Water Salinity Should Be Reduced for Irrigation to Minimize Its Risk of Increased Soil N₂O Emissions

• Published in: International journal of environmental research and public health 2018-09, Vol.15 (10), p.2114
• Main Authors: Wei, Qi, Xu, Junzeng, Liao, Linxian, Li, Yawei, Wang, Haiyu, Rahim, Shah Fahad
• Format: Article
• Language: English
• Subjects: Agricultural Irrigation; Nitrogen; Nitrous Oxide - analysis; Risk; Saline Waters; Salinity; Sodium Chloride; Soil - chemistry; Temperature; Water
• ISSN: 1660-4601; 1661-7827; 1660-4601
• DOI: 10.3390/ijerph15102114

To reveal the effect of irrigation salinity on soil nitrous oxide (N₂O) emission, pot experiments were designed with three irrigation salinity levels (NaCl and CaCl₂ of 1, 2.5 and 4 g/L equivalence, Ec = 3.6, 8.1 and 12.7 ds/m), either for 0 kg N/ha (N0) or 120 kg N/ha (N120) nitrogen inputs. N₂O emissions from soils irrigated at different salinity levels varied in a similar pattern which was triggered by soil moisture dynamics. Yet, the magnitudes of pulse N₂O fluxes were significantly varied, with the peak flux at 5 g/L irrigation salinity level being much higher than at 2 and 8 g/L. Compared to fresh water irrigated soils, cumulative N₂O fluxes were reduced by 22.7% and 39.6% (N0), 29.1% and 39.2% (N120) for soils irrigated with 2 and 8 g/L saline water, while they were increased by 87.7% (N0) and 58.3% (N120) for soils irrigated with 5 g/L saline water. These results suggested that the effect degree of salinity on consumption and production of N₂O might vary among irrigation salinity ranges. As such, desalinating brackish water to a low salinity level (such as 2 g/L) before it is used for irrigation might be helpful for solving water resources crises and mitigating soil N₂O emissions.