Abstract
Biochar continues to attract growing interest as a promising soil amendment, particularly in areas contaminated with heavy metals. The present experiment was conducted on soil contaminated with zinc (Zn), copper (Cu), and nickel (Ni) in the following treatments: contamination with a single heavy metal (Zn, Cu, or Ni) and with a combination of heavy metals (ZnCu, ZnNi, CuNi, and ZnCuNi). The analysis was performed in soil samples with and without biochar addition. The biochar dose was 15 g kg−1 soil. The biochar was produced from sunflower husks, with the following composition: ash—7.49%; organic carbon (Corg)—83.92%; total nitrogen (Ntotal)—0.91%; hydrogen—2.56%; sulfur—0.02%; oxygen—3.30%; and pH—9.79. Nickel, followed by Cu, induced the greatest decrease in Zea mays yields, whereas the smallest decline in yields was observed in response to Zn contamination. The combined application of the tested heavy metals had more damaging effects, in particular by decreasing maize yields. The values of the heavy metal impact index (IFHm) confirmed that heavy metals exerted a negative impact on the biochemical activity of soil. Copper applied alone and in combination with other heavy metals had the most inhibitory effect on soil enzyme activity. The toxicity of the analyzed heavy metals for plants and soil enzymes was reduced by biochar. This is confirmed by the tolerance index (TI) values for copper and nickel in Zea mays. The TI values for copper increased from 0.318 in soil without biochar to 0.405 in soil with biochar. For nickel, the TI values increased from 0.015 to 0.133. The values of the biochar impact index (IFCB) also suggest that biochar stimulated enzyme activity in all treatments. Biochar also improved the chemical and physicochemical properties of soil, including the content of Corg and Ntotal and soil pH.
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Claims 12
Claim · model-written summary
Nickel caused the greatest decrease in maize yield.
Zea maysOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nickel, followed by Cu, induced the greatest decrease in Zea mays yields, whereas the smallest decline in yields was observed in response to Zn contamination.”
Claim · model-written summary
Copper had the second greatest yield decrease after nickel.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nickel, followed by Cu, induced the greatest decrease in Zea mays yields, whereas the smallest decline in yields was observed in response to Zn contamination.”
Claim · model-written summary
Zinc caused the smallest yield decline.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nickel, followed by Cu, induced the greatest decrease in Zea mays yields, whereas the smallest decline in yields was observed in response to Zn contamination.”
Claim · model-written summary
Combined metals had more damaging effects on maize yields.
- Treatment
- combined application of the tested heavy metalse0
- Outcome
- maize yieldse0
- Direction
- decreasinge0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The combined application of the tested heavy metals had more damaging effects, in particular by decreasing maize yields.”
Claim · model-written summary
Heavy metals negatively affected soil biochemical activity.
Not reportedTaxon
Verbatim
e0“The values of the heavy metal impact index (IFHm) confirmed that heavy metals exerted a negative impact on the biochemical activity of soil.”
t0“Zea mays”
Claim · model-written summary
Copper alone and with other metals inhibited soil enzyme activity most.
- Treatment
- Copper applied alone and in combination with other heavy metalse0
- Outcome
- soil enzyme activitye0
- Direction
- most inhibitorye0
Not reportedTaxonComparator
Verbatim
e0“Copper applied alone and in combination with other heavy metals had the most inhibitory effect on soil enzyme activity.”
Claim · model-written summary
Biochar reduced heavy metal toxicity for plants.
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The toxicity of the analyzed heavy metals for plants and soil enzymes was reduced by biochar.”
t0“Zea mays”
Claim · model-written summary
Biochar reduced heavy metal toxicity for soil enzymes.
Not reportedTaxonComparator
Verbatim
e0“The toxicity of the analyzed heavy metals for plants and soil enzymes was reduced by biochar.”
Claim · model-written summary
Biochar increased copper tolerance index in maize from 0.318 to 0.405.
- Treatment
- soil with biochare0
- Outcome
- TI values for coppere0
- Direction
- increasede0
- Value
- 0.405e0
- Qualifier
- 0.318e0
- Comparator
- soil without biochare0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The TI values for copper increased from 0.318 in soil without biochar to 0.405 in soil with biochar.”
e1“in Zea mays. The TI values for copper”
Claim · model-written summary
Biochar increased nickel tolerance index in maize from 0.015 to 0.133.
- Treatment
- soil with biochare2
- Outcome
- TI valuese0
- Direction
- increasede0
- Value
- 0.133e0
- Qualifier
- 0.015e0
- Comparator
- soil without biochare2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“For nickel, the TI values increased from 0.015 to 0.133.”
e1“in Zea mays. The TI values for copper”
e2“soil without biochar to 0.405 in soil with biochar”
Claim · model-written summary
Biochar stimulated soil enzyme activity in all treatments.
Not reportedTaxonComparator
Verbatim
e0“biochar stimulated enzyme activity in all treatments.”
Claim · model-written summary
Biochar improved soil organic carbon, nitrogen, and pH.
Not reportedTaxonComparator
Verbatim
e0“Biochar also improved the chemical and physicochemical properties of soil, including the content of Corg and Ntotal and soil pH.”
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8 of 10 groups shown: named compounds and organisms first, then groups whose results differ (checked claim by claim), then those with positive and negative results, then the smaller groups.
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.