20 EXPERIMENT STATION RECOED. 



groimd-water levels maintained at heights of 15.76, 31.52, and 47.28 in., and of 

 soil aeration on the yield of oats. It is stated that the season was very dry. 



The high water levels increased the yield of straw substantially as compared 

 with the lower levels. A ground-water level of 31.52 in. below the surface was 

 most advantageous and the amount of water required by this method for the 

 production of a pound of dry matter was 618 lbs. as compared with 550 lb.S;_by^ 

 sprinkling. Aerating the soil decreased the yield of crops in most cases, which 

 was thought to be due to the sandy soils used and to the dry season. 



The flow of subsoil water, H. E. Hurst {Cairo Sd. Jour., 6 {1912), No. 65, 

 pp. 27-32). — In this paper an attempt is made to give part of the theory of the 

 flow of a liquid through a porous medium, and to obtain the general equation 

 of flow as simply as possible without applying the theory to the solution of any 

 problems. The phenomena dealt with are those occurring in the saturated por- 

 tions of the soil. 



Conservation of the soil, A. GbiSgoiee {Rev. Econ. Internat., 8 {1911), IV, 

 No. 2, pp. 368-383; 9 {1912), I, No. 2, pp. 391-408; II, No. 2. pp. .',17-^32).— 

 This is a discussion by the director of the agi'icultural experiment station of 

 Gembloux, Belgium, of the chemical, physical, and economic factors of soil 

 conservation. 



The adsorption phenomena of cultivated soils, J. H. Abeeson (Meded. 

 Rijks Eoogere Land, Tuin en 3osc1i'bouwsch. [Wageningen], 5 {1911), No. 1, pp. 

 l-JfS^figs. 4; Ztschr. Chem. u. Indus. Kolloide, 10 {1912), No. 1, pp. 13-22; abs. 

 in Jour. Soc. Chem. Indus., 31 {1912), No. 5, p. 243). — From the results of 

 experiments with clay soils treated with varying amounts and concentrations 

 of solutions of ammonium chlorid alone and with additions of calcium, potas- 

 sium, and sodium chlorids and sodium nitrate, the author concludes that during 

 the process of adsorption an equilibrium was established in the exchange of ions 

 of the soil and of the added solution. It is held that this exchange of ions 

 was not the result of a purely chemical reaction in the sense maintained by 

 Guldberg and Waage. The addition of ions which reacted with those in the 

 solution reduced the adsorption. Soil adsorption followed the same law as 

 adsorption by charcoal, wool, silk, etc. Adsorption in the s oiljs held to be a 

 function of the surface of the colloidal substances. 



It would seem probable that the aluminum silicates in the soil are the com- 

 pounds which take up the calcium, magnesium, potassium, and sodium ions, 

 thus forming the adsorption compounds. There was a certain relation, al- 

 though no exact proportionality, between adsorption and hygroscopicity (as 

 determined by the Mitscherlich method) of the soil. Increasing the tempera- 

 ture lowered the adsorption of the soil just as in the case of other colloidal 

 substances. 



The biological absorption of soils, J. Stoklasa {Chem. Ztg., 35 {1911), 

 No. 154, PP- 1)25-1427 ; abs. in Chem. Zcntbh, 1912, I, No. 12, p. .939).— Studies 

 of the absorption of phosphate, potassium, ammonium, and nitrate ions from 

 solutions of ammonium and potassium sulphates, ammonium and potassium 

 chlorids, monocalcium phosphate, and potassium and calcium nitrates by steril- 

 ized and unsterilized soils, and soils inoculated with a culture of Bacillus 

 mycoides, are reported. The process of absorption continued from 23 to 30 

 days, the solutions being allowed to percolate through the soil during tliis 

 time. 



The absorption of the phosphoric acid was from 3.8 to 14.5 per cent greater 

 for the unsterilized than for the sterilized soils. This difference is attributed 

 to the bacterial activity and is called the biological absorption. The biological 

 absorption of all the ions was substantially smaller for acid or unsaturated 

 and less fertile soils than for the alkaline or saturated and fertile soils. The 



