Abstract
A net negative emissions technology is the transformation of CO 2 and its storage in agricultural soils in form of soil organic carbon (SOC). One possibility to increase SOC stocks in agriculture is to grow and incorporate cover crops in the upper soil layer. However, incorporation of fresh plant material can also increase N 2 O emissions and thereby reduce the overall greenhouse gas mitigation effect. While the effect of removing plant material is relatively well understood, the effect of different incorporation methods and the inoculation of cover crops with microbial inoculant (MI) is still poorly known. To investigate these effects, we conducted an incubation study and a field trial where a grass-clover cover crop was followed by maize. We measured greenhouse gas emissions (N 2 O, CO 2 ), soil parameters (Nmin, DOC, soil moisture and temperature), soil organic carbon (SOC) stocks and maize yield. In the four weeks following cover crop incorporation, shallow rotary tillage induced 30 % higher CO 2 emissions than ploughing and removal of cover crop biomass resulted in significantly lower N 2 O and CO 2 emissions as if it was mulched and inoculated with MI. Regarding the whole season, removal of aboveground cover crop biomass reduced N 2 O field emissions in tendency by 21 %, whereby the trend in N 2 O reduction by adding MI in the field was less pronounced. Total N 2 O emissions did not differ between tillage implements used for incorporation. SOC stocks did not change within 0–20 cm within a year. Maize yield was 23 % higher with ploughing than rotary tillage. Overall, the addition of MI during cover crop incorporation might improve the greenhouse gas balance, but potential effects are superimposed too strongly by other management and meteorological factors. Therefore, claims that MI are an option to mitigate greenhouse gas emissions from agriculture remain weakly substantiated. • Cover crop removal reduced N 2 O and CO 2 the four weeks following incorporation. • Ploughing or rotary tillage made a difference to CO 2 but not to N 2 O emissions after incorporation. • Cover crop removal or microbial inoculant slightly lowered cumulative seasonal N 2 O emissions. • SOC stock changes were not affected by cover crop incorporation within a year • Silage maize yields were higher after ploughing compared with rotary tillage
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Claims 8
Claim · model-written summary
Shallow rotary tillage induced 30% higher CO2 emissions than ploughing in the four weeks after cover crop incorporation.
Verbatim
e1“shallow rotary tillage induced 30 % higher CO 2 emissions than ploughing”
e2“grass-clover cover crop”
Claim · model-written summary
Removal of cover crop biomass resulted in significantly lower N2O and CO2 emissions than when it was mulched and inoculated with MI.
Verbatim
e1“removal of cover crop biomass resulted in significantly lower N 2 O and CO 2 emissions as if it was mulched and inoculated with MI”
e2“grass-clover cover crop”
Claim · model-written summary
Over the whole season, removal of aboveground cover crop biomass reduced N2O field emissions in tendency by 21%.
- Taxon
- grass-clover cover crope2
- Treatment
- removal of aboveground cover crop biomasse1
- Outcome
- N 2 O field emissionse1
- Direction
- reducede1
- Value
- 21 %e1
- Qualifier
- in tendencye1
Not reportedComparator
Verbatim
e1“removal of aboveground cover crop biomass reduced N 2 O field emissions in tendency by 21 %”
e2“grass-clover cover crop”
Claim · model-written summary
The trend in N2O reduction from adding MI in the field was less pronounced.
- Taxon
- grass-clover cover crope2
- Treatment
- adding MIe1
- Outcome
- N 2 O reductione1
- Direction
- less pronouncede1
- Setting
- in the fielde1
Not reportedComparator
Verbatim
e1“the trend in N 2 O reduction by adding MI in the field was less pronounced”
e2“grass-clover cover crop”
Claim · model-written summary
Total N2O emissions did not differ between tillage implements used for incorporation.
- Taxon
- grass-clover cover crope2
- Treatment
- tillage implementse1
- Outcome
- Total N 2 O emissionse1
- Direction
- did not differe1
Not reportedComparator
Verbatim
e1“Total N 2 O emissions did not differ between tillage implements used for incorporation”
e2“grass-clover cover crop”
Claim · model-written summary
SOC stock changes were not affected by cover crop incorporation within a year.
- Taxon
- cover crope1
- Treatment
- cover crop incorporatione1
- Outcome
- SOC stock changese1
- Direction
- not affectede1
Not reportedComparator
Verbatim
e1“SOC stock changes were not affected by cover crop incorporation within a year”
Claim · model-written summary
Maize yield was 23% higher with ploughing than with rotary tillage.
Zea maysOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Maize yield was 23 % higher with ploughing than rotary tillage”
Claim · model-written summary
Adding MI during cover crop incorporation might improve the greenhouse gas balance, but potential effects are superimposed too strongly by other management and meteorological factors.
- Taxon
- cover crope1
- Treatment
- addition of MIe1
- Outcome
- greenhouse gas balancee1
- Direction
- improvee1
- Qualifier
- potential effects are superimposed too strongly by other management and meteorological factorse1
Not reportedComparator
Verbatim
e1“the addition of MI during cover crop incorporation might improve the greenhouse gas balance, but potential effects are superimposed too strongly by other management and meteorological factors”
The same questions in other papers
tillage · yield · Zea mays (maize)Positive and negative results
811 papers in the same direction as this paper · 230 in the opposite direction · 57 reporting no difference from an alternative
- no effect
- negative
- no effect
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See all 1,099 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.