826 



EXPERIMENT STATION RECORD. 



The average amounts of water required to make 1 lb. of dry matter and 1 lb. 

 of grain for the different crops at Akron, Colo., in 1911 were as follows: 



Water requirement vf crops grown at Akron, Colo., in 1911. 



Crop. 



Alfalfa 



Field peas... 

 Artemisia . . . 

 Spring rye. . 

 Sweet clover 



Oats 



Bnclim-heat. 

 Barley 



Dry 

 matter. 



Pounds. 

 1,068 

 800 

 765 

 724 

 709 

 614 

 578 

 539 



Grain 

 production. 



Pounds. 



2,218 

 '2,'2i5' 



1,6S0 

 1.037 

 1,244 



Crop. 



Wheat 



Potato 



Rape 



Sugar beet 



Corn 



Weeds 



Sorghum.. 

 Millet 



Dry 



matter. 



Pounds. 

 507 

 448 

 441 

 377 

 369 

 322 

 306 

 275 



Grain 

 production. 



Pounds. 

 1,357 



790 

 923 



The determinations made in the different years and at the different localities 

 showed some fluctuation, which would be expected from the differences in evapo- 

 ration fi'om free water surfaces. 



II. A review of the literature. — The authors here give a summary of investi- 

 gations bearing upon the subject, reviewing the papers with reference to the 

 various factors which affect water requirement. A bibliography is appended. 



Summer evaporation intensity as a determining' factor in the distribution 

 of veg'etation in Connecticut, G. E. Nichols (Bot. Gaz., 56 (1913), No. 2, pp. 

 1.^3-152). — During the summer of 1912 continuous evaporation records were 

 taken at numerous localities in the State by means of porous clay atmometers. 

 It was found that the period of maximum evaporation coincides approximately 

 with the more critical period of vegetative activity. It appears also that the 

 area dominated largely by the mesophytic northern hard wood type of forest 

 and the strip along the east coast constitute regions of relatively low evapora- 

 tion intensity, and that the rate of evaporation in the eastern highland, where 

 oaks predominate in the forest, is somewhat higher than in the central lowland, 

 where the more mesophytic chestnut is the characteristic tree. Attention is 

 called in this connection to the more maritime climate of the eastern portion of 

 Connecticut beyond Long Island. 



Calcareous chlorosis of green plants: The role of root excretions in the 

 absorption of iron in calcareous soils, P. Maz^, M. Ruot, and M. Lemoigne 

 (Compt. Rend. Acad. Sci. [Paris']. 151 (1913), No. 12, pp. 495-498) .—In continu- 

 ation of previous investigations (E. S. R., 28. p. 242), the authors report on the 

 effect of a lack of iron on chlorosis. 



Vetches and peas were grown in nutrient solutions, and when 2 per cent 

 calcium carbonate was added chlorosis immediately appeared, although iron 

 sulphate was present in all the solutions. A few drops of iron nitrate in the 

 solution caused the return of the green color to the plants. The addition of 

 organic acids that are capable of dissolving iron in the presence of calcium 

 carbonate had the same effect within a few days. In some of the solutions the 

 plants became chlorotic even when there was originally no calcium carbonate 

 present. This is explained by the absorption of other calcium salts by the roots 

 and the excretion of calcium carbonate from them. The difference observed in 

 plants regarding their resistance to chlorosis is said to depend In part at least 

 on the acidity of the cell sap. 



In treating plants for chlorosis iron nitrate has given good results when a 

 0.2 per cent solution was sprayed on the leaves. For leguminous plants iron 

 sulphate is said to be preferred, as it furnishes sulphur, the lack of which is 

 also said to cause chlorosis. 



