A potentially underestimated source of CO₂ and other greenhouse gases in agriculture

Agriculture is a well-known global contributor to greenhouse gas (GHG) emissions responsible for the global rise in temperatures. A substantial amount of agricultural GHG emissions is linked to the application of synthetic fertilizers. Studies in this field have addressed the related microbiological processes, leaving the purely chemical ones out of focus. Our hypothesis was that some common mineral fertilizers produce environmentally significant GHG effluxes chemically because of their composition, large quantities of application, and specific conditions frequently present in soil. Therefore, the purpose of our work was to test whether Nitroammofoska (a commercial nitrogen-phosphorus-potassium fertilizer) and other common and readily available mineral fertilizers produce considerable CO₂ effluxes from chemical reactions in water with and without participation of CaCO₃. Based on our results, as much as 20.41% of all CO₂ annually emitted from all activities on land could be produced by (NH₄)₂SO₄ alone, provided all mineral nitrogen fertilizers are used as a mixture of (NH₄)₂SO₄ and K₂HPO₄, and in the presence of CaCO₃. The results also suggested a possibility of considerable economic loss due to intense NH₃ volatilization from ammonium-containing mineral fertilizers, occurring when enough carbonate and/or bicarbonate ions are available.