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Aims <p>Cup plant (<i>Silphium perfoliatum</i>) contributes to sustainable bioenergy production. However, little is known about the role of intensive litter fall and increased soil biodiversity on respiration and denitrification in its cultivation. This study aimed to assess CO<sub>2</sub>, N<sub>2</sub>O and N<sub>2</sub> emissions of annual and perennial energy cropping systems affected by earthworms when supplied with senescent cup plant or maize litter.</p> Methods <p>In a 32-day laboratory incubation, the <sup>15</sup>N gas flux method was applied in an N<sub>2</sub>-reduced atmosphere to a repacked silt loam soil, inoculated with <i>Lumbricus terrestris</i> L., and amended with senescent maize and cup plant litter. During incubation, CO<sub>2</sub>, N<sub>2</sub>O and N<sub>2</sub> emissions were measured. After incubation, NO<sub>3</sub><sup>−</sup>, NH<sub>4</sub><sup>+</sup>, total C, and total N was analysed in soil and casts. Litter removal from the soil surface and net nitrification rates were calculated.</p> Results <p>Earthworms caused a fivefold increase in maize litter removal and a threefold increase regarding cup plant litter. Highest N<sub>2</sub>O + N<sub>2</sub> fluxes were observed in treatments with earthworms and cup plant litter, although the high CN ratio of senescent cup plant litter implied higher N immobilisation than the CN ratio of senescent maize litter. Earthworms increased CO<sub>2</sub>, N<sub>2</sub>O, and especially N<sub>2</sub> emissions lowering the product ratio of denitrification (<i>N</i><sub><i>2</i></sub><i>Oi</i>).</p> Conclusions <p>Earthworm-controlled litter incorporation increased labile C from decomposition of recalcitrant litter as substrate for denitrification. Mineralisation patterns of senescent litter cannot be explained by CN ratio alone. The combination of both mechanisms affected denitrification, lead to elevated N<sub>2</sub>O and N<sub>2</sub> emissions and N loss from the soil.</p>

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Earthworm-controlled CO2, N2O and N2 emissions from a silt loam soil amended with senescent litter of two energy crops (Silphium perfoliatum and Zea mays)

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年8月20日

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  • Lena Wöhl,
  • Björn Kemmann,
  • Thorsten Ruf,
  • Christoph Emmerling,
  • Reinhard Well,
  • Stefan Schrader

摘要

Aims

Cup plant (Silphium perfoliatum) contributes to sustainable bioenergy production. However, little is known about the role of intensive litter fall and increased soil biodiversity on respiration and denitrification in its cultivation. This study aimed to assess CO2, N2O and N2 emissions of annual and perennial energy cropping systems affected by earthworms when supplied with senescent cup plant or maize litter.

Methods

In a 32-day laboratory incubation, the 15N gas flux method was applied in an N2-reduced atmosphere to a repacked silt loam soil, inoculated with Lumbricus terrestris L., and amended with senescent maize and cup plant litter. During incubation, CO2, N2O and N2 emissions were measured. After incubation, NO3−, NH4+, total C, and total N was analysed in soil and casts. Litter removal from the soil surface and net nitrification rates were calculated.

Results

Earthworms caused a fivefold increase in maize litter removal and a threefold increase regarding cup plant litter. Highest N2O + N2 fluxes were observed in treatments with earthworms and cup plant litter, although the high CN ratio of senescent cup plant litter implied higher N immobilisation than the CN ratio of senescent maize litter. Earthworms increased CO2, N2O, and especially N2 emissions lowering the product ratio of denitrification (N2Oi).

Conclusions

Earthworm-controlled litter incorporation increased labile C from decomposition of recalcitrant litter as substrate for denitrification. Mineralisation patterns of senescent litter cannot be explained by CN ratio alone. The combination of both mechanisms affected denitrification, lead to elevated N2O and N2 emissions and N loss from the soil.