New Perspectives on Nitrogen Cycling in the Temperate and Tropical Americas

Inputs of nitrogen to terrestrial and aquatic ecosystems have increased several-fold over the last one hundred and fifty years, with the steepest increases during the last four decades. The expansion of fertilizer manu­ facture and use, the increase in fossil fuel combustion, the intensification of animal husbandry, and widespread cultivation of N2 fixing crops have all contributed to the dramatic...