NITROGEN AS INDICATOR OF SUSTAINABILITY IN IRRIGATED AREAS OF NORTHERN MEXICO

Long term irrigation in arid and semiarid agricultural areas may affect soil and water quality both within the areas’ boundaries (soil degradation, aquifer contamination, human health risks) and outside their boundaries (greenhouse gas emissions, eutrophication). Three large irrigated areas in arid northern Mexico were investigated with respect to soil and water sustainability using nitrogen (N) as indicator. The results show stark differences on how sustainability is perceived and addressed in each region. Common hazards to all three are aquifer depletion and a gradual increase in groundwater contamination. Salinization (Na) of groundwater is a threat common to all three regions, whereas nitrate (NO₃^-) content is worse to one of them. Excess N-fertilization causes high gaseous N₂O emissions (a greenhouse gas), which are reported as very high in agricultural areas, however these are measured in only one of the three regions. Overall, research conducted in these areas focuses still in increasing crop yield, but an awareness of the advantages of implementing measures towards soil and water sustainability is emerging.