Composting as a Key Driver for Sustainable Agricultural Scenarios—Volume II

A special issue of Agronomy (ISSN 2073-4395). This special issue belongs to the section "Agricultural Biosystem and Biological Engineering".

Deadline for manuscript submissions: 30 January 2025 | Viewed by 19419

Special Issue Editors

GIAAMA, Department of Agrochemistry and Environment, Miguel Hernández University, EPS-Orihuela, Ctra. Beniel km 3.2, 03312 Alicante, Orihuela, Spain
Interests: organic waste management; compost; organic fertilization; co-composting; soil quality; sustainable agriculture; climate change mitigation; soil organic matter; soilless growing media
Special Issues, Collections and Topics in MDPI journals
GIAAMA, Department of Agrochemistry and Environment, Miguel Hernández University, EPS-Orihuela, Ctra. Beniel km 3.2, 03312 Alicante, Orihuela, Spain
Interests: organic waste management; compost; climate change mitigation; greenhouse gas emissions; organic fertilization; co-composting; soil quality; sustainable agriculture; soil organic matter; soilless growing media
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Currently, agriculture faces the challenge of securing production for an increasing human population, but also including environmental and sustainability aspects, reducing the use of non-renewable resources and energy and favoring climate change mitigation. Composting cannot be considered a new technology and allows not only the management of organic wastes, but also the optimization of the resources contained in them and a brake reduction in the greenhouse effect associated to soil organic matter. However, depending on the organic wastes used and process development, compost can also be a route of entry into the environment for contaminants. Thus, acknowledgment of the link between organic waste management, compost quality, and the sustainable biomass production required for food security and the wider bioeconomy is crucial.

This Special Issue aims to study the strategies based on compost production from different type of organic wastes, compost quality, and the use of compost in different agricultural scenarios to achieve sustainable crop production and to ensure the sustainability of agricultural systems. Original research, reviews, or opinions on composting of different organic waste fractions, with special interest in compost quality, and on the role of compost for sustainable agriculture, the effects on C sequestration, soil quality, and conservation in different environments are welcome.

Dr. Maria Angeles Bustamante Muñoz
Dr. Raul Moral Herrero
Guest Editors

Manuscript Submission Information

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Keywords

  • compost quality
  • organic waste management
  • soil fertility
  • soil quality
  • C sequestration
  • organic fertilization
  • soilless substrates
  • agricultural soils
  • nutrient recovery
  • climate change mitigation

Published Papers (11 papers)

