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Residue incorporation depth is a controlling factor of earthworm‐induced nitrous oxide emissions
Author(s) -
Paul Birthe K.,
Lubbers Ingrid M.,
Groenigen Jan Willem
Publication year - 2012
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1111/j.1365-2486.2011.02525.x
Subject(s) - earthworm , nitrous oxide , denitrification , chemistry , mesocosm , soil water , lumbricus rubellus , nitrogen , residue (chemistry) , lumbricus terrestris , zoology , manure , environmental chemistry , agronomy , soil science , biology , nutrient , environmental science , biochemistry , organic chemistry
Earthworms can increase nitrous oxide ( N 2 O ) emissions, particularly in no‐tillage systems where earthworms are abundant. Here, we study the effect of residue incorporation depth on earthworm‐induced N 2 O emissions. We hypothesized that cumulative N 2 O emissions decrease with residue incorporation depth, because (i) increased water filled pore space ( WFPS ) in deeper soil layers leads to higher denitrification rates as well as more complete denitrification; and (ii) the longer upward diffusion path increases N 2 O reduction to N 2 . Two 84‐day laboratory mesocosm experiments were conducted. First, we manually incorporated maize ( Z ea mays L .) residue at different soil depths (incorporation experiment). Second, 13 C ‐enriched maize residue was applied to the soil surface and anecic species L umbricus terrestris ( L .) and epigeic species L umbricus rubellus ( H offmeister) were confined to different soil depths (earthworm experiment). Residue incorporation depth affected cumulative N 2 O emissions in both experiments ( P < 0.001). In the incorporation experiment, N 2 O emissions decreased from 4.91 mg N 2 O–N kg −1 soil (surface application) to 2.71 mg N 2 O–N kg −1 soil (40–50 cm incorporation). In the earthworm experiment, N 2 O emissions from L . terrestris decreased from 3.87 mg N 2 O–N kg −1 soil (confined to 0–10 cm) to 2.01 mg N 2 O–N kg −1 soil (confined to 0–30 cm). Both experimental setups resulted in dissimilar WFPS profiles that affected N 2 O dynamics. We also found significant differences in residue C recovery in soil organic matter between L . terrestris (28–41%) and L . rubellus (56%). We conclude that (i) N 2 O emissions decrease with residue incorporation depth, although this effect was complicated by dissimilar WFPS profiles; and (ii) larger residue C incorporation by L . rubellus than L . terrestris indicates that earthworm species differ in their C stabilization potential. Our findings underline the importance of studying earthworm diversity in the context of greenhouse gas emissions from agro‐ecosystems.