Abstract
There are several tunnelling projects underway in Europe and worldwide to facilitate connections between distant areas or ones with geographical constraints (e.g. mountains). As a result, the tunnel industry has been producing huge amounts of excavated material (spoil material: SM), which can be re-used for different purposes (including green areas). Adding lime can be a practical procedure at a construction site for the stabilization of SM and makes it possible to manage it better at its final destination site. This work reports a nature-based solution (NBS) for decreasing the highly basic pH (12.53 ± 0.01) of the SM after adding lime, using three different organic fertilizers which are by-products of local olive oil (pomace), compost and digestate production. For this purpose, microcosm experiments were performed with SM amended with compost, pomace or digestate. Half of the microcosms were also seeded with Medicago sativa to evaluate its growth in terms of biomass. The changes in pH and in the structure and functional potential of the microbial community were evaluated in the amended SM at the start and end (4 months) of the experiment. Aerial and root plant biomass and concentrations of leaf chlorophyll and total phenolic compounds were also measured. The microbial biodiversity was evaluated using amplicon sequencing (16S rRNA gene) and a predictive functional analysis was performed by processing sequencing data with the PICRUSt2 tool. Adding the amendments to SM significantly decreased the pH values by 4 units and introduced organic carbon, nitrogen, and active microbial populations. Although pomace promoted the lowest pH decrease (7.98 ± 0.18) and the highest microbial abundance and activity, it did not favour the highest plant growth. Adding compost and digestate to SM can be considered the best NBS for decreasing pH and supporting plant development. M. sativa did not have any direct effect on lowering pH, demonstrating in this study the key role of microorganisms in responding efficiently to this environmental stress and mitigating it. In accordance with these results, predicted bacterial genes coding for membrane proteins (nuo, mrp) and for indoleacetic acid metabolism (ami, nthA, ipdC) involved in pH regulation were identified among the microbial populations.
Abstract from the paper’s OpenAlex record; open copy licensed cc-by. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 9
Claim · model-written summary
Organic amendments reduced spoil material pH by four units.
- Taxon
- Medicago sativa
Medicago sativae1 - Treatment
- amendmentse0
- Outcome
- pH valuese0
- Direction
- decreasede0
- Value
- 4 unitse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Adding the amendments to SM significantly decreased the pH values by 4 units”
e1“seeded with Medicago sativa”
Claim · model-written summary
Organic amendments introduced carbon, nitrogen and active microbes to spoil material.
- Taxon
- Medicago sativaMedicago sativae1
- Treatment
- amendmentse0
- Outcome
- organic carbon, nitrogen, and active microbial populationse0
- Direction
- introducede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Adding the amendments to SM significantly decreased the pH values by 4 units and introduced organic carbon, nitrogen, and active microbial populations”
e1“seeded with Medicago sativa”
Claim · model-written summary
Pomace gave the lowest pH decrease, reaching 7.98 ± 0.18.
- Taxon
- Medicago sativaMedicago sativae1
- Treatment
- pomacee0
- Outcome
- pH decreasee0
- Direction
- loweste0
- Value
- 7.98 ± 0.18e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“pomace promoted the lowest pH decrease (7.98 ± 0.18)”
e1“seeded with Medicago sativa”
Claim · model-written summary
Pomace supported the highest microbial abundance and activity.
- Taxon
- Medicago sativaMedicago sativae1
- Treatment
- pomacee0
- Outcome
- microbial abundance and activitye0
- Direction
- higheste0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“pomace promoted the lowest pH decrease (7.98 ± 0.18) and the highest microbial abundance and activity”
e1“seeded with Medicago sativa”
Claim · model-written summary
Pomace did not give the highest plant growth.
- Taxon
- Medicago sativaMedicago sativae2
- Treatment
- pomacee1
- Outcome
- plant growthe0
- Direction
- did not favour the higheste0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“it did not favour the highest plant growth”
e1“pomace promoted the lowest pH decrease”
e2“seeded with Medicago sativa”
Claim · model-written summary
Compost was recommended for decreasing pH and supporting plant development.
- Taxon
- Medicago sativaMedicago sativae1
- Treatment
- composte0
- Outcome
- decreasing pH and supporting plant developmente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Adding compost and digestate to SM can be considered the best NBS for decreasing pH and supporting plant development”
e1“seeded with Medicago sativa”
Claim · model-written summary
Digestate was recommended for decreasing pH and supporting plant development.
- Taxon
- Medicago sativaMedicago sativae1
- Treatment
- digestatee0
- Outcome
- decreasing pH and supporting plant developmente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Adding compost and digestate to SM can be considered the best NBS for decreasing pH and supporting plant development”
e1“seeded with Medicago sativa”
Claim · model-written summary
Medicago sativa did not directly lower spoil material pH.
- Taxon
- Medicago sativaMedicago sativae1
- Outcome
- lowering pHe0
- Direction
- did not have any direct effecte0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“M. sativa did not have any direct effect on lowering pH”
e1“seeded with Medicago sativa”
Claim · model-written summary
Predicted microbial genes for membrane proteins and indoleacetic acid metabolism involved in pH regulation were identified.
- Taxon
- Medicago sativaMedicago sativae1
- Outcome
- predicted bacterial genes coding for membrane proteins (nuo, mrp) and for indoleacetic acid metabolism (ami, nthA, ipdC) involved in pH regulation were identifiede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“predicted bacterial genes coding for membrane proteins (nuo, mrp) and for indoleacetic acid metabolism (ami, nthA, ipdC) involved in pH regulation were identified among the microbial populations”
e1“seeded with Medicago sativa”
The same questions in other papers
other · soil: biology · Medicago sativa (alfalfa)Positive and negative results
1 paper in the same direction as this paper · 1 in the opposite direction
- no effect
- positive
other · soil: chemistry · Medicago sativa (alfalfa)Results agree
5 papers in the same direction as this paper
- positive
- positive
- positive
2 papers more in this group
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.