1919] FIELD CROPS. 82] 



Some factors in the winterkilling of grain crops, S. <'. SALM09 </ 

 Katu. Acad, sd., 28 (1916-17), pp . 129-iSl).— It is thought that of the wheat 

 area not harvested, (more than 16 per cent of the total wheat una of Kan- 

 sas) more than one-half (10 per cent of the total wheat area) Is winterkilled. 

 A study of the causes of loss from winterkilling lias been carried on tor about 

 four years and has developed a method of seeding grain In furrow* The 

 plants are protected from wind by the ridges and from freezing by the snow 

 which tills the furrow. The crop is also Injured less by bearing of the soil 

 during freezing and thawing weather (being better rooted in the soil), and Is 

 in a better position to absorb moisture. Results of Studies on different Bolls 

 sin i\v that winter annuals suffer more on wet soils, except in case of easily 

 injured plants which may be killed by comparatively brief periods of breezing, 

 and that such plants suffer more on sandy soils than on those of the heaviest 

 type except when heaving of the soil occurs. 



On the quantitative differences in the water conductivity of the wood in 

 trees and shrubs, J. B. Farmer (Proc. Roy. Soc. [London'], Ser. B, 90 (1918), 

 No. B G2S, pp. 218-250, figs. 5). — This contribution is made up of two parts, the 

 first dealing with the evergreens and the second with the deciduous plants. 

 The author attempted to find whether the water conductivity of wood in a 

 given species could be ascertained and usefully expressed in quantitative form, 

 whether conductivity could be correlated with any obvious character such as 

 deciduous habit, and whether definite changes in external conditions may 

 cause corresponding changes In water conductivity. 



The results, as presented In tabular detail with discussion, are considered 

 to throw light on the habit of many xerophilous plants. Deciduous species, 

 which may also vary among themselves, considerably exceed evergri re- 



gards specific conductivity, absolute fluctuation, plasticity, and sensitivity to 

 external influences. Considerable difference appears to exist between nor- 

 mal adult wood of a given tree and that of leaders of young trees, this differ- 

 ence (a lowering of conductivity) being notable in the main shoot of must 

 climbers. Arborescent and frutescent monocotyledons are defective as re- 

 gards water conductivity, this feature entering probably into the determination 

 of the habit of growth. It is suggested that the filling up of the wood of de- 

 ciduous trees during early autumn, owing to the persistence of root pressure 

 after transpiration is lowered, may find practical application in shortening the 

 time normally required for the seasoning of felled timber. It is thought that 

 the lower conductivity of evergreens is attributable to narrowness and short- 

 ness of the conducting vessels. 



FIELD CROPS. 



Nitrogen relations of certain crop plants when grown alone and in associa- 

 tion, R. C. Wright (Jour. Amer. Soc. Agron., 11 (1919). No. 2. /</>. ',9-<lt>. pi. 1. 

 fig Sm 4) _ This paper, a contribution from the Bureau of Plant Industry of the 

 U. S. Department of Agriculture, describes Investigations conduct 'he 



Arlington (Va.) Farm during 1914 and 1915 in a study of the effects 

 dative growth of legumes and nonlegumes under control conditions. pa 



were grown to maturity in galvanized corrugated iron bo use of 



which in studies of this sort has already been noted (E. S. R.. 36, p. 524), the 

 plants harvested close to the surface of the soil, dried, weighed, and ground 

 fine for analysis for total nitrogen. The roots were removed from the soil, 

 dried, ground, and returned and thoroughly Incorporated with the soil, and 

 the latter then sampled for a determination of total nitrogen. When two 



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