Abstract
The effects of Bradyrhizobium japonicum inoculation and pre‐plant additions of N fertilizer on soybean ( Glycine max L. Merrill) yields and levels of N 2 fixation were studied under field conditions at two sites in Thailand. Bacterial inoculants were composed of B. japonicum strains selected for high N 2 fixation levels in Thai soils. Nitrogen fertilizer addition rates used were from 0 to 250 kg N/ha in 50 kg N/ha increments. At the Chiang Mai site in northern Thailand, bacterial inoculation increased nodule weights on plants receiving 100 kg N/ha or less. Increases in nodule parameters due to inoculation were evident at 45 d after planting (DAP) but disappeared by 60 DAP. Addition of N fertilizers decreased the incidence of nodulation and sap ureide contents and decreased the contribution of N 2 fixation to the N content of plants at maturity as measured by N‐15 isotope dilution methods. At the Kampang Saen site in central Thailand, bacterial inoculation had significant positive effects on nodule numbers and weights, ARA, sap ureide contents and levels of N 2 fixed as measured by N‐15 isotope dilution methods. Addition of N fertilizers at this site also reduced the effectiveness of N 2 ‐fixing symbioses. It was concluded that small additions of N fertilizer added before planting did not significantly decrease N 2 fixation levels, but did have a significant positive effect on plant growth. Larger N additions would reduce N 2 fixation levels in excess of the benefits of adding more N in chemical form.
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Claims 11
Claim · model-written summary
Inoculation increased nodule weights at Chiang Mai with no more than 100 kg N/ha.
- Taxon
- plantsViridiplantaee0
- Treatment
- bacterial inoculatione0
- Outcome
- nodule weightse0
- Direction
- increasede0
- Qualifier
- 100 kg N/ha or lesse0
- Setting
- Chiang Mai site in northern Thailande0
Not reportedComparator
Verbatim
e0“At the Chiang Mai site in northern Thailand, bacterial inoculation increased nodule weights on plants receiving 100 kg N/ha or less.”
Claim · model-written summary
Inoculation-related nodule increases were present at 45 days but absent by 60 days.
- Treatment
- inoculatione0
- Outcome
- nodule parameterse0
- Direction
- Increasese0
- Qualifier
- 45 d after planting (DAP) but disappeared by 60 DAPe0
Not reportedTaxonComparator
Verbatim
e0“Increases in nodule parameters due to inoculation were evident at 45 d after planting (DAP) but disappeared by 60 DAP.”
Claim · model-written summary
Nitrogen fertilizer reduced nodulation.
- Taxon
- plantsViridiplantaee0
- Treatment
- Addition of N fertilizerse0
- Outcome
- incidence of nodulatione0
- Direction
- decreasede0
Not reportedComparator
Verbatim
e0“Addition of N fertilizers decreased the incidence of nodulation and sap ureide contents and decreased the contribution of N 2 fixation to the N content of plants at maturity”
Claim · model-written summary
Nitrogen fertilizer reduced sap ureide content.
- Taxon
- plantsViridiplantaee0
- Treatment
- Addition of N fertilizerse0
- Outcome
- sap ureide contentse0
- Direction
- decreasede0
Not reportedComparator
Verbatim
e0“Addition of N fertilizers decreased the incidence of nodulation and sap ureide contents and decreased the contribution of N 2 fixation to the N content of plants at maturity”
Claim · model-written summary
Nitrogen fertilizer reduced the fixation contribution to plant nitrogen at maturity.
- Taxon
- plantsViridiplantaee0
- Outcome
- contribution of N 2 fixation to the N content of plants at maturitye0
- Direction
- decreasede0
Not reportedTreatmentComparator
Verbatim
e0“decreased the contribution of N 2 fixation to the N content of plants at maturity”
Claim · model-written summary
Inoculation increased nodule numbers and weights at Kampang Saen.
- Treatment
- bacterial inoculatione0
- Outcome
- nodule numbers and weightse0
- Direction
- positivee0
- Setting
- Kampang Saen site in central Thailande0
Not reportedTaxonComparator
Verbatim
e0“At the Kampang Saen site in central Thailand, bacterial inoculation had significant positive effects on nodule numbers and weights, ARA, sap ureide contents and levels of N 2 fixed”
Claim · model-written summary
Inoculation increased ARA, sap ureides and nitrogen fixed at Kampang Saen.
- Treatment
- bacterial inoculatione0
- Outcome
- ARA, sap ureide contents and levels of N 2 fixede0
- Direction
- positivee0
- Setting
- Kampang Saen site in central Thailande0
Not reportedTaxonComparator
Verbatim
e0“At the Kampang Saen site in central Thailand, bacterial inoculation had significant positive effects on nodule numbers and weights, ARA, sap ureide contents and levels of N 2 fixed”
Claim · model-written summary
Nitrogen fertilizer reduced fixation symbiosis effectiveness at Kampang Saen.
- Treatment
- Addition of N fertilizerse0
- Outcome
- effectiveness of N 2 ‐fixing symbiosese0
- Direction
- reducede0
Not reportedTaxonComparator
Verbatim
e0“Addition of N fertilizers at this site also reduced the effectiveness of N 2 ‐fixing symbioses.”
Claim · model-written summary
Small preplant nitrogen additions did not significantly reduce fixation but increased plant growth.
- Taxon
- plante0
- Treatment
- small additions of N fertilizer added before plantinge0
- Outcome
- N 2 fixation levelse0
- Direction
- decreasee0
Not reportedComparator
Verbatim
e0“small additions of N fertilizer added before planting did not significantly decrease N 2 fixation levels, but did have a significant positive effect on plant growth.”
Claim · model-written summary
Small preplant nitrogen additions significantly increased plant growth.
- Taxon
- plante0
- Treatment
- small additions of N fertilizer added before plantinge0
- Outcome
- plant growthe0
- Direction
- positivee0
Not reportedComparator
Verbatim
e0“small additions of N fertilizer added before planting did not significantly decrease N 2 fixation levels, but did have a significant positive effect on plant growth.”
Claim · model-written summary
Larger nitrogen additions were concluded to reduce fixation beyond their chemical nitrogen benefit.
Not reportedTaxonComparator
Verbatim
e0“Larger N additions would reduce N 2 fixation levels in excess of the benefits of adding more N in chemical form.”
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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.