Abstract
Summary Adverse effects on crop yield or quality have been reported in sewage‐sludge treated soils at soil total metal concentrations below those of the current EU directives. A field trial was set up in Belgium (2002–2004) to assess crop response to the application of sewage sludge below these soil thresholds but with sludge metal concentrations either above (high‐metal) or below (low‐metal) sludge metal limits. Two lime‐stabilized and two raw, dewatered sludges were applied annually at rates of 10, 25 and 50 t dry matter (dm) ha −1 for 3 years with four rates of N‐fertilizer as a reference. Final soil metal concentrations increased to maximums of 1.6 mg Cd kg −1 and 225 mg Zn kg −1 through sludge applications. Maize yield was marginally affected by treatments in year 1, whereas wheat and barley grain yields in subsequent years increased up to threefold with increasing sludge or fertilizer rates and were mainly explained by grain‐N. However, the grain yield of winter wheat in year 2 was reduced by about 14% in lime‐stabilized high‐metal sludge treatments compared with wheat receiving N‐fertilizer at equivalent grain‐N. Wheat grain and straw analysis showed no nutrient deficiencies but Zn concentrations in grain and straw were greater than in N‐fertilizer and lime‐stabilized, low‐metal sludge treatments, suggesting Zn toxicity. Sludge properties other than Cd concentration (e.g. electrical conductivity) affected crop Cd in the first year (maize), whereas significant correlations between Cd application and wheat grain Cd were found in the second year. Wheat grain Cd concentrations reached the international trade guideline of 0.1 mg Cd kg −1 fresh weight in the plots amended with lime‐treated, high‐metal sludge even though soil Cd remained below EU limits. In the third year, barley grain Cd remained largely below EU limits. We discuss the possibility that sludge properties rather than soil total metal concentrations are related to effects on crops in the initial years after sludge applications. In none of the 3 years were any adverse effects on crops found for sludge meeting current EU regulations.
Abstract from the paper’s OpenAlex record, shown for indexing and research. Copyright remains with the authors or the publisher. 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 13
Claim · model-written summary
Sludge application increased final soil Cd and Zn concentrations to reported maxima.
Not reportedTaxon
Verbatim
e0“Final soil metal concentrations increased to maximums of 1.6 mg Cd kg −1 and 225 mg Zn kg −1 through sludge applications.”
Claim · model-written summary
Maize yield was marginally affected by treatments in year one.
Zea maysOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Maize yield was marginally affected by treatments in year 1”
Claim · model-written summary
Wheat grain yield increased up to threefold with increasing sludge or fertilizer rates.
- Taxon
- wheat
Triticum aestivume0 - Treatment
- increasing sludge or fertilizer ratese0
- Outcome
- grain yieldse0
- Direction
- increasede0
- Value
- threefolde0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“wheat and barley grain yields in subsequent years increased up to threefold with increasing sludge or fertilizer rates”
Claim · model-written summary
Barley grain yield increased up to threefold with increasing sludge or fertilizer rates.
- Taxon
- barley
.jpg?width=60)
Hordeum vulgaree0 - Treatment
- increasing sludge or fertilizer ratese0
- Outcome
- grain yieldse0
- Direction
- increasede0
- Value
- threefolde0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“wheat and barley grain yields in subsequent years increased up to threefold with increasing sludge or fertilizer rates”
Claim · model-written summary
Grain nitrogen mainly explained the yield increases.
- Taxon
- wheat and barleyHordeum vulgareTriticum aestivume1
- Compound
- grain‐Ne0
- Outcome
- grain yieldse1
- Direction
- explainede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“were mainly explained by grain‐N”
e1“wheat and barley grain yields”
Claim · model-written summary
Lime-stabilized high-metal sludge reduced winter wheat grain yield by about 14% relative to equivalent grain-N fertilizer.
