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Abstract

A combination of physical, chemical, spectroscopic and biochemical parameters, along with different plant assays, was used to assess the maturity and stability of nine finished composts obtained from several raw materials (biodegradable fraction of municipal solid waste, green waste, sewage sludge, manure, and grape marc), and by different procedures (aerobic and anaerobic processing, industrial-scale and laboratory scale). Measures of total, alkali-soluble and water-soluble organic matter, N forms, colour, absorbance, respiration, dehydrogenase activity, and phytotoxicity were performed. The selection of a single parameter for stability and maturity evaluation for all the composts was not possible. A significant positive correlation (P<0.01) was found between microbial respiration and dehydrogenase activity. Also, significant correlations were found between dehydrogenase activity and water-soluble C (P<0.05) and water-soluble N (P<0.05), which are presumably the main forms of energy used by microorganisms. Nevertheless, common maturity/stability indicators, such as the C/N ratio in the solid and the aqueous phase, were not related either to microbial activity or phytotoxicity. In fact, the results of the plant growth tests were not correlated to any other parameter. A principal component analysis was performed to differentiate those parameters giving the maximum information about the status of each compost. A combination of a measure of humification and a measure of microbial activity or water-soluble organic carbon could be used to explain the differences in the stability of the composts, whereas for maturity evaluation plant tests are necessary.
... It is the most accessible organic nutrient to microorganisms because it consists of sugars, hemicellulose, and phenolic substances, amino acids, peptides, and other easily biodegradable substances during composting. It has been frequently used as maturity index in the literature (Gajalakshmi and Abbasi, 2008;Paradelo et al., 2010b). ...
... Ammonium and nitrate are the forms of N, which could be changed during composting. Poor aeration during composting resulted in excessive ammonium (Paradelo et al., 2010b). The N 4 + / N 3 − ratio has also been proposed to estimate the compost stability. ...
... Paradelo et al. (2010b) measured the TOC, total N, WSC, WSN, total alkali-extractable carbon in compost. The WSC/N should be less than 0.5 for mature compost great differences were observed for the ratio N 4 + − / N 3 − − among the composts. ...
... It must be noted that variation in all physiological tests was high due to heterogeneity in the BGPs'feedstock between the sampling times. The results of the biotests varied depending on the plant species, growth substrate (soil or peat) and the test used, as described also by several other studies [5,6]. In general, germination and root growth of cress were better in peat than in standard soil, whereas the opposite held true for barley roots. ...
... Aspects such as easy preparation and reproducibility should be taken into account when choosing appropriate control substrates in biological tests. It has previously been concluded that no single test alone is satisfactory when assessing compost stability or maturity [5]. The results of the biotests can also be influenced by intrinsic sensitivity of plants species, by growth conditions and phases, and by the physicochemical characteristics of thegrowth substrates [5,6]. ...
... It has previously been concluded that no single test alone is satisfactory when assessing compost stability or maturity [5]. The results of the biotests can also be influenced by intrinsic sensitivity of plants species, by growth conditions and phases, and by the physicochemical characteristics of thegrowth substrates [5,6]. ...
... Composting has been traditionally used and leads to stabilized organic amendments with fertilization potential. During vermicomposting the presence of worms induces a continuous aeration resulting in a faster OM transformation Paradelo et al, 2009Paradelo et al, , 2010. Though beneficial, vermicomposting and composting both emit greenhouse gases such as CO2, CH4 and N2O (Hobson et al, 2005;Chan et al, 2011;Thangarajan et al, 2013). ...
... In the context of ecological engineering, addition of worms to compost may be used to enhance OM decomposition Paradelo et al, 2009Paradelo et al, , 2010 and plant available nutrient contents of the end-products, in particularly P (Garg et al, 2006;Ghosh et al, 1999). In general, worms' presence during composting leads to greater CO2 release than regular composting; in the presence of mineral bulking agents, worms enhanced carbon stability due to the simultaneous ingestion of OM and minerals (Barthod et al, 2016). ...
