Methane uptake by saline-alkaline soils with varying electrical conductivity in the Hetao Irrigation District of Inner Mongolia, China.

Soil salinization adversely affects sustainable land use and limitation of greenhouse gas emission. Methane (CH₄) uptake and the specific activity of methanotrophs in three saline-alkaline soils—S1, electrical conductivity (EC) 4.80 dS m⁻¹; S2, EC 2.60 dS m⁻¹; and S3, EC 0.74 dS m⁻¹—were observed and measured across crop phenological development in the Hetao Irrigation District of Inner Mongolia, China. There were significant differences in CH₄ uptake between the three soil types. The cumulative uptake of CH₄ was 97.97 mg m⁻², 109.49 mg m⁻², and 150.0 mg m⁻² in S1, S2, and S3, respectively. Cumulative CH₄ uptake was 35%, 35%, and 53% lower in S1 than in S3, and was 27%, 28%, and 19% lower in S2 than in S3 in 2014, 2015, and 2016, respectively. Differences in CH₄ uptake were driven by the different specific activities of the methanotrophs in the three soils, of which the key controlling factor was soil EC. The findings demonstrate that saline-alkaline soils with high EC led to low CH₄ uptake and thereby significantly increased the total greenhouse effect of CH₄. [ABSTRACT FROM AUTHOR]