Enhanced Efficiency Nitrogen Products Influence Ammonia Volatilization and Nitrous Oxide Emission from Two Contrasting Soils

Abstract

Core Ideas Ammonia volatilization and N2O emissions from N‐sources were assessed in two soils. The N‐(n‐butyl) thiophosphoric triamide reduced NH3 volatilization losses from both sandy loam and silty clay soils. Nitrapyrin and SuperU reduced N2O emissions from sandy loam soil only. Polymer coated urea was effective in reducing both NH3 and N2O emissions from sandy loam soil. Right N‐source could mitigate gaseous N losses from agroecosystems. Potentials of enhanced efficiency nitrogen (EEN) products to control N losses can vary with soil pH, cation exchange capacity, organic matter, water, temperature, and management. A laboratory experiment was conducted to quantify and compare ammonia (NH3) volatilization and nitrous oxide (N2O) losses with (i) control, (ii) urea, urea treated with (iii) urease inhibitor, NBPT [N‐(n‐butyl) thiophosphoric triamide], (iv) nitrification inhibitor, nitrapyrin (NP) [2‐chloro‐6‐trichloro methyl pyridine], (v) urea stabilized with NBPT and nitrification inhibitor dicyandiamide (SuperU), and (vi) slow release N fertilizer polymer coated urea (PCU) amendments from Ulen sandy loam and Fargo silty clay soils. Across N amendments, cumulative NH3–N losses from sandy loam soil ranged from 0.7 to 4.3% of applied N, and were higher than those from silty clay soil (0.1–0.4% of applied N). In sandy loam, compared to urea, NBPT and PCU reduced NH3–N volatilization by 32.3 and 84.2%, respectively, whereas NP and SuperU increased NH3–N losses by 98.7 and 20.3%, respectively. However, in silty clay soil, only NBPT exhibited significant reduction in NH3–N losses of 71.4%, relative to urea. Cumulative N2O emissions did not differ between soil textures and ranged from 3.7 to 7.4% of applied N across N sources. However, soil N2O emissions differed among N sources in sandy loam soil. In sandy loam soil, NP, SuperU, and PCU treatments significantly reduced N2O‐N emissions by 23.5, 43.8, and 51.1%, respectively, compared to urea. Applicability of using EEN products to mitigate NH3 and N2O emission losses varies with soil texture.