Small artificial waterbodies are larger emitters of carbon dioxide (CO₂) and methane (CH₄) than natural waterbodies. The Intergovernmental Panel on Climate Change (IPCC) recommends these waterbodies are accounted for in national emission inventories, yet data is extremely limited for irrigated landscapes. To derive a baseline of their greenhouse gas footprint, we investigated 38 irrigation farm dams in horticulture and broadacre cropping in semi-arid NSW, Australia. Dissolved CO₂, CH₄, and nitrous oxide (N₂O) were measured in spring and summer, 2021–2022. While all dams were sources of CH₄ to the atmosphere, 52% of irrigation farm dams were sinks for CO₂ and 70% were sinks for N₂O. Relationships in the linear mixed effect models indicate that CO₂ concentrations were primarily driven by dissolved oxygen (DO), ammonium, and sediment carbon content, while N₂O concentration was best explained by an interaction between DO and ammonium. Methane concentrations did not display any relationship with typical biological variables and instead were related to soil salinity, trophic status, and size. Carbon dioxide-equivalent emissions were highest in small (< 0.001 km²) dams (305 g CO₂-eq m⁻² season⁻¹) and in those used for recycling irrigation water (249 g CO₂-eq m⁻² season⁻¹), with CH₄ contributing 70% of average CO₂-eq emissions. However, irrigation dams had considerably lower CH₄ emissions (mean 40 kg ha⁻¹ yr⁻¹) than the IPCC emission factor (EF) of 183 kg CH₄ ha⁻¹ yr⁻¹ for constructed ponds and lower N₂O EF of 0.06% than the indirect EF for agricultural surface waters (0.26%). This synoptic survey reveals existing models may be severely overestimating (4–5 times) farm dam CH₄ and N₂O emissions in semi-arid irrigation areas. Further research is needed to define these artificial waterbodies in emissions accounting.

小型人工水体比天然水体排放更多的二氧化碳 (CO ₂ ) 和甲烷 (CH _{4 )。}政府间气候变化专门委员会 (IPCC) 建议将这些水体纳入国家排放清单，但灌溉景观的数据极其有限。为了得出其温室气体足迹的基线，我们调查了澳大利亚半干旱新南威尔士州的 38 个园艺和大田种植灌溉农场水坝。2021-2022 年春季和夏季测量了溶解的 CO ₂、CH ₄和一氧化二氮 (N _{2 O)。}虽然所有水坝都是大气中CH _{4的来源，但 52% 的灌溉农场水坝是 CO 2}的汇，70% 是 N ₂ O 的汇。线性混合效应模型中的关系表明，CO ₂浓度主要由溶解量驱动氧 (DO)、铵和沉积物碳含量，而 N ₂ O 浓度最好通过 DO 和铵之间的相互作用来解释。甲烷浓度与典型的生物变量没有任何关系，而是与土壤盐度、营养状态和大小有关。^{小型（< 0.001 km 2}）水坝（305 g CO ₂ -eq m ^-2  season ^-1）和用于回收灌溉水的水坝（249 g CO ₂ -eq m ^-2  season -1 ）的二氧化碳当量排放量最高^{。 1} )，其中CH ₄贡献了平均CO ₂当量排放量的70%。然而，灌溉水坝的 CH ₄排放量（平均 40 kg ha ^-1  yr ^-1）远低于 IPCC 建造池塘排放因子（EF）183 kg CH ₄  ha ^-1  yr ^-1，并且 N ₂ O EF较低比农业地表水间接 EF (0.26%) 低 0.06%。这项综合调查显示，现有模型可能严重高估（4-5 倍）半干旱灌溉区农场大坝的 CH ₄和 N _{2 O 排放量。}需要进一步研究来定义排放核算中的这些人工水体。