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- Title
Soil gross N<sub>2</sub>O emission and uptake under two contrasting agroforestry systems: riparian tree buffer versus alley-cropping tree row.
- Authors
Luo, Jie; Beule, Lukas; Shao, Guodong; Niu, Dan; Veldkamp, Edzo; Corre, Marife D.
- Abstract
In addition to the removal of excess mineral nitrogen (N) via root uptake, trees in agroforestry systems may mitigate negative effects of high N fertilization of adjacent crops by enhancing complete denitrification of excess mineral N aside from root uptake. Presently, little is known about the potential for NO3− reduction through denitrification (conversion to greenhouse gas N2O and subsequently to non-reactive N2) in contrasting agroforestry systems: riparian tree buffer versus tree row of an upland alley-cropping system. Our study aimed to (1) quantify gross N2O emissions (both N2O + N2 emissions) and gross N2O uptake (N2O reduction to N2), and (2) determine their controlling factors. We employed the 15N2O pool dilution technique to quantify gross N2O fluxes from 0 to 5 cm (topsoil) and 40 to 60 cm (subsoil) depths with seasonal field measurements in 2019. The riparian tree buffer exhibited higher topsoil gross N2O emissions and uptake than the alley-cropping tree row (P < 0.03). Gross N2O emissions were regulated by N and carbon (C) availabilities and aeration status rather than denitrification gene abundance. Gross N2O uptake was directly linked to available C and nirK gene abundance. In the subsoil, gross N2O emission and uptake were low in both agroforestry systems, resulting from low mineral N contents possibly due to N uptake by deep tree roots. Nonetheless, the larger available C and soil moisture in the subsoil of riparian tree buffer than in alley-cropping tree row (P < 0.05) suggest its large potential for N2O uptake whenever NO3− is transported to the subsoil.
- Subjects
RIPARIAN areas; AGROFORESTRY; CROPPING systems; SOILS; SOIL moisture; TREES
- Publication
Biogeochemistry, 2024, Vol 167, Issue 6, p871
- ISSN
0168-2563
- Publication type
Article
- DOI
10.1007/s10533-024-01141-3