186 



NATURE AND PROPERTIES OP SOILS 



98. Influence of water on the plant.^ — ^As the amount 

 of water available to a crop is increased up to a certain point, 

 the vegetative growth also is usually increased, the plant be- 

 coming more succulent. The percentage of moisture in the 

 crop, even at harvest time, is usually high. Shipping qualities 

 are depressed with increased moisture, especially if the water 

 available is excessive. With an enlargement of the plant 

 cell a change probably occurs in the cell contents, tending 

 toward a greater susceptibility to disease. 



Ripening especially is delayed by large amounts of mois- 

 ture, tillering is diminished, and the percentage of protein 

 content of the crop is decreased. ' It is a curious fact that 

 many of the general and morphological effects of large quan- 

 tities of available water on plant growth are the same as those 

 caused by the presence of too much soluble nitrogen. In 

 cereals the stimulation from a large supply of water is 

 shown especially in the ratio of grain to straw. Widt- 

 soe's ^ findings in this regard are representative of the data ^ 

 available on this point: 



Table XXXIII 



niSTRIBUTION OF DRY MATTER BETWEEN GRAIlSr AND STRAW WITH 

 VARYING AMOUNTS OF WATER. 



Inches of water ap- 

 plied 



Grain in percentage 

 of dry matter of 

 entire crop 



44 



71/2 

 43 



10 

 43 



15 



^X 



25 



38 



35 

 37 



50 

 33 



^ Mitscherlich, E. A._, Das Wasser aJs Vegetationsfaktor; Lanclw. Jahr., 

 Band 42, Seite 701-717, 1912. 



^ Widtsoe, J. A., The Production of Dry Matter with Different Quan- 

 tities of Irrigation Water; Utah Agr, Exp. Sta., Bui. 116, p. 49, 1912. 



^Bunger, H., V'her den 'Einfiuss VerscMeden EoJien Wassergehalts des 

 Bodens in den MmzeXhen Vegetationsstadien lei Versehiedenem Nahr- 

 stoffreichtum auf die EntwicMwig des HaferpftanBen; Landw. Jahrb., 

 Band 35, Seite 941-1051, 1906. 



Also, Seelhorst, C, von, und Fxeckmann, W., Der Einfiuss des Was- 

 sergehaltes des Bodens auf die Ernten %nd die AusMlding VerscMedener 

 Getriedevarietaten; Jour. f. Landw., Band 51, Seite 253-269, 1903. 