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Research

Jump to: Review

13 pages, 1107 KiB  
Article
Municipal Solid Waste Management in a Decentralized Composting Scenario: Assessment of the Process Reproducibility and Quality of the Obtained Composts
by Cristina Álvarez-Alonso, María Dolores Pérez-Murcia, Silvia Sánchez-Méndez, Encarnación Martínez-Sabater, Ignacio Irigoyen, Marga López, Isabel Nogués, Concepción Paredes, Luciano Orden, Ana García-Rández and María Ángeles Bustamante
Agronomy 2024, 14(1), 54; https://doi.org/10.3390/agronomy14010054 - 24 Dec 2023
Viewed by 985
Abstract
Over the last several years, the models for organic waste management have changed to implement circular economy in the productive cycle. In this context, new scenarios have emerged, where the management of different organic waste streams by composting is conducted with decentralized models [...] Read more.
Over the last several years, the models for organic waste management have changed to implement circular economy in the productive cycle. In this context, new scenarios have emerged, where the management of different organic waste streams by composting is conducted with decentralized models that manage organic wastes in a more local way. However, in these new models, the standardization of the process control and of the end-product characteristics is necessary to guarantee the quality and agronomic value of the compost obtained, avoiding potential risks for human health and the environment. Thus, the aim of this work was to study two different scenarios of community composting of the organic fraction of municipal solid waste separately collected in order to guarantee the effectiveness and reproducibility of the composting processes and the quality of the composts obtained. For this, the development of the process and the characteristics of the composts at agronomic, hygienic–sanitary and environmental levels were assessed in real conditions and during three cycles of the process. The results obtained show high similarity among the different composting cycles, indicating an important degree of reproducibility among the processes. In addition, the composts obtained showed a good sanitary quality, absence of phytotoxicity and low contents of potentially toxic elements, which guarantee their use in agriculture without posing any risk to human health and to the environment. Full article
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18 pages, 1697 KiB  
Article
Industrial-Scale Composting of Rice Straw and Sewage Sludge
by Isabel Rodríguez-Carretero, Rodolfo Canet, Ana Quiñones and Ana Pérez-Piqueres
Agronomy 2023, 13(9), 2295; https://doi.org/10.3390/agronomy13092295 - 30 Aug 2023
Viewed by 843
Abstract
Composting is an interesting option to recycle big quantities of organic waste because it helps to mitigate different environmental problems. Complementary characteristics of rice straw (RS) and sewage sludge (SS) create a suitable mixture to be used in a composting process. This work [...] Read more.
Composting is an interesting option to recycle big quantities of organic waste because it helps to mitigate different environmental problems. Complementary characteristics of rice straw (RS) and sewage sludge (SS) create a suitable mixture to be used in a composting process. This work studies industrial-scale RS and SS composting to assess both its viability and optimization. Windrow composting was conducted during two seasons. The complete characterisation (moisture, pH, electrical conductivity, total, oxidisable and water-soluble organic carbon, humic substances, organic and mineral nitrogen, macronutrients, micronutrients, heavy metals) of starting materials, samples taken periodically and final composts were carried out. During the first season, an RS:SS ratio of 1:8 (w:w fresh weight) was used, which led to a process with adequate temperatures for biodegradation, but not for ensuring materials’ sanitation. During the second season, the RS:SS ratio was increased (1:6) to enhance the energy process and, thus, temperatures. Although this increase took place, degradation slowed down as oxidisable organic carbon and water-soluble organic carbon indicated. During both seasons, final composts presented adequate pH, high N-richness, and interesting macro- and micronutrient values. Notwithstanding, they also presented certain salinity and high ammonium contents, which must be considered for their field application. The obtained composts have interesting agronomic characteristics, which suggest their potential as an alternative to conventional fertilisers. Full article
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12 pages, 4836 KiB  
Article
Using Fluorescence Spectroscopy to Assess Compost Maturity Degree during Composting
by Yao-Tsung Chang, Chia-Hsing Lee, Chi-Ying Hsieh, Ting-Chien Chen and Shih-Hao Jien
Agronomy 2023, 13(7), 1870; https://doi.org/10.3390/agronomy13071870 - 15 Jul 2023
Cited by 5 | Viewed by 1513
Abstract
Uncertainty remains over composting time and maturity degree for compost production. The objectives of this study were to establish maturity indicators for composting based on spectral and chemical components and to provide a reference for future composting management. Several indicators of composting were [...] Read more.
Uncertainty remains over composting time and maturity degree for compost production. The objectives of this study were to establish maturity indicators for composting based on spectral and chemical components and to provide a reference for future composting management. Several indicators of composting were assessed for three commercial composts at 0, 7, 15, 30, 45, and 60 days during the germination of Chinese cabbage, including (1) central temperature, (2) moisture content, (3) pH, (4) electrical conductivity, (5) C/N ratio, (6) E4/E6 ratio, (7) fluorescence humification index (HIX), and (8) germination index (GI). We evaluated the optimal composting time using these indicators, reflecting the changes in hog manure, chicken manure, and agricultural by-product composts throughout their composting process to provide a basis for maturity time. The results showed that the E4/E6 ratio, C/N ratio, humic acid (HA), fulvic acid (FA), and germination rate, which reached a stable status after 30 days of composting, could be the indicators of “early-stage” maturity. In contrast, central temperature, electrical conductivity, HIX, and GI reached stable values after 45 days of composting and thus could be more suitable indicators of full maturity. Based on our results, we recommend a minimum composting time of 30 days to achieve primary maturity, while fully matured compost may be obtained after 45 days. Full article
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15 pages, 1836 KiB  
Article
Effects of Iron Nanoparticles Addition on Bacterial Community and Phytotoxicity in Aerobic Compost of Pig Manure
by Wenqing Yang, Qian Zhuo, Yuanping Zhong, Qinghua Chen and Zuliang Chen
Agronomy 2023, 13(5), 1239; https://doi.org/10.3390/agronomy13051239 - 27 Apr 2023
Viewed by 956
Abstract
