NOTES AND ABSTRACTS. 



307 



Soil Bacteria to Evaporation, The Relation of. (U.S.A. Exp. 

 Stn., Wisconsin, Bull. 23; April 1912) — The conclusions drawn from 

 the experiments are that bacterial action increases the rate of surface 

 evaporation from soils. 



The bacteria do not of themselves cause the increase, but the 

 by-products which are formed greatly influence the factors which 

 go to make up the movement of soil water. — G. P. C. 



Soils, Examination of, for Organic Constituents. By Oswald 

 Schreiner and Elbert C. Lathrop (U.S.A. Dep. Agr., Bur. Soils, 

 Bull. 80 ; 2 plates, 1 table). — It is known that certain soils are un- 

 fertile, although chemical analysis shows them to contain all that is 

 generally recognized as essential in a sufficient quantity. Experi- 

 ments have proved the presence in such soils of some toxic substance 

 or substances, soluble in water, which are inhibitory to healthy plant 

 development ; and the authors of this bulletin, having satisfied them- 

 selves that such substances were organic, are undertaking a systematic 

 research with a view to isolating and identifying such contents. 

 Their experiments have spread over a large number of soils from 

 various parts in the States. They have already isolated a large 

 number of organic substances, including dihydroxystearic acid, 

 various paraffin hydrocarbons, organic acids, esters, alcohols, carbo- 

 hydrates, pyridine derivatives, &c. The work is still being carried 

 forward and further results are promised. Methods adopted are 

 clearly shown. Some experiments are also detailed showing the 

 noxious effect of dihydroxystearic acid upon wheat seedlings. — W.A.V. 



Soils, Salt, Plants for. By J. Brichet (Rev. Hort. de VAlg., 

 No. 8, p. 251, Aug. 1912). — From his experiences with the salt soils of 

 Northern Africa the writer has compiled a list of plants, trees, and 

 shrubs which it is possible to grow : — 



1. Where the soil contains no chloride, but where watering can be 

 done only with brackish water. 



2. Where the soil contains not more than 5 or 6 per cent, of 

 chlorides and where watering is done with water containing not 

 more than 3 per cent, of salt. 



3. Where the soil contains 5 per cent, of chlorides and where 

 irrigation water contains 5 per cent, of salt. 



In many cases the cultivator may prevent the salt in soil or water 

 from accumulating until it arrives at poisonous doses. 



With salt but permeable soils, where fresh water is obtainable, a 

 system of drainage can sometimes be installed in which the irrigation 

 water dissolves and carries away the excess of salt. On the other hand, 

 when brackish water has to be used as little watering as possible 

 should be done during hot weather, and the soil should be well tilled 

 directly afterwards. This prevents the water charged with salt from 

 rising to the surface to evaporate and deposit its salt there until all 

 surface growth becomes impossible. 



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