191 i.J Summary of Agricultural Experiments. 673 



and Mr. Rew are the British representatives), to consider the 

 question with the Bureau of the Institute and to report to trie 

 next Session at Vienna in 1913. 



SUMMARY OF AGRICULTURAL EXPERIMENTS* 

 Soils and Manuring. 



Flow of Air and Water through Soils (W. H. Green and G. A. 

 Ampt, Jour. Agric. Science, Vol. IV., Part I., May, 191 1; Cambridge 

 University Press). — This paper gives an account of experiments designed 

 to show an accord between certain theoretical expressions for the per- 

 meability of soil and experimental results. It is recognised that the 

 mechanical analysis of a soil is no guide to one of the most important 

 factors of fertility — the permeability of the soil to air and water. 

 What is required is a quantitative expression of the relations of the 

 soil to the movements of air and water through it. The authors con- 

 clude that the required relation can be stated in terms of three con- 

 stants dependent on the mechanical constitution of the soil in regard 

 to the composition, size, and arrangement of its particles, and measured 

 by (a) the specific interstitial space ; (b) the permeability to water ; 

 and (c) the surface tension. These constants are liable to vary, how- 

 ever, when the soil is disturbed in any way. Mathematical expressions 

 for these constants, in terms of quantities capable of measurement in 

 relation to a laboratory sample contained in a glass tube are given, 

 and the modifications necessary according as the soil moisture travels 

 upwards, downwards, or horizontally, are evaluated. The paper con- 

 cludes with a verification of these formulas by means of laboratory 

 experiments on three classes of soil enclosed in a glass tube. The 

 apparatus used is fully described and illustrated. The authors suggest 

 that the evaluation of these constants is of more importance than, and 

 should replace, the measurement of the size of the soil particles, as is 

 ordinarily done by means of the " mechanical analysis " of a soil. 



Absorption of Ammonia from the Atmosphere (A. D. Hall and 

 *N. H. J. Miller, Jour. Agric. Science, Vol. IV., Part I., May, 1911; 

 Cambridge University Press). — The object of this investigation was to 

 find whether the soil usually absorbs ammonia from the atmosphere 

 or gives it off. The proportion of ammonia in the air is in any case 

 exceedingly small, but the question is of some importance in attempts 

 to construct a balance-sheet for the nitrogen received by and removed 

 from an experimental plot over any length of time. Attempts to 

 measure the amount of ammonia absorbed or given up by a current 

 of air drawn through a tube filled with soil were unsuccessful, no 

 appreciable effect being observed in the small scale experiment carried 

 out. The method was then employed of exposing dishes of dilute 

 sulphuric acid to the air. A pair of dishes was exposed at each of 



A summary of all reports on agricultural experiments and investigations 

 recently received will be given each month. The Board are anxious to obtain 

 for inclusion copies of reports on inquiries, whether carried out by agricultural 

 colleges, societies, or private persons. 



