Nutrient balance models- a management tool? A nutrient stock (e.g.P,K,Ca,Mg) ◇ input from the atmosphere input from mineral weathering fertilization losses with seepage losses with harvestNutrient balance models – a management tool? Δ nutrient stock (e.g. P, K, Ca, Mg) = input from the atmosphere + input from mineral weathering + fer4liza4on - losses with seepage - losses with harvest