Abstract
Abstract Nitrogen (N) is an essential plant nutrient, but low and variable plant‐available N levels in agricultural soils often limit maximum grain production. The objective of this study was to determine if a free‐living nitrogen‐fixing bacterial inoculant (NFI) could supply biologically‐fixed N as an additional N source and if this enhances maize ( Zea mays L.) N uptake and grain yield. Maize was grown at four site‐years in Illinois during 2019–2021. The NFI, a mixture of edited Klebsiella variicola and Kosakonia sacchari , was applied in furrow at planting with urea‐N rates from 0 to 225 kg N ha −1 . Using quadratic regression models, across N rates, the NFI supplemented the fertilizer‐N equivalent of 38.5 or 12.1 kg N ha −1 at V8 or R1, respectively. Increases in N accumulation were observed in all plant fractions, and δ 15 N abundance measurements confirmed that some of this additional N was derived from biological N fixation. The NFI treatment increased N accumulation by an average of 4.8% and 3.7% at V8 and R1, respectively, which was the result of greater biomass, with no effect on plant N concentration. Application of NFI resulted in an average of 1.5% more kernels m −2 and 0.11 Mg ha −1 more grain yield. This work reveals that NFI can provide an additional source of N for maize production but identifies that the season‐long benefit of fixed‐N from an NFI is yet to be fully optimized.
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Claims 9
Claim · model-written summary
The inoculant supplied fertilizer-equivalent nitrogen of 38.5 kg N ha −1 at V8.
- Organ / stage
- V8e0
- Treatment
- NFIe0
- Interactor
- Klebsiella variicolaKlebsiella variicolae2symbiont
- Second interactor
- Kosakonia sacchariKosakonia saccharie2symbiont
- Outcome
- fertilizer‐N equivalente0
- Direction
- supplementede0
- Value
- 38.5 or 12.1 kg N ha −1e0
Zea maysNot reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the NFI supplemented the fertilizer‐N equivalent of 38.5 or 12.1 kg N ha −1 at V8 or R1, respectively.”
e1“maize ( Zea mays L.)”
e2“The NFI, a mixture of edited Klebsiella variicola and Kosakonia sacchari”
Claim · model-written summary
Nitrogen accumulation increased across all maize plant fractions after inoculation.
- Organ / stage
- all plant fractionse0
- Treatment
- NFIe2
- Interactor
- Klebsiella variicolaKlebsiella variicolae2symbiont
- Second interactor
- Kosakonia sacchariKosakonia saccharie2symbiont
- Outcome
- N accumulatione0
- Direction
- Increasese0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Increases in N accumulation were observed in all plant fractions”
e1“maize ( Zea mays L.)”
e2“The NFI, a mixture of edited Klebsiella variicola and Kosakonia sacchari”
Claim · model-written summary
Nitrogen isotope abundance confirmed that some additional nitrogen came from biological fixation.
- Outcome
- some of this additional N was derived from biological N fixatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“δ 15 N abundance measurements confirmed that some of this additional N was derived from biological N fixation.”
e1“maize ( Zea mays L.)”
Claim · model-written summary
The inoculant increased maize nitrogen accumulation by 4.8% at V8.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The NFI treatment increased N accumulation by an average of 4.8% and 3.7% at V8 and R1, respectively”
e1“maize ( Zea mays L.)”
Claim · model-written summary
The inoculant increased maize nitrogen accumulation by 3.7% at R1.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The NFI treatment increased N accumulation by an average of 4.8% and 3.7% at V8 and R1, respectively”
e1“maize ( Zea mays L.)”
Claim · model-written summary
Higher nitrogen accumulation was attributed to greater maize biomass.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“which was the result of greater biomass, with no effect on plant N concentration.”
e1“The NFI treatment increased N accumulation”
e2“maize ( Zea mays L.)”
Claim · model-written summary
The inoculant had no effect on maize nitrogen concentration.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“with no effect on plant N concentration.”
e1“The NFI treatment increased N accumulation”
e2“maize ( Zea mays L.)”
Claim · model-written summary
The inoculant increased maize kernel density by 1.5%.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Application of NFI resulted in an average of 1.5% more kernels m −2 and 0.11 Mg ha −1 more grain yield.”
e1“maize ( Zea mays L.)”
Claim · model-written summary
The inoculant increased maize grain yield by 0.11 Mg ha −1.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Application of NFI resulted in an average of 1.5% more kernels m −2 and 0.11 Mg ha −1 more grain yield.”
e1“maize ( Zea mays L.)”
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