Unlocking fertilization potential of anaerobically digested sewage sludge centrate for protein-rich rice cultivation with composted sludge amendment.

The use of composted sewage sludge (CSS) and centrate as alternatives to synthetic fertilizers in rice cultivation holds great promise. This study aims to determine the effects of varying doses and timings of centrate derived from anaerobically digested sewage sludge on rice yield, nutrient quality, and soil fertility when applied as a topdressing to rice fields fertilized with CSS. At the panicle initiation (PI) stage, 100, 300, and 500 kg N ha-1 of centrate topdressing (CT100, CT300, and CT500, respectively) was applied. In addition, different topdressing timings at a total dose of 500 kg N ha-1 were evaluated, including a two-split application (40% at active tillering (AT) and 60% at PI; CT500S2) and a three-split application (40% at AT + 40% at PI + 20% at heading; CT500S3). At a rate of 160 kg N ha-1, CSS was used as a base fertilizer in all treatments. A control treatment received synthetic fertilizers at a rate of 160 kg N ha-1 as a base application and 100 kg N ha-1 as a topdressing. Results showed that CSS-treated rice plants exhibited a lower N status and leaf chlorophyll content during the vegetative growth stage; however, the split application of centrate topdressing improved plant N status, resulting in an increase in biomass and grain yield. Centrate and CSS tended to increase the mineral content of rice; nevertheless, a significant accumulation of As in grains raised concerns about food safety. Combining CSS and centrate has the potential to increase rice production, improve grain nutritional value, and decrease reliance on synthetic fertilizers. However, it is essential to optimize this fertilization, mitigate environmental risks, and ensure food safety by employing appropriate fertilization dosing and timing as well as appropriate field management strategies.

Effects of CuO nanoparticles in composted sewage sludge on rice-soil systems and their potential human health risks.

The release of metal-based nanoparticles (MNPs) into sewage systems is worrisome due to their potential impact on crop-soil systems that are amended with sewage sludge. This study aimed to investigate the effects of copper oxide nanoparticles (CuO NPs) in composted sewage sludge (CSS) on rice-soil systems and to assess the health risks associated with consuming CuO NP-contaminated rice produced by CSS amendment. CSS was treated with three doses of CuO NPs, resulting in Cu levels below the sludge limits (1500 mg Cu kg-1) for reuse as a soil amendment. Results showed that CuO NPs in CSS at environmentally acceptable levels had no negative effect on rice growth and yield. In fact, they enhanced biomass production, tillering capacity, and soil fertility by increasing N and K levels in the soil. In addition, CuO NPs in CSS (450-1450 mg Cu kg-1) promoted the accumulation of macro- and micro-minerals in rice grains, thereby improving the nutritional value of rice. However, Cu contamination in CSS led to elevated levels of toxic metals, especially As, in rice grains, posing potential health risks to both adults and children. In the presence of higher CuO NPs contamination in CSS, the hazard quotient of As exceeded one, indicating an increased risks of toxic metal exposure via rice consumption. This study raises concerns about potential long-term threats to human health posed by MNPs contamination in CSS and highlights the need to reevaluate the permissible limits of hazardous elements in sludge to ensure its safe reuse in agriculture.

Environmental risks of organic fertilizer with increased heavy metals (Cu and Zn) to aquatic ecosystems adjacent to farmland in the northern biosphere of Japan.

In Abashiri, Hokkaido, northern Japan, composted sewage sludge (CSS) containing a large amount of zinc (Zn) and copper (Cu) is used as fertilizer in agriculture. The local environmental risks of Cu and Zn from such organic fertilizers were studied. The study area, especially the brackish lakes located near the farmlands, is important for inland fisheries. The risks posed by heavy metals to the brackish-water bivalve, Corbicula japonica, was therefore investigated as an example. First, the long-term effect of CSS application in agricultural fields was monitored. Second, using pot cultivation, factors influencing Cu and Zn availability in the presence of organic fertilizers were evaluated under different scenarios of SOM content. In addition, the mobility and availability of Cu and Zn in organic fertilizers were evaluated in a field experiment. In the pot cultivation, both organic and chemical fertilizers increased the availability of Cu and Zn with a decrease in pH, possibly caused by nitrification. However, this decrease in pH was inhibited by higher SOM content, i.e. SOM mitigated the heavy metal risk from organic fertilizer. In the field experiment, potato (Solanum tuberosum L.) was cultivated using CSS and pig manure (PM). As observed in the pot cultivation, the applied chemical and organic fertilizers increased the soil-soluble and 0.1 N HCl-extractable Zn with increased nitrate. Considering the habitat and the LC50 values of C. japonica that were lower than the concentration of Cu and Zn in the soil solution phase, there is no significant risk from heavy metals in the organic fertilizers. However, the Kd values for Zn were significantly lower for CSS or the PM-applied plot in the field experiment soil, indicating a higher Zn desorption rate from organically fertilized soil particles. The potential risk of heavy metals from agricultural lands under changing climate conditions must therefore be monitored carefully.

Absorption, accumulation and distribution of metals and nutrient elements in poplars planted in land amended with composted sewage sludge: A field trial.

Interest in the application of sewage sludge as amendments to grow trees has continued to increase, especially for fast-growing trees such as poplars. In this study, two-year field trial was conducted to determine the effects of compost sewage sludge (CSS) soil application on the distributions of metal and nutrient elements in poplars (Populus × euramericana 'Guariento') and poplar growth. Soil was amended with one of four CSS treatments in both study years: control (2012, 2013: 0 t/ha), SS1 (2012: 7.5 t/ha, 2013: 15 t/ha), SS2 (2012: 15 t/ha, 2013: 30 t/ha), and SS3 (2012: 30 t/ha, 2013: 45 t/ha). During the two-year field trial period, CSS treatments significantly affected leaf K, Mg, Ni, Cr, and Pb contents and root P contents. The element contents in different plant parts responded differently to the different CSS application rates; microelement contents in roots and trace element contents in leaves were significantly affected by the high sludge treatment. The CSS application significantly influenced Ca, Na, Cu, Ni, and Pb accumulation in aerial parts of poplar and the distributions of N, S, Ni, Mg, and P between roots and leaves or stems, and significantly increased the diameter at breast height (DBH) of poplars by 2.4-18.6%. The CSS application of 15 t/ha per year resulted in the largest average increase in DBH of 11.1%; therefore, it could be considered as the most suitable application rate. In summary, CSS application can improve nutrition uptake in various parts of poplars and promote the growth of poplar. Poplar forest amendment is a good CSS disposal strategy.

Degradation of Triclosan and Carbamazepine in Two Agricultural and Garden Soils with Different Textures Amended with Composted Sewage Sludge.

Composted sewage sludge (CSS) has been extensively used in agriculture and landscaping, offering a practical solution for waste disposal. However, some pharmaceutical and personal care products (PPCPs) like triclosan (TCS) and carbamazepine (CBZ) have restricted its land application. In this study, CSS was added to agricultural soil and garden soil at 0%, 5%, 10%, and 25% (w/w soil), and 4 mL of TCS and CBZ stock solution (1000 mg/L in methanol) was spiked into soil amended with CSS of each bottle to arrive at the concentration of 10 mg/kg. Samples were then collected after incubation for 120 days and analyzed for concentrations and half-life (t1/2) of TCS and CBZ, and soil physicochemical properties, together with enzyme activities. The results showed that TCS was degraded completely during the incubation period. In contrast, only about 5.82⁻21.43% CBZ was degraded. CSS amendment inhibited TCS and CBZ degradation and prolonged t1/2 compared to the control, and the t1/2 of TCS and CBZ increased with CSS addition amount in all treatments except for CBZ in the garden soil amended with 10% CSS. Correlation studies showed a significantly positive relationship between t1/2 of TCS and CBZ and total organic carbon (TOC), while a significantly negative relationship between t1/2 of the two PPCPs and pH was observed. Alkaline phosphatase showed a significantly negative relationship with the Ct/C0 of TCS in garden soil amended with 25% CSS and CBZ in the control. The urease activity was negatively correlated with the Ct/C0 of TCS in 10% and 25% CSS treatments and CBZ in 10% CSS treatment for garden soil.

Determination of heavy metals and their availability to plants in soil fertilized with different waste substances.

Field trials were conducted in 2004-2015, in Balcyny, on haplic Luvisol formed out of light boulder clay. The experiment consisted of the following treatments: control (no fertilization), NPK, manure (FYM), dried pelleted sewage sludge (DPSS), composted sewage sludge (CSS), compost made from municipal sewage sludge and straw (SSCS), compost Dano made from unsorted household waste (CUHW), and compost produced from urban green waste (CUGW). Over a period of 12 years, 30 t DM/ha of each manure and composts were used, that is, 10 t DM/ha in each rotation of a crop rotation sequence. Nitrogen fertilization was kept on the same level on all experimental plots. Soil samples from the 0- to 20-cm horizon were collected after the third rotation crop, which was winter wheat harvested in 2015. It has been demonstrated that CUHW raised the soil total Cu content the highest, while the soil content of Zn was elevated the most by DPSS. The content of the remaining heavy metals (Pb, Ni, Cr, Mn, and Fe) increased as well, but to a lesser extent. The soil abundance of phytoavailable forms of copper improved even greater (from 75% when fertilized with CUGW or CSS, up to 124% when treated with CUHW). Soil content of soluble forms of such metals as Zn, Pb, Cr, Mn, and Fe changed less. The content of all analyzed heavy metals in soil (a form approximating the total content) was significantly positively correlated with the content of organic carbon (C-org.). This is the evidence for stronger adsorption of the above elements in soil richer in organic matter. On the other hand, the content of available forms of heavy metals depended more on the soil pH than on its content of C-org.

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A field experiment was conducted with sandy fluvo-aquic soil under wheat-maize rotation system during 2012 to 2016 in Henan Province, with four treatments: Chemical fertilizer (CK), composted sewage sludge (CS) 15 t·hm-2(CS1), 30 t·hm-2(CS2), 45 t·hm-2(CS3). We investigated the effects of CS on soil active organic nitrogen and its allocation ratio. Results showed that CS significantly enhanced soil water content, decreased soil pH, increased contents of soil organic carbon and total nitrogen (TN) and available nutrients. Soil TN was increased by 93.1%-284.3%. The CS3 treatment significantly improved the content of light fraction organic nitrogen (LFON), particulate organic nitrogen (PON) and microbial biomass nitrogen (MBN). CS treatments promoted the allocation of PON/TN and MBN/TN. with an enhancement of 12.3% and 539.9% in the CS2 treatment, respectively. The distributions of LFON/TN and DON/TN were decreased by 17.3%-40.1% and 38.5%-71.3%, respectively. The contribution of soil active organic nitrogen fractions to TN was: PON>LFON>DON>MBN. Results from the principal component analysis showed that organic nitrogen and their distribution had high load value in CS2 and CS3 treatments. Results from redundancy analysis showed that positive correlations existed between the soil physicochemistry, enzymatic activity and soil active organic nitrogen as well as their distribution. In summary, CS had positive impacts on soil organic matter, soil properties, and the formation of active organic nitrogen. The rates of 30 and 45 t·hm-2 CS application had significant effects on soil fertility, which could be an effective way to improve sandy fluvo-aquic soil quality.

Effects of Medium-Term Amendment with Diversely Processed Sewage Sludge on Soil Humification-Mineralization Processes and on Cu, Pb, Ni, and Zn Bioavailability.

The organic fraction of sewage sludge administered to agricultural soil can contribute to slowing down the loss of soil's organic carbon and, in some cases, can improve the physical and mechanical properties of the soil. One of the main constraints to the agricultural use of sewage sludge is its heavy metals content. In the long term, agricultural administration of sewage sludge to soil could enhance the concentration of soil heavy metals (as total and bioavailable fractions). The aim of this research was to evaluate the effects of medium-term fertilization with diversely processed sewage sludge on the soil's organic carbon content and humification-mineralization processes, on the physical-mechanical properties of soil and their influence on the pool of potentially bioavailable heavy metals, in order to assess their effectiveness as soil organic amendments. After eight years of sludge administration; an increase in the concentrations of bioavailable form was evidenced in all the heavy metals analyzed; independently of the type of sludge administered. The form of sludge administration (liquid, dehydrated, composted) has differently influenced the soil humification-mineralization processes and the physical-mechanical properties of soil. The prolonged amendment with composted sewage sludge contributed to keeping the soil humification-mineralization process in equilibrium and to improving the physical and mechanical qualities of the treated soil.

Effect of composted sewage sludge on morpho-physiological growth parameters, grain yield and selected functional compounds of barley.

BACKGROUND: Several studies have evaluated the effects of composted sewage sludge on barley and found a positive influence on crop productivity. No studies have investigated the effects of composted sewage sludge on functional compounds of the caryopsis, such as phenolics and ß-glucans. The former play a role in plant defence mechanisms and both could be influenced by variations of kernel size related to fertilization intensity. The present study aimed to evaluate the effect of different doses (3-12 mg ha-1 ) of composted sewage sludge applied alone or in combination with mineral fertilization on morpho-physiological and yield qualitative parameters, especially phenolics and ß-glucans contents of grains, in barley. RESULTS: Increasing fertilization rates, irrespective of fertilizer type, improved morpho-physiological and yield parameters, whereas the phenolic compounds and the related antioxidant activity significantly decreased (P < 0.05). The ß-glucans and the main color indices did not show significant differences. The combined application of 6 mg ha-1 sewage sludge and nitrogen was not significantly different from mineral fertilization. Morpho-physiological and qualitative parameters, as well as bioactive compounds, were all significantly correlated with nutrient levels, with higher r values for nitrogen. CONCLUSION: Composted sewage sludge had a similar effect compared to mineral fertilization. © 2016 Society of Chemical Industry.

Aided phytostabilization of a trace element-contaminated technosol developed on steel mill wastes.

Aided phytostabilization of a barren, alkaline metal(loid)-contaminated technosol developed on steel mill wastes, with high soluble Cr and Mo concentrations, was assessed in a pot experiment using (1) Ni/Cd-tolerant populations of Festuca pratensis Huds., Holcus lanatus L., and Plantago lanceolata L. sowed in mixed stand and (2) six soil treatments: untreated soil (UNT), ramial chipped wood (RCW, 500m3ha-1), composted sewage sludge (CSS, 120t DW ha-1), UNT soil amended with compost (5% w/w) and either vermiculite (5%, VOM) or iron grit (1%, OMZ), and an uncontaminated soil (CTRL). In the CSS soil, pH and soluble Cr decreased whereas soluble Cu, K, Fe, Mn, Mg, Ni and P increased. The RCW treatment enhanced soluble Fe, Mn, and Mg concentrations. After 15 weeks, shoot DW yield and shoot Cd, Cu, Fe, Mn, Mo, Zn, and Mg removals peaked for F. pratensis grown on the CSS soil, with lowest shoot Cr, Ni and Mo concentrations. Holcus lanatus only grew on the CTRL, UNT, and CSS soils and P. lanceolata on the CTRL soil. Best treatment, F. pratensis grown on the CSS soil, led to a dense grass cover but its shoot Mo concentration exceeded the maximum permitted concentration in forage.