Nitrous Oxide Losses from Managed Agricultural Soil in a Semi-Arid Region of Texas.

Both anthropogenic and natural emissions of greenhouse gases (GHGs) are contributing to increased atmospheric concentrations, and research has begun to determine how to reduce both sources. Greenhouse gas production from agricultural soil accounts for about 10% of the US production of GHGs and about 84% of nitrous oxide (N₂O) production, which is the most potent of the “big three” GHGs [carbon dioxide (CO₂), methane (CH₄), N₂O].The global warming potential of N₂O is 298 times that of CO_2­. Nitrous oxide is produced through both nitrification and denitrification, which makes mitigation of the flux of this gas complicated. Conservation management practices are being evaluated on the Texas High Plains, with the hope of correlating these practices with a decrease in GHG production and an increase in crop yield. Conservation practices used include three tillage regimes: no-till with winter wheat cover, no-till winter fallow, and conventional tillage. In addition to tillage, five nitrogen fertilizer treatments are used: control (no fertilizer added), 100% pre-plant, 100% side-dressed, 40% pre-plant and 60% side-dressed, and 100% pre-plant with a nitrogen stabilizer. This study is set up as a factorial, resulting in 15 unique combinations, replicated three times for a total of 45 plots. Data collected over the first half of this project demonstrated a general reduction of GHGs when combining no-tillage and wheat cover with split applied nitrogen fertilizer. Sinks of N₂O have been observed when mineral nitrogen is limiting in the soil. Future studies will include determining the major source of N₂O from agricultural soils on the Texas High Plains which will further influence management decisions pertaining to the mitigation of the flux of this gas.