SOILS FERTILIZERS. 319 



Tbe development of heat accompanying swelling in soils? is said to be prob- 

 ably proportional to the degree of swelling. The hygroscopicity of the soils 

 examined averaged 5.62 and bore an almost constant relation to the degree of 

 swelling. The adsorptive power of the soils for coloring matter decreased with 

 its concenti'ation and bore a close relation to the degi-ee of swelling and hygro- 

 scopicity. The absoiptive power for ammonia bore no close relation to the 

 adsorptive power for coloring matter, degree of swelling, and hygroscopicity, 

 and was not governed by the surface area of the colloids as much as was the 

 adsorptive power for coloring matter. The constant for the absorption equiva- 

 lent was found to be greater in acid soils poor in humus than in acid soils rich 

 in humus and A-aried with different concentrations of the ammonia solution. 

 • The absorption coefficient of the soils for ammonia in normal ammonium 

 phosphate solution was greater than for normal ammonium chlorid solution. 

 It is thought possible that the phosphoric acid of ammonium phosphate com- 

 bines directly with aluminum, forming an insoluble compound which increases 

 the absorptive power of the soil for ammonia. 



Preliminary note on iron in Florida soils, C. A. Brautlecht and A. B. 

 Parlin i^Jour. Indus, and Engin. Chem., 6 (WW, No. 11, p. 960). — In 73 sam- 

 ples of Florida soils examined the iron, calculated as FezOs, ranged from 0.23 

 to 11.53 per cent. In general there appeared to be a direct correlation between 

 the humus and iron. A certain correlation between the character of vegeta- 

 tion and the iron content was also indicated. 



The absorption of certain radicals by leaves in varying stages of decay, 

 and the effect of leaves on the absorption of these radicals by a soil, II. A. 

 Notes (Jour. Indus, and Engin. Chem., 6 (1914), No. 7, pp. 57-^-576; abs. in 

 Chem. Ahs., 8 {1914), No. 11, pp. 3090, SOW).— Laboratory experiments are 

 reported which lead to the general conclusion that humus-forming substances, 

 such as leaves, play a part in soil absorption dei)endent upon their state of 

 decay. 



A note on leaf -fall as a cause of soil deterioration, W. L. Balls (Proc. 

 Cambridge Phil. Soc., 11 (1914), No. 6, p. 466; abs. in Chem-. Abs., 8 (1914), No. 

 17, p. 3090). — It was observed that the soil of certain cotton breeding plats in 

 which the leaves from the cotton had been incorporated became unproductive. 

 It is suggested that this may have been due to sodium chlorid which occurred in 

 small amounts in the soil or to toxic compounds resulting from the decomposi- 

 tion of the leaves. The latter explanation was supiwrted by the fact that cotton 

 leaf mold was found very unsatisfactory for potting purposes. 



Crop residues, B. Schulze (Deut. Landw. Presse, 41 (1914), No. 14, pp. 171, 

 172; abs. in Jour. Bd. Agr. [London], 21 (1914), No. 4, pp. 333, 334).— It is 

 pointed out that previous investigations on the value of the residue left by crops 

 have given unreliable results, mainly because the amount of roots was not 

 accurately determined. The author has formulated from numerous observations 

 a ratio between the weight of the above-ground parts of plants and their root 

 .systems at the time of maturity by means of which it is easy to calculate the 

 root residue from the weight of air-dried above-ground portions of the plant. 



Applying this method to the various crops, he reaches the general conclusion 

 that the value of plant residue, especially as regards nitrogen, is not so high 

 as is generally supposed. His averages for the nitrogen content in pounds per 

 acre are for various crops as follows: Winter rye, 14.2; winter wheat. 14.4; 

 oats, 15.4; barley, 9.6; beans, 56.2; red clover (14 days after the second cutting), 

 41; red clover (after unhindered growth to the middle of November of the 

 second year), 157.8; Victoria peas, 15.5; yellow lupines, 26.7; and white lupines, 

 20.8. 



