786 EXPERIMENT STATION RECORD. [Vol.41 



is the protection given by tlie ineguhir layer of even very slight bits of moss, 

 twigs, l)ark, and other litter weathered from the trees. ... An opposing in- 

 fluence appears in the ability of the brushes, tree trunks, and other large ob- 

 jects to hasten melting by radiating or reflecting into the snow the heat which 

 they receive from various sources. ... * 



" Expressed in irrigation terms, the figures given mean that on the areas 

 studied the average square mile of forest cover retained the equivalent of 

 between 720 and 160, averaging 400, acre-feet of water in the form of snow 

 after the open areas had become bare. ... In terras of time, the effect of the 

 forests was to sprea'd the 400 acre-feet of retained snow through a period aver- 

 aging 17 days in length. The retardation of this amount of snow is sufficient 

 to be of great importance to irrigation interests, especially as it is generally 

 understood that a forest cover tends to ' flatten out ' the crest of a flood and 

 thus to increase the minimum flow at periods of low water." 



Irrigation of lowland moor soils, M. Oehme {Jahrb. Moork., 3-5 {1914- 

 1916, pp. XXVII-XXXIX). — Five years' experiments on a moor soil growing 

 grain are reported. Irrigation by flooding from a i-eservoir and furrow irriga- 

 tion were practiced. The plats were unfertilized, fertilized with potash or 

 phosphoric acid alone, or completely fertilized. 



It was found that the best crop results were obtained in four out of five years 

 on the unirrigated plats which were completely fertilized. On the irrigated 

 plats furrow irrigation gave better results than flooding. Irrigation added 

 only a very small amount of plant nutrients to the soil. 



A second set of four years' experiments with soil tanks in which drainage 

 and ventilation of the soil were controlled gave similar results as far as irriga- 

 tion affected crop yield. A third set of four-year experiments on a low-lying 

 moor soil showed that the best results wei'e obtained with complete fertiliza- 

 tion and spring irrigation. 



It is concluded that irrigation of lowland moor soils in general gives un- 

 favorable results, except where under normal conditions plenty of water con- 

 taining considerable plant nutrients is available and the soil is well drained 

 naturally. 



Drainage of lands under irrigation, D. G. Miller (Proc. loiva Engin. Soc, 

 SO (1918), pp. 28-38). — This is a brief summary of the important general fea- 

 tures to be considered in the planning of drainage .'systems for irrigated lands. 



Some engineering methods used in the construction of tile drainage dis- 

 tricts, D. P. Dale {Proc. loiva Engin. Soc, 30 {1918), pp. 39-J,7).—A brief out- 

 line of methods is given. 



An investigation of tests of Iowa shale draintile, AV. J. Schlick (Iowa 

 Engin. Expt. i:>ta. Bui. 49 {1918). pp. 71, figs. i8).— Investigations (1) to deter- 

 mine the best method of making actual accelerated freezing and thawing tests 

 upon draintile, (2) to study the effects of such tests upon Iowa tile, (3) to de- 

 termine the best method of making absorption tests, and (4) to discover the 

 relations between the results of the freezing and thawing tests and the absorp- 

 tion and strength tests, are reported. The investigations were confined to hard 

 burned and soft burned shale tile from four representative Iowa factories, 

 together with a few concrete tile. 



It was found that " Iowa shale tile such a.s were Included in this investiga- 

 tion will withstand 100 freezings and thawlngs without excessive deterioration 

 when the absorption obtained by the standard boiling test does not exceed 9 

 per cent. All of the tile tested met the freezing and tliawing requirements of 

 the American Society for Testing Materials for ' extra quality ' draintile with 

 the exception of a certain 8-in. soft tile from one factory, which had a very 

 high percentage of absorption. 



