Abstract
Biochars are cost effective, carbonaceous amendments that can immobilize potentially toxic elements (PTEs) in soils. Application of silicon (Si) has been shown to mitigate the effect of soil PTEs on plants. Studies on the interaction effects of Si and biochars in PTE-contaminated soils are limited. Thus, the aim of this study was to investigate the interaction effects of biochars, from sheep manure (SMB) and rice husk (RHB) produced at 300 and 500 °C, and 2 levels of Si (as sodium (Na) metasilicate), on growth and chemical composition of corn (Zea mays) in a nickel (Ni)-polluted calcareous soil. The combined application of Si and biochars significantly reduced soil available Ni (17-32%) and the corn shoot Ni concentrations (29-58%), associated with soil pH increase (r = 0.56-0.60, P < 0.01). Application of SMB resulted in greater soil pH increases compared to RHB, and increased soil electrical conductivity (EC) to saline levels, attributed to its higher ash content. Increasing Si application levels also increased soil pH and EC values. Application of all the biochars resulted in significant biomass increases, with RHB having the most positive effect. Despite the positive effect on soil Ni immobilization, the combined application of Si and biochars generally resulted in a decrease in corn shoot biomass yields compared to biochars alone. The biomass decrease was attributed to the significantly higher soil sodicity and pH in the combined treatments which resulted in suppression of macro and micronutrient uptake by the corn. Although the combination of biochar and Na metasilicate was effective at immobilizing soil Ni, future studies should rather employ other essential basic cation metasilicates.
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Claims 10
Claim · model-written summary
Combined silicon and biochars reduced soil available nickel by 17–32%.
- Treatment
- combined application of Si and biocharse0
- Outcome
- soil available Nie0
- Direction
- reducede0
- Value
- 17-32%e0
Not reportedTaxonComparator
Verbatim
e0“The combined application of Si and biochars significantly reduced soil available Ni (17-32%)”
Claim · model-written summary
Combined silicon and biochars reduced corn shoot nickel concentrations by 29–58%.
- Taxon
- corn
Zea mays subsp. mayse0 - Treatment
- combined application of Si and biocharse0
- Outcome
- corn shoot Ni concentrationse0
- Direction
- reducede0
- Value
- 29-58%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The combined application of Si and biochars significantly reduced soil available Ni (17-32%) and the corn shoot Ni concentrations (29-58%)”
Claim · model-written summary
Soil pH increase was associated with lower available soil and corn shoot nickel.
- Taxon
- cornZea mays subsp. mayse0
- Outcome
- corn shoot Ni concentrationse0
- Qualifier
- soil pH increasee0
Not reportedSettingDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“corn shoot Ni concentrations (29-58%), associated with soil pH increase (r = 0.56-0.60, P < 0.01)”
Claim · model-written summary
Sheep manure biochar increased soil pH more than rice husk biochar.
Zea maysOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Zea mays L.”
e0“Application of SMB resulted in greater soil pH increases compared to RHB”
Claim · model-written summary
Sheep manure biochar raised soil electrical conductivity to saline levels.
Not reportedTreatmentComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Zea mays L.”
e0“increased soil electrical conductivity (EC) to saline levels”
Claim · model-written summary
Increasing silicon application increased soil pH and electrical conductivity.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Zea mays L.”
e0“Increasing Si application levels also increased soil pH and EC values”
Claim · model-written summary
All biochars significantly increased corn biomass, with rice husk biochar having the largest positive effect.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Application of all the biochars resulted in significant biomass increases, with RHB having the most positive effect”
t0“Zea mays L.”
Claim · model-written summary
Combined silicon and biochars generally decreased corn shoot biomass relative to biochars alone.
- Taxon
- cornZea mays subsp. mayse0
- Treatment
- combined application of Si and biocharse0
- Outcome
- corn shoot biomass yieldse0
- Direction
- decreasee0
- Comparator
- biochars alonee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the combined application of Si and biochars generally resulted in a decrease in corn shoot biomass yields compared to biochars alone”
Claim · model-written summary
Higher sodicity and pH in combined treatments suppressed corn nutrient uptake, explaining lower biomass.
- Taxon
- cornZea mays subsp. mayse0
- Outcome
- macro and micronutrient uptake by the corne0
- Qualifier
- higher soil sodicity and pHe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“significantly higher soil sodicity and pH in the combined treatments which resulted in suppression of macro and micronutrient uptake by the corn”
Claim · model-written summary
The authors recommend testing other essential basic cation metasilicates.
- Outcome
- employ other essential basic cation metasilicatese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Zea mays L.”
e0“future studies should rather employ other essential basic cation metasilicates”
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