Abstract
Abstract Nitrogen and heavy metals derived from sewage sludge may potentially affect N 2 fixation and soybean [ Glycine max (L.) Merr.] growth. Field studies were conducted at two locations in 1983 and 1984 to examine the residual effects of sewage sludge on N 2 fixation in soybean. The Fairland plots (Typic Hapludults) were amended with two rates of anaerobically digested sludge in 1975. The Beltsville plots (Typic Paleudults) were 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. Nonnodulating and nodulating isolines of ‘Clark’ soybean were grown on the sludge‐treated plots, which consisted of various sludge rates and pH regimes. Dry matter and total N accumulation were determined in the shoots at the R4 stage of maturity. Dry matter and N accumulation by nonnodulating soybean generally increased due to greater availability of soil N on the sludge plots. In nodulating soybean, dry matter production and N 2 fixation were enhanced by most sludges with the greatest increase occurring under moisture stress. In 1983, a dry year, dry matter of nodulating soybean and N 2 fixation (estimated by the difference method) were increased by all sludges at Beltsville. During this year, dry matter and amount of N fixed increased from 16.5 g plant −1 and 285 mg N plant −1 (control) to 31.1 g plant −1 and 706 mg N plant −1 at the 672 Mg ha −1 limed‐compost sludge rate, respectively. In 1984, a normal rainfall year, dry matter and N 2 fixation was moderately higher on sludge plots compared to control levels. Dry matter and N 2 fixation showed a quadratic response due to overliming by high applications of limed‐digested and limed‐raw sludges. Evidence for toxicity of sludge metals on N 2 fixation was not found at Beltsville sludge plots. However, a toxic effect may be suggested by high metal sludge at Fairland sludge plots. In addition to a decrease in the amount of N 2 fixed, nonnodulating plant dry matter increased with sludge, whereas nodulating plant dry matter decreased. Results suggest that while sludge amended soil may enhance soybean growth, such beneficial results may be limited to sludges low in heavy metals.
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Claims 13
Claim · model-written summary
Dry matter and N accumulation of nonnodulating soybean generally increased on sludge plots, due to greater soil N availability.
- Taxon
- Glycine max
Glycine maxe1 - Material
- nonnodulatinge2
- Treatment
- sludge plotse2
- Outcome
- Dry matter and N accumulatione2
- Direction
- generally increasede2
- Qualifier
- due to greater availability of soil Ne2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Glycine max (L.) Merr.”
e2“Dry matter and N accumulation by nonnodulating soybean generally increased due to greater availability of soil N on the sludge plots”
Claim · model-written summary
Dry matter production and N2 fixation of nodulating soybean were enhanced by most sludges, with the greatest increase under moisture stress.
- Taxon
- Glycine maxGlycine maxe1
- Material
- nodulatinge3
- Treatment
- most sludgese3
- Outcome
- dry matter production and N 2 fixatione3
- Direction
- enhancede3
- Qualifier
- under moisture stresse3
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Glycine max (L.) Merr.”
e3“In nodulating soybean, dry matter production and N 2 fixation were enhanced by most sludges with the greatest increase occurring under moisture stress”
Claim · model-written summary
In the dry year 1983, all sludges increased dry matter and N2 fixation of nodulating soybean at Beltsville.
- Taxon
- Glycine maxGlycine maxe1
- Material
- nodulatinge4
- Treatment
- all sludgese4
- Outcome
- dry matter of nodulating soybean and N 2 fixatione4
- Direction
- increasede4
- Qualifier
- In 1983, a dry yeare4
- Setting
- Beltsvillee4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Glycine max (L.) Merr.”
e4“In 1983, a dry year, dry matter of nodulating soybean and N 2 fixation (estimated by the difference method) were increased by all sludges at Beltsville”
Claim · model-written summary
In 1983 at the 672 Mg ha rate of limed-compost sludge, dry matter of nodulating soybean increased to 31.1 g plant−1 from 16.5 g plant−1 in the control.
- Taxon
- Glycine maxGlycine maxe1
- Treatment
- sludge ratee5
- Outcome
- dry mattere5
- Direction
- increasede5
- Value
- 31.1 g plant −1e5
- Comparator
- controle5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Glycine max (L.) Merr.”
e5“dry matter and amount of N fixed increased from 16.5 g plant −1 and 285 mg N plant −1 (control) to 31.1 g plant −1 and 706 mg N plant −1 at the 672 Mg ha −1 limed‐compost sludge rate, respectively”
Claim · model-written summary
At the 672 Mg ha rate of limed-compost sludge, the amount of N fixed by nodulating soybean increased to 706 mg N plant−1 from 285 mg N plant−1 in the control.