... stabilisation plus rapide de la matière organique Paradelo et al, 2009Paradelo et al, , 2010. Malgré les avantages de ces deux procédés, de larges quantités de gaz à effet de serre sont produits lors de la décomposition de la matière organique tels que CO2, CH4 ou encore N2O (Hobson et al, 2005 ;Chan et al, 2011 ;Thangarajan et al, 2013). ...
Thesis
Due to bio-oxidative mechanisms, composting and vermicomposting produce a large amount of CO2 emissions. Therefore, in this study we aimed to assess (1) the potential stabilization of carbon of fresh organic matter due to mineral presence, with and without worms, and (2) the influence of minerals on maturity and quality of the finished products. The first experiment was based on a laboratory incubation of fresh organic matter, which allowed to obtain composts and vermicomposts, with and without minerals, to monitor carbon emissions and to analyse the final products. A second incubation was carried out to investigate the effect of these products as organic amendment on an arenic cambisol. Finally, the last experiment was carried out to assess the use of co-composts and co-vermicomposts as potting media, by following the growth of. A.Thaliana. The presence of minerals during composting induced a decrease of carbon emission, likely due to the formation of organo-mineral associations or shift of microbial communities. Moreover, the use of co-compost as soil conditioner may allow to increase soil carbon storage, compared to a regular compost. Although the physico-chemical characteristics of the end-products were optimum for its use as potting media, no beneficial aspects on A.Thaliana growth has been observed. In presence of worms during co-composting, the carbon emissions were increased due to worm activities but the positive effect of minerals was still observed. In addition, worms improved the nutrient availability in the end products. Therefore, co-vermicompost tended to improve soil properties and to enhance plant growth compared to a regular (vermi)compost.
... MIX2 decreased from 19.1 to 13.9 and 15.5 for MT and ST strategy. The C/N ratio decreased mainly due to the conversion of organic carbon into carbon dioxide [84], and also to the increase in total nitrogen content in the final composted material [85]. ...
... For this reason, the NH 4 + -N to NO 3 − -N ratio has also been used to estimate compost stability and maturity [88]. Generally, NH 4 + -N/NO 3 − -N value lower than 1.0, is considered indicative of mature compost [78,85,88]. In our study, this ratio decreased during the composting process and, in all investigated treatments, fell below 0.50 after 105 days of composting indicating a good degree of compost maturation (data not shown). ...
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The main challenge of this work is to identify a novel approach to reuse and valorize brewers’ spent grain (BSG) to produce a new source of income for the brewers in terms of self-consumption or selling goods. Therefore, this study explored the composting behavior of BSG mixed with different organic materials: wheat straw with pig slurry solid fraction and wheat straw with sheep manure, MIX1 and MIX2, respectively. The composting process was carried out in bins by comparing two different composting strategies: manual turning (MT) and static composting xxx– without turning operations (ST). During the experimental trial, BSG mixtures were chemically analyzed for pH, total Kjeldahl nitrogen, ammoniacal nitrogen, nitrate-nitrogen, total organic carbon, volatile solids, carbon to nitrogen ratio, and moisture content. Furthermore, the final composted materials were evaluated according to the physicochemical and biological limits fixed by the European regulation (2019/1009) and the Italian law (D.Lgs 75/2010). At the end of the composting process, the C/N ratio ranged from 11.6 to 15.5, the humification ratio ranged from 12.4 to 13.8 and the NH4+-N/NO3−-N ratio was lower than 0.5 indicating, in all investigated treatments, a good degree of maturation. However, as evidenced by the high pH values and low Germination Index, the sheep manure, as starting material, proved less effective than the solid fraction of pig slurry, probably due to excessive trampling and slow litter change. Finally, concerning the two composting strategies investigated, the obtained results highlighted that the composting strategy did not affect the final compost quality.
