Abstract
The study of the distribution of various forms of Zn under fluctuating oxidation-reduction (redox) conditions is necessary to improve predictions of Zn solubility and bioavailability when Zn is added to soils with large quantites of organic C that oxidize over time. We conducted plant-soil interaction studies to determine the effect of redox potential in flooded and unflooded soils on the solubility and uptake of Zn by rice (Oryza sativa L., Calrose-76), wheat (Triticum aestivum L.), and barley (Hordeum vulgare L.) in a growth chamber. Sequential extractions were used to fractionate Zn in biosolids-amended and unamended A horizon samples (25-cm depth) of three soil series of a typical toposequence from the Coastal Plain of Maryland: a Galestown loamy sand (Psammentic Hapludults), a Bertie silt loam (Typic Hapludults), and an Othello silt loam (Typic Endoaquults). Addition of organic C (as biosolids) increased the leaf dry matter yield, but not leaf tissue Zn concentration, compared with Zn-amended soil with no organic C addition. Flooding decreased leaf dry matter yield and Zn concentrations in the leaf tissue of all plants, especially in the organic waste-amended soils. Among the crops, rice had higher levels (P < 0.05) of Zn (7.4–34 μmol/g) than did wheat (0.3–4.3 μmol/g) and barley (1.2–6.1 μmol/g). Exchangeable Zn (25 to 48% of added Zn) extracted by Ca(NO3)2 was correlated with the concentration of leaf Zn of the three crops (r = 0.62, P < 0.05), whereas the fraction of nonexchangeable Zn (48 to 78% of added Zn) extracted by 100 m M NH2OH · HCL in 1 M HNO3 was negatively correlated with leaf Zn (r = −0.49, P < 0.05). Reduced soil conditions depressed exchangeable Zn and enhanced nonexchangeable Zn in all of the ponded soils, apparently the result of the enhancement of surface-induced hydrolysis of Zn caused by increases in pH after flooding. The addition of organic C increased the fraction of Zn in nonexchangeable forms in the flooded soils, whereas the Zn levels in nonexchangeable forms in the unflooded soils were not affected by the addition of organic C. Thus, Zn availability to the crops was more dependent on pH changes induced by flooding than on the addition of organic C.
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Claims 12
Claim · model-written summary
Biosolids organic carbon increased crop leaf dry matter yield relative to Zn-amended soil without organic carbon.
- Taxon
- rice (Oryza sativa L., Calrose-76), wheat (Triticum aestivum L.), and barley (Hordeum vulgare L.)
Hordeum vulgareOryza sativa
Triticum aestivume1 - Treatment
- Addition of organic C (as biosolids)e0
- Outcome
- leaf dry matter yielde0
- Direction
- increasede0
- Comparator
- Zn-amended soil with no organic C additione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)

Verbatim
e0“Addition of organic C (as biosolids) increased the leaf dry matter yield, but not leaf tissue Zn concentration, compared with Zn-amended soil with no organic C addition.”
e1“rice (Oryza sativa L., Calrose-76), wheat (Triticum aestivum L.), and barley (Hordeum vulgare L.)”
Claim · model-written summary
Biosolids organic carbon did not increase crop leaf tissue zinc concentration relative to soil without organic carbon.
- Taxon
- rice (Oryza sativa L., Calrose-76), wheat (Triticum aestivum L.), and barley (Hordeum vulgare L.)
Hordeum vulgareOryza sativa
Triticum aestivume1 - Treatment
- Addition of organic C (as biosolids)e0
- Outcome
- leaf tissue Zn concentratione0
- Direction
- note0
- Comparator
- Zn-amended soil with no organic C additione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)

Verbatim
e0“Addition of organic C (as biosolids) increased the leaf dry matter yield, but not leaf tissue Zn concentration, compared with Zn-amended soil with no organic C addition.”
e1“rice (Oryza sativa L., Calrose-76), wheat (Triticum aestivum L.), and barley (Hordeum vulgare L.)”
Claim · model-written summary
Flooding decreased leaf dry matter yield in all three crops, particularly in organic waste amended soil.
- Taxon
- rice (Oryza sativa L., Calrose-76), wheat (Triticum aestivum L.), and barley (Hordeum vulgare L.)
Hordeum vulgareOryza sativa
Triticum aestivume1 - Treatment
- Floodinge0
- Outcome
- leaf dry matter yielde0
- Direction
- decreasede0
- Qualifier
- especially in the organic waste-amended soilse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)

Verbatim
e0“Flooding decreased leaf dry matter yield and Zn concentrations in the leaf tissue of all plants, especially in the organic waste-amended soils.”
e1“rice (Oryza sativa L., Calrose-76), wheat (Triticum aestivum L.), and barley (Hordeum vulgare L.)”
Claim · model-written summary
Flooding decreased leaf tissue zinc concentrations in all three crops, particularly in organic waste amended soil.
- Taxon
- rice (Oryza sativa L., Calrose-76), wheat (Triticum aestivum L.), and barley (Hordeum vulgare L.)
Hordeum vulgareOryza sativa
Triticum aestivume1 - Treatment
- Floodinge0
- Outcome
- Zn concentrations in the leaf tissuee0
- Direction
- decreasede0
- Qualifier
- especially in the organic waste-amended soilse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)

