16 EXPEEIMENT STATION EECOED. [Vol. 88 



Inst. Agr. [Rome], Intemat. Rev. Sci. and Pract. Agr., 8 (1917), No. 3, pp. 3^2- 

 346). — From the results of a study at the Temir experiment station in south 

 Russia of the specific action of meteorological factors on the development of 

 millet, the following conclusions are drawn : 



" Germination only takes place when the mean soil temperature (24 hours) 

 at the spot where the grains are situated is not below 10-12° O. * The higher 

 the temperature the more rapid are germination and growth. . . . Thermal 

 conditions have a clear Influence on the flowering phase, which is more rapid 

 the greater the daily rise and fall of temperature. . . . 



" The rainfall values are spread over various periods of development. In 

 this case six periods only are distinguished instead of eight ; they are ( 1 ) 

 sowing, (2) appearance of young plants, (3) development of the third leaf — 

 stooling, (4)stooling — earing, (5) earing — flowering, (6) flowering — complete 

 maturity. The critical period for millet with respect to rainfall coincides with 

 the stooling phase, although it is not yet exactly known whether the notable 

 need of water by the plant at this moment is to be correlated with the actual 

 stooling process or with the development of the lateral rootlets. In the atmos- 

 pheric layer where the millet develops its epigeal portions (stem and flowers) 

 the plant itself takes special precautions, thanks to which the meteorological 

 factors are modified and fixed as the result of quite special combinations and 

 relationships. It creates a kind of ' microclimate '." 



SOILS— FERTILIZEES. 



Further studies on the freezing point lowering of soils, G. J. Boinrotrcos 

 and M. M. McCooL (Michigan 8ta. Tech. Bid. 31 (1916), pp. 51, fig. 1). — In con- 

 tinuation and extension of work previously reported (E. S. R., 34, p. 721), 

 in which the freezing point lowering was measured in over 58 soils at very 

 low and very high moisture contents, it was found that the original experi- 

 mental data, general conclusions, and hypotheses were confirmed. The soils 

 used included characteristic types from the States of Rhode Island, Pennsyl- 

 vania, Michigan, Kentucky, Florida, Texas, Wisconsin, Minnesota, Washing- 

 ton, and California. 



"The results obtained from this study show (1) that the lowering of the 

 freezing point of soils is entirely different at the two moisture contents in all 

 the different soUs. (2) The degree of the freezing point lowering is quite 

 small at the high moisture content and varies rather appreciably in the differ- 

 ent soils, while at the low moisture content it is tremendously high and varies 

 considerably in the various soils. At the maximum percentage of water 

 the lowering of the freezing point varies from 0.01° C. in the case of some 

 sands to 0.075° in the case of some clay loams and clays, while at the mini- 

 mum percentage of moisture it ranges from about 0.11° in some sands to 

 about 1.37° in some of the loams and clays. The degree of depression for 

 heavy sandy loams, silts, clay loams, and clay tends to be above 1° at the 

 minimum water content, whUe that of sands and very light sandy loam lies 

 as a rule close to 0.4°. . . . 



" It was found that the magnitude of the lowering of the freezing point of 

 soils at the low moisture content decreases with successive freezings. This 

 was true, however, with the agricultural soils, but not with artificial sub- 

 stances such as quartz sand, kaolin, burned soils, etc. For explaining these 

 phenomena the hypothesis is offered that the greatest portion of the water 

 which is made inactive or unavailable and thus removed from the field of ac- 

 tion as far as the freezing point lowering Lb concerned, is due to the colloids 

 which the soils contain. . . . 



