10 LAND DRAINAGE 



well as lengthwise and crosswise. A duplication of this 

 incident has not been discovered in forty years of observa- 

 tion. The later behavior of the crop was entirely in 

 accord with these early days of its history a seemingly 

 uninterrupted growth, early crop maturity, and an abun- 

 dant yield. This example illustrates the importance of a 

 good start, due to many favorable conditions. 



14. Temperature and root action. The plant receives 

 all of its food, excepting carbon, through its roots. This 

 food can be taken only after it is dissolved in large quanti- 

 ties of water. The plants on an acre of oats, yielding 

 50 bushels of grain, would take through their roots dur- 

 ing their growth at least 700 tons 1,400,000 pounds 

 of water. 1 This water is required to dissolve the plant- 

 food, to assist it to reach its place in the plant, and gen- 

 erally to assist in promoting the well-being of the plant. 

 The part the roots play in taking in this great quantity 

 of water is involuntary, excepting as they place them- 

 selves in position to receive it. The process by which 

 this soil water enters the roots is called osmosis ; that by 

 which the foods in solution move inward to be used by 

 the plant, diffusion. Both water and food enter the 

 roots from the soil chiefly, if not entirely, by way of the 

 root-hairs. It is important, therefore, that the plants 

 develop extensive and vigorous root systems. In all of 

 this, temperature becomes an important factor. 



15. Root pressure. When a soil is over-cold, the 

 rate at which water enters the roots growing upon it may 

 be so slow that the plants assume a wilted appearance. 



1 This is in accord with the best service of water reported by 

 King, but is much below that obtained under arid conditions 

 and under very close control by Briggs and Shantz, and reported 

 in No. 1, Vol. Ill, Journal of Agricultural Research. 