Verbatim
e0“Flooding decreased leaf dry matter yield and Zn concentrations in the leaf tissue of all plants, especially in the organic waste-amended soils.”
e1“rice (Oryza sativa L., Calrose-76), wheat (Triticum aestivum L.), and barley (Hordeum vulgare L.)”
Claim · model-written summary
Rice leaf zinc was higher than wheat and barley leaf zinc.
- Taxon
- rice
Oryza sativae0
- Outcome
- Zne0
- Direction
- highere0
- Value
- 7.4–34 μmol/ge0
- Qualifier
- wheat (0.3–4.3 μmol/g) and barley (1.2–6.1 μmol/g)e0
- Comparator
- wheate0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“rice had higher levels (P < 0.05) of Zn (7.4–34 μmol/g) than did wheat (0.3–4.3 μmol/g) and barley (1.2–6.1 μmol/g)”
Claim · model-written summary
Exchangeable soil zinc correlated positively with leaf zinc concentration across the three crops.
- Taxon
- rice (Oryza sativa L., Calrose-76), wheat (Triticum aestivum L.), and barley (Hordeum vulgare L.)
Hordeum vulgareOryza sativa
Triticum aestivume1 - Outcome
- concentration of leaf Zne0
- Direction
- correlatede0
- Value
- r = 0.62e0
- Comparator
- Exchangeable Zne0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)

Verbatim
e0“Exchangeable Zn (25 to 48% of added Zn) extracted by Ca(NO3)2 was correlated with the concentration of leaf Zn of the three crops (r = 0.62, P < 0.05)”
e1“rice (Oryza sativa L., Calrose-76), wheat (Triticum aestivum L.), and barley (Hordeum vulgare L.)”
Claim · model-written summary
Nonexchangeable soil zinc correlated negatively with leaf zinc across the three crops.
- Taxon
- rice (Oryza sativa L., Calrose-76), wheat (Triticum aestivum L.), and barley (Hordeum vulgare L.)
Hordeum vulgareOryza sativa
Triticum aestivume1 - Outcome
- leaf Zne0
- Direction
- negatively correlatede0
- Value
- r = −0.49e0
- Comparator
- fraction of nonexchangeable Zne0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)

Verbatim
e0“the fraction of nonexchangeable Zn (48 to 78% of added Zn) extracted by 100 m M NH2OH · HCL in 1 M HNO3 was negatively correlated with leaf Zn (r = −0.49, P < 0.05)”
e1“rice (Oryza sativa L., Calrose-76), wheat (Triticum aestivum L.), and barley (Hordeum vulgare L.)”
Claim · model-written summary
Reduced soil conditions depressed exchangeable zinc in ponded soil.
- Taxon
- rice (Oryza sativa L., Calrose-76), wheat (Triticum aestivum L.), and barley (Hordeum vulgare L.)
Hordeum vulgareOryza sativa
Triticum aestivume1 - Treatment
- Reduced soil conditionse0
- Outcome
- exchangeable Zne0
- Direction
- depressede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)

Verbatim
e0“Reduced soil conditions depressed exchangeable Zn and enhanced nonexchangeable Zn in all of the ponded soils”
e1“rice (Oryza sativa L., Calrose-76), wheat (Triticum aestivum L.), and barley (Hordeum vulgare L.)”
Claim · model-written summary
Reduced soil conditions enhanced nonexchangeable zinc in ponded soil.
- Taxon
- rice (Oryza sativa L., Calrose-76), wheat (Triticum aestivum L.), and barley (Hordeum vulgare L.)
Hordeum vulgareOryza sativa
Triticum aestivume1 - Treatment
- Reduced soil conditionse0
- Outcome
- nonexchangeable Zne0
- Direction
- enhancede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)

Verbatim
e0“Reduced soil conditions depressed exchangeable Zn and enhanced nonexchangeable Zn in all of the ponded soils”
e1“rice (Oryza sativa L., Calrose-76), wheat (Triticum aestivum L.), and barley (Hordeum vulgare L.)”
Claim · model-written summary
Added organic carbon increased nonexchangeable zinc in flooded soil.
- Taxon
- rice (Oryza sativa L., Calrose-76), wheat (Triticum aestivum L.), and barley (Hordeum vulgare L.)
Hordeum vulgareOryza sativa
Triticum aestivume1 - Treatment
- addition of organic Ce0
- Outcome
- fraction of Zn in nonexchangeable formse0
- Direction
- increasede0
- Setting
- flooded soilse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)

Verbatim
e0“The addition of organic C increased the fraction of Zn in nonexchangeable forms in the flooded soils”
e1“rice (Oryza sativa L., Calrose-76), wheat (Triticum aestivum L.), and barley (Hordeum vulgare L.)”
Claim · model-written summary
Added organic carbon did not affect nonexchangeable zinc in unflooded soil.
- Taxon
- rice (Oryza sativa L., Calrose-76), wheat (Triticum aestivum L.), and barley (Hordeum vulgare L.)
Hordeum vulgareOryza sativa
Triticum aestivume1 - Treatment
- addition of organic Ce0
- Outcome
- Zn levels in nonexchangeable formse0
- Direction
- not affectede0
- Setting
- unflooded soilse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)

Verbatim
e0“the Zn levels in nonexchangeable forms in the unflooded soils were not affected by the addition of organic C”
e1“rice (Oryza sativa L., Calrose-76), wheat (Triticum aestivum L.), and barley (Hordeum vulgare L.)”
Claim · model-written summary
The authors interpret crop zinc availability as more dependent on flood induced pH changes than organic carbon addition.
- Taxon
- rice (Oryza sativa L., Calrose-76), wheat (Triticum aestivum L.), and barley (Hordeum vulgare L.)
Hordeum vulgareOryza sativa
Triticum aestivume1 - Outcome
- Zn availability to the cropse0
- Qualifier
- pH changes induced by floodinge0
- Comparator
- addition of organic Ce0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)

Verbatim
e0“Zn availability to the crops was more dependent on pH changes induced by flooding than on the addition of organic C”
e1“rice (Oryza sativa L., Calrose-76), wheat (Triticum aestivum L.), and barley (Hordeum vulgare L.)”
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