Combined influence of external nitrogen and soil contact on plant residue decomposition and indications from stable isotope signatures

• Published in: Environmental science and pollution research international Vol. 26; no. 7; pp. 6791 - 6800
• Main Authors: Jiang, Chunming, Yu, Wantai
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.03.2019; Springer Nature B.V
• Subjects: Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; carbon; carbon sequestration; Cunninghamia lanceolata; Decay; Decomposition; Earth and Environmental Science; Ecotoxicology; Environment; Environmental Chemistry; Environmental Health; Environmental science; Eucalyptus; Eucalyptus urophylla; Factorial experiments; leaves; Microorganisms; Nitrogen; Pine needles; plant residues; Research Article; Residues; Signatures; soil; Soil conditions; Soil dynamics; Soil investigations; Soils; Stable isotopes; synergism; Synergistic effect; Terrestrial ecosystems; Timing issues; Waste Water Technology; Water Management; Water Pollution Control; Plant residue decomposition; Soil contact; Stable isotope signature; Increasing nitrogen deposition
• DOI: 10.1007/s11356-019-04135-z
• ISSN: 0944-1344; 1614-7499

External nitrogen (N) supply has been testified to exert important impacts on plant residue decomposition. The influence of N may be interactive with soil contact in terrestrial ecosystems. However, the joint mechanisms of decomposition of plant residues driven by soil contact and N addition remain incomplete. Using contrasting residues, including needles of Chinese fir ( Cuninghamia lanceolata ) ( Cl ) (relatively hard to degrade) vs. leaves of eucalyptus ( Eucalyptus urophylla ) ( Eu ) (relatively easy to degrade), a full factorial experiment was conducted by 360-day experiment to investigate the combined effect of N addition and soil contact on residue decay. As the microbe-manipulated decomposition could leave an imprint on the residue carbon (C) and N stable isotope, variations of the two signatures (δ 13 C and δ 15 N) were synchronously monitored. Our results firstly showed that added N sped up initial decomposition, while it played an opposite role in subsequent stage, and soil contact always stimulated decay. Under soil contact condition, we found a markedly more accelerating effect of N addition on decay of Cl than without soil contact. Linking with residue N dynamics, we thought that although N immobilized from soil could not completely meet microbial needs for decay of Cl , this N limitation was just relieved by added N, leading to this synergistic effect. At late decay stage, the N inhibiting influence was partly offset under soil contact condition, and this phenomenon was more dramatic for Eu . Our results lastly revealed that the 13 C and 15 N signatures mirrored and explained the underlying mechanisms of the above interactions. Overall, we concluded that external N and soil contact could interactively affect decay, depending on plant residue decomposability. These results would be used to accurately predict C sequestration for terrestrial ecosystems under heightened N scenario in the future.