Abstract
Abstract. The effects of nitrogen and straw management on global warming potential (GWP) and greenhouse gas intensity (GHGI) in a winter wheat–summer maize double-cropping system on the North China Plain were investigated. We measured nitrous oxide (N2O) emissions and studied net GWP (NGWP) and GHGI by calculating the net exchange of CO2 equivalent (CO2-eq) from greenhouse gas emissions, agricultural inputs and management practices, as well as changes in soil organic carbon (SOC), based on a long-term field experiment established in 2006. The field experiment includes six treatments with three fertilizer N levels (zero N (control), optimum and conventional N) and straw removal (i.e. N0, Nopt and Ncon) or return (i.e. SN0, SNopt and SNcon). Optimum N management (Nopt, SNopt) saved roughly half of the fertilizer N compared to conventional agricultural practice (Ncon, SNcon), with no significant effect on grain yields. Annual mean N2O emissions reached 3.90 kg N2O-N ha−1 in Ncon and SNcon, and N2O emissions were reduced by 46.9% by optimizing N management of Nopt and SNopt. Straw return increased annual mean N2O emissions by 27.9%. Annual SOC sequestration was 0.40–1.44 Mg C ha−1 yr−1 in plots with N application and/or straw return. Compared to the conventional N treatments the optimum N treatments reduced NGWP by 51%, comprising 25% from decreasing N2O emissions and 75% from reducing N fertilizer application rates. Straw return treatments reduced NGWP by 30% compared to no straw return because the GWP from increments of SOC offset the GWP from higher emissions of N2O, N fertilizer and fuel after straw return. The GHGI trends from the different nitrogen and straw management practices were similar to the NGWP. In conclusion, optimum N and straw return significantly reduced NGWP and GHGI and concomitantly achieved relatively high grain yields in this important winter wheat–summer maize double-cropping system.
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Claims 11
Claim · model-written summary
Optimum nitrogen used roughly half the fertilizer nitrogen of conventional management without a significant grain yield difference.
- Taxon
- winter wheat–summer maize
Triticum aestivum
Zea mayse1 - Treatment
- Optimum N management (Nopt, SNopt)e0
- Outcome
- grain yieldse0
- Direction
- no significant effecte0
- Qualifier
- roughly half of the fertilizer Ne0
- Comparator
- conventional agricultural practice (Ncon, SNcon)e0
Not reportedMaterialGeneCompoundOrgan / stageInteractorInteractor roleSecond interactorSecond interactor roleSettingValue
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Optimum N management (Nopt, SNopt) saved roughly half of the fertilizer N compared to conventional agricultural practice (Ncon, SNcon), with no significant effect on grain yields”
t0“Net global warming potential and greenhouse gas intensity in a double-cropping cereal rotation as affected by nitrogen and straw management”
e1“in a winter wheat–summer maize double-cropping system on the North China Plain”
Claim · model-written summary
Conventional nitrogen treatments had annual mean N2O emissions of 3.90 kg N2O-N ha−1.
- Taxon
- winter wheat–summer maizeTriticum aestivumZea mayse1
- Treatment
- Ncon and SNcone0
- Outcome
- Annual mean N2O emissionse0
- Value
- 3.90 kg N2O-N ha−1e0
Not reportedMaterialGeneCompoundOrgan / stageInteractorInteractor roleSecond interactorSecond interactor roleComparatorSettingDirectionQualifier
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Annual mean N2O emissions reached 3.90 kg N2O-N ha−1 in Ncon and SNcon”
t0“Net global warming potential and greenhouse gas intensity in a double-cropping cereal rotation as affected by nitrogen and straw management”
e1“in a winter wheat–summer maize double-cropping system on the North China Plain”
Claim · model-written summary
Optimizing nitrogen reduced N2O emissions by 46.9%.
- Taxon
- winter wheat–summer maizeTriticum aestivumZea mayse1
- Treatment
- optimizing N management of Nopt and SNopte0
- Outcome
- N2O emissionse0
- Direction
- reducede0
- Value
- 46.9%e0
Not reportedMaterialGeneCompoundOrgan / stageInteractorInteractor roleSecond interactorSecond interactor roleComparatorSettingQualifier
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“N2O emissions were reduced by 46.9% by optimizing N management of Nopt and SNopt”
t0“Net global warming potential and greenhouse gas intensity in a double-cropping cereal rotation as affected by nitrogen and straw management”
e1“in a winter wheat–summer maize double-cropping system on the North China Plain”
Claim · model-written summary
Straw return increased annual mean N2O emissions by 27.9%.
- Taxon
- winter wheat–summer maizeTriticum aestivumZea mayse1
- Treatment
- Straw returne0
- Outcome
- annual mean N2O emissionse0
- Direction
- increasede0
- Value
- 27.9%e0
Not reportedMaterialGeneCompoundOrgan / stageInteractorInteractor roleSecond interactorSecond interactor roleComparatorSettingQualifier
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Straw return increased annual mean N2O emissions by 27.9%”
t0“Net global warming potential and greenhouse gas intensity in a double-cropping cereal rotation as affected by nitrogen and straw management”
e1“in a winter wheat–summer maize double-cropping system on the North China Plain”
Claim · model-written summary
Plots with nitrogen and/or straw return sequestered 0.40–1.44 Mg C ha−1 yr−1.
