210 EXPEEIMENT STATION RECORD. [Vol.36 



SOILS— FERTILIZERS. 



The present status and future development of soil classification, G. N. 

 Coffey {Jour. Arner. Soe. Agron., 8 {1916), No. If, pp. 239-243). — An outline of 

 the present status of soil classification is given, it being pointed out that 

 " the tendency at the present time is to develop a system of classification 

 based upon actual differences in the character of the soil itself. . . . For 

 the worliing out of such a system in detail it is essential to have a knowledge 

 not only of the peculiarities and differences in soils but also the relative im- 

 portance of these in terms of crop production." 



Field operations of the Bureau of Soils, 1913 (fifteenth report), M. Whit- 

 key ET AL. ( U. S. Dept. Agr., Field Operations Btir. Soils, 1913, pp. 2^38, pis. 43, 

 figs. 62, maps 54). — This report contains a general review of the field operations 

 of the Bureau of Soils during 1913 by the chief of the Bureau, together with 

 detailed accounts of 53 surveys which have already been noted in the Record. 

 During the calendar year 1913 a total area of 31,676 square miles, or 29,272,640 

 acres, were surveyed and mapped in detail, malting the total area surveyed and 

 mapped up to the end of that year 315,794 square miles, or 202.108,160 acres. 

 There were .also conducted reconnoissance surveys covering an area of 15,917 

 square miles, or 10,186,880 acres. 



[Soil analyses] (Biol. Agr. [Sao Paulo], 17. ser.. No. 4-5 {1916), pp. 337- 

 344)- — Chemical analyses of 79 samples of different soil types of the State of 

 Sao Paulo, Brazil, are reported and discussed. 



"Water penetration in the gumbo soils of the Belle Fourche Reclamation 

 Project, O. R. Mathews {U. S. Dept. Agr. Bui. 447 {1916), pp. 12, figs. 4).— 

 Studies of the rate of flow of water in very heavy clay gumbo soils of residual 

 origin when loose and saturated and when wet and dry under field conditions 

 are reported. 



These soils are said to be highly productive, with large water capacity, but 

 the large content of clay makes them subject to extreme changes in volume 

 with changes in water content. Three-in. samples of the soil to a depth of 24 

 In. w^ere studied, and it was found that the time taken for an inch of water 

 to pass through 3-in. layers of loose saturated soil was four hours for the 

 first-foot sample and 12 hours for the second-foot sample. It was further 

 found that " on a dry soil, penetration takes place rapidly to a depth of about 

 2 ft. because of the cracked condition of the soil near the surface. After the 

 layer of easily penetrated soil becomes wet, it becomes so swollen and com- 

 pact that it is nearly impervious, and further water movement is very slow. 

 The fact that moisture can move only very slowly in the wet surface soil would 

 make it necessary to run water over the soil for a very long time in order 

 that any considerable portion might be absorbed. This is not practicable, 

 for the experiment with a dry subsoil showed that water from the surface pene- 

 trated almost as deep in a few minutes as it did in 10 days." 



The freezing point method as a new means of determining the nature of 

 acidity and lime requirement of soils, G. J. Boityoitcos {Michigan Sta. Tech. 

 Bui. 27 {1916), pp. 56, figs. iS).— The freezing point method was tested with a 

 large number of soils of different kinds under a variety of conditions to de- 

 termine their lime requirement, as well as to study the absorption by the soil 

 of sodium, potassium, and ammonium from solutions of potassium, sodium, 

 and ammonium hydroxids ; and the effect of acids and acid salts and of soluble 

 salts upon the lime requirement of soil. 



The method as used consists of adding to 2 gm. of soil 10 cc. of water and 

 determining the lowering of the freezing point. Then to this mixture are 

 added various amounts of Ca(0H)2 until there occurs a change in the magni- 