- Taxon
- winter wheatTriticum aestivume0
- Treatment
- lime‐stabilized high‐metal sludge treatmentse0
- Outcome
- grain yielde0
- Direction
- reducede0
- Value
- about 14%e0
- Comparator
- wheat receiving N‐fertilizer at equivalent grain‐Ne0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the grain yield of winter wheat in year 2 was reduced by about 14% in lime‐stabilized high‐metal sludge treatments compared with wheat receiving N‐fertilizer at equivalent grain‐N.”
Claim · model-written summary
Wheat grain and straw showed no nutrient deficiencies.
- Taxon
- WheatTriticum aestivume0
- Organ / stage
- grain and strawe0
- Outcome
- nutrient deficienciese0
- Direction
- noe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Wheat grain and straw analysis showed no nutrient deficiencies”
Claim · model-written summary
Wheat grain and straw Zn concentrations exceeded those under N fertilizer and low-metal sludge.
- Taxon
- WheatTriticum aestivume1
- Treatment
- lime‐stabilized high‐metal sludge treatmentse2
- Outcome
- Zn concentrations in grain and strawe0
- Direction
- greatere0
- Qualifier
- suggesting Zn toxicitye0
- Comparator
- N‐fertilizer and lime‐stabilized, low‐metal sludge treatmentse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Zn concentrations in grain and straw were greater than in N‐fertilizer and lime‐stabilized, low‐metal sludge treatments, suggesting Zn toxicity.”
e1“Wheat grain and straw analysis”
e2“lime‐stabilized high‐metal sludge treatments”
Claim · model-written summary
Sludge properties other than Cd concentration affected first-year maize Cd.
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Sludge properties other than Cd concentration (e.g. electrical conductivity) affected crop Cd in the first year (maize)”
Claim · model-written summary
Cd application correlated significantly with wheat grain Cd in the second year.
- Taxon
- wheatTriticum aestivume0
- Treatment
- Cd applicatione0
- Outcome
- grain Cde0
- Direction
- correlationse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“significant correlations between Cd application and wheat grain Cd were found in the second year.”
Claim · model-written summary
Wheat grain Cd reached 0.1 mg Cd kg −1 fresh weight under lime-treated high-metal sludge while soil Cd remained below EU limits.
- Taxon
- WheatTriticum aestivume0
- Treatment
- lime‐treated, high‐metal sludgee0
- Outcome
- grain Cd concentrationse0
- Direction
- reachede0
- Value
- 0.1 mg Cd kg −1 fresh weighte0
- Qualifier
- soil Cd remained below EU limitse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Wheat grain Cd concentrations reached the international trade guideline of 0.1 mg Cd kg −1 fresh weight in the plots amended with lime‐treated, high‐metal sludge even though soil Cd remained below EU limits.”
Claim · model-written summary
Third-year barley grain Cd remained largely below EU limits.
- Taxon
- barleyHordeum vulgaree0
- Outcome
- grain Cde0
- Direction
- belowe0
- Qualifier
- third yeare0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In the third year, barley grain Cd remained largely below EU limits.”
Claim · model-written summary
Sludge meeting current EU regulations caused no adverse crop effects over three years.
Verbatim
e0“In none of the 3 years were any adverse effects on crops found for sludge meeting current EU regulations.”
The same questions in other papers
lime · nutrient: content · Triticum aestivum (wheat)Positive and negative results
8 papers in the same direction as this paper · 46 in the opposite direction
- positive
- positive
- positive
51 papers more in this group
See all 55 papers →organic · nutrient: content · Triticum aestivum (wheat)Positive and negative results
9 papers in the same direction as this paper · 79 in the opposite direction
- positive
- positive
- positive
85 papers more in this group
See all 89 papers →lime · yield · Triticum aestivum (wheat)Positive and negative results
32 papers in the same direction as this paper · 140 in the opposite direction
- positive
- positive
- positive
169 papers more in this group
See all 173 papers →organic · yield · Triticum aestivum (wheat)Positive and negative results
40 papers in the same direction as this paper · 281 in the opposite direction
- positive
- positive
- positive
318 papers more in this group
See all 322 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.