Comparison of Nitrous Oxide Consumption of Paddy Soils Developed from Three Parent Materials in Subtropical China

Paddy soils developed from various parent materials are widely distributed in the subtropical region in China and have a non-negligible but unclear potential to consume nitrous oxide (N₂O) due to long-term flooding. This study selected three of the most common paddy soils in subtropical China, developing from quaternary red soil (R), lake sediment sand (S), and alluvial soil (C), to study their total N₂O consumption and total nitrogen (N₂) production using N₂-free microcosm experiments. These paddy soils were treated with N₂O addition (N₂O treatment) or helium (He) addition (CK treatment) and incubated under flooding and anoxic conditions. The results showed that three alluvial soils (C1, C2, and C3) consumed over 99.93% of the N₂O accumulated in the soil profile, significantly higher than R and S soils (p < 0.05). And the N₂ production in three C soils was also significantly higher than other soils, accounting for 81.61% of the total N₂O consumption. The main soil factors affecting N₂O consumption in C, S, and R soils were soil clay content (p < 0.05), soil sand content (R² = 0.95, p < 0.001), and soil available potassium (AK) (p < 0.01), respectively. These results indicate flooding paddy soils, no matter the parent materials developed, could consume extremely large amount of N₂O produced in soil profiles.