Abstract
Abstract The potential for excessive crop uptake of heavy metals from land previously amended with sludge is of concern because of the persistence of heavy metals. Field studies were therefore conducted at two locations in 1983 and 1984 to examine the residual effects of sewage sludge on heavy metal uptake by soybean [ Glycine max (L.) Merr.]. The Fairland plots (Typic Hapludults) had been amended with two rates of anaerobically degested sludge in 1975. The Beltsville plots (Typic Paleudults) had been established in 1976 with limed‐anaerobically digested, limed‐raw, limed‐compost, or heat‐treated sludge and in 1978 with Nu‐Earth (Chicago, IL) anaerobically digested sludge. Treatments consisted of various sludge rates and pH regimes. The concentrations of metals in soybean shoots at the R4 growth stage varied according to sludge type, application rate, and soil pH. Metal uptake from low metal, limed sludges was similar to that of controls. Metal uptake was, however, increased by unlimed sludges that were high in metal content. Digested sludge linearly increased shoot metal concentrations of Zn, Cd, Cu, and Ni. Compared to the unamended control, soybean Zn increased from 24 to 165 mg kg −1 and Cd increased from 0.06 to 0.25 mg kg −1 at the 112 Mg ha −1 rate. The shoot Cd concentration was over seven times higher from Cd rich Nu‐Earth sludge as compared to the other sludges. Shoot Zn and Cd concentrations exhibited significant linear and quadratic relationships with rates of heat‐treated and Nu‐Earth sludge. There was a greater response of shoot Zn and Cd accumulation to sludge rate at low soil pH. At the 100 Mg ha −1 rate of Nu‐Earth sludge, soybean Zn and Cd concentrations, respectively, were 59 and 1.75 mg kg −1 at soil pH 6.4 and 84 and 2.54 mg kg −1 at soil pH 5.8. These results indicate that sludge composition and soil pH can have a substantial influence on soybean metal uptake for at least 9 yr after the initial sludge application.
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Claims 13
Claim · model-written summary
Soybean shoot metal concentrations varied by sludge type, rate, and soil pH.
- Taxon
- soybean
Glycine maxe0 - Organ / stage
- R4 growth stagee0
- Treatment
- sludge type, application rate, and soil pHe0
- Outcome
- concentrations of metals in soybean shootse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The concentrations of metals in soybean shoots at the R4 growth stage varied according to sludge type, application rate, and soil pH.”
Claim · model-written summary
Low-metal limed sludges produced metal uptake similar to controls.
- Taxon
- soybeanGlycine maxt0
- Treatment
- low metal, limed sludgese0
- Outcome
- Metal uptakee0
- Direction
- similare0
- Comparator
- controlse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Metal uptake from low metal, limed sludges was similar to that of controls.”
t0“Soybean”
Claim · model-written summary
Unlimed high-metal sludges increased soybean metal uptake.
- Taxon
- soybeanGlycine maxt0
- Treatment
- unlimed sludges that were high in metal contente0
- Outcome
- Metal uptakee0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Metal uptake was, however, increased by unlimed sludges that were high in metal content.”
t0“Soybean”
Claim · model-written summary
Digested sludge linearly increased shoot Zn concentration.
- Taxon
- soybeanGlycine maxt0
- Treatment
- Digested sludgee0
- Outcome
- shoot metal concentrations of Zne0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Digested sludge linearly increased shoot metal concentrations of Zn, Cd, Cu, and Ni.”
t0“Soybean”
Claim · model-written summary
Digested sludge linearly increased shoot Cd concentration.
- Taxon
- soybeanGlycine maxt0
- Treatment
- Digested sludgee0
- Outcome
- Cde0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Digested sludge linearly increased shoot metal concentrations of Zn, Cd, Cu, and Ni.”
t0“Soybean”
Claim · model-written summary
Digested sludge linearly increased shoot Cu and Ni concentrations.
- Taxon
- soybeanGlycine maxt0
- Treatment
- Digested sludgee0
- Outcome
- Cu, and Nie0
- Direction
- increasede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Digested sludge linearly increased shoot metal concentrations of Zn, Cd, Cu, and Ni.”
t0“Soybean”
Claim · model-written summary
At 112 Mg ha −1, sludge increased soybean Zn from 24 to 165 mg kg −1.