- Taxon
- Glycine maxGlycine maxe1
- Treatment
- sludge ratee5
- Outcome
- amount of N fixede5
- Direction
- increasede5
- Value
- 706 mg N plant −1e5
- Comparator
- controle5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Glycine max (L.) Merr.”
e5“dry matter and amount of N fixed increased from 16.5 g plant −1 and 285 mg N plant −1 (control) to 31.1 g plant −1 and 706 mg N plant −1 at the 672 Mg ha −1 limed‐compost sludge rate, respectively”
Claim · model-written summary
In the normal rainfall year 1984, dry matter and N2 fixation were moderately higher on sludge plots than at control levels.
- Taxon
- Glycine maxGlycine maxe1
- Treatment
- sludge plotse6
- Outcome
- dry matter and N 2 fixatione6
- Direction
- moderately highere6
- Qualifier
- In 1984, a normal rainfall yeare6
- Comparator
- control levelse6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Glycine max (L.) Merr.”
e6“In 1984, a normal rainfall year, dry matter and N 2 fixation was moderately higher on sludge plots compared to control levels”
Claim · model-written summary
Dry matter and N2 fixation showed a quadratic response to overliming.
- Taxon
- Glycine maxGlycine maxe1
- Treatment
- overliminge7
- Outcome
- Dry matter and N 2 fixatione7
- Direction
- quadratic responsee7
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Glycine max (L.) Merr.”
e7“Dry matter and N 2 fixation showed a quadratic response due to overliming”
Claim · model-written summary
No evidence of toxicity of sludge metals on N2 fixation was found at Beltsville sludge plots.
- Taxon
- Glycine maxGlycine maxe1
- Treatment
- sludge metalse2
- Outcome
- toxicity of sludge metals on N 2 fixatione2
- Direction
- not founde2
- Setting
- Beltsville sludge plotse2
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Glycine max (L.) Merr.”
e2“Evidence for toxicity of sludge metals on N 2 fixation was not found at Beltsville sludge plots”
Claim · model-written summary
A toxic effect may be suggested by high metal sludge at Fairland sludge plots.
- Taxon
- Glycine maxGlycine maxe1
- Treatment
- high metal sludgee3
- Outcome
- toxic effecte3
- Setting
- Fairland sludge plotse3
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Glycine max (L.) Merr.”
e3“However, a toxic effect may be suggested by high metal sludge at Fairland sludge plots”
Claim · model-written summary
Sludge was associated with a decrease in the amount of N2 fixed by soybean.
- Taxon
- Glycine maxGlycine maxe1
- Treatment
- sludgee4
- Outcome
- amount of N 2 fixede4
- Direction
- decreasee4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Glycine max (L.) Merr.”
e4“In addition to a decrease in the amount of N 2 fixed, nonnodulating plant dry matter increased with sludge, whereas nodulating plant dry matter decreased”
Claim · model-written summary
Dry matter of nonnodulating soybean increased with sludge.
- Taxon
- Glycine maxGlycine maxe1
- Material
- nonnodulatinge4
- Treatment
- sludgee4
- Outcome
- plant dry mattere4
- Direction
- increasede4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Glycine max (L.) Merr.”
e4“In addition to a decrease in the amount of N 2 fixed, nonnodulating plant dry matter increased with sludge, whereas nodulating plant dry matter decreased”
Claim · model-written summary
Dry matter of nodulating soybean decreased with sludge.
- Taxon
- Glycine maxGlycine maxe1
- Material
- nodulatinge4
- Treatment
- sludgee4
- Outcome
- plant dry mattere4
- Direction
- decreasede4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Glycine max (L.) Merr.”
e4“In addition to a decrease in the amount of N 2 fixed, nonnodulating plant dry matter increased with sludge, whereas nodulating plant dry matter decreased”
Claim · model-written summary
Sludge-amended soil may enhance soybean growth, and such benefits may be limited to sludges low in heavy metals.
- Taxon
- soybeanGlycine maxe1
- Treatment
- sludge amended soile2
- Outcome
- soybean growthe2
- Direction
- enhancee2
- Qualifier
- may be limited to sludges low in heavy metalse2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“soybean growth”
e2“Results suggest that while sludge amended soil may enhance soybean growth, such beneficial results may be limited to sludges low in heavy metals”
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