Effect of soil pH on availability to crops of metals in sewage sludge-treated soils. II. Cadmium uptake by crops and implications for human dietary intake

ABSTRACTThis study aimed to evaluate the residual effect of sewage sludge fertilization on yield and nutrition of sunflower in its second cycle. The experiment was carried out from April to August 2012. The treatments consisted of four doses of sewage sludge (0, 10, 20 and 30 t ha-1, dry basis) applied in the first cycle of sunflower, distributed in a randomized block design, with six replicates. Sunflower stem diameter, plant height, capitulum diameter and yield increased with the increment in sewage sludge doses, with maximum values observed with the dose of 30 t ha-1. The contents of calcium and magnesium in the soil, pH, sum of bases, effective and potential cation exchange capacity and base saturation increased, while potential acidity and the contents of manganese and iron in the leaves decreased, with the increment in the residual doses of sewage sludge. There was a reduction in yield and growth characteristics of sunflower in the second cycle; thus, additional fertilization with sewage sludge is recommended in each new cycle.

Download Full-text

Nutrient and microbial dynamics of soils amended with sewage sludge stabilized with clay minerals and biochar; a preliminary study.

10.5194/egusphere-egu21-367 ◽

2021 ◽

Author(s):

Georgios Giannopoulos ◽

Anastasia-Garyfallia Karagianni ◽

Athanasios Balidakis ◽

Ioannis Ipsilantis ◽

Theodora Matsi

Keyword(s):

Heavy Metal ◽

Sewage Sludge ◽

Clay Minerals ◽

Soil Ph ◽

Acidic Soil ◽

Alkaline Soil ◽

Critical Levels ◽

Microbial Dynamics ◽

Air Drying ◽

Organic C

Sewage sludge production from wastewater treatment plants (WWTP) progressively exceeds 60 Million m3 p.a. in the EU. Although it is rich in organic matter (OM) and essential nutrients for crop production, sewage sludge is mainly disposed in landfills. Under the framework of Cyclic Economy and EU Green Deal, sewage sludge represents an ideal soil amendment and fertilizer with a potential to increase soil OM, provide nutrients and reduce chemical fertilization. Nonetheless, its agronomic use comes with limitations due to the presence of heavy metals and pathogenic microorganisms. Several stabilization technologies, including composting, thermal treatment and liming, aim to produce safe sewage sludge products suitable for agronomic use.This incubation study investigated the effects of municipal sewage sludge (stabilized by alternative and common methods) on nutrient and microbial dynamics in two soils; an acidic (pH 5) and an alkaline (pH 8). Stabilized sewage sludge (Thessaloniki WWTP, Greece) with clay minerals (bentonite and vermiculite), biochar (pine residues), Ca(OH)2 and air-drying, was applied at 1% and 3% dw, in soil mesocosms (300 g). Non-amended soils were also included as control. Soils were incubated (15 days; 25oC) and equilibrated with periodic wetting and air-drying. Then, chemical soil properties, heavy metal concentrations and microbial abundance were determined using standard methods.Treated sewage sludge addition in the acidic soil, noticeably increased soil pH (pH 5.2 &#8211; 8.5), compared to the control treatment (pH 5.0). In the alkaline soil, pH remained at similar levels (pH 8.1 &#8211; 8.6). Interestingly, EC increased from 0.42 up to 4.10 and 0.80 up to 3.08 dS m-1 for the acidic and alkaline soils, respectively. The C/N ratio was approx. 10 for all treatments, except biochar (C/N=16). Higher NO3-&#160;concentrations were observed for (CaOH)2, biochar and vermiculite stabilized sewage sludge treatments, and higher NH4+ concentrations were observed for air-dried, bentonite and vermiculite stabilized sewage sludge treatments, in both soils, when compared to the control. Heavy metal concentration increased in all treatments, yet, it remained below legislative critical levels. Sewage sludge amendment increased total heterotroph abundance in all treatments (5.4 &#8211; 7.5 log10 CFU g-1) compared to the control. Antibiotic resistant prokaryote abundance ranged between 3.9 &#8211; 7.0 log10 CFU g-1 and no persistent pattern was found. Pathogens remained below legislative critical levels in all treatments.Our preliminary results show that stabilized sewage sludge has the potential to be a safe soil conditioner and fertilizer under the framework of Cyclic Economy and EU Green Deal. A desirable increase in soil fertility and organic C was observed for both soils, and an advantageous pH increase for acidic soil. Though, care should be taken not to exceed EC>2 dS m-1 when amending agricultural soils with sewage sludge products. Also, further experimentation is required to understand the effects of soil amendments on plant nutrition and productivity.&#160;Funding Acknowledgement: The research work was supported by the Hellenic Foundation for Research and Innovation (H.F.R.I.) under the &#8220;First Call for H.F.R.I. Research Projects to support Faculty members and Researchers and the procurement of high-cost research equipment grant&#8221; (Project Number: HFRI-FM17-1907).

