320 EXPEEIMENT STATION EECOED. 



/)/). 1S7-195). — During 10 years plats represeuting 7 different kinds of soil 

 were used for a regular rotation of crops, with a clieck plat on which no plants 

 wex'e grown except the natural vegetation, which was allowed to die and decay 

 on the soil. 



Determinations of humus in the soils of the different plats showed that the 

 humus content of the uncropped soil was greater than that of the cultivated 

 soil, and that the finer the particles of the soil the greater the humus. The 

 water extract was neutral in the case of the cropped soil but acid in the case 

 of the uncropped soil. The water extract of the cropped soil was less highly 

 coloi-ed than that of the uncropped soil, but at the same time the amount of 

 water-soluble substances in the uncropped soil was smaller than in the cropped 

 soil. The water-soluble humus in the light open soils was higher than in the 

 heavy soils. 



The amount of carbon dioxid yielded by the water-soluble organic matter was 

 ])ractieally the same in cropped and uncropped soils, indicating the same number 

 of carbon atoms in the liumus of the two soil types, although in varying degrees 

 of oxidation. Oxidation by means of potassium permanganate showed practi- 

 cally the same results as regards total humus, but when applied to the water 

 extract the results by this method varied widely from those obtained by the 

 combustion method, indicating that the potassium permanganate method shows 

 only humus of a certain stage of oxidation. 



The humus acids of peat, A, Stutzer {Deut. Landw. Pressc, S7 {1910), 'No. 81, 

 pp. S82-883; lUiis. Landw. Ztg., 30 (1910), No. 82, pp. 769, 770; Ztschr. Angew. 

 Chem., 23 (1910), No. 37, pp. 1760, 1761; abs. in Jour. Soc. Chem. Indus., 29 

 (1910), No. 19, p. 1171). — This is a note on investigations by Baumann and 

 Gully which have already been referred to (E. S. R., 23, p. 715), in which 

 certain pi-actical conclusions are drawn regarding the cultivation of upland 

 moors. 



On the basis of the investigations referred to, it is recommended that potash 

 be used on such moors in liberal amounts, but only in the form of 40 per cent 

 potash salt and not as kainit and carnallit, phosplioric acid in liberal amounts 

 in the form of Thomas slag, and only so much burnt lime as is sufficient to 

 neutralize the mineral acids set free in the soil from the potash salts used. 

 The larger the amount of Thomas slag used, the less will be the quantity of 

 lime required, and in many cases it may be entirely dispensed with. 



On the humus acids of bleisand and ortstein, Ii. IIorndergee (Landw. Vers, 

 ^iat., 73 (1910), No. 1-3, pp. 221-233; al)s. in Chem. Al)s., 4 (1910), No. 19, 

 p. 2703). — The author finds from 63.5 to 64.1 ]ier cent of cai'bon in the humus 

 extract of bleisand (gray sand) and from 42.4 to 42.5 per cent in ortstein 

 (hardpan). These results agree in general with those of Mayer (E. S. R., 15, 

 p. 761; 16, p. 859) in showing a higher percentage of carbon in the humus of 

 bleisand than in that of ortstein. The higher carbon content was associated 

 with a lower ash content. 



With the method used a large amount of alumina was precipitated with the 

 humus and this alumina when heated to 120° retained as much as 86 per cent 

 of water, with the result that the calculated composition of the humus was too 

 high in hydrogen and oxygen and too low in carbon in some cases. 



The author did not find in his experiments the reduction of the carbon con- 

 tent of the bleisand humus acids through the action of iron chlorid as reported 

 by Mayer. 



A contribution to the question of determination of the plant food content 

 of a soil plat, H. Kaserer (Ztschr. Landw. Versuchsw. Ostcrr., 13 (1910), 

 No. 8, pp. 7}f2-7Jf7, fig. 1). — In view of the variation in plant food within very 

 small areas, the author undertook a study on a plat of known history of 

 methods of sampling to obtain reliable data as to the amount and distribution 