... La estabilidad se refiere al grado de humificación de un fertilizante orgánico y la madurez está relacionada con el tiempo de elaboración y la reducción de sustancias tóxicas, tales como ácidos orgánicos, que se sintetizan durante el proceso de biodegradación o fermentación de un abono orgánico. Es muy importante que el compost cumpla con estos dos parámetros, ya que si se aplica estando inmaduro o no estabilizado puede tener un comportamiento tóxico y afectar el desarrollo de los cultivos (Paradelo et al., 2001;Zubillaga y Lavado, 2006). ...
... Diferentes trabajos se han realizado para conocer la fitotoxicidad de los abonos orgánicos, pero debido a que los materiales que dan origen a los compost suelen ser sustancialmente diferentes, los resultados obtenidos son muy diversos o contrastantes (Paradelo et al., 2001), y no puede generalizarse al resto de abonos, resultando incluso necesario hacer las pruebas de un lote a otro en el proceso de producción y en las etapas finales del proceso de elaboración de los mismos. Al respecto, Zucconi et al. (1981) establece que un abono orgánico puede considerarse como apto para ser usado cuando muestra un índice de fitotoxicidad superior al 70%. ...
... La estabilidad se refiere al grado de humificación de un fertilizante orgánico y la madurez está relacionada con el tiempo de elaboración y la reducción de sustancias tóxicas, tales como ácidos orgánicos, que se sintetizan durante el proceso de biodegradación o fermentación de un abono orgánico. Es muy importante que el compost cumpla con estos dos parámetros, ya que si se aplica estando inmaduro o no estabilizado puede tener un comportamiento tóxico y afectar el desarrollo de los cultivos (Paradelo et al., 2001;Zubillaga y Lavado, 2006). ...
... Diferentes trabajos se han realizado para conocer la fitotoxicidad de los abonos orgánicos, pero debido a que los materiales que dan origen a los compost suelen ser sustancialmente diferentes, los resultados obtenidos son muy diversos o contrastantes (Paradelo et al., 2001), y no puede generalizarse al resto de abonos, resultando incluso necesario hacer las pruebas de un lote a otro en el proceso de producción y en las etapas finales del proceso de elaboración de los mismos. Al respecto, Zucconi et al. (1981) establece que un abono orgánico puede considerarse como apto para ser usado cuando muestra un índice de fitotoxicidad superior al 70%. ...
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Los fertilizantes orgánicos líquidos tales como lixiviados, tés de compost, biofermentos etc. pueden sustituir o complementar al uso de fertilización química, y son un componente fundamental en un programa de fertilización en agricultura orgánica. Por las características y calidad físico química diversa de los fertilizantes orgánicos, es necesario realizar una caracterización y valoración previa de éstos para evitar efectos negativos en el crecimiento y producción de cultivos. Una técnica sencilla para detectar el efecto tóxico de abonos, es el uso de bioensayos de germinación en especies indicadoras sensibles a productos poco estabilizados. En el presente estudio, se comparó el efecto tóxico de un lixiviado de lombricomposta, tres biofermentos elaborados a base de estiércol porcino, vacuno, biosólidos de granja piscícola y un abono comercial, aplicados a tres proporciones (0,25:5, 0,5:5 y 1:5 v:v del producto en agua) en acelga y lechuga en un bioensayo de germinación, bajo condiciones controladas de temperatura (25°C) y humedad relativa (65%), y con un total de 32 tratamientos distribuidos en un diseño experimental completamente al azar. Se midió longitud de raíz y brote, porcentaje de germinación, índice de germinación, crecimiento relativo de raíz y porcentaje de germinación relativo. Todos los productos utilizados mostraron un bajo grado de toxicidad, pero se observó una tendencia a un mayor índice de toxicidad con aumentos graduales en las dosis y se consiguió una respuesta diferente en función de la especie utilizada.
... Even the composts MV and MSGW, which presented the lowest concentrations of trace elements, would be categorized as class C composts and could not be used in agricultural soils at rates higher than 5 Mg dry matter ha −1 year −1 . More detailed information about phytotoxicity, maturity and heavy metal distribution and availability is available in previous works [22,32,33]. Table 2 shows the results of the growth experiment with ryegrass and lettuce. ...
