Lecture 7 



— 161 — 



Potassium Nutrition 



We need to understand the chemistry of the soil 

 as it pertains to potassium, but the immediate way 



550 

 500 



^450 



>- 



Q400 



q: 



Q--350H 



^300 



O 

 a. 

 O2504 



>- 



m 



o200 



UJ 



> 



O 



2 I50^ 





iOO- 



50- 



[] NON- REPLACEABLE K 

 REPLACEABLE K 



SOIL 38 

 NP2K 



UP 



SOIL 30 

 NP2K 



NP 



SOIL 36 



NP2K 



SOIL 37 

 NP2K 



NP 



n 



AB AB AB AB AB AB AB AB 



NUMBER OF CROPS GROWN 



(A--CROPS 1-4 B=CROPS 5-8) 



Textfigure 43. — The absorption of potas- 

 sium by crops from replaceable and non-re- 

 placeable forms, as influenced by character- 

 istics of soil and duration of cropping. Increas- 

 ing amounts of potassium, referable to the 

 non-replaceable fraction, are absorbed as crop- 

 ping reduces relative amounts of replaceable 

 potassium. (Hoagland and Martin, 1933), 



to find out how much potassium is in a condition to 

 be absorbed by plants is to determine how much 

 potassium plants do absorb over long or short periods 

 of time under conditions which are not otherwise 



