| The food demands of the increasing world population puts pressure on land use and N availability. In this paper an overview is given of the different N cycling processes affected by agricultural activities. Of the amount of N added to the soil, about half is removed from the field as harvested crop, while the remainder of the N is incorporated into soil organic matter or is lost to other parts of the environment. During the last decades there has been much research on environmental consequences of agricultural activities, mainly on emission of gaseous N compounds (NH3, NO, N2O and N2), but also on N leaching, runoff and erosion. Study of the factors controlling loss of N is complex because of their multiplicity and mutual interactions. More recently... |
