Kt pools and pathways 1 Almost entirely inorganic except organic matter holds Kt because it is negatively charged living organisms act as sink because they need K Redistribution between available inorganic pools is rapid so solution K+ is replenished rapidly K released only slowly during weathering of minerals
K+ pools and pathways 1 • Almost entirely inorganic except: – organic matter holds K+ because it is negatively charged – living organisms act as sink because they need K+ • Redistribution between available inorganic pools is rapid so solution K+ is replenished rapidly • K released only slowly during weathering of minerals
K pools and pathways 2 crop atmosphere stable labile InorganIc ordanIc plants microbes labile soil stable InorganIc solution organIc leaching erosion
K+ pools and pathways 2 soil solution stable inorganic labile inorganic microbes plants stable organic labile organic leaching erosion crop atmosphere
P cycling P is scarce and most of p is insoluble P is present in soil solution as H2 PO4 and HPO42 P cycling involves both inorganic and organic pools Replacement of P lost to oceans is very, very SIOW Accessible deposits of phosphate rocks will run out in 80 years
P cycling • P is scarce and most of P is insoluble • P is present in soil solution as H2PO4 - and HPO4 2- • P cycling involves both inorganic and organic pools • Replacement of P lost to oceans is very, very slow • Accessible deposits of phosphate rocks will run out in ~ 80 years;