Inhibitory effect of high nitrate on N2O reduction is offset by long moist spells in heavily N loaded arable soils

• Published in: Biology and fertility of soils 2022, Vol.58 (1), p.77-90
• Main Authors: Senbayram, Mehmet, Wei, Zhijun, Wu, Di, Shan, Jun, Yan, Xiaoyuan, Well, Reinhard
• Format: Article
• Language: English
• Subjects: Agricultural production; Agriculture; Arable land; Bacteria; Biomedical and Life Sciences; Continuous flow; Crop residues; Denitrification; Emissions; Fertilizer application; Fertilizers; Incubation period; Laboratories; Life Sciences; Microorganisms; Moisture content; Nitrates; Nitrification; Nitrous oxide; Original Paper; Reduction; Soil; Soil moisture; Soil Science & Conservation; Soil sciences; Soil types; Soil water; Stoichiometry; Straw; Terrestrial ecosystems; Vegetables; Water content
• ISSN: 0178-2762; 1432-0789
• DOI: 10.1007/s00374-021-01612-x

Numerous interrelated factors (e.g., the labile C, soil NO 3 − concentration, and soil moisture content) are involved in controlling the microbial sources of N 2 O and the product stoichiometry of denitrification; however, the interactions among different factors are still poorly understood. Here, a fully robotized continuous flow soil incubation system (allowing simultaneous measurements of N 2 and N 2 O fluxes) was employed to investigate the interactive effects of a 51-day duration of moist spell, straw amendment, and the NO 3 − level on the rate and product stoichiometry (N 2 O/(N 2 O + N 2 ) ratio) of denitrification in heavily N loaded arable soils (i.e., paddy, vegetable, and orchard soils). The rewetting-induced N 2 O emissions mainly originated from bacterial denitrification in all soil types, with a clear shift to fungal denitrification (plus contingent nitrification) over time. The vegetable and orchard soils showed a higher share of bacterial N 2 O (62–70%) than that in the paddy soils (50–54%), which may be attributed to more labile-C driven bacterial activity induced by the greater manure and crop residue input therein. Interestingly, the inhibitory effect of high soil NO 3 − on N 2 O reduction in these soils was offset by a 51-day-long moist spell, regardless of the amendment of straw. To our knowledge, our study is the first to show that the inhibitory effect of high residual NO 3 − on N 2 O reduction is suppressed by a moist spell with a certain duration in heavily N loaded arable soils, suggesting that the water regime history should be considered when optimizing the N fertilizer application timing to mitigate soil N 2 O emissions.