Abstract
Long-term straw return is an important carbon source for improving soil organic carbon (SOC) stocks in croplands, and straw removal through burning is also a common practice in open fields in South China. However, the specific effects of long-term rice straw management on SOC fractions, the related enzyme activities and their relationships, and whether these effects differ between crop growing seasons remain unknown. Three treatments with equal nitrogen, phosphorus, and potassium nutrient inputs, including straw/ash and chemical nutrients, were established to compare the effects of straw removal (CK), straw return (SR), and straw burned return (SBR). Compared to CK, long-term SR tended to improve the yield of early season rice (P=0.057), and significantly increased total organic carbon (TOC) and microbial biomass carbon (MBC) in double-cropped rice paddies. While SBR had no effect on TOC, it decreased light fraction organic carbon (LFOC) in early rice and easily oxidizable organic carbon (EOC) in late rice, significantly increased dissolved organic carbon (DOC), and significantly decreased soil pH. These results showed that MBC was the most sensitive indicator for assessing changes of SOC in the double-cropped rice system due to long-term straw return. In addition, the different effects on SOC fraction sizes between SR and SBR were attributed to the divergent trends in most of the soil enzyme activities in the early and late rice that mainly altered DOC, while DOC was positively affected by β-xylosidase in both early and late rice. We concluded that straw return was superior to straw burned return for improving SOC fractions, but the negative effects on soil enzyme activities in late rice require further research.
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Claims 12
Claim · model-written summary
Long-term straw return tended to improve early season rice yield (P=0.057).
- Taxon
- rice
Oryza sativae1 - Treatment
- long-term SRe1
- Outcome
- the yield of early season ricee1
- Direction
- tended to improvee1
- Qualifier
- P=0.057e1
- Comparator
- CKe1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Compared to CK, long-term SR tended to improve the yield of early season rice (P=0.057), and significantly increased total organic carbon (TOC) and microbial biomass carbon (MBC) in double-cropped rice paddies”
Claim · model-written summary
Long-term straw return significantly increased total organic carbon and microbial biomass carbon in double-cropped rice paddies.
- Taxon
- riceOryza sativae1
- Treatment
- long-term SRe1
- Outcome
- total organic carbon (TOC) and microbial biomass carbon (MBC)e1
- Direction
- significantly increasede1
- Comparator
- CKe1
- Setting
- double-cropped rice paddiese1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Compared to CK, long-term SR tended to improve the yield of early season rice (P=0.057), and significantly increased total organic carbon (TOC) and microbial biomass carbon (MBC) in double-cropped rice paddies”
Claim · model-written summary
Straw burned return had no effect on total organic carbon in rice.
- Taxon
- riceOryza sativae2
- Treatment
- SBRe2
- Outcome
- TOCe2
- Direction
- had no effecte2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e2“While SBR had no effect on TOC, it decreased light fraction organic carbon (LFOC) in early rice and easily oxidizable organic carbon (EOC) in late rice, significantly increased dissolved organic carbon (DOC), and significantly decreased soil pH”
Claim · model-written summary
Straw burned return decreased light fraction organic carbon in early rice.
- Taxon
- riceOryza sativae2
- Treatment
- SBRe2
- Outcome
- light fraction organic carbon (LFOC)e2
- Direction
- decreasede2
- Qualifier
- early ricee2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e2“While SBR had no effect on TOC, it decreased light fraction organic carbon (LFOC) in early rice and easily oxidizable organic carbon (EOC) in late rice, significantly increased dissolved organic carbon (DOC), and significantly decreased soil pH”
Claim · model-written summary
Straw burned return decreased easily oxidizable organic carbon in late rice.
- Taxon
- riceOryza sativae2
- Treatment
- SBRe2
- Outcome
- easily oxidizable organic carbon (EOC)e2
- Direction
- decreasede2
- Qualifier
- late ricee2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e2“While SBR had no effect on TOC, it decreased light fraction organic carbon (LFOC) in early rice and easily oxidizable organic carbon (EOC) in late rice, significantly increased dissolved organic carbon (DOC), and significantly decreased soil pH”
Claim · model-written summary
Straw burned return significantly increased dissolved organic carbon in rice.
- Taxon
- riceOryza sativae2
- Treatment
- SBRe2
- Outcome
- dissolved organic carbon (DOC)e2
- Direction
- significantly increasede2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e2“While SBR had no effect on TOC, it decreased light fraction organic carbon (LFOC) in early rice and easily oxidizable organic carbon (EOC) in late rice, significantly increased dissolved organic carbon (DOC), and significantly decreased soil pH”
Claim · model-written summary
Straw burned return significantly decreased soil pH in rice paddies.
- Taxon
- riceOryza sativae2
- Treatment
- SBRe2
- Outcome
- soil pHe2
- Direction
- significantly decreasede2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e2“While SBR had no effect on TOC, it decreased light fraction organic carbon (LFOC) in early rice and easily oxidizable organic carbon (EOC) in late rice, significantly increased dissolved organic carbon (DOC), and significantly decreased soil pH”
Claim · model-written summary
Microbial biomass carbon was the most sensitive indicator of SOC change under long-term straw return in double-cropped rice.
- Taxon
- riceOryza sativae3
- Treatment
- long-term straw returne3
- Outcome
- MBC was the most sensitive indicator for assessing changes of SOCe3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e3“These results showed that MBC was the most sensitive indicator for assessing changes of SOC in the double-cropped rice system due to long-term straw return”
Claim · model-written summary
The different effects of SR and SBR on SOC fraction sizes are attributed to divergent trends in most soil enzyme activities.
- Taxon
- riceOryza sativae4
- Outcome
- the different effects on SOC fraction sizes between SR and SBRe4
- Qualifier
- divergent trends in most of the soil enzyme activitiese4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e4“the different effects on SOC fraction sizes between SR and SBR were attributed to the divergent trends in most of the soil enzyme activities in the early and late rice that mainly altered DOC”
Claim · model-written summary
β-xylosidase positively affected dissolved organic carbon in both early and late rice.
- Taxon
- riceOryza sativae4
- Gene
- β-xylosidasee4
- Outcome
- DOCe4
- Direction
- positively affectede4
- Qualifier
- in both early and late ricee4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e4“while DOC was positively affected by β-xylosidase in both early and late rice”
Claim · model-written summary
Straw return was superior to straw burned return for improving SOC fractions in rice.
- Taxon
- riceOryza sativae5
- Treatment
- straw returne5
- Outcome
- SOC fractionse5
- Direction
- superiore5
- Comparator
- straw burned returne5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e5“We concluded that straw return was superior to straw burned return for improving SOC fractions, but the negative effects on soil enzyme activities in late rice require further research”
Claim · model-written summary
Straw burned return had negative effects on soil enzyme activities in late rice.
- Taxon
- riceOryza sativae5
- Outcome
- soil enzyme activitiese5
- Qualifier
- late ricee5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e5“the negative effects on soil enzyme activities in late rice require further research”
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