Abstract
To reduce reliance on synthetic nitrogen (N) fertilizer and sustain food production, replacing synthetic N fertilizer with animal manure as an effective method is widely used. However, the effects of replacing synthetic N fertilizer with animal manure on crop yield and nitrogen use efficiency (NUE) remain uncertain under varying fertilization management practices, climate conditions, and soil properties. Here, we performed a meta-analysis of wheat ( Triticum aestivum L.), maize ( Zea mays L.), and rice ( Oryza sativa L.) based on 118 published studies conducted in China. Overall, the results indicated that substituting synthetic N fertilizer with manure increased yield by 3.3%−3.9% for the three grain crops and increased NUE by 6.3%−10.0%. Crop yields and NUE did not significantly increase at a low N application rate (≤120 kg ha −1 ) or high substitution rate (>60%). Yields and NUE values had higher increases for upland crops (wheat and maize) in temperate monsoon climate/temperate continental climate regions with less average annual rainfall (AAR) and lower mean annual temperature (MAT), while rice had higher increases in subtropical monsoon climate regions with more AAR and higher MAT. The effect of manure substitution was better in soil with low organic matter and available phosphorus. Our study shows that the optimal substitution rate was 44% and the total N fertilizer input cannot be less than 161 kg ha −1 when substituting synthetic N fertilizer with manure. Moreover, site‐specific conditions should also be considered.
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Claims 10
Claim · model-written summary
Replacing synthetic N fertilizer with manure increased yield by 3.3%−3.9% across three grain crops.
- Taxon
- wheat ( Triticum aestivum L.), maize ( Zea mays L.), and rice ( Oryza sativa L.)
Oryza sativa
Triticum aestivum
Zea mayse1 - Treatment
- substituting synthetic N fertilizer with manuree0
- Outcome
- yielde0
- Direction
- increasede0
- Value
- 3.3%−3.9%e0
- Comparator
- synthetic N fertilizere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“substituting synthetic N fertilizer with manure increased yield by 3.3%−3.9% for the three grain crops”
e1“wheat ( Triticum aestivum L.), maize ( Zea mays L.), and rice ( Oryza sativa L.)”
Claim · model-written summary
Replacing synthetic N fertilizer with manure increased NUE by 6.3%−10.0%.
- Taxon
- wheat ( Triticum aestivum L.), maize ( Zea mays L.), and rice ( Oryza sativa L.)Oryza sativaTriticum aestivumZea mayse1
- Treatment
- substituting synthetic N fertilizer with manuree0
- Outcome
- NUEe0
- Direction
- increasede0
- Value
- 6.3%−10.0%e0
- Comparator
- synthetic N fertilizere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“substituting synthetic N fertilizer with manure increased yield by 3.3%−3.9% for the three grain crops and increased NUE by 6.3%−10.0%.”
e1“wheat ( Triticum aestivum L.), maize ( Zea mays L.), and rice ( Oryza sativa L.)”
Claim · model-written summary
At low N application rates, crop yields and NUE did not significantly increase with manure substitution.
- Taxon
- wheat ( Triticum aestivum L.), maize ( Zea mays L.), and rice ( Oryza sativa L.)Oryza sativaTriticum aestivumZea mayse1
- Treatment
- low N application rate (≤120 kg ha −1 )e0
- Outcome
- Crop yields and NUEe0
- Direction
- did not significantly increasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Crop yields and NUE did not significantly increase at a low N application rate (≤120 kg ha −1 )”
e1“wheat ( Triticum aestivum L.), maize ( Zea mays L.), and rice ( Oryza sativa L.)”
Claim · model-written summary
At substitution rates above 60%, crop yields and NUE did not significantly increase.
- Taxon
- wheat ( Triticum aestivum L.), maize ( Zea mays L.), and rice ( Oryza sativa L.)Oryza sativaTriticum aestivumZea mayse1
- Treatment
- high substitution rate (>60%)e0
- Outcome
- Crop yields and NUEe0
- Direction
- did not significantly increasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Crop yields and NUE did not significantly increase at a low N application rate (≤120 kg ha −1 ) or high substitution rate (>60%).”
e1“wheat ( Triticum aestivum L.), maize ( Zea mays L.), and rice ( Oryza sativa L.)”
Claim · model-written summary
Wheat and maize showed larger yield and NUE increases in cooler, drier temperate regions.
- Taxon
- wheat and maizeTriticum aestivumZea mayse0
- Outcome
- Yields and NUE valuese0
- Direction
- higher increasese0
- Qualifier
- less average annual rainfall (AAR) and lower mean annual temperature (MAT)e0
- Setting
- temperate monsoon climate/temperate continental climate regionse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Yields and NUE values had higher increases for upland crops (wheat and maize) in temperate monsoon climate/temperate continental climate regions with less average annual rainfall (AAR) and lower mean annual temperature (MAT)”
Claim · model-written summary
Rice showed larger yield and NUE increases in wetter, warmer subtropical monsoon regions.
- Taxon
- riceOryza sativae0
- Outcome
- higher increasese0
- Direction
- highere0
- Qualifier
- more AAR and higher MATe0
- Setting
- subtropical monsoon climate regionse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“rice had higher increases in subtropical monsoon climate regions with more AAR and higher MAT.”
Claim · model-written summary
Manure substitution performed better in soils with low organic matter and available phosphorus.
- Taxon
- wheat ( Triticum aestivum L.), maize ( Zea mays L.), and rice ( Oryza sativa L.)Oryza sativaTriticum aestivumZea mayse1
- Outcome
- effect of manure substitutione0
- Direction
- bettere0
- Setting
- soil with low organic matter and available phosphoruse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The effect of manure substitution was better in soil with low organic matter and available phosphorus.”
e1“wheat ( Triticum aestivum L.), maize ( Zea mays L.), and rice ( Oryza sativa L.)”
Claim · model-written summary
The estimated optimal manure substitution rate was 44%.
- Taxon
- wheat ( Triticum aestivum L.), maize ( Zea mays L.), and rice ( Oryza sativa L.)Oryza sativaTriticum aestivumZea mayse1
- Outcome
- optimal substitution ratee0
- Value
- 44%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the optimal substitution rate was 44%”
e1“wheat ( Triticum aestivum L.), maize ( Zea mays L.), and rice ( Oryza sativa L.)”
Claim · model-written summary
The authors recommend at least 161 kg ha −1 total N input when substituting manure for synthetic fertilizer.
- Taxon
- wheat ( Triticum aestivum L.), maize ( Zea mays L.), and rice ( Oryza sativa L.)Oryza sativaTriticum aestivumZea mayse1
- Outcome
- total N fertilizer input cannot be less than 161 kg ha −1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the total N fertilizer input cannot be less than 161 kg ha −1 when substituting synthetic N fertilizer with manure.”
e1“wheat ( Triticum aestivum L.), maize ( Zea mays L.), and rice ( Oryza sativa L.)”
Claim · model-written summary
The authors recommend considering site-specific conditions for manure substitution.
- Taxon
- wheat ( Triticum aestivum L.), maize ( Zea mays L.), and rice ( Oryza sativa L.)Oryza sativaTriticum aestivumZea mayse1
- Outcome
- site‐specific conditions should also be considerede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“site‐specific conditions should also be considered.”
e1“wheat ( Triticum aestivum L.), maize ( Zea mays L.), and rice ( Oryza sativa L.)”
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See all 3,455 papers →8 of 9 groups shown: named compounds and organisms first, then groups whose results differ (checked claim by claim), then those with positive and negative results, then the smaller groups.
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.