Abstract
Abstract Effects of sludge‐borne heavy metals on plant growth, nodulation, and nitrogen (N 2 ) fixation of alfalfa ( Medicago sativa L.), white clover ( Trifolium repens L.), and red clover ( Trifolium pratense L.) were examined. Plants were grown in the greenhouse in pots containing soil (Typic Paleudults) obtained from plots where heat‐treated and Nu‐Earth sludges were applied in 1976 and 1978, respectively. Two soil pH regimes (low and high) were examined for each of the treatments. Nitrogen fertilizer (NH 4 NO 3 ) was applied to one‐half the pots and each legume was inoculated with the appropriate Rhizobium culture. Soil pH and sludge type significantly affected uptake of metals with phytotoxicity observed in the Nu‐Earth, low pH soil. Nodulation was reduced, but not always completely eliminated in all low pH treatments, including the controls. Symbioses were generally ineffective in low pH treatments. In soils where pH was above 6.0, there was a significant increase in shoot weight and total shoot N with sludge addition. Plants derived significant quantities of N from soil, where sludge was applied many years ago. When pH was maintained at 6.0 or higher the results show that heavy metals in soil, and the resulting concentration in plants, had no effect on any of the parameters examined.
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Claims 9
Claim · model-written summary
Soil pH significantly affected metal uptake by the legumes.
- Taxon
- alfalfa
Medicago sativae1 - Outcome
- uptake of metalse0
- Setting
- Soile0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Soil pH and sludge type significantly affected uptake of metals”
e1“alfalfa ( Medicago sativa L.), white clover ( Trifolium repens L.), and red clover ( Trifolium pratense L.)”
Claim · model-written summary
Sludge type significantly affected metal uptake by the legumes.
- Taxon
- alfalfaMedicago sativae1
- Treatment
- sludge typee0
- Outcome
- uptake of metalse0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Soil pH and sludge type significantly affected uptake of metals”
e1“alfalfa ( Medicago sativa L.), white clover ( Trifolium repens L.), and red clover ( Trifolium pratense L.)”
Claim · model-written summary
Phytotoxicity was observed in Nu-Earth sludge soil at low pH.
- Taxon
- alfalfaMedicago sativae1
- Treatment
- Nu‐Earthe0
- Outcome
- phytotoxicity observede0
- Qualifier
- low pH soile0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“phytotoxicity observed in the Nu‐Earth, low pH soil”
e1“alfalfa ( Medicago sativa L.), white clover ( Trifolium repens L.), and red clover ( Trifolium pratense L.)”
Claim · model-written summary
Low-pH treatments reduced nodulation, including controls, without always eliminating it.
- Taxon
- alfalfaMedicago sativae1
- Treatment
- low pH treatmentse0
- Outcome
- Nodulatione0
- Direction
- reducede0
- Comparator
- controlse0
RhizobiumOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Nodulation was reduced, but not always completely eliminated in all low pH treatments, including the controls.”
e1“alfalfa ( Medicago sativa L.), white clover ( Trifolium repens L.), and red clover ( Trifolium pratense L.)”
e2“each legume was inoculated with the appropriate Rhizobium culture”
Claim · model-written summary
Legume symbioses were generally ineffective under low pH.
- Taxon
- alfalfaMedicago sativae1
- Treatment
- low pH treatmentse0
- Outcome
- Symbioses were generally ineffectivee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Symbioses were generally ineffective in low pH treatments.”
e1“alfalfa ( Medicago sativa L.), white clover ( Trifolium repens L.), and red clover ( Trifolium pratense L.)”
e2“each legume was inoculated with the appropriate Rhizobium culture”
Claim · model-written summary
Sludge addition significantly increased shoot weight where soil pH exceeded 6.0.
- Taxon
- alfalfaMedicago sativae1
- Treatment
- sludge additione0
- Outcome
- shoot weighte0
- Direction
- increasee0
- Qualifier
- pH was above 6.0e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In soils where pH was above 6.0, there was a significant increase in shoot weight and total shoot N with sludge addition.”
e1“alfalfa ( Medicago sativa L.), white clover ( Trifolium repens L.), and red clover ( Trifolium pratense L.)”
Claim · model-written summary
Sludge addition significantly increased total shoot nitrogen where soil pH exceeded 6.0.
- Taxon
- alfalfaMedicago sativae1
- Treatment
- sludge additione0
- Outcome
- total shoot Ne0
- Direction
- increasee0
- Qualifier
- pH was above 6.0e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In soils where pH was above 6.0, there was a significant increase in shoot weight and total shoot N with sludge addition.”
e1“alfalfa ( Medicago sativa L.), white clover ( Trifolium repens L.), and red clover ( Trifolium pratense L.)”
Claim · model-written summary
Plants obtained significant amounts of nitrogen from soils that had received sludge years earlier.
- Taxon
- alfalfaMedicago sativae1
- Treatment
- sludge was applied many years agoe0
- Outcome
- quantities of N from soile0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Plants derived significant quantities of N from soil, where sludge was applied many years ago.”
e1“alfalfa ( Medicago sativa L.), white clover ( Trifolium repens L.), and red clover ( Trifolium pratense L.)”
Claim · model-written summary
At pH of at least 6.0, soil heavy metals and plant metal concentrations had no effect on the examined parameters.
- Taxon
- alfalfaMedicago sativae1
- Treatment
- heavy metals in soile0
- Outcome
- parameters examinede0
- Direction
- no effecte0
- Qualifier
- pH was maintained at 6.0 or highere0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“When pH was maintained at 6.0 or higher the results show that heavy metals in soil, and the resulting concentration in plants, had no effect on any of the parameters examined.”
e1“alfalfa ( Medicago sativa L.), white clover ( Trifolium repens L.), and red clover ( Trifolium pratense L.)”
The same questions in other papers
organic · growth · Medicago sativa (alfalfa)Positive and negative results
2 papers in the same direction as this paper · 2 in the opposite direction
- positive
- negative
- no effect
1 paper more in this group
See all 5 papers →ph · Rhizobium · Medicago sativa (alfalfa)Results agree
1 paper in the same direction as this paper
- negative
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.