SOILS— FERTILIZERS. 811 



Soils study according to the geological-agTonoinic survey, with especial 

 reference to the soils types of the lower Rhine districts, E. Zimmermann 

 {FiihUmfs Landw. Zty., 64 {1915), No. IS-lJf, pp. 329-S.'f 7). —This is a general 

 discussion of tlie methods, results, and advantages of this kind of soil survey 

 as applied to the lower Rhine districts. 



Successful soil-sampling- tools, A. M. Shaw {Engin. News, 7Jf {1915), No. 26, 

 p. 1228, fig. 1). — ^A soil-sampling outfit consisting of an auger and pipe extension 

 for taking deep samples is described. 



Recent brovsm soil and humus formation in Java and the Malay Peninsula, 

 together with remarks on climatic weathering, R. Lang {Ceritbl. Min., Geol.u. 

 PaUiontol., 1914, Nos. 17, pp. 513-518; 18, i)p. 545-551; abs. in Zenihl. Agr. 

 Cliem., U {1915), No. J,-5, pp. 148-150) .—The author reports the results of 

 observations on tlio occurrence and origin of the so-called brown soils and 

 humus soil of Java and the Malay Peninsula and the influence of climatic 

 factors on their formation. 



It is concluded that the main factor in the formation of both these soils is 

 an extraordinarily heavy rainfall. Brown soils are formed when the waters 

 of a tropical region are so impregnated with mineral salts as to efi'ect an 

 adsorptive saturation of the soil humus substances with which they come in 

 contact. 



Raw humus is formed where the waters of tropical regions do not contain 

 sufficient mineral salts to effect an adsorptive saturation of humus substances. 

 It is further concluded that dampness and coolness favor humus formation, 

 while heat and dryness retard it. 



Determination of amino acids and nitrates in soils, R. S. Potter and R. S. 

 Snydeh (Iowa Sta. Research Bui. 24 {1915), pp. 327-352, figs. S).— This bulletin 

 briefly reviews the work of others bearing on the subject and reports the 

 details of the experiments noted below and of experiments previously noted 

 from another source (E. S. R., 34, p. 112). 



The amino acid nitrogen of soil, R. S. Potter and R. S. Snyder {Jour. 

 Indus, and Enyin. Chon., 7 {1915), No. 12, pp. 1049-1053, fig<i. S).— Laboratory 

 and pot experiments are reported in which it was found that by use of the 

 Kober copper method of determining amino acids (E. S. R., 31, p. 211) no 

 amino acid nitrogen could be detected in the dilute acid extract of soils. Upon 

 adding small quantities of amino acid to a soil and extracting with dilute 

 acids no amino acid was found. " Upon adding small quantities of amino 

 acids to a soil and extracting with dilute alkali, practically the entire amount 

 added was recovered. There v/as found to be no difference in the quantity 

 of amino acid nitrogen extracted by dilute alkali in one, two, four, and six 

 hours." 



From the pot experiments it is concluded that " there is no tendency for 

 amino acid to accumulate ... in a limed and unlimed acid soil, in a heavily 

 manured and limed, and a heavily manured unlimed acid soil. The amino 

 acid nitrogen was present in the soil in less amounts than the ammonia nitro- 

 gen, but in a general way it fluctuktes with the ammonia nitrogen. The soils 

 with the higher amounts of manure show a decided decrease in the amount 

 of nitrate nitrogen at first, but after from four to six weeks there is a decided 

 increase." 



The origin of the " niter spots " in certain western soils, W. G. Sackett 

 and R. I\I. Isham {Science, n. ser., 42 {1915), No. 1083, pp. 452, .^.53).— The 

 authors disagree with the theory of Stewart and Peterson (E. S. R., 33, p. 121) 

 with reference to the cause of the brown coloration of the so-called niter spots 

 in some western soils, and adhere to the theory of pigmentation of Azotobacter 



