Greenhouse Gas Emissions from Salt-Affected Soils: Mechanistic Understanding of Interplay Factors and Reclamation Approaches

Salt-affected soils contain high levels of soluble salts (saline soil) and exchangeable sodium (alkali soil). Globally, about 932 million ha (Mha), including 831 Mha agricultural land, is salt-affected. Salinity sodicity adversely affect soil microbial diversity enzymatic activities, thereby carbon nitrogen dynamics greenhouse gas (GHG) emissions from soils. In this review article, we synthesize published information to understand the impact salinity on GHG production salt-affected soils, how various reclamation amendments (gypsum, phosphogypsum, organic manure, biochar, etc.) reclaimed Nitrous oxide (N2O) methane (CH4) are greater concern due their 298 28 times higher global warming potential, respectively, compared dioxide (CO2), a 100-year time scale. Therefore, CO2 given negligible/smaller significance other two. Generally, nitrous at lower reduced mainly to: (a) ammonification nitrification resulting in substrate for denitrification; (b) denitrifying bacteria lowered down microbial-mediated denitrification process; (c) dissimilatory nitrate reduction ammonium (DNRA), processes compete with each common substrate/nitrate. Overall, normal than those High suppresses activity both methanogens (CH4 production) methanotrophs consumption). However, it imposes more inhibitory effects methanotrophs, CH4 subsequent these may enhance N2O emissions. gypsum best agent, which significantly mitigates paddy cultivation sodic non-sodic mitigation rate its application. Gypsum amendment increases sulfate ion concentrations reduces inhibition methanogenesis by reductase enhancement redox potential. Biochar also good among mitigating emission The application fresh matter FYM This suggests need systematic investigations studying impacts technologies order develop low that can sequestration potential