ABSTRACT
Nutrient ¡ux in the soil-plant system is controlled by complex interactions among plant roots, soil microorganisms, chemical reactions, and pathways for loss. The concentration dependence of most oftheprocessesthattakeplaceinthesoilimpliesthatwhentheimmediatesupplyexceedstheabilityoftheplanttotakeupanutrient,variousprocesseswillacttoreduceitsconcentration(Shaviv andMikkelsen,1993).Suchprocessesincludetransformationsinducedbymicrobessuchas nitri-˜cation, denitri˜cation, and immobilization. Further included are chemical processes such as exchange,˜xation,precipitation,andhydrolysisaswellasphysicalonessuchasleaching,runoff, andvolatilization.Theextentbywhichnutrientsareremovedfromsolutionbytheprocessescompetingwithplantuptakecanthusaffectbothnutrientuseef˜ciencyandtheenvironment(Shaviv and Mikkelsen, 1993).
