Abstract
Abstract A long-term field experiment was conducted for 8 years on a Vertisol in central India to assess quantitatively the direct and residual N effects of soybean inoculation with Bradyrhizobium and wheat inoculation with Azotobacter in a soybean–wheat rotation. After cultivation of soybean each year, its aerial residues were removed before growing wheat in the same plots using four N levels (120, 90, 60 and 30 kg ha−1) and Azotobacter inoculation. Inoculation of soybean increased grain yield by 10.1% (180 kg ha−1), but the increase in wheat yields with inoculation was only marginal (5.6%; 278 kg ha−1). There was always a positive balance of soil N after soybean harvest; an average of +28 kg N ha−1 yr−1 in control (nodulated by native rhizobia) plots compared with +41 kg N ha−1 yr−1 in Rhizobium-inoculated plots. Residual and direct effects of Rhizobium and Azotobacter inoculants caused a fertilizer N credit of 30 kg ha−1 in wheat. Application of fertilizers or microbial inoculation favoured the proliferation of rhizobia in crop rhizosphere due to better plant growth. Additional N uptake by inoculation was 14.9 kg N ha−1 by soybean and 20.9 kg N ha−1 by wheat crop, and a gain of +38.0 kg N ha−1 yr−1 to the 0–15 cm soil layer was measured after harvest of wheat. So, total N contribution to crops and soil due to the inoculants was 73.8 kg N ha−1 yr−1 after one soybean–wheat rotation. There was a total N benefit of 13.8 kg N ha−1 yr−1 to the soil due to regular long-term use of microbial inoculants in soybean–wheat rotation. Keywords: biofertilizerbiological nitrogen fixation (BNF) Bradyrhizobium Azotobacter soil carbon Acknowledgements We are grateful to the Indian Council of Agricultural Research for financial support through the All India Network Project on Soil Biodiversity-Biofertilizers, Indian Institute of Soil Science, Bhopal, India.
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Claims 10
Claim · model-written summary
Soybean inoculation increased grain yield by 10.1%.
- Taxon
- soybean
Glycine maxe0 - Treatment
- Inoculatione0
- Interactor
- Bradyrhizobium
Bradyrhizobiumt0symbiont - Outcome
- grain yielde0
- Direction
- increasede0
- Value
- 10.1%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Inoculation of soybean increased grain yield by 10.1% (180 kg ha−1)”
t0“soybean inoculation withBradyrhizobium”
Claim · model-written summary
Wheat inoculation increased yield marginally by 5.6%.
- Taxon
- wheat
Triticum aestivume0 - Treatment
- inoculatione0
- Interactor
- Azotobacter
Azotobactert0symbiont - Outcome
- wheat yieldse0
- Direction
- increasee0
- Value
- 5.6%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the increase in wheat yields with inoculation was only marginal (5.6%; 278 kg ha−1)”
t0“wheat inoculation withAzotobacter”
Claim · model-written summary
Soil nitrogen balance after soybean harvest averaged +28 in control plots versus +41 with inoculation.
- Taxon
- soybeanGlycine maxt0
- Treatment
- Rhizobium-inoculatede0
- Outcome
- Ne0
- Direction
- compared withe0
- Value
- +41 kg N ha−1 yr−1e0
- Qualifier
- +28 kg N ha−1 yr−1e0
- Comparator
- controle0
RhizobiumOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“an average of +28 kg N ha−1 yr−1 in control (nodulated by native rhizobia) plots compared with +41 kg N ha−1 yr−1 in Rhizobium-inoculated plots.”
t0“soybean”
Claim · model-written summary
Inoculants gave a fertilizer N credit of 30 kg ha−1 in wheat.
- Taxon
- wheatTriticum aestivume0
- Treatment
- Rhizobium and Azotobacter inoculantse0
- Second interactor
- AzotobacterAzotobactere0symbiont
- Outcome
- fertilizer N credite0
- Value
- 30 kg ha−1e0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Residual and direct effects of Rhizobium and Azotobacter inoculants caused a fertilizer N credit of 30 kg ha−1 in wheat.”
Claim · model-written summary
Fertilizers or inoculation favored rhizobial proliferation in the crop rhizosphere.
- Taxon
- crope0
- Treatment
- Application of fertilizers or microbial inoculatione0
- Interactor
- rhizobiae0symbiont
- Outcome
- proliferation of rhizobia in crop rhizospheree0
- Direction
- favourede0
Not reportedComparator
Verbatim
e0“Application of fertilizers or microbial inoculation favoured the proliferation of rhizobia in crop rhizosphere due to better plant growth.”
Claim · model-written summary
Soybean inoculation added 14.9 kg N ha−1 uptake.
- Taxon
- soybeanGlycine maxe0
- Treatment
- inoculatione0
- Outcome
- N uptakee0
- Direction
- Additionale0
- Value
- 14.9 kg N ha−1e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Additional N uptake by inoculation was 14.9 kg N ha−1 by soybean”
Claim · model-written summary
Wheat inoculation added 20.9 kg N ha−1 uptake.
- Taxon
- wheatTriticum aestivume0
- Treatment
- inoculatione0
- Outcome
- N uptakee0
- Direction
- Additionale0
- Value
- 20.9 kg N ha−1e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Additional N uptake by inoculation was 14.9 kg N ha−1 by soybean and 20.9 kg N ha−1 by wheat crop”
Claim · model-written summary
The soil layer gained +38.0 kg N ha−1 yr−1 after wheat harvest.
- Taxon
- wheatTriticum aestivume0
- Outcome
- soil layere0
- Direction
- gaine0
- Value
- +38.0 kg N ha−1 yr−1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“a gain of +38.0 kg N ha−1 yr−1 to the 0–15 cm soil layer was measured after harvest of wheat.”
Claim · model-written summary
Inoculants contributed 73.8 kg N ha−1 yr−1 to crops and soil after rotation.
- Taxon
- soybean–wheatGlycine maxTriticum aestivume0
- Treatment
- inoculantse0
- Outcome
- total N contribution to crops and soile0
- Value
- 73.8 kg N ha−1 yr−1e0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“total N contribution to crops and soil due to the inoculants was 73.8 kg N ha−1 yr−1 after one soybean–wheat rotation.”
Claim · model-written summary
Long-term inoculant use benefited soil nitrogen by 13.8 kg N ha−1 yr−1.
- Taxon
- soybean–wheatGlycine maxTriticum aestivume0
- Treatment
- regular long-term use of microbial inoculantse0
- Outcome
- total N benefite0
- Value
- 13.8 kg N ha−1 yr−1e0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“total N benefit of 13.8 kg N ha−1 yr−1 to the soil due to regular long-term use of microbial inoculants in soybean–wheat rotation.”
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See all 11 papers →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.