394 Journal of Agricultural Research Voi. xii. No. e 



Preliminary experiments have been carried out with the use of sand 

 and water-culture methods with the nutrient solutions whose concentra- 

 tions are comparable with those of the soil solution. The results have 

 indicated that the osmotic pressures existing in the soil are also most 

 favorable to the growth of barley in culture solutions. When con- 

 siderably greater concentrations are maintained, decreased yields result, 

 while very much lower osmotic pressures are suboptimum. Further 

 experiments are now in progress. 



It has not been possible in this investigation to make any general 

 correlation with crop yield, although it is worthy of note that the two 

 soils of lowest production. No. 9 and 12, show consistently low con- 

 centrations of the soil solution and also yield water extracts containing 

 exceptionally small quantities of nutrient elements. In the discussions 

 of Stewart and Burd the relations of chemical analysis of the medium 

 to crop production are discussed more completely. 



SUMMARY 



(i) Freezing-point depressions have been determined on 13 soils 

 under a variety of conditions. 



(2) The concentration of the soil solution has been found to vary with 

 the season and also as a result of treatment with carbon dioxid, leaching, 

 incubation, etc. 



(3) The growth of a crop markedly diminishes the concentration of 

 the soil solution. This effect is still evident at the beginning of the 

 following season. 



(4) The soil solutions under conditions favorable to crop growth were 

 found to be very dilute, particularly at the height of the growing season. 



(5) Certain general agreements between the extraction and freezing- 

 point methods are discussed. 



LITERATURE CITED 



(1) BOUYOUCOS, G. J. 



I917. MEASUREMENT OP THE INACTIVE, OR UNFREE, MOISTURE IN THE SOIL 



BY MEANS OF THE DiLATOMETER METHOD. In Jour. Agf. Research, v. 8, 

 no. 6, p. 195-217, I fig. Literature cited, p. 217. 



(2) and McCooL, M. M. 



1916. THE Freezing-point method as a new means of measuring the 



CONCENTRATION OF THE SOIL SOLUTION DIRECTLY IN THE SOIL. Mich. 



Agr. Exp. Sta. Tech. BuL 24, p. 592-631, 2 figs. 



(3) BURD, J. S. 



1917. WATER EXTRACTIONS OF SOILS AS CRITERIA OF THEIR CROP-PRODUCING 



POWER. In Jour. Agr. Research, v. 12, no. 6, p. 297-309, i fig. 



(4) King, F. H. 



1905. INVESTIGATIONS IN SOIL MANAGEMENT. U. S. Dcpt. Agr. Bur. Soils Bul. 



26, 205 p., 7 figs., 4 pis. 



