Nitrification inhibitor DMPP offsets the increase in N2O emission induced by soil salinity

Abstract

To evaluate the effect of a nitrification inhibitor on reducing N2O emissions from saline soils, we undertook a field plot experiment with three salinity levels (non-saline, NS = 0.21 dS m−1; low saline, LS = 1.02 dS m−1; and high saline, HS = 5.23 dS m−1), factorially combined with two nitrification inhibitor treatments (with and without DMPP (3,4-dimethylpyrazole phosphate)). The low saline soil had the highest N2O flux peak and its cumulative N2O emissions were 2.2-fold those of the non-saline soil and 3.1-fold those of the high saline soil. Low salinity strongly inhibited nitrite oxidation and only slightly inhibited ammonia oxidation, which resulted in a high accumulation of NO2−-N and high N2O emissions. The nitrification inhibitor DMPP reduced cumulative N2O emissions (p < 0.05) by 61% in non-saline soil (reduction of 88.3 mg N m−2) and by 75% in low saline soil (reduction of 239.8 mg N m−2). DMPP offsets low salinity-induced high N2O emissions by inhibiting ammonia oxidation.