118 EXPERIMENT STATION RECORD. [Vol.36 



" The addition of sodium cliloi-id, potassium clilorid, and barium chloi-id to 

 certain soil suspensions was found to increase the hydrogen-ion concentration." 

 There was found to be apparently a simultaneous removal of positive and 

 negative ions from solutions of various hydrates by soils. 



A list of 35 references to literature bearing on the subject is appended. 



Soil alkali studies: Quantities of alkali salts which, prohibit the growth 

 of crops in certain Utah soils, F. S. Harris (Utah Sta. Bui. 145 {1916}, pp. 21, 

 figs. 16). — In an extension to field conditions of studies previously reported 

 (E. S. R., 34, p. 125), determinations of the total soluble salts, including chlorids, 

 carbonates, and sulphates, to a depth of 4 ft. in soils from seven counties in 

 Utah were made. The crops growing on the soils were wheat in five cases and 

 oats and alfalfa one each. " Samples were taken from typical alkali spots, from 

 parts of the same field producing good crops, and from places surrounding the 

 bare spots where only about a half crop was produced." The results are reported 

 graphically. 



It was found that the highest concentration and the location of salts varied 

 considerably, occurring in some soils in the surface foot and in others at depths 

 of 2, 3, and 4 ft. The total soluble salts in the parts of the fields producing 

 the best crops varied from 2.440 parts per million in Salt Lake County to 10,852 

 parts per million in Millard County, with an average of 5.089 for all seven 

 counties. The parts of the field where the yield had been reduced to about half 

 what it was in the better places varied in total soluble salts from 2,956 parts 

 per million in Carbon County to 18.325 parts per million in Millard County, with 

 an average of 9.2G3 parts per million for all the counties. The total salts varied 

 in tlie bare places from 0,938 parts per million in Salt Lake County to 30,148 

 parts per million in Cache County, with an average of 14,397 parts per million. 

 There was considerable variation in the chlorids and carbonates, but very much 

 more in the sulphates, the latter running as low as 543 parts per million in 

 Boxelder County and as high as 23,027 in Cache County. 



The toxic limits for total salts were considerably lower in the eastern coun- 

 ties. " No crops grew where there were 14,397 parts per million of salts. . . . 

 As an average of the three counties where sulphates were low, no crops were 

 produced with a concentration of 10.709 parts per million of salts, while there 

 was only half a crop with 6,455 parts per million." 



[Studies on soils] {Calif ornia Sta. Rpt. 1916, pp. 59, 60). — In studies by 

 W. P. Kelley on the effect of sodium nitrate on soils, it was found that the con- 

 tinued use of this material resulted (1) in a well-defined deterioration in the 

 physical properties of the soils, (2) in a rapid loss of soil calcium, and (3) in 

 an unusually high content of soluble sodium in proportion to other bases in the 

 water extracts from such soils. It was concluded that sodium nitrate reacts 

 with calcium carbonate in soils to form small amounts of sodium carbonate. 



Studies of nitrification in California soils are said to show the favorable in- 

 fluence of manure and leguminous cover crops and only a slight effect of inor- 

 ganic fertilizers on nitrification. Leguminous cover crops are said to undergo 

 much more rapid nitrification than barley or manure. The results of a com- 

 parative study of the nitrification of leguminous cover crops are taken to indi- 

 cate that Mclilotus indica, purple vetch, common vetch, and bur clover each 

 contain about the same amounts of nitrogen and likewise undergo rapid nitrifi- 

 cation. Canada field peas and Windsor beans, on the other hand, were some- 

 what inferior in this respect. 



The results of studies on the movement of nitrates in soils are taken to indi- 

 cate that nitrates are naturally formed in cultivated zones to the greatest ex- 

 tent and that where cover crops and manure are plowed down the porosity of 