Article
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Interest in using urban waste composts as amendments in urban agriculture is growing nowadays. However, concerns about the potential transference of pollutants present in urban waste to the food chain are very relevant when they are recycled for food or animal feed production. Thus, for the safe use of urban waste composts, it has to be assured that no risk of metal transference to plants from compost exists. In this work, the transference of heavy metals from urban waste composts to plants has been studied in an experiment with lettuce and Italian ryegrass, grown in substrates based on five metal-rich composts and a manure vermicompost (included for comparison). A two-month pot experiment was performed under controlled light and temperature conditions, and plant growth and uptake of Cu, Pb, Cd and Zn were analyzed. For both species, the concentration of metals in plant tissue followed the sequence Zn > Cu >> Pb ≈ Cd, the same as the metal concentrations in four out of the five composts. Plant concentrations of Zn, Cu and Cd increased with their concentrations in compost, whereas this relation was not observed for Pb. The ratio between element concentration in plant and compost were much higher for Zn, Cd and Cu than for Pb, showing the lower bioavailability of Pb with respect to other metals.
... List A includes respiration and self-heating measures, whilst List B considers the risk of phytotoxicity through the analysis of the ammonia: nitrate ratio, the concentration of ammonium, the concentration of volatile organic acids, or a plant test. Similarly, Paradelo et al. (2010a) recommend examining at least three groups of properties: a measurement of the degree of humification, a measurement of the microbial activity or of the watersoluble organic matter, and a plant germination or growth test. ...
Article
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Given the common use of compost in agriculture, forestry, landscaping and environmental restoration, it is essential that it is perfectly compatible with plant growth and, if possible, that it increases production and quality of plant biomass. It is therefore necessary to evaluate the absence of phytotoxic substances in the compost, which not only informs about its quality, but also on the proper handling of the composting process. Procedures for assessing the phytotoxicity as an indicator of compost maturity can be grouped into two types: a) seed germination and seedling elongation tests with extracts of compost; b) direct seeding tests on substrates made wholly or partly by compost. For the compost to be considered mature, the results of germination and elongation, or plant biomass, should be at least 80-90% of those obtained in a control. These tests have proven to be sensitive to various toxins, such as salts, organic acids, ammonia, or metals, and can be used to evaluate the process conditions and the degree of stabilization of organic matter, and the suitability of the raw materials. However, the great variability in testing methods make difficult the comparison and interpretation of results, so it is necessary to advance in the standardization of procedures and determine phytotoxicity thresholds for potential phytotoxic compounds in compost. Abbreviations: FMr 25% , plant production in fresh weight of 25% compost mixture; FMr 50% , plant production in fresh weight of 50% compost mixture; GI, germination index; MSW, municipal solid waste CONTENTS
... In this regard, the biological treatment of grape marc through aerobic and anaerobic biodegradation processes could be an appropriate alternative to handle and process these wastes from winery industries offering solutions to an environmental problem and obtaining derivate economic benefits from the commercialization of the manufactured products [10]. Composting has been successfully and widely used for processing grape marc under aerobic conditions with a dual purpose, i.e. environmental protection and fertilizer production [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] (Figure 2). Paradelo et al. [32] found, however, drawbacks when raw grape marc was composted alone; and when acid-hydrolyzed marc, which is the residue generated after pretreatment for lignocellulosic bioethanol production, was composted together with vinification lees at a lab-scale. ...
Article
Grapes are one of the most cultivated fruit crops worldwide. Either for wine or juice production, grape processing generates a large amount of residues that must be treated, disposed of or reused properly to reduce their pollution load before being applied to the soil. In this review, a special focus is given to the treatment and valorization of the winemaking by-product like grape marc via anaerobic digestion, composting and vermicomposting at laboratory, pilot, and industrial scales. The impact of the final products (digestates, composts, and vermicomposts) on soil properties is briefly addressed. Moreover, the role of grape marc and seeds as a valuable source of natural phytochemicals that include polyphenols and other bioactive compounds of interest for pharmaceutical, cosmetic, and food industries is also discussed. This is of paramount importance given the fact that sustainability requires the use of management and valorization strategies that allow the recovery of valuable compounds (e.g. antioxidants) with minimum disposal of waste streams.
