Ascription of nosZ gene, pH and copper for mitigating N2O emissions in acidic soils

Abstract

Soil nitrous oxide (N₂O) emissions are alarming for global warming and climate change. N₂O reduction is carried out only by nosZ gene encoded N₂O-reductase, which is highly sensitive to acidic pH and copper (Cu) contents. Therefore, a microcosm study was conducted to examine the attribution of soil pH management, Cu supply and nosZ gene abundance for N₂O emission mitigation. Cu was applied at the dose of 0, 10, 25 and 50 mg kg^-1 to three acidic soils (Soil 1, 2 and 3) without and with dolomite (0 and 5 g kg^-1). Cu application and soil pH increment substantially enlarged the abundance of nosZ gene, and consequently mitigated soil N₂O emissions; highest reduction with 25 Cu mg kg^-1. Decline in NH₄⁺ and subsequently accumulation of NO₃^-, and large contents of MBC and DOC in dolomite treated soils led to a substantial N₂O reduction. The cumulative N₂O emissions were lowest in the treatment of 25 Cu mg kg^-1 with dolomite application for each soil. Results suggest that soil pH increment, an adequate Cu supply, and nosZ gene abundance can potentially lower soil N₂O emissions in acidic soils.

Keywords: Acidic soils; Climate change; Copper; Nitrous oxide; Soil pH management; nosZ gene.