Abstract
Abstract Nitrogen fertilizer application to soybean [ Glycine max (L.) Merr.] in Iowa, USA, has shown inconsistent results. We performed a study in central Iowa (2015 and 2016) to investigate the effect of N fertilizer rate (0, 45, 90, 135 kg N ha −1 ) and application timing (planting, flowering, pod setting) on soybean yield, yield components, and to calculate the economic net return to N fertilizer. Results showed a positive effect of N fertilizer on soybean yield and yield components both years. Seed and aboveground biomass dry weight were positively correlated to N fertilizer, and both were 17% greater than No‐N treatment. Nitrogen fertilizer rate that significantly increased seed and aboveground biomass was 135 kg N ha −1 regardless of application timing (2015), or at planting (2016). Moreover, the same N fertilizer addition applied at planting benefitted seed and aboveground biomass N accumulation only in 2016 (avg. 32.00 and 34.68 g N uptake m −2 , respectively), both 1.5‐times higher than No‐N treatment. Favorable environmental conditions during 2016 lead to hand‐measured yield difference of 22% compared to 2015. Economic net return analysis showed that the additional revenue from increased yield attributed to supplemental N fertilization offset the application cost, resulting in net return gains between US$5.83 to $281.89 ha −1 (all treatments except 45 kg N ha −1 on 2015). This study highlights the importance to parse out soybean yield in its components, and the need to quantify yield gains from N fertilizer additions in economic terms which shed some light on any tradeoffs.
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Claims 8
Claim · model-written summary
N fertilizer had a positive effect on soybean yield and yield components in both years.
- Taxon
- soybean
Glycine maxe0 - Treatment
- N fertilizere1
- Outcome
- soybean yield and yield componentse1
- Direction
- positivee1
- Setting
- Iowa, USAe0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nitrogen fertilizer application to soybean [ Glycine max (L.) Merr.] in Iowa, USA, has shown inconsistent results”
e1“Results showed a positive effect of N fertilizer on soybean yield and yield components both years”
Claim · model-written summary
Seed and aboveground biomass dry weight were positively correlated with N fertilizer.
- Taxon
- soybeanGlycine maxe0
- Treatment
- N fertilizere2
- Outcome
- Seed and aboveground biomass dry weighte2
- Direction
- positively correlatede2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nitrogen fertilizer application to soybean [ Glycine max (L.) Merr.] in Iowa, USA, has shown inconsistent results”
e2“Seed and aboveground biomass dry weight were positively correlated to N fertilizer, and both were 17% greater than No‐N treatment”
Claim · model-written summary
Seed and aboveground biomass dry weight were 17% greater with N fertilizer than in the No-N treatment.
- Taxon
- soybeanGlycine maxe0
- Treatment
- N fertilizere2
- Outcome
- Seed and aboveground biomass dry weighte2
- Direction
- greatere2
- Value
- 17%e2
- Comparator
- No‐N treatmente2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nitrogen fertilizer application to soybean [ Glycine max (L.) Merr.] in Iowa, USA, has shown inconsistent results”
e2“Seed and aboveground biomass dry weight were positively correlated to N fertilizer, and both were 17% greater than No‐N treatment”
Claim · model-written summary
Nitrogen at 135 kg ha-1 significantly increased seed and aboveground biomass regardless of application timing.
- Taxon
- soybeanGlycine maxe0
- Treatment
- 135 kg N ha −1e3
- Outcome
- seed and aboveground biomasse3
- Direction
- significantly increasede3
- Qualifier
- regardless of application timing (2015), or at planting (2016)e3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nitrogen fertilizer application to soybean [ Glycine max (L.) Merr.] in Iowa, USA, has shown inconsistent results”
e3“Nitrogen fertilizer rate that significantly increased seed and aboveground biomass was 135 kg N ha −1 regardless of application timing (2015), or at planting (2016)”
Claim · model-written summary
N applied at planting increased seed and aboveground biomass N accumulation only in 2016, 1.5-fold above the No-N treatment.
- Taxon
- soybeanGlycine maxe0
- Treatment
- the same N fertilizer addition applied at plantinge4
- Outcome
- seed and aboveground biomass N accumulatione4
- Direction
- benefittede4
- Value
- 1.5‐timese4
- Qualifier
- only in 2016e4
- Comparator
- No‐N treatmente4
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nitrogen fertilizer application to soybean [ Glycine max (L.) Merr.] in Iowa, USA, has shown inconsistent results”
e4“the same N fertilizer addition applied at planting benefitted seed and aboveground biomass N accumulation only in 2016 (avg. 32.00 and 34.68 g N uptake m −2 , respectively), both 1.5‐times higher than No‐N treatment”
Claim · model-written summary
Hand-measured soybean yield in 2016 differed by 22% from 2015 under favorable environmental conditions.
- Taxon
- soybeanGlycine maxe0
- Outcome
- hand‐measured yield differencee5
- Value
- 22%e5
- Qualifier
- Favorable environmental conditions during 2016e5
- Comparator
- 2015e5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nitrogen fertilizer application to soybean [ Glycine max (L.) Merr.] in Iowa, USA, has shown inconsistent results”
e5“Favorable environmental conditions during 2016 lead to hand‐measured yield difference of 22% compared to 2015”
Claim · model-written summary
Supplemental N fertilization gave soybean net return gains between US$5.83 and $281.89 per hectare, offsetting application cost.
- Taxon
- soybeanGlycine maxe0
- Treatment
- supplemental N fertilizatione6
- Outcome
- net returne6
- Direction
- gainse6
- Value
- US$5.83 to $281.89 ha −1e6
- Qualifier
- all treatments except 45 kg N ha −1 on 2015e6
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nitrogen fertilizer application to soybean [ Glycine max (L.) Merr.] in Iowa, USA, has shown inconsistent results”
e6“supplemental N fertilization offset the application cost, resulting in net return gains between US$5.83 to $281.89 ha −1 (all treatments except 45 kg N ha −1 on 2015)”
Claim · model-written summary
Soybean yield should be parsed into its components, and yield gains from N fertilizer quantified in economic terms.
- Taxon
- soybeanGlycine maxe7
- Outcome
- parse out soybean yield in its componentse7
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e7“This study highlights the importance to parse out soybean yield in its components, and the need to quantify yield gains from N fertilizer additions in economic terms”
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