Oct. 15. I9I9 Rate of Absorption of Soil Constituents 



67 



stitu^ut by the plant will be accompanied by exactly equal losses or gains 

 in the soil extract. The more obvious reasons for this are that the water 

 extract is to be regarded only as an indicator of the general magnitudes of 



Fig. 10. — Absorption of potassium by barley, computed to parts per million of soil. 



the solutes present and not as the equivalent of the soil solution, that ions 

 absorbed by the plants may be partially or entirely replaced in the water 

 extract by solution from the soil minerals, and that solutes lost from the 

 plants may not reappear in the form determined in the soil extract. 



.55 r 



j»- 



'-% 





^'•^/Hc 



%>p 



•X 



y 



/ 



"■ CALCIUM (Ca) \ 



\ / 



^-%. 



%>, 





/ 



£LANr 



E 

 i. 



vk^ T J j r 3 n 13 ij 17 i6f 20 



Fig. II. — Absorption of calcium by barley, computed to parts per million of soil. 



Nitrogen absorption. — (Fig. 9.) The maximum absorption of nitro- 

 gen took place between the third week from planting (time of germina- 

 tion) and the ninth week from planting. Almost the entire amount of 

 122504°— 19 2 