... In the context of ecological engineering, composting with worms may be used to enhance OM decomposition (Lazcano et al., 2008;Paradelo et al., 2009Paradelo et al., , 2010 and increase the contents of the end-products in plant available nutrients, in particularly P (Ghosh et al., 1999;Garg et al., 2006). In general, worm presence during composting leads to larger CO 2 release than regular composting (Lim et al., 2016). ...
Article
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Municipal solid waste (MSW) compost from aerobic or anaerobic bioprocesses was evaluated as components of substrates for potted plant production. Experiments were conducted with potted media consisting of MSW compost mixed with other conventional substrates (peat or composted pine bark). Spring barley (Hordeum vulgare L.) and cress (Lepidium sativum L.) were used to evaluate the biological quality of composts. Higher germination rates of spring barley were obtained when MSW compost from aerobic treatment was employed as compared with MSW compost from the anaerobic bioprocess. Improved biological indices were observed when MSW composts were mixed with composted pine bark rather than with peat. Mixtures of 75% aerobic MSW compost and 25% composted pine bark were more favorable for cress growth than peat as sole substrate.
Chapter
Composting enables a detailed evaluation of the humification process of various organic wastes within a short period of time (3 to 6 months). Humic substances (HS) constitute a large fraction of the organic matter (OM) in compost, and they are its most active fraction due to their effects on soil ecology, structure, fertility and metal complexes, and plant growth. The formation and properties of HS extracted from various composts such as municipal solid waste (MSW), grape marc (GM), composted separated cattle manure (CSM), sewage sludge (SS), wood compost (WC) and other organic wastes were studied. Degradative and non-degradative techniques (FTIR, DRIFT, 13C-NMR) were used to study the transformation of HS during composting of the various organic wastes. Time-course studies of composting some of these wastes showed an increase in the relative amount of humic acid (HA) (from 18% to 45% of OM in CSM compost and from 5% to 20% in MSW compost), whereas the formation rate of fulvic acid (FA) was inconsistent. A humification ratio (HR – the ratio of HA/FA) was used to evaluate compost maturity. Values of 0.9 to 3.4 and 3.0 to 9.2 were typical for immature and mature composts, respectively. Another humification index (HI) used to define compost maturity was calculated as the ratio between non-humified fraction (NHF) and the humified fraction (HA+FA). A HI decrease during composting represents the formation of HS. Elemental- and functional-group analyses indicated only minor differences between HA extracted from composts at various stages. Moreover, these values fell into a wide range, similar to that of soil HA. The 13C-NMR spectra of the HA exhibited strong bands representing aliphatic structures in various composts (50% of total C in CSM, 30% in MSW and 61% in GM) and a lower level of aromatic components (37% in CSM, 22% in MSW and 22% in GM). The FTIR spectra showed similar trends of strong aliphatic and carbohydrate components. Both techniques provided more qualitative information indicating that HA extracted from mature compost exhibits more aromatic structures and carboxyl groups and less carbohydrate components than that from immature compost. Studies on the effects of HS on plant growth showed stimulative effects. Typical response curves indicated enhanced growth with increasing HS concentration in solution, followed by decreases in growth at higher concentrations. In soils, the addition of composts was found to stimulate growth beyond that provided by mineral nutrients, presumably because of the effects of HS.
Article
It seems to be possible to evaluate chemical stabilization of organic wastes on the basis of various humification indexes determined in the laboratory, i.e., a place in which controls can be applied more rigorously than in the field. Among the parameters tested, the HI seems to be the most appropriate, even though it is less simple and rapid. Before defining which among the parameters is the most suitable for evaluating the degree of maturity of organic wastes and utility in crop production, a much greater number of wastes of the same kind but composed under different conditions must be tested.
