WATER OF SOIL IN ITS BJSLATION TO PLANTS 251 



Relative Water REQUiREMENTb of Corn on Different 

 Types of Nebraska Soils, 1911. Montgomery ^ 



Soil 



Dby Weight op Plants 

 IN Grams per Pot 



Transpiration Ratio 





Manured 



Unmanured 



Manured 



Unmanured 



Poor (15 bushels) . . 

 Medium (30 bushels) . 

 Fertile (50 bushels) . . 



376 

 413 

 472 



113 

 184 

 270 



350 

 341 

 346 



549 

 479 

 392 



173. Effect of texture on transpiration. — The effects 

 of texture have been investigated by a number of men, 

 the work of Von Seelhorst ^ and of Widtsoe ^ being per- 

 haps the most rehable. While these investigators found 

 in general that crops on heavy soils exhibited a lower 

 transpiration ratio, hasty conclusions must not be drawn. 

 Since the fine-textured soils contain more plant-food 

 materials, it is probable that this is the balancing factor 

 rather than texture alone. 



174. Actual amounts of water necessary to mature a 

 crop. — Although it can be seen from the transpiration 

 ratio that the amount of water necessary to bring an 

 average crop to maturity is very large, a concrete example 

 may be cited to advantage. A fair estimate of the dry 

 matter produced in raising a forty-bushel crop of wheat 

 would be about two tons. Assuming the transpiration 



^Montgomery, E. G. Water Requirements of Corn. 

 Nebraska Agr. Exp. Sta., 25th Ann. Rept., p. xi. 1912. 



^ Seelhorst, C. von, tJber den Wasserverbraueh von 

 Roggen, Gerste, Weizen, und Kartoffeln. Jour. f. Land- 

 wirtsehaft, Band 54, Heft 4, Seite 316-342. 1906. 



3 Widtsoe, J. A. Irrigation Investigations. Factors Influ- 

 encing Evaporation and Transpiration. Utah Agr. Exp. Sta., 

 Bui. 105. 1909. 



