Oral Presentation Society for Freshwater Science 2026 Annual Meeting

Nitrous oxide emissions from tailwater recovery systems (135909)

Auldyn L. Faulk 1 , Shannon L. Speir 1 , Nellie I. Little 1 , Frank E. Johnson III 2 , Mike B. Daniels 1
  1. University of Arkansas, Fayetteville, ARKANSAS, United States
  2. U.S. Department of Agriculture, Agricultural Research Service, Oxford, Mississippi, United States

Though agriculture is a cornerstone of the Arkansas economy, it is also a significant contributor to gaseous nutrient losses and the biggest driver of water consumption, accounting for about 70% of freshwater withdrawal globally. Additionally, nitrous oxide (N2O) is a potent reactive gas in the atmosphere. While irrigation tailwater recovery systems (TWRS) have gained traction in Eastern Arkansas for their ability to conserve groundwater, recycle irrigation water, and reduce nutrient losses, there is limited evidence regarding their role in gaseous nutrient losses. This gap in knowledge has prevented such systems from being recognized as a resilient conservation practice. As such, TWRS may either mitigate or contribute to emissions depending on their management. Without clear data, their potential tradeoffs remain poorly understood. To address this gap, we conducted year-round monitoring of N2O emissions within three different TWRS located on Arkansas Discovery Farm sites across Eastern Arkansas. To quantify N2O emissions in TWRS, we sampled emissions utilizing floating chambers placed at three distributed locations in each TWRS, quantifying emissions via gas chromatography. Preliminary results show that N2O emissions vary seasonally across sites, with the spring season having the highest emissions. Additionally, emissions are driven by nitrate concentrations in the TWRS, indicating that increased fertilizer runoff will enhance N2O loss to the atmosphere. Additionally, preliminary data indicates that tailwater recovery systems are typically net sources of N2O to the atmosphere. These findings emphasize the potential tradeoff between water conservation and greenhouse gas emissions from TWRS, suggesting that net environmental benefits depends on the implantation of targeted strategies to also reduce nitrate-driven N2O losses.