Earthworms offset straw-induced increase of greenhouse gas emission in upland rice production

Katharina John; Baldur Janz; Ralf Kiese; Reiner Wassmann; Andrey S Zaitsev; Volkmar Wolters

doi:10.1016/j.scitotenv.2019.136352

Earthworms offset straw-induced increase of greenhouse gas emission in upland rice production

Sci Total Environ. 2020 Mar 25:710:136352. doi: 10.1016/j.scitotenv.2019.136352. Epub 2019 Dec 30.

Authors

Katharina John¹, Baldur Janz², Ralf Kiese², Reiner Wassmann³, Andrey S Zaitsev⁴, Volkmar Wolters⁴

Affiliations

¹ Justus-Liebig-University, Department of Animal Ecology, Heinrich-Buff-Ring 26-32, 35392 Giessen, Germany. Electronic address: kjohn@zo.jlug.de.
² Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research (IMK-IFU), Kreuzeckbahnstraße 19, 82467 Garmisch-Partenkirchen, Germany.
³ Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research (IMK-IFU), Kreuzeckbahnstraße 19, 82467 Garmisch-Partenkirchen, Germany; International Rice Research Institute (IRRI), Crop and Environmental Sciences Division (CESD), Los Baños, Philippines.
⁴ Justus-Liebig-University, Department of Animal Ecology, Heinrich-Buff-Ring 26-32, 35392 Giessen, Germany.

PMID: 31927290
DOI: 10.1016/j.scitotenv.2019.136352

Abstract

Increasing water scarcity and rapid socio-economic development are driving farmers in Asia to transform traditionally flooded rice cropping systems into non-flooded crop production. The management of earthworms in non-flooded rice fields appears to be a promising strategy to support residue recycling and mitigate greenhouse gas (GHG) emissions triggered by residue amendment. We conducted a field experiment on non-flooded rainfed rice fields, with and without residue amendment. In-situ mesocosms were inoculated with endogeic earthworms (Metaphire sp.), with either low (ET1: 150 individuals m^-²), or high density (ET2: 450 individuals m^-²), and a control (ET0: no earthworms). We measured GHG emissions (methane (CH₄); nitrous oxide (N₂O); carbon dioxide (CO₂)) twice a week during the cropping season with static chambers. Effects of earthworms on yield and root growth were additionally assessed. Earthworms offset the enormous increase of CH₄ emissions induced by straw amendment (from 4.6 ± 5 to 75.3 ± 46 kg CH₄-C ha^-¹ in ET0). Earthworm activity significantly reduced CH₄ release, particularly at ET2, by more than one-third (to 22 ± 15 kg CH₄-C ha^-¹). In contrast, earthworm inoculation did not affect N₂O emission. Straw amendment more than doubled the global warming potential (GWP). Earthworms reduced GWP by 39% at low (ET1) and 55% at high densities (ET2). Earthworm activity reduced root mass density under conditions of straw amendment but did not affect yield. Earthworms can significantly reduce detrimental effects of rice crop residue amendment on GHG release under upland rice production. Organic carbon (C) might be preserved in earthworm casts and thereby limit C availability for CH₄ production. At the same time, earthworm activity might increase methanotrophic CH₄ consumption, due to improved soil aeration or less root exudates. Consequently, earthworms have a strong potential for regulating ecosystem functions related to rice straw decomposition, nutrient allocation and thus GHG reduction.

Keywords: Aerobic rice; Bioturbation; Ecosystem services; Global warming potential; Residue decomposition; Soil fauna.

MeSH terms

Agriculture
Animals
Asia
Global Warming
Greenhouse Gases*
Methane
Nitrous Oxide
Oligochaeta*
Oryza*
Soil

Substances

Greenhouse Gases
Soil
Nitrous Oxide
Methane