In China, the treatment of pig manure for land application is an important issue. In this paper, green synthesized iron nanoparticles (G-nFe) were evaluated for their effectiveness in the aerobic composting of pig manure. G-nFe were evenly mixed into [...] Read more.
In China, the treatment of pig manure for land application is an important issue. In this paper, green synthesized iron nanoparticles (G-nFe) were evaluated for their effectiveness in the aerobic composting of pig manure. G-nFe were evenly mixed into the compost, and the pH and oxidation-reduction potential (ORP) of the compost in the presence of G-nFe both decreased. FTIR showed that G-nFe promoted the formation of humus during composting. The addition of G-nFe (200 mL kg−1) to the compost also promoted bacterial growth, significantly increasing the colony-forming units (CFU, up to 25.6 × 104 CFU mL−1) and OD600 (up to 0.634) in 5 days. Furthermore, G-nFe promoted the fermentation of the pig manure, thus reducing the phytotoxicity of the compost produced. For example, the final volatile solids (VS) degradation rate and seed germination index (GI) of the compost were the highest and reached 20.8% and 0.76%, respectively. Finally, G-nFe improved both the bacterial diversity and community richness of the compost. This indicated that the addition of G-nFe could result in the prolonging of the acidic fermentation time during composting, leading to increased compost maturity. Overall, the beneficial impact of G-nFe on compost was far greater than the potential harm to bacterial communities in the compost and perceived phytotoxicity. Full article
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14 pages, 3208 KiB  
Article
Composting as an Alternative for the Treatment of Solid Waste from the Kraft Pulp Industry
by Marcia Zambrano Riquelme, Dante Rodríguez-Luna, Francisco Javier Alcalá, Olga Rubilar, Marysol Alvear, Francisco Encina-Montoya and Gladys Vidal
Agronomy 2023, 13(4), 1099; https://doi.org/10.3390/agronomy13041099 - 12 Apr 2023
Viewed by 2189
Abstract
The increasing industrial pulp production has led to a negative growth of the associated solid wastes, thus making necessary alternative ways of handling them in suitable sanitary landfills to minimize adverse effects on the environment and well-being of people. Solid waste treatment prior [...] Read more.
The increasing industrial pulp production has led to a negative growth of the associated solid wastes, thus making necessary alternative ways of handling them in suitable sanitary landfills to minimize adverse effects on the environment and well-being of people. Solid waste treatment prior to its disposal is a target to minimize pollution of the natural resources (air, soil, water) due to accidental leaching. This paper aims to determine better experimental conditions in the container to develop an optimal composting design for pulp solid wastes. For this, an experimental methodology is introduced. This paper presents the results about the influence of independent control variables (grits addition and composting process time) on dependent variables (chemical and biological), for which a composting design was used, and a face-centered central composite factor was applied. The results showed mature compost over 60-day treatment, with the following experimental observations (i) the grits addition did not decrease the pH in the first stage of the composting process; and (ii) the microbial activities were high during the active stage of the composting progress and evolved to stable, lower values together with a proper trend of N–NH4+ and N–NO3 at the end. Grits addition of around 6% is the optimal experimental amount to use for the composting process of the secondary sludge from the Kraft mill industry. In conclusion, treating secondary sludges and grit residues from the Kraft mill industry to produce compost is feasible and sustainable. This action reduces the environmental pollution risk (evidenced by soil pH change and possible water pollution) and improves the soil assimilation capability of inorganic micronutrients and organic compounds after application. Thus, the controlled waste reuse will pass from a negative input to the environment to a positive, sustainable solution, which can be used as a soil-nutrient improver in agriculture. Full article
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16 pages, 1486 KiB  
Article
Agronomic, Economic and Environmental Comparative of Different Aeration Systems for On-Farm Composting
by Víctor Valverde-Orozco, Irene Gavilanes-Terán, Julio Idrovo-Novillo, Lourdes Carrera-Beltrán, Cristian Basantes-Cascante, Maria Angeles Bustamante and Concepción Paredes
Agronomy 2023, 13(3), 929; https://doi.org/10.3390/agronomy13030929 - 21 Mar 2023
Cited by 2 | Viewed by 1645
Abstract
On-farm composting of agro-livestock wastes can be considered the most appropriate method for their recycling. Pile turning (PW) is one of the most widely used aeration systems for composting. However, this system has long composting periods and is inefficient at supplying oxygen and [...] Read more.
On-farm composting of agro-livestock wastes can be considered the most appropriate method for their recycling. Pile turning (PW) is one of the most widely used aeration systems for composting. However, this system has long composting periods and is inefficient at supplying oxygen and controlling the temperature. To minimize these drawbacks, the combination of turnings with forced aeration (PR) is an option; in this work, this combination was compared to PW as an aeration system for the co-composting of vegetable waste with different manures. In this comparative study, the evolution of the process, the compost quality and the economic and environmental impacts of the process were evaluated. The PR system was more appropriate for obtaining sanitized composts (the temperature was ≥55 °C for at least three consecutive days) with an adequate degree of maturity. Furthermore, this system reduced the organic matter and nutrient losses, yielding composts with higher agronomic value and a higher total combined value of the nutrients than those obtained using the PW system. However, the energy consumption and associated CO2 emissions were lower for the PW system, since this aeration system was based only on turnings without the use of forced aeration, as in the case of the PR system. Agricultural valorization of composts will offset this energy consumption and its impact, since it will contribute to reducing the use of synthetic fertilizers. However, more studies are required on the PR composting system and other agro-livestock wastes for the creation of centralized on-farm composting sites, where all steps of the composting chain are optimized. Full article
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16 pages, 2292 KiB  
Article
Composting Sugarcane Filter Mud with Different Sources Differently Benefits Sweet Maize
by Muhammad Salman, Inamullah, Aftab Jamal, Adil Mihoub, Muhammad Farhan Saeed, Emanuele Radicetti, Iftikhar Ahmad, Asif Naeem, Jawad Ullah and Silvia Pampana
Agronomy 2023, