Effects Of Sewage Sludge Application Research Articles

Effects of surface and mixed application of sewage sludge on Neolamarckia cadamba root growth

The utilization of sewage sludge in forests is an important way of recycling. However, the effect of sewage sludge application on woody plant root growth has been rarely reported. The effects of surface application and mixed application of sewage sludge (mass ratio in 10%) on the dynamics in root morphology of a fast-growing tree species (Neolamarckia cadamba), soil pH, electric conductivity, and heavy metal content of roots in different soil layers were analyzed by a rhizobox experiment. The relationship between root length and soil pH value, electric conducti-vity, and root heavy metal content were further analyzed. Results showed that mixed application of sewage sludge inhibited root length, root surface area, and root volume. After 120 and 240 days of mixed application, total root length in the 0-20 cm soil layer was 76.9% and 67.4% of that of no sewage sludge application, respectively. Surface application of sewage sludge did not affect root length and root surface area but increased root volume. The mixed application of sewage sludge significantly increased soil pH, electric conductivity, and root heavy metal content. Root Cd contents in 0-20 cm and 20-40 cm soil layers with the mixed application of sewage sludge were 11.5 and 10.0 times as that of no sewage sludge application, respectively. Soil electric conductivity had a significant nega-tive correlation with root length in 0-20 cm soil layer among different treatments. Root Cd content had a significant negative correlation with root length in both the surface and the mixed applications of sewage sludge. These results indicated that mixed application of sewage sludge could inhibit N. cadamba root growth mainly by increasing soil electric conductivity and root Cd content, while the surface application of sewage sludge did not affect root growth.

Plant uptake potential and soil persistence of volatile methylsiloxanes in sewage sludge amended soils

Volatile methylsiloxanes (VMSs) are organosilicon compounds, ubiquitous in modern life. Due to their high use in consumer products, large amounts of these compounds are released into sewer systems, reaching wastewater treatment plants (WWTPs). Its frequent detection in sewage sludge can be of concern when considering its land application, not only due to potential negative impacts on the environment, but also on human health. In this work, the effects of sewage sludge application on plant development and crop productivity were studied, as well as VMSs persistence in the soil and their plant uptake. This study focused on 7 VMSs (D3, D4, D5, D6, L3, L4 and L5) and consisted of a 12-week greenhouse pot experiment, where sewage sludge-amended soils were used to cultivate Pisum sativum (peas). Sewage sludge application to soils had no negative effects on plant development and was tied to crop productivity improvements. Most of the VMSs were still present in soils at the end of the experiment and plant uptake and translocation of the 4 cyclic VMSs (D3, D4, D5, D6) occurred. VMSs were detected in plant tissues up to 161 ± 27 ng g−1 dw (samples of stems, leaves and tendrils), but did not exceed 50 ± 19 ng g−1 dw in peas, which did not translate into a human exposure risk due to ingestion, according to an intake risk assessment. However, soil risk assessments showed that for L5 the hazardous ratios were higher than the threshold value of 1. This means a potential environmental risk despite the low levels of this compound in soils (up to 7.3 ± 0.7 ng g−1 dw). Considering these results, sewage sludge monitoring plans should be defined for VMSs, namely when its final destination is land application, thus allowing a safer management of this residue, taking advantage of its valorization potential.

Effects of Sewage Sludge Application on Plant Growth and Soil Characteristics at a Pinus sylvestris var. mongolica Plantation in Horqin Sandy Land

The application of domestic sewage sludge (SS) may affect plant growth and soil quality through altering nutrient availability. However, the effect of SS application on the plant–soil system in sandy soils is poorly understood. In this study, we established SS application treatment plots (SL, 25 t ha−1) and control treatment plots without sewage sludge application (CK, 0 t ha−1). SS was applied to the soil surface of a Mongolian pine (Pinus sylvestris var. mongolica) plantation in Horqin Sandy Land, Inner Mongolia, China, to assess its potential effects on plants and soil. We analyzed tree growth performances (tree height, basal diameter, and diameter at breast height), understory traits (species diversity, coverage, and aboveground biomass), soil physical and chemical parameters (nutrient content, dissolved organic carbon, soil water content, bulk density, pH), and proxies of ecosystem services (soil organic carbon and total nitrogen stocks). The results showed that SS addition not only significantly increased soil nutrient contents, but also markedly enhanced aboveground productivity and plant coverage. Specifically, SS addition decreased soil bulk density and increased concentrations of soil organic carbon, total nitrogen, and total phosphorus and mineral nitrogen, and it also increased soil carbon and nitrogen stocks. Furthermore, the addition of SS significantly increased soil dissolved organic carbon contents and enhanced the fluorescence intensities of dissolved organic carbon components (humic acid-like and UV fulvic acid-like) in the topsoil (0–5 cm). This study provides evidence that SS is an acceptable, and possibly preferred organic fertilizer for improving the soil quality and tree–grass growth of Mongolian pine plantations.

PH and salinity are the dominant limiting factors for the application of mariculture sludge to paddy soil

With the rapid development of mariculture industry, the disposal of mariculture sludge (MS) has become a serious environmental problem. Despite MS containing abundant organic matter, there may be some risks following MS application in agricultural practice. Many studies focus on the effects of sewage sludge application on crops. The potential of MS application on the microbial ecosystem and the above ground rice growth has not been systematically analyzed. We used 16S rDNA high-throughput sequencing to investigate the effects of MS application on soil microbial community and the rice growth. Soil samples were collected during rice growth under a pot experiment comprised of three treatments: without sludge (CK), native soil: sludge = 20:1 (LS) and native soil: sludge = 10:1 (HS). Application of MS enhanced soil nutrient content, but a high level of soil pH and salinity remained in the initial phase. Soil microbial biomass and extracellular enzyme activity were inhibited. The microbial diversity was decreased, including Chao1, Richness and Shannon index. Moreover, the specific bacterial taxa (Rhodobacteraceae, Flavobacteriaceae and Synergistales) were enhanced. The relative abundance of bacterial genes related to process of nitrification and denitrification were reduced, while the relative abundance of genes involved in N-fixation were increased. Partial Least Squares Path Modeling (PLS-PM) showed that soil pH and salinity were the dominant limiting factors during rice growth by indirectly affecting bacterial diversity. These findings strengthen the understanding of direct application of mariculture sludge in agriculture and provide a theoretical basis for resourceful utilizations of mariculture sludge.

Stakeholders' Perspectives on Microplastics in Sludge Applied to Agricultural Land

Microplastic (MPs) inputs to agricultural lands from wastewater and sewage sludge reuse in Europe have been estimated to be between 65,000 and 230,000 tons/year making the farm environment one of the major receptors and, possibly, environmental reservoirs of MPs. In Sweden there have been ongoing discussions since 1994 about environmental and health effects of sewage sludge application to agricultural lands. This debate on sludge use focused initially on metals, then moved on to pharmaceutical residues and currently has turned to MPs. In spite of the limited scientific information about environmental impacts of MPs in soils, governmental approval in Sweden to allow increased spreading of sludge on productive agricultural lands is moving forward. To study individual perceptions of the potential risks, interviews were conducted in 2020 with Swedish stakeholders who in some way work with the issue of sludge management. The results of these interviews provide an indication of not only how environmental risk information is interpreted by representatives from different sectors but also the degree to which perceived risks may shape environmental policy.

Cumulative effect of sewage sludge application on soil adsorption complex and nutrient balance: a field study in semi-arid region (Oued Souhil, Tunisia)

Cumulative effect of sewage sludge application on soil adsorption complex and nutrient balance: a field study in semi-arid region (Oued Souhil, Tunisia)

Application of Sewage Sludge and Its Impact on Soil Characteristics, Including Morphological and Biochemical Properties of Vigna radiata Plant

This experiment was conducted in pots to study the effects of sewage sludge application on some morphological, physiological and accumulation characters of Vigna radiata. The experiment contained the following treatments: control (C) 0 gm sludge/30 kg soil, (T1) 300 gm sludge/30 kg soil, (T2) 600 gm sludge/30 kg soil and (T3) 900 gm sludge/30 kg soil. All sludge treatments showed a significant increase in all morphological, physiological and accumulation characters compared with control. (T2 ) treatment gave a significant increase as compared to other treatments in all morphological characters (height of the plant, leaf area, and total dry weight for shoots and roots). It increased by 34.1 cm, 33.1 cm2, 29.8 gm and 3.3 gm, respectively, compared with the control. T2 treatment also gave significant values in all physiological characters (chlorophyll and protein content) as compared to other treatments and the control treatment, (2.60 μg/gm and 17.7%) respectively compared with the control. T3 treatment showed a higher accumulation of Cd and Pb in all plant parts, the root system showed greater susceptibility to bioaccumulation than the shoot system for both the heavy metals.

INFLUÊNCIA DO LODO DE ESGOTO, COMO SUBSTRATO, NA RECUPERAÇÃO DE UMA COMUNIDADE VEGETAL DO SEMIÁRIDO

In the northeastern semiarid, environmental degradation, combined with climatic and socioeconomic factors, can cause loss of soil quality and biological diversity, requiring application of techniques that recover and offer benefits to it, providing a nutritional support for the introduced species. This work has assessed the effects of sewage sludge application as fertilizer on the horizontal and vertical structures of a plant community in the seasonally dry tropical forest (caatinga) in the process of recovery. The research took place in the campus of Instituto Federal do Ceara in the city of Quixada. Three treatments with three repetitions each were applied: raw sludge, sanitized sludge and unmanipulated treatment. There were nine plots containing 20 seedlings each, making a total of 180 seedlings. They were all tagged, and planted away from each other according to specific lengths using the nucleation technique. They also had their ground-level diameter and height measured throughout seven months. As far as the vertical structure is concerned, sanitized sludge was responsible for producing better results in terms of minimum height, average height and height growth rate. In regard to maximum height, there was a difference between sanitized sludge and unmanipulated treatment, but there was no difference between raw sludge and other treatments. After seven months, sanitized sludge produced more individuals with great height, differing from the other two treatments. When the horizontal structure is taken into consideration, minimum and maximum diameters did not increase as a consequence of sludge use; however, differences in average diameter, diameter growth rate and basal area could be noticed from sanitized sludge manipulation. After six months, sanitized sludge produced increased diameters and thicker individuals. Thus, it was observed that the use of sanitized sludge can be a good tool for obtaining quick soil cover in surroundings under recovery.

Effect of sewage sludge application on growth and photosynthetic pigments in vetiver grass (<em>Vetiveria zizanioides</em> L. Nash)

The study was conducted to evaluate the effect of sewage sludge application on growth and photosynthetic pigments in vetiver grass. Vetiver plants were grown in poly-ethylene U-V stabilized grow bags (24 X 24 X 40) for a period of three months (90 days), where the soil treated with different sewage sludge concentrations (0, 25, 50 and 75%). Physico-chemical characterization of sewage sludge showed that it was slightly acidic with significant concentrations of heavy metals (Cd, Cr, Cu, Pb and Zn), nutrients and mineral ions. Results showed that there were no apparent symptoms of toxicity on the morphology (leaf color, plant height and number of leaves) of the sludge amended vetiver plants. It has been observed that 25% sludge concentration has a favorable effect on the growth and photosynthetic pigments of plants. But at 50 and 75% sludge concentration, photosynthetic pigments such as chlorophylls and Pheophytin content showed a gradual decline with increase in sludge concentration while the carotenoid content was increased gradually. Even though compared to control plants sludge amendment increased the total wet biomass production in all the experimental plants with a gradual increase with increase in sludge concentration. This study proves that use of sewage sludge as an amendment will improve the growth and biomass production in vetiver plants up to 25% of the total soil. But even at this concentration carotenoid content was high and it may be due to defense mechanisms induced in response to heavy metal stress. The study, therefore, suggests that even though the sewage sludge is highly enriched with various nutrients, considering the heavy metal content, the fertilizer application of sewage sludge is dangerous, because the risk of environmental contamination is very high. The study pointed out that the vetiver plants growing in sludge amended area have potentially developed the defense strategy to combat against heavy metal toxicity. Therefore, the highly tolerant vetiver plants (Vetiveria zizanioides, L. Nash) may be used for phytoremediation purposes.

Effect of Sewage Sludge on Heavy Metals Accumulation in Soil and Wheat, Mung Bean and Quinoa Crops

This study was conducted to study the effects of sewage sludge application to agricultural soil on the heavy metal accumulation in soil and plant and on availability of certain nutrients for plant together with the productivity of wheat, mung bean, and quinoa. The experiment were included four treatments i.e., (Control; inorganic fertilizer according to Ministry of Agriculture-Iraq.; sludge (the amount of sludge containing MoAR recommendation) of N without any addition of mineral N; and twice the amount of sludge without any addition of mineral N) with four replications in the feed crop studies station of the Ministry of Agriculture - Haditha agriculture division located in the village of Sakran (Hasweh Al-Jazeera) of Haditha district 260 km west of Baghdad during the seasons 2017-2018.2019. The applied sludge was described and soil was analyzed prior to cultivation. Upon harvesting, the heavy metals (Cd, Pb, Ni and Cr) were estimated in soil and plant in addition to certain nutrients (Total N, mineral N, available P, macronutrients) and organic matter. About heavy metal in soil and plant, significant buildup of the heavy metal in soil and plant was noticed by increasing the addition of sludge as compared to the control. Significant increase in organic matter and total N of soil in sludge-fertilized treatment was noticed as compared to the control. Moreover, a significant increase in mineral N, available P, Cu, Mn and Zn was also noticed by increasing the addition of sludge. There was significant increasing in plant productivity for various crops during the seasons by increasing the addition of sludge as compared to the control.

Efficiency of ethanol and hexane extraction of sunflower oil from seeds of plants inoculated with Azospirillum brasilense and fertilized with sewage sludge

Helianthus annuuss L. is an annual oilseed crop that grows well in various types of soil. Sunflower oil can be used for several purposes, including human consumption, biodiesel production, and as an ingredient in cosmetics, pharmaceuticals, and veterinary products. Sewage sludge application can provide essential nutrients for plant development. This study aimed to determine the efficiency of ethanol and hexane in extracting sunflower oil and assess the effects of sewage sludge application and inoculation with Azospirillum brasilense on sunflower oil yield. Sunflower oil was obtained from dried ground seeds by Soxhlet extraction. Thrity-eigth samples were used and the experiment was carried out in a completely randomized block design. Each treatment had four repetitions. The following doses were applied: 0 (control); 5,000; 10,000; 20,000; and 40,000 kg/ha sewage sludge. Seeds were either inoculated (150 mL per 50 kg of seed) or not. Hexane and ethanol did not differ in extraction efficiency. The seeds inoculated with the bacteria and the presence of sewage sludge showed a higher yield, being 42% with higher doses of sewage sludge. The results show that ethanol, an environmentally friendly and sustainable solvent, is as efficient in extracting sunflower oil as hexane. Sludge fertilization and inoculation of sunflower with A. brasilense improve oil yield, probably by enhancing nitrogen fixation and uptake. The results show that ethanol, an environmentally friendly and sustainable solvent, is as efficient in extracting sunflower oil as hexane. Sludge fertilization and inoculation of sunflower with A. brasilense improve oil yield, probably by enhancing nitrogen fixation and uptake.

Effect of sewage sludge application on heavy metals contamination in soil and carrot

One of the many environmental problems in the modern world is the disposal of production and consumption waste, including sewage sludge. The aim of our research was to study the content and accumulation of heavy metals in soil and carrots when using increasing doses of sewage sludge as fertilizer and its effect on the yield of products. Sewage sludge with a moisture content of 44.5% was introduced into gray forest soils. After fertilizing the soil, agrochemical analyzes of soil samples from the plots of the experimental plot for the content of heavy metals were carried out. We also studied the content of heavy metals in carrot biomass and its yield. It was found that the content of heavy metals in various variants of experiments with the use of sewage sludge increased. It was found that the dynamics of migration of heavy metals into the biomass of carrots correlates with an increase in their concentration in the soil and affects the yield of carrots.

Sewage sludge application alters the composition and co-occurrence pattern of the soil bacterial community in southern China forestlands

Application of sewage sludge to forested land has been regarded as a promising method for sewage sludge disposal, because it can improve soil fertility and productivity. It is also likely to alter the soil nutrient cycle, which is mainly mediated by soil microorganisms. However, how the soil bacterial community responds to the application of sewage sludge in subtropical planted forests is poorly understood. Unlike farmland soil, forestland soil is covered with leaf litter, which might influence the effects of sewage sludge on the soil bacterial community. In this study, we investigated the effects of sewage sludge application (30 t/ha) on the soil bacterial community at 0–10 cm depth in three forest plantations (Eucalyptus urophylla, Pinus elliottii, and Schima superba) in southern China. The treatments included sewage sludge addition (treatment S), sewage sludge addition and leaf litter removal (treatment SLR), and a control (CK). The composition of the soil bacterial community differed in the three forest plantations and was affected by treatment S, but the effects of treatment S were not greatly altered by litter removal in the three forest plantations. At the community level, the composition of the soil bacterial community was significantly related to soil pH, available phosphorus (P) and potassium (K), and cadmium (Cd). At the phylum level, the relative abundance of Actinobacteria, Bacteroidetes, and Chloroflexi was increased by treatments S and SLR, while that of Acidobacteria, Proteobacteria, and Verrucomicrobia was decreased. The changes in the abundance of these bacteria were significantly related to the increase in the contents of available nutrients and heavy metals. Sewage sludge application resulted in an increased number of positive interactions among bacterial taxa, lower modularity, and higher connectivity, which indicated an unstable bacterial community. Changes in the composition, co-occurrence pattern, and keystone taxa of the bacterial community might reflect adaptation to sewage sludge application.

Impacts of Using Mineral Fertilization Combined with Sewage Sludge in the Amendment of Luvisol on Oat Crop. II. Influence on Metal Accumulation

The objective of the present paper was to investigate the effects of sewage sludge application on metals (Cu, Mn, Zn, Cd, Co, Pb) accumulation in oat (Avena sativa L.) grains, Somesan variety. It were used various doses of sewage sludge corresponding to equivalent doses of 0-600 kg N/ha associated or not with NPK mineral fertilization. The results evidenced that copper and zinc levels in oat grains increased significant with sewage sludge fertilization starting with a dose equivalent with 200 kg N/ha. Mineral fertilization led to significant decrease of copper content in comparison with sewage sludge treatments only. For manganese, fertilization with sewage sludge has produced a significant decrease, this trend being accentuated up to the equivalent dose of 300 kg N/ha. For cadmium, application of sewage sludge in an equivalent dose of 200 kg N/ha led to concentrations in oat grains higher than 1 mg Cd/kg (imposed limit for grains used for animal feed). This behavior is a consequence of high cadmium content of sewage sludge (of 7.2 times over maximum admitted limit). Cobalt contents of oat grains increased with sewage sludge doses, but the levels are between normal values and concordant with literature data. Application of sewage sludge in an equivalent doses of 500 and 600 kg N/ha generated a significant increase of lead content in oat grains, average values being 1.87 and 2.17 mg Pb/kg, respectively.

The Effects of Sewage Sludge Applications on Growth, Yield and Flower Quality of Limonium sinuatum (Statice) under Salinity Conditions

In this study conducted in greenhouse conditions, the effects of sewage sludge application on plant growth, yield and flower quality of Limonium sinuatum (Statice) under salinity conditions were investigated. For this purpose, application of 25%, 50% and 75% sewage sludge doses and 50 mM and 100 mM salt treatment was preferred. Research was conducted as 3 replicates and according to two factor random plots experimental design and in such a way as to have 5 plants in each plot. During in the study, the number of the leaves, the number of flowers harvested per plant, flower peduncle length and thickness were determined. At the end of this study, the root length, the fresh and dry weight of upper parts of plant, the root fresh and dry weight were examined. As expected, while salt application negatively affected the vegetative growth parameters of the plant, yield and flower quality, the increasing sewage sludge doses affected all parameters examined during the research positively. In light of the findings of the current research, it has been determined that in the salty conditions the increasing sewage sludge application doses affected plant growth, yield and flower quality positively by removing the negative effect of salt.

Agricultural use of sewage sludge under sub-humid Mediterranean conditions: effect on growth, yield, and metal content of a forage plant

A field experiment was carried out in order to investigate the effects of sewage sludge application on the growth and yield components of triticale (X Triticosecale Wittmack). Five treatments were compared: a control (C) without application of sludge or nitrogen fertilization; a mineral fertilization treatment (MF) applied as ammonium nitrate; and three sewage sludge treatments (SS), 6, 12, and 18 t ha−1, applied 15 days prior to triticale sowing. The main results showed that SS application improved plant growth by increasing leaf area index, tillering capacity, accumulated aboveground dry matter, and plant height of triticale. As a result, 18 t ha−1 of SS could be recommended the suitable dose for triticale, where dry matter production was more than twofold above the control value. No toxic effects arising from the heavy metals in triticale plants were observed. The Cu concentration was the only trace element that increased in the straw tissues with sludge application, although the values recorded were below critical environmental thresholds. Furthermore, growth and yield responses of triticale to all SS rates are comparable even sometimes more important than those for mineral fertilizer.

Effects of sewage sludge application on unfertile tropical soils evaluated by multiple approaches: A field experiment in a commercial Eucalyptus plantation

Sewage sludge (SS) reuse in forest plantation as soil fertilizer/amendment has tremendously increased in recent years. However, SS may have high concentrations of potentially toxic elements (PTE), representing a potential risk for soil and the whole ecosystem. This paper was aimed to assess the toxicity of PTE in unfertile tropical soils amended with SS in a commercial Eucalyptus plantation, with an integrated multiple approaches combining: i) the use of a battery of bioassays (Daphnia magna, Pseudokcrichirella subcapitata, Lactuca sativa, and Allium cepa); and ii) the evaluation of some PTE (Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) and their availability into the pedoenvironment. Differences in total and available PTE between SS doses and time of treatments were evaluated using ANOVA; correlations between PTE and bioassays by a sparse partial robust M-regression (SPRM), while multiple correlations among parameters were performed by principal factor analysis (PFA). Results show that PTE contents in soils tended to increase with SS application doses. However this cannot be assumed as a general rule since in all the investigated treatments the PTE concentrations were consistently below both soil natural background concentrations and quality reference values. Bioassays showed a generalized low eco- and genotoxicity of SS with an increase in toxicity at increasing SS doses but with a clear decreasing trend as time went by. A. cepa was the most sensitive bioassay followed by P. subcapitata > D. magna > L. sativa. Overall, the results indicate that in realistic open field conditions SS risk may be lower than expected due to dynamic decrease in PTE toxicity with time after application. This study has an important implication that open-field trials should be strongly encouraged for evaluating environmental risk of SS application in forestry.

Influence of sewage sludge, as a substrate, in the plasticity of functional characteristics of plants.

This work aimed to evaluate the effect of sewage sludge application as fertilizer on the plasticity of functional characteristics of species commonly found in the Caatinga. The research was developed in the nursery of the Federal Institute of Education, Science and Technology of Ceará (IFCE), Quixadá campus, located in northeastern Brazil. Three treatments were applied: raw sludge, sanitized sludge, and no manipulation. In each treatment, five species were planted, each with five individuals, totaling 75 individuals, which were tagged, and 4months after germination, they were destroyed to obtain dry matter content (TMSF) from leaf, stem (TMSC), fine root (TMSRF), and thick root (TMSRG); leaf area; height and diameter of the seedling; and length above and below the ground. The sanitized sludge was responsible for giving higher values for leaf area, height of the seedlings, and diameter and length of stem and root. However, the dry matter content of the fine roots was higher in the treatment without manipulation. At the community level, as TMSRG increased, TMSC also increased, the same occurred between TMSRG and TMSRF, TMSC and TMSRF, and stem length and leaf area. In the treatment without manipulation, there was a positive correlation between leaf area, height and plant diameter, and negative correlation between root length and plant diameter. Thus, it can be concluded that the use of sanitized sludge is a good tool to increase the availability of soil resources, conferring to individuals' greater dry matter content, greater leaf area, and higher height and diameter above the ground.

Modification of properties of energy crops under Polish condition as an effect of sewage sludge application onto degraded soil

Energy crops are one of the possible solutions for reclamation of degraded or contaminated terrain. Their cultivation requires adequate fertilization typically containing high content of organic matter, nitrogen and phosphorous. While sewage sludge may be one source of these necessary nutrients, it may also modify some plant biomass properties, such as total carbon content. In our study, we determined whether sewage sludge (containing different value of heavy metals) could be an effective fertilizer to obtain good quality energy crops (such as Miscanthus x gigantheus and reed canary grass, Phalaris arundinacea) and simultaneously play positive role for improvement of phytoremediation. The 3-year experiment was performed on degraded soil from terrain of steel mill of Czestochowa (Silesian region, Poland). During the study, it was confirmed that sewage sludge (also in combination with urea, CH4N2O) influences the mobility of Pb, Zn, Cd in soil solution, however the intensity of the process can be limited by plant species and time. Both miscanthus, and reed canary grass were characterized by the low value of bioconcentration factor (BCF), but because biomass was high, the total concentration of heavy metals in crops was comparable with hyperaccumulators. Additionally, modification of the fertilization affected energetic parameters, such as the content of carbon, S/Cl ratio, unitary CO2 emission. However, this effect was not statistically significant.

Sewage sludge as a soil amendment in a Larix decidua plantation: Effects on tree growth and floristic diversity

Sewage sludge application in forest plantations is an interesting complementary alternative practice to sewage sludge reutilization and recycling, with a significant and sustainable net effect in climate change mitigation. However, to optimize it a detailed knowledge of its effects on ecosystem components such as plants, soil, water and fauna is needed. We investigated the effects of sewage sludge application on soil, tree growth and floristic diversity in a ten-year-old plantation of European larch (Larix decidua Mill.). Our one-hectare study site, located at Mélisey, Haute-Saône, France (47°753′ Lat., 6°580′ Long.), was subdivided into six plots. Three plots, alternating with three control plots (no sewage sludge application), were amended in June 2008 with 0.4tDWha−1 obtained from a municipal urban wastewater treatment plant in Mélisey. Within each plot, one subplot was delimited and sludge was again manually applied at 3t of DWha−1 in July 2009 and March 2010 to the soil surface of the amended subplots without incorporation. The results showed no effect on radial and height growth of European larch amended with 0.4tDWha−1. While a significant temporary increase in pH, macro-element contents (N, P and Ca) and the trace metal (Cu and Zn) concentration in the soil was observed, it had no significant effect on needles and sporocarp contents. The number of species in the amended subplots with 3tDWha−1year−1 increased by 80% compared to the control. However, the relative species abundance present only in amended subplots remains <1, except for Hypericum humifusum.