Saline Soils Emit More N2O than productive soils in the Northern Great Plains

Saline/sodic soils in the Northern Great Plains are intertwined with productive soils. Although plant growth is limited, they are often cropped in the same way as more productive areas.

In a two-year study published in the Journal of Environmental Quality, researchers compared greenhouse gas (GHG) emissions from highly productive and saline/sodic soils treated with 0 or 200 lb N/ac. They measured emissions every four hours for seven days in mid-July. Scientists analyzed soil samples for inorganic N, microbial biomass, and copy numbers of specific denitrification functional genes.

The team found that productive soil had greater CO₂–C emission and microbial biomass and less N₂O–N emission than saline/sodic soils. Nitrogen application did not influence CO₂–C emission; however, fertilizer-derived N₂O–N emissions were 57–84% greater from saline/sodic soil than productive soil. The nitrite reductase gene, nirS, copy number was 42-fold greater in the saline/sodic than productive soil.

These data suggest that saline/sodic soil has a large denitrification potential and N₂O–N emissions would be reduced by not applying N to these areas.