Synergistic effects of biochar and plants can reduce greenhouse gas emissions from salt affected soil

Applying biochar and using cover crops are two potential approaches to reduce greenhouse gas (GHG) emissions. However, the effectiveness of these methods, individually or in combination, in salt-affected soils remains unclear. Thus, the objective was to determine the impact of barley (Hordeum vulgare) and biochar on N2O and CO2 emissions from salt-affected soil. During the 28-day replicated study, GHG emissions were measured near-continuously and the number of nirK, nirS, qnorB, and nosZ gene copies were measured 12 and 28 days after planting (DAP). Biochar accelerated barley emergence and reduced N2O-N and CO2-C emissions by 68% and 44% from 8 to 14 DAP, respectively. Barley reduced N2O-N emissions by 30.4% between 8 and 14 DAP, and at 12 DAP it reduced the number of nirK gene copies, that encodes for nitrite reductase by 40.9% and increased the number of nosZ gene copies, that encodes for nitrous oxide reductase by 193%. The biochar impact on N2O emissions was attributed to the 44% reduction in soil respiration, whereas the impact of barley was attributed to changes in the number of nirK and nosZ gene copies leading to increased efficiency of N2O reduction to N2. Overall, combining barley with biochar resulted in the greatest reduction (85%) of N2O emissions compared to soil alone.