exceeding 1 mmhos/cm or <br />equivalent dissolved salt concentrations betcaeen 7 and 11 meq./liter. <br />These data sicnify dissolved salt concentrations found in the <br />1:1 extracts are low, and it is the author's opinion these are <br />comparable to the levels of dissolved salts one would find in <br />surface runoff after a heavy rain. <br />6) L. A. Richards, et. a ., U.S. Salinity Laboratory Staff, <br />Diagnosis and Im~rovcm~ nt of Saline and Allcalinc Soils, • <br />Agriculture flanclboolc Nu. bU, U.S.U.A, b` <br />