Article
The changes in the different organic matter (OM) fractions of lignocellulosic wastes during composting were studied and related to OM humification parameters and compost maturation degree. For this purpose, four mixtures of lignocellulosic materials (lemon tree prunings, cotton waste, brewery waste, olive husk, olive leaves and the solid fraction of olive mill wastewater) were composted in a static pile system with forced ventilation. The evolution of the parameters humic acid to NaOH-extractable organic carbon proportion or PAH (HAC/EXC × 100), humic to fulvic acid ratio (HAC/FAC), cation exchange capacity to total organic carbon ratio (CEC/TOC), and water-soluble organic carbon to organic nitrogen ratio (HOC/Organic-N), clearly reflected the increase in the degree of humification and stability of the OM during the composting process in all four mixtures. The concentration of water-soluble carbohydrates was significantly correlated with PAH, HAC/FAC and the HOC/Organic-N ratio in only two mixtures along the composting processes. In general, there were statistically significant correlations between the polyphenol concentration in different fractions (water soluble, NaOH extractable, and fulvic and humic acids) and the humification parameters and maturity indices, especially with PAH, HAC/FAC and HOC/Organic-N, which shows the participation of these compounds in the synthesis of humic substances. On the other hand, the lignocellulosic compounds, lignin, cellulose and hemicellulose, seem to play an important role in the increase of cationic exchange sites in the OM, as can be seen from their correlation with CEC/TOC ratio.
Article
Experiments involved the comparison of three procedures used to determine compost maturity/phytotoxicity. The three tests evaluated were the CCME germination test (1996), a modified Zucconi et al. (1981) extract and a direct seed procedure. Three different plant species and seven types of ‘composts’ were used. The species were cress (Lepidium sativum), radish (Raphanus sativus), and Chinese cabbage (Brassica chinensis). Germination and growth experiments were performed on three types of mature composts: 1) racetrack manure-food waste; 2) two different samples of municipal solid waste; and 3) racetrack manure-sewage sludge), two types of immature composts (farmyard manure-food waste and farmyard manure-yard waste-food waste], and a control (soil or water). Four replicates for each species, ‘compost’ and test procedure were evaluated. The study concluded that the commonly used compost extract test and the compost-soil germination and growth tests were not sensitive enough to detect differences between mature and immature ‘composts’, that other test(s) must be used to evaluate compost maturity.
Article
Assessment of compost maturity is important for successful use of composts in agricultural and horticultural production. We assessed the “maturity” of four different sawdust-based composts. We composted sawdust with either cannery waste (CW), duck manure (DM), dairy (heifer) manure (HM) or potato culls (PC) for approximately one year. Windrows were turned weekly for the first 60 days of composting, covered for four winter months and then turned monthly for six more months. We measured compost microbial respiration (CO2 loss), total C and N, C:N ratio, water soluble NO3-N and NH4-N, dissolved organic carbon (DOC), pH and electrical conductivity at selected dates over 370 days. Compost effects on ryegrass biomass and N uptake were evaluated in a greenhouse study. We related compost variables to ryegrass growth and N uptake using regression analysis. All composts maintained high respiration rates during the first 60 days of composting. Ammonium-N concentrations declined within the first 60 days of composting, while NO3-N concentrations did not increase until 200+ days. After 250+ days, DM and PC composts produced significantly more ryegrass biomass than either CW or HM composts. Total C, microbial respiration and water-extractable NO3-N were good predictors of compost stability/maturity, or compost resistance to change, while dissolved organic carbon, C:N ratio and EC were not. The compost NO3-N/CO2-C ratio was calculated as a parameter reflecting the increase in net N mineralization and the decrease in respiration rate. At ratio values >8 mg NO3-N/mg CO2-C/day, ryegrass growth and N uptake were at their maximum for three of the four composts, suggesting the ratio has potential as a useful index of compost maturity.