Download Full-text

AVAILABILITY OF ZINC, COPPER AND NICKEL TO PLANTS GROWN IN SEWAGE-TREATED SOILS

Canadian Journal of Soil Science ◽

10.4141/cjss78-045 ◽

1978 ◽

Vol 58 (3) ◽

pp. 381-389 ◽

Cited By ~ 21

Author(s):

A. J. MACLEAN ◽

A. J. DEKKER

Keyword(s):

Sewage Sludge ◽

Toxic Effect ◽

Soil Ph ◽

Clay Soil ◽

Pot Experiment ◽

Toxic Effects ◽

Order Of Magnitude ◽

Loam Soil ◽

Extractable Metals

In a pot experiment with additions of Zn, Cu and Ni to a loam soil (pH, 6.3) at rates up to 480 ppm, sewage sludge eliminated the toxic effect of Cu and reduced the toxic effect of Ni on corn, reduced the concentrations of Zn and Ni in the plants, and reduced the amounts of DTPA-extractable metals and of 0.01 M CaCl2-soluble Zn and Ni in the soil. Lettuce grown with the metals and sludges was more susceptible than corn to the toxic effects of the three metals in the loam soil and to Zn in a clay soil (pH 5.9). In the latter soil, Ni was less toxic to lettuce than to corn. The concentrations of metals were considerably higher in lettuce than in corn. Liming of the clay soil to a pH of 6.5 eliminated the toxic effect of Ni on corn and of Zn and Ni on lettuce and reduced the concentrations of the metals in the plants and the amounts of DTPA-extractable and CaCl2-soluble metals in the soil. The order of magnitude of the DTPA-extractable metals was Cu > Zn > Ni whereas the order for CaCl2-soluble metals was Ni > Zn> Cu. Variability in the effect of the metals between crops and soils precluded the use, except as a preliminary guide, of a Zn equivalent concept based on the assumption that Cu is twice as toxic and Ni is eight times as toxic as Zn.

Download Full-text

The effect of biosolids on cereals in central New South Wales, Australia. 1. Crop growth and yield

Australian Journal of Experimental Agriculture ◽

10.1071/ea03099 ◽

2005 ◽

Vol 45 (4) ◽

pp. 435 ◽

Cited By ~ 10

Author(s):

J. L. Cooper

Keyword(s):

Sewage Sludge ◽

Soil Ph ◽

New South ◽

New South Wales ◽

Acid Soils ◽

Crop Growth ◽

Growth And Yield ◽

South Wales ◽

Sludge Cake ◽

Dewatered Sewage Sludge

Two forms of biosolids, with and without lime, were applied to acid soils at 2 sites in central New South Wales. Wheat and triticale were then grown on these sites to determine the effect of biosolids on crop growth and yield. The forms of biosolids used were dewatered sewage sludge cake, and N-Viro Soil which is a lime amended sewage sludge. Dewatered sewage sludge cake was applied at rates of 0, 6, 12 and 24 dry Mg/ha, and N-Viro soil at 0, 1.5, 3.0 and 4.5 dry Mg/ha. Biosolids produced grain yield increases of over 50% at both sites, with the largest yield increases at the highest rate of dewatered sewage sludge. Continued cropping at 1 of the sites showed that significant yield increases were still obtained 3 years after the initial application. The addition of lime and N-Viro Soil raised soil pH, and produced small but long lasting yield increases. However, the main benefit of biosolids seems to have come from the nutrients they supplied rather than changes in soil pH.

Download Full-text

Impact of organic and mineral fertilising on aluminium mobility and extractability in two temperate Cambisols

Plant Soil and Environment ◽

10.17221/587/2019-pse ◽

2019 ◽

Vol 65 (No. 12) ◽

pp. 581-587 ◽

Cited By ~ 1

Author(s):

Jiří Balík ◽

Martin Kulhánek ◽

Jindřich Černý ◽

Ondřej Sedlář ◽

Pavel Suran

Keyword(s):

Sewage Sludge ◽

Soil Ph ◽

Farmyard Manure ◽

Close Correlation ◽

Control Treatment ◽

Aluminium Content ◽

Mobile Forms ◽

Exchangeable Al ◽

Positive Correlations

Different fertilisation systems cause changes in the content of mobile aluminium (Al) forms in the soil as a result of soil pH changes. Long-term stationary fertilisation experiments established in 1996 at 2 sites were evaluated. Experiments consisted of unfertilised control treatment and 6 other treatments, combining mineral fertilisation with the application of farmyard manure, sewage sludge and straw. To record the changes in mobile Al forms, we used 5 extraction procedures with agents: water, CaCl2, KCl, CaCl2/DTPA (CAT) and Mehlich 3 solutions. At treatment nitrogen (N) + straw, topsoil acidification was observed, resulting in the increased content of mobile Al. At treatments with mineral fertilisation (N, NPK), increased content of mobile forms of Al was recorded. Application of cattle manure and sewage sludge helped to stabilise the soil pH and reduce mobile Al forms. The close correlation between the methods determining the exchangeable Al (CaCl2 and KCl solutions) was observed; however, KCl extraction was more favourable in soils of low Al extractability, as the amount of extracted Al was 3–4 times higher. Positive correlations were determined between Al extracted by Mehlich 3 solution and the content of exchangeable Al. The less frequently used CAT method also turned out to be perspective for mobile Al determination. Furthermore, aluminium content determined in Mehlich 3 extract was compared with mobile phosphorus amounts in H2O, CAT and Mehlich 3, respectively. All three investigated phosphorus forms showed significantly negative correlations with Al.

Download Full-text