Abstract
Manganese ion (Mn(Ⅱ)) toxicity in acidic soils is a global agricultural and environmental issue that severely constrains crop productivity and soil ecosystem functioning. Systematic understanding of the effects of Mn(Ⅱ) stress on soil nitrogen (N) transformation processes and their underlying mechanisms remains limited. A short-term pot experiment using sugarcane (Saccharum officinaru250-wordm) was conducted to investigate the effects of varying Mn(Ⅱ) concentrations on sugarcane N uptake, soil N transformation processes, and the underlying microbial mechanisms. High Mn(Ⅱ) concentrations (≥ 900 mg·kg⁻¹) significantly inhibited N uptake in sugarcane, reducing plant N accumulation by approximately 50%. Elevated Mn(Ⅱ) levels stimulated soil urease activity but suppressed ammonia monooxygenase (AMO) activity and nitrification potential. Concurrently, the concentration of soil soluble organic nitrogen dropped from 88.46 to 20.78 mg kg⁻¹ , whereas ammonium nitrogen (NH₄⁺-N) rose from 3.29 to 14.50 mg kg⁻¹ . This divergence suggests that nitrification was suppressed, leading to the accumulation of NH₄⁺-N. The α-diversity index of the soil bacterial community exhibited a U-shaped response to increasing Mn(Ⅱ) concentrations, although its composition remained relatively stable. Ammonia-oxidizing archaea (AOA) showed greater OTU richness and diversity than the ammonia-oxidizing bacteria (AOB). AMO activity correlated negatively with Nitrososphaera abundance but positively with Nitrosospira abundance. With increasing Mn(Ⅱ), Nitrosospira declined progressively while the tolerant genus Nitrosovibrio became dominant, reflecting community shifts under Mn stress. High Mn(Ⅱ) levels thus reshaped the AOB community structure, suppressed nitrification, and reduced plant N uptake efficiency. These findings offer a theoretical basis for improving nitrogen management and ecological remediation in Mn-contaminated acidic farmlands.
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Claims 12
Claim · model-written summary
High Mn concentrations reduced sugarcane nitrogen accumulation by about half.
- Taxon
- sugarcanee0
- Treatment
- High Mn(Ⅱ) concentrations (≥ 900 mg·kg⁻¹)e0
- Outcome
- plant N accumulatione0
- Direction
- reducinge0
- Value
- approximately 50%e0
Not reportedComparator
Verbatim
e0“High Mn(Ⅱ) concentrations (≥ 900 mg·kg⁻¹) significantly inhibited N uptake in sugarcane, reducing plant N accumulation by approximately 50%”
Claim · model-written summary
Elevated Mn stimulated soil urease activity.
Not reportedTaxonComparator
Verbatim
e0“Elevated Mn(Ⅱ) levels stimulated soil urease activity”
Claim · model-written summary
Elevated Mn suppressed soil ammonia monooxygenase activity and nitrification potential.
- Treatment
- Elevated Mn(Ⅱ) levelse0
- Outcome
- ammonia monooxygenase (AMO) activity and nitrification potentiale0
- Direction
- suppressede0
Not reportedTaxonComparator
Verbatim
e0“Elevated Mn(Ⅱ) levels stimulated soil urease activity but suppressed ammonia monooxygenase (AMO) activity and nitrification potential”
Claim · model-written summary
Soil soluble organic nitrogen fell from 88.46 to 20.78 mg kg⁻¹.
Not reportedTaxon
Verbatim
e0“the concentration of soil soluble organic nitrogen dropped from 88.46 to 20.78 mg kg⁻¹”
Claim · model-written summary
Soil ammonium nitrogen rose from 3.29 to 14.50 mg kg⁻¹.
Not reportedTaxon
Verbatim
e0“ammonium nitrogen (NH₄⁺-N) rose from 3.29 to 14.50 mg kg⁻¹”
Claim · model-written summary
Soil bacterial alpha diversity had a U-shaped response to increasing Mn.
- Treatment
- increasing Mn(Ⅱ) concentrationse0
- Outcome
- α-diversity index of the soil bacterial communitye0
- Direction
- U-shaped responsee0
Not reportedTaxon
Verbatim
e0“The α-diversity index of the soil bacterial community exhibited a U-shaped response to increasing Mn(Ⅱ) concentrations”
Claim · model-written summary
Soil bacterial composition remained relatively stable.
- Outcome
- compositione0
Not reportedTaxon
Verbatim
e0“its composition remained relatively stable”
Claim · model-written summary
AOA had greater OTU richness and diversity than AOB.
Not reportedTaxon
Verbatim
e0“Ammonia-oxidizing archaea (AOA) showed greater OTU richness and diversity than the ammonia-oxidizing bacteria (AOB)”
Claim · model-written summary
AMO activity correlated negatively with Nitrososphaera abundance.
- Interactor
- Nitrososphaera
Nitrososphaerae0other - Outcome
- AMO activitye0
- Direction
- negativelye0
Not reportedTaxon
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“AMO activity correlated negatively with Nitrososphaera abundance”
Claim · model-written summary
AMO activity correlated positively with Nitrosospira abundance.
- Interactor
- NitrosospiraNitrosospirae0other
- Outcome
- AMO activitye0
- Direction
- positivelye0
Not reportedTaxon
Verbatim
e0“AMO activity correlated negatively with Nitrososphaera abundance but positively with Nitrosospira abundance”
Claim · model-written summary
Nitrosospira declined as Mn increased.
Not reportedTaxon
Verbatim
e0“With increasing Mn(Ⅱ), Nitrosospira declined progressively”
Claim · model-written summary
Nitrosovibrio became dominant as Mn increased.
Not reportedTaxon
Verbatim
e0“With increasing Mn(Ⅱ), Nitrosospira declined progressively while the tolerant genus Nitrosovibrio became dominant”
The same questions in other papers
manganese atom · nutrient: content · Saccharum officinarum (sugarcane)Results agree
3 papers in the same direction as this paper
- negative
- negative
- negative
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.