- Taxon
- soybeanGlycine maxe0
- Treatment
- 112 Mg ha −1 ratee0
- Outcome
- soybean Zne0
- Direction
- increasede0
- Value
- 24 to 165 mg kg −1e0
- Comparator
- unamended controle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Compared to the unamended control, soybean Zn increased from 24 to 165 mg kg −1 and Cd increased from 0.06 to 0.25 mg kg −1 at the 112 Mg ha −1 rate.”
Claim · model-written summary
At 112 Mg ha −1, sludge increased soybean Cd from 0.06 to 0.25 mg kg −1.
- Taxon
- soybeanGlycine maxe0
- Treatment
- 112 Mg ha −1 ratee0
- Outcome
- Cde0
- Direction
- increasede0
- Value
- 0.06 to 0.25 mg kg −1e0
- Comparator
- unamended controle0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Compared to the unamended control, soybean Zn increased from 24 to 165 mg kg −1 and Cd increased from 0.06 to 0.25 mg kg −1 at the 112 Mg ha −1 rate.”
Claim · model-written summary
Shoot Cd concentration was over seven times higher with Cd-rich Nu-Earth sludge than other sludges.
- Taxon
- soybeanGlycine maxt0
- Treatment
- Cd rich Nu‐Earth sludgee0
- Outcome
- shoot Cd concentratione0
- Direction
- highere0
- Value
- over seven timese0
- Comparator
- the other sludgese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The shoot Cd concentration was over seven times higher from Cd rich Nu‐Earth sludge as compared to the other sludges.”
t0“Soybean”
Claim · model-written summary
Shoot Zn and Cd concentrations had significant linear and quadratic relationships with heat-treated and Nu-Earth sludge rates.
- Taxon
- soybeanGlycine maxt0
- Treatment
- rates of heat‐treated and Nu‐Earth sludgee0
- Outcome
- Shoot Zn and Cd concentrationse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Shoot Zn and Cd concentrations exhibited significant linear and quadratic relationships with rates of heat‐treated and Nu‐Earth sludge.”
t0“Soybean”
Claim · model-written summary
Shoot Zn and Cd accumulation responded more strongly to sludge rate at low soil pH.
- Taxon
- soybeanGlycine maxt0
- Treatment
- sludge ratee0
- Outcome
- shoot Zn and Cd accumulatione0
- Direction
- greatere0
- Comparator
- low soil pHe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“There was a greater response of shoot Zn and Cd accumulation to sludge rate at low soil pH.”
t0“Soybean”
Claim · model-written summary
At 100 Mg ha −1 Nu-Earth sludge, soybean Zn was 59 mg kg −1 at pH 6.4 and 84 mg kg −1 at pH 5.8.
- Taxon
- soybeanGlycine maxe0
- Treatment
- 100 Mg ha −1 rate of Nu‐Earth sludgee0
- Outcome
- soybean Zne0
- Direction
- higherinferrede0
- Value
- 59 and 1.75 mg kg −1e0
- Qualifier
- soil pH 6.4 and 84 and 2.54 mg kg −1 at soil pH 5.8e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At the 100 Mg ha −1 rate of Nu‐Earth sludge, soybean Zn and Cd concentrations, respectively, were 59 and 1.75 mg kg −1 at soil pH 6.4 and 84 and 2.54 mg kg −1 at soil pH 5.8.”
Claim · model-written summary
At 100 Mg ha −1 Nu-Earth sludge, soybean Cd was 1.75 mg kg −1 at pH 6.4 and 2.54 mg kg −1 at pH 5.8.
- Taxon
- soybeanGlycine maxe0
- Treatment
- 100 Mg ha −1 rate of Nu‐Earth sludgee0
- Outcome
- Cd concentrationse0
- Direction
- higherinferrede0
- Value
- 2.54 mg kg −1e0
- Qualifier
- soil pH 5.8e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At the 100 Mg ha −1 rate of Nu‐Earth sludge, soybean Zn and Cd concentrations, respectively, were 59 and 1.75 mg kg −1 at soil pH 6.4 and 84 and 2.54 mg kg −1 at soil pH 5.8.”
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