SOILS FERTILIZERS. 425 



conclusion of Ehrenberg (see above) regarding the accumulation of nitrogen in 

 the soil from atmospheric sources is warranted. 



Ammonia evaporation from soil, O. Lemmkrmann and L. Fresenius 

 (Landw. JaJirb., .',5 il[^13). No. 1, pp. 127-15/,; ahs. in Ztschr. Angeic. Chem., 

 27 {191Jf), No. 17, Refemtentcil, p. i5//).— Tests of 6 soils, including sandy loam 

 and moor soils, were made to determine the influence of the addition of calcium 

 carbonate on the ammonia absorbing power of the soils. The soils were treated 

 with different amounts of ammonium carbonate and submitted to aeration under 

 various conditions. 



Each soil was foimd to have an individual action regarding the absorption of 

 ammonia, and the effect of calcium carbonate varied with the physical and 

 chemical character of the soils, promoting ammonia evaporation in some, re- 

 tarding it in others, and in one soil having no effect. In three of the soils it 

 was found that with a large application of ammonium carbonate the absorption 

 of ammonia was promoted by the addition of calcium carbonate, while with a 

 small application it was retarded. 



It is concluded that the absorption of ammonia salts depends almost entirely 

 on the exchange of bases of the zeolitic combinations in the soil. This is either 

 promoted, retarded, or not at all affected by the addition of calcium carbonate, 

 according to the chemical character of the soil, and that the effect of calcium 

 carbonate is influenced by the absolute quantity of ammonium carbonate added 

 and by the amount of exchangeable potassium present. 



The catalytic power of agricultural soil, H. Kappen {Fiihling's Landw. 

 Ztg., 62 {1918), No. 11, pp. 877-392) .—The author reviews a number of investi- 

 gations on the catalytic power of soils. 



Sterilization by heat and by poisonous substances so as to change the physi- 

 cal and chemical composition of soils was found to reduce greatly the rate of 

 decomposition of hydrogen peroxid, while sterilization in which the physical 

 and chemical composition remained unchanged produced no change in the 

 rate of decomposition. A comparison of the rate of decomposition of compounds, 

 wlien treated with colloidal substances and with samples of cultivated soils 

 in their natural state, showed a marked similarity. The general conclusion 

 is that although the decomposition of matter in soils is promoted by enzyma 

 and bacterial activity, the real catalytic power of soils is due to the colloids, 

 which through the agencies of physical adsorption of su*bstances on their sur- 

 faces and an intermediary reaction, have the power of decomposing these sub- 

 stances without losing their own identity. 



It is further concluded that the catalytic power of a soil depends largely 

 on its good physical condition and its alkalinity, and that these factors govern 

 the relations between catalytic power and productiveness of a soil. 



The food and habits of life of earthworms in relation to agriculture. 

 B. Keup (Mitt. Deut. Landw. Gesell, 28 (1913), Nos. 89, pp. 538-542; 40, pp. 

 552-555; 41, PP- 566-570). — In a review of numerous investigations on the life 

 and activity of earthworms in their relations to agriculture, the author briefly 

 describes the anatomical structure of these animals, their habits, and actions, 

 and sums up their beneficial effect on soils as regards fertility as follows: 

 They prevent the formation of peat bogs and swamps, especially in forests, by 

 destroying the plant residue on the soil surface. Through the taking up and 

 digesting of soil constituents the percentage of fine matter is increased, upper 

 and lower soils are intimately mixed together and with plant food, the soil 

 is loosened and crumbled, bacterial action is favored, the soil is fortified 

 against drought, deep rooting is promoted, plant food is placed in more readily 

 assimilable condition, and in short, the soil is put in better physical and 

 chemical condition for plant growth. 



