Abstract
ABSTRACT Biological nitrogen (N2) fixation (BNF) is an important aspect of sustainable and environmentally-friendly food production and long-term crop productivity. It has been established that free-living N2-fixing microbes and Endophytic bacteria play a vital role in the maintenance of soil fertility in flooded rice culture. The potential use of these microorganisms as a natural biofertilizer under an acidic paddy soil was evaluated in this study. Three soil amendments (composted rice straw, sewage sludge, and NPK) and three combinations of N2 fixers [bacteria, blue-green algae (BGA), and BGA + bacteria] were studied for rice (Oryza sativa L.) in a pot experiment. The soil pH which was moderated by the soil amendments had a significant effect on the potential of N2 fixation by BGA and bacteria. Pots amended with straw manure exhibited a lower N2-fixing ability than those amended with sludge. Nitrogen mineralization rate was significantly affected by both type of soil amendments and microorganisms. The NH4-N increased with composted straw application, but the utilization of nitrogen in the rice culture inoculated with bacteria was delayed. BGA + bacteria treatment showed higher N2-fixing rate and proportion of plant nitrogen derived from N2 fixation (Pfix) than cultures inoculated separately with bacteria or BGA. A negative correlation was found between the Pfix and the shoot N uptake under the different soil amendments. The results show that free-living N2-fixing microbes in an acid soil are governed not only by the soil nitrogen content but also by the type of soil amendment. The addition of sludge to BGA + bacteria inoculated soil increased BNF and consequently could be beneficial to rice production especially in an acidic soil.
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Claims 9
Claim · model-written summary
The BGA + bacteria treatment showed a higher N2-fixing rate and proportion of plant nitrogen derived from N2 fixation than cultures inoculated separately with bacteria or BGA in rice.
- Taxon
- rice
Oryza sativae0 - Treatment
- BGA + bacteriae1
- Interactor
- blue-green algae (BGA)Cyanobacteriotae2other
- Outcome
- N2-fixing rate and proportion of plant nitrogen derived from N2 fixation (Pfix)e1
- Direction
- highere1
- Comparator
- cultures inoculated separately with bacteria or BGAe1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“studied for rice (Oryza sativa L.) in a pot experiment”
e1“BGA + bacteria treatment showed higher N2-fixing rate and proportion of plant nitrogen derived from N2 fixation (Pfix) than cultures inoculated separately with bacteria or BGA”
e2“three combinations of N2 fixers [bacteria, blue-green algae (BGA), and BGA + bacteria]”
Claim · model-written summary
Pfix was negatively correlated with shoot N uptake under the different soil amendments in rice.
- Taxon
- riceOryza sativae0
- Treatment
- different soil amendmentse3
- Outcome
- shoot N uptakee3
- Direction
- negative correlatione3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“studied for rice (Oryza sativa L.) in a pot experiment”
e3“A negative correlation was found between the Pfix and the shoot N uptake under the different soil amendments”
Claim · model-written summary
Pots amended with straw manure showed a lower N2-fixing ability than pots amended with sludge in rice.
- Taxon
- riceOryza sativae0
- Treatment
- straw manuree4
- Outcome
- N2-fixing abilitye4
- Direction
- lowere4
- Comparator
- sludgee4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“studied for rice (Oryza sativa L.) in a pot experiment”
e4“Pots amended with straw manure exhibited a lower N2-fixing ability than those amended with sludge”
Claim · model-written summary
The soil pH moderated by the soil amendments had a significant effect on the potential of N2 fixation by BGA and bacteria in rice soil.
- Taxon
- riceOryza sativae0
- Treatment
- soil amendmentse5
- Interactor
- BGAe5other
- Outcome
- potential of N2 fixatione5
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“studied for rice (Oryza sativa L.) in a pot experiment”
e5“The soil pH which was moderated by the soil amendments had a significant effect on the potential of N2 fixation by BGA and bacteria”
Claim · model-written summary
Nitrogen mineralization rate was significantly affected by the type of soil amendments and by microorganisms in rice soil.
- Taxon
- riceOryza sativae0
- Treatment
- type of soil amendmentse6
- Outcome
- Nitrogen mineralization ratee6
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“studied for rice (Oryza sativa L.) in a pot experiment”
e6“Nitrogen mineralization rate was significantly affected by both type of soil amendments and microorganisms”
Claim · model-written summary
NH4-N increased with composted straw application in rice culture.
- Taxon
- riceOryza sativae0
- Treatment
- composted straw applicatione7
- Outcome
- NH4-Ne7
- Direction
- increasede7
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“studied for rice (Oryza sativa L.) in a pot experiment”
e7“The NH4-N increased with composted straw application”
Claim · model-written summary
Nitrogen utilization was delayed in rice culture inoculated with bacteria.
- Taxon
- riceOryza sativae0
- Treatment
- inoculated with bacteriae1
- Outcome
- utilization of nitrogene1
- Direction
- delayede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“studied for rice (Oryza sativa L.) in a pot experiment”
e1“the utilization of nitrogen in the rice culture inoculated with bacteria was delayed”
Claim · model-written summary
Adding sludge to BGA + bacteria inoculated soil increased BNF in rice soil.
- Taxon
- riceOryza sativae0
- Treatment
- addition of sludge to BGA + bacteria inoculated soile1
- Interactor
- BGAe1other
- Outcome
- BNFe1
- Direction
- increasede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“studied for rice (Oryza sativa L.) in a pot experiment”
e1“The addition of sludge to BGA + bacteria inoculated soil increased BNF”
Claim · model-written summary
Free-living N2-fixing microbes in an acid soil are governed not only by soil nitrogen content but also by the type of soil amendment.
- Taxon
- riceOryza sativae0
- Treatment
- type of soil amendmente1
- Outcome
- free-living N2-fixing microbese1
- Setting
- acid soile1
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“studied for rice (Oryza sativa L.) in a pot experiment”
e1“The results show that free-living N2-fixing microbes in an acid soil are governed not only by the soil nitrogen content but also by the type of soil amendment”
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