Environmental impacts of nitrogen in pastoral agriculture

Abstract

The principal environmental impacts of nitrogen in pastoral agriculture are identified as: ammonia volatilisation, nitrous oxide emission, reduction of methane oxidation, and contamination of waters with organic nitrogen or inorganic nitrogen (nitrate, nitrite and ammonium). Each of these impacts is analysed in terms of its sensitivity to the form in which N enters the farming system, symbiotically or as fertiliser. Indirect effects that flow through from any changes in productivity are also examined. With the exception of organic N pollution of waters, all the impacts are shown to be directly affected by fertiliser N. Keywords: ammonia, leaching, methane, nitrate, nitrous oxide