Abstract
Abstract The influence of different rates of sludge applications to calcareous loamy soils of Saudi Arabia, on nodulation and symbiotic N 2 −fixation in alfalfa plants ( Medicago sativa L.) was studied in a pot experiment. The effect of heavy metals accumulation in soil due to continuous irrigation of the test soil with sewage water was also investigated. Application of up to 80 g sludge per pot enhanced nodulation, nitrogenase activity, dry matter yield and N‐contents of alfalfa plants growing in loamy soils either previously irrigated with sewage water or well water. However, sludge applied at the rate of 160–200 g pot −1 inhibited the nodulation, N accumulation and dry matter yield of alfalfa. The response of alfalfa to sludge was dependent on the rhizobial strain used. Our results also showed that accumulation of heavy metals due to continuous irrigation of a calcareous sandy loam soil with sewage water, for more than 10 years, didn't inhibit N 2 −fixation in alfalfa plants, but enhanced it. Microelements in alfalfa plants increased with increase in the rate of sludge application. Although high rates of sludge application affected nodulation and N 2 −fixation of alfalfa, dry matter and the nitrogen contents of the plants were not highly affected. Therefore, the inhibitory effect of high rates of sludge was most probably due to the toxic effect of heavy metals on the microsymbiont rather than on the plants.
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Claims 8
Claim · model-written summary
Up to 80 g sludge per pot enhanced nodulation and nitrogenase activity of alfalfa in loamy soils.
- Taxon
- alfalfa
Medicago sativae1 - Treatment
- Application of up to 80 g sludge per pote1
- Outcome
- nodulation, nitrogenase activitye1
- Direction
- enhancede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Application of up to 80 g sludge per pot enhanced nodulation, nitrogenase activity, dry matter yield and N‐contents of alfalfa plants”
Claim · model-written summary
Up to 80 g sludge per pot enhanced dry matter yield and N contents of alfalfa in loamy soils.
- Taxon
- alfalfaMedicago sativae1
- Treatment
- Application of up to 80 g sludge per pote1
- Outcome
- dry matter yield and N‐contentse1
- Direction
- enhancede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Application of up to 80 g sludge per pot enhanced nodulation, nitrogenase activity, dry matter yield and N‐contents of alfalfa plants”
Claim · model-written summary
Sludge at 160-200 g per pot inhibited nodulation, N accumulation and dry matter yield of alfalfa.
- Taxon
- alfalfaMedicago sativae1
- Treatment
- sludge applied at the rate of 160–200 g pot −1e1
- Outcome
- nodulation, N accumulation and dry matter yielde1
- Direction
- inhibitede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“sludge applied at the rate of 160–200 g pot −1 inhibited the nodulation, N accumulation and dry matter yield of alfalfa”
Claim · model-written summary
The response of alfalfa to sludge depended on the rhizobial strain used.
- Taxon
- alfalfaMedicago sativae1
- Interactor
- rhizobial straine1symbiont
- Outcome
- response of alfalfa to sludgee1
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“The response of alfalfa to sludge was dependent on the rhizobial strain used”
Claim · model-written summary
More than 10 years of continuous irrigation with sewage water, which accumulated heavy metals in a calcareous sandy loam, did not inhibit but enhanced N2-fixation in alfalfa.
- Taxon
- alfalfaMedicago sativae1
- Treatment
- continuous irrigation of a calcareous sandy loam soil with sewage watere1
- Outcome
- N 2 −fixatione1
- Direction
- enhancede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“accumulation of heavy metals due to continuous irrigation of a calcareous sandy loam soil with sewage water, for more than 10 years, didn't inhibit N 2 −fixation in alfalfa plants, but enhanced it”
Claim · model-written summary
Microelements in alfalfa plants increased as the sludge application rate increased.
- Taxon
- alfalfaMedicago sativae1
- Treatment
- rate of sludge applicatione1
- Outcome
- Microelementse1
- Direction
- increasede1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“Microelements in alfalfa plants increased with increase in the rate of sludge application”
Claim · model-written summary
High sludge rates did not strongly affect dry matter and nitrogen contents of alfalfa plants.
- Taxon
- alfalfaMedicago sativae1
- Treatment
- high rates of sludge applicatione1
- Outcome
- dry matter and the nitrogen contentse1
- Direction
- not highly affectede1
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“high rates of sludge application affected nodulation and N 2 −fixation of alfalfa, dry matter and the nitrogen contents of the plants were not highly affected”
Claim · model-written summary
The authors consider the inhibitory effect of high sludge rates most probably due to heavy-metal toxicity to the microsymbiont rather than to the alfalfa plants.
- Taxon
- alfalfaMedicago sativat0
- Interactor
- microsymbionte1symbiont
- Compound
- heavy metalse1
- Outcome
- inhibitory effect of high rates of sludgee1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e1“the inhibitory effect of high rates of sludge was most probably due to the toxic effect of heavy metals on the microsymbiont rather than on the plants”
t0“alfalfa”
The same questions in other papers
organic · symbiosis · Medicago sativa (alfalfa)Results differ
1 paper in the same direction as this paper · 1 in the opposite direction
- positive
- no effect
irrigation · symbiosis · Medicago sativa (alfalfa)Positive and negative results
2 papers in the same direction as this paper · 1 in the opposite direction
- no effect
- positive
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organic · growth · Medicago sativa (alfalfa)Positive and negative results
1 paper in the same direction as this paper · 3 in the opposite direction
- positive
- positive
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1 paper more in this group
See all 5 papers →organic · yield · Medicago sativa (alfalfa)Results agree
5 papers in the same direction as this paper
- positive
- positive
- positive
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See all 6 papers →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.