ABSTRACT
In the agricultural sciences, soil fertility and plant nutrition played an important role during the twentiethcenturyinincreasingcropyields.Inthetwenty-˜rstcentury,theimportanceofthis˜eldis expectedtoincreaseduetolimitednaturalresources(landandwater),theneedformoresustainable agriculturalsystems,andconcernaboutenvironmentalpollution.Inthiscontext,increasingcrop yields will be a major challenge to agricultural scientists, in general, and soil scientists, in particular. Increasing crop yields under these constraints will require a rational use of chemical fertilizers, anincreasinguseoforganicsourcesofnutrients,arecyclingofplantavailablenutrients,andan exploitation of the genetic potential of crop species and cultivars to make ef˜cient use of nutrients.