- Taxon
- winter wheat–summer maizeTriticum aestivumZea mayse1
- Treatment
- N application and/or straw returne0
- Outcome
- Annual SOC sequestratione0
- Value
- 0.40–1.44 Mg C ha−1 yr−1e0
Not reportedMaterialGeneCompoundOrgan / stageInteractorInteractor roleSecond interactorSecond interactor roleComparatorSettingDirectionQualifier
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Annual SOC sequestration was 0.40–1.44 Mg C ha−1 yr−1 in plots with N application and/or straw return”
t0“Net global warming potential and greenhouse gas intensity in a double-cropping cereal rotation as affected by nitrogen and straw management”
e1“in a winter wheat–summer maize double-cropping system on the North China Plain”
Claim · model-written summary
Optimum nitrogen reduced net global warming potential by 51% relative to conventional nitrogen.
- Taxon
- winter wheat–summer maizeTriticum aestivumZea mayse1
- Treatment
- optimum N treatmentse0
- Outcome
- NGWPe0
- Direction
- reducede0
- Value
- 51%e0
- Comparator
- conventional N treatmentse0
Not reportedMaterialGeneCompoundOrgan / stageInteractorInteractor roleSecond interactorSecond interactor roleSettingQualifier
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Compared to the conventional N treatments the optimum N treatments reduced NGWP by 51%”
t0“Net global warming potential and greenhouse gas intensity in a double-cropping cereal rotation as affected by nitrogen and straw management”
e1“in a winter wheat–summer maize double-cropping system on the North China Plain”
Claim · model-written summary
The reduction in N2O emissions accounted for 25% of the NGWP decrease under optimum nitrogen.
- Taxon
- winter wheat–summer maizeTriticum aestivumZea mayse1
- Outcome
- N2O emissionse0
- Direction
- decreasinge0
- Value
- 25%e0
- Qualifier
- decreasing N2O emissionse0
Not reportedMaterialGeneCompoundOrgan / stageInteractorInteractor roleSecond interactorSecond interactor roleTreatmentComparatorSetting
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“comprising 25% from decreasing N2O emissions”
t0“Net global warming potential and greenhouse gas intensity in a double-cropping cereal rotation as affected by nitrogen and straw management”
e1“in a winter wheat–summer maize double-cropping system on the North China Plain”
Claim · model-written summary
Reduced nitrogen fertilizer rates accounted for 75% of the NGWP decrease.
- Taxon
- winter wheat–summer maizeTriticum aestivumZea mayse1
- Treatment
- N fertilizere0
- Outcome
- N fertilizer application ratese0
- Direction
- reducinge0
- Value
- 75%e0
Not reportedMaterialGeneCompoundOrgan / stageInteractorInteractor roleSecond interactorSecond interactor roleComparatorSettingQualifier
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“75% from reducing N fertilizer application rates”
t0“Net global warming potential and greenhouse gas intensity in a double-cropping cereal rotation as affected by nitrogen and straw management”
e1“in a winter wheat–summer maize double-cropping system on the North China Plain”
Claim · model-written summary
Straw return reduced NGWP by 30% relative to no straw return.
- Taxon
- winter wheat–summer maizeTriticum aestivumZea mayse1
- Treatment
- Straw return treatmentse0
- Outcome
- NGWPe0
- Direction
- reducede0
- Value
- 30%e0
- Comparator
- no straw returne0
Not reportedMaterialGeneCompoundOrgan / stageInteractorInteractor roleSecond interactorSecond interactor roleSettingQualifier
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Straw return treatments reduced NGWP by 30% compared to no straw return”
t0“Net global warming potential and greenhouse gas intensity in a double-cropping cereal rotation as affected by nitrogen and straw management”
e1“in a winter wheat–summer maize double-cropping system on the North China Plain”
Claim · model-written summary
SOC gains offset higher N2O, fertilizer, and fuel emissions after straw return.
- Taxon
- winter wheat–summer maizeTriticum aestivumZea mayse1
- Treatment
- straw returne0
- Outcome
- GWP from higher emissions of N2O, N fertilizer and fuele0
- Direction
- offsete0
- Qualifier
- increments of SOCe0
Not reportedMaterialGeneCompoundOrgan / stageInteractorInteractor roleSecond interactorSecond interactor roleComparatorSettingValue
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“GWP from increments of SOC offset the GWP from higher emissions of N2O, N fertilizer and fuel after straw return”
t0“Net global warming potential and greenhouse gas intensity in a double-cropping cereal rotation as affected by nitrogen and straw management”
e1“in a winter wheat–summer maize double-cropping system on the North China Plain”
Claim · model-written summary
GHGI followed trends similar to NGWP across nitrogen and straw management practices.
- Taxon
- winter wheat–summer maizeTriticum aestivumZea mayse1
- Outcome
- GHGI trendse0
- Direction
- similare0
- Comparator
- NGWPe0
Not reportedMaterialGeneCompoundOrgan / stageInteractorInteractor roleSecond interactorSecond interactor roleTreatmentSettingValueQualifier
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The GHGI trends from the different nitrogen and straw management practices were similar to the NGWP”
t0“Net global warming potential and greenhouse gas intensity in a double-cropping cereal rotation as affected by nitrogen and straw management”
e1“in a winter wheat–summer maize double-cropping system on the North China Plain”
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