Single-event nitrous oxide losses under maize production as affected by soil type, tillage, rotation, and fertilization

Soil nitrate (NO3) can be especially susceptible to leaching and denitrification in late spring under maize (Zea mays L.) production. This study examined the effects of tillage (untilled; tilled), fertilizer application (full season rate or starter-only at planting), rotation (maize after orchardgrass (Dactylis glomerata L); continuous maize), and soil type (clay loam; loamy fine sand) on short-term nitrous oxide (N2O) emissions after a 50-mm late-spring simulated precipitation event. N2O emissions were measured daily for a week following the event. Soil NO3, temperature, physical properties and total N were also measured. N2O emissions peaked on the second day after a simulated rainfall event for all treatments. N2O losses were significantly higher on the clay loam compared to the loamy sand. Full season fertilizer application at planting on untilled soil resulted in 4.7 and 2.3 kg N ha(-1) greater cumulative N2O losses than starter-only fertilizer application on maize-after-grass and continuous maize, respectively. Under tilled conditions, cumulative N2O losses over a week averaged 0.88 kg N ha(-1) greater for the full fertilizer application compared to the starter-only application. Higher N2O losses from untilled soil were related to lower soil porosity and higher bulk density, and higher emissions under maize-after-grass were correlated with higher soil C levels. In conclusion, untilled soil and sod-based crop rotations increase late-spring N2O losses under maize production, especially with early fertilization. (C) 2008 Elsevier B.V. All rights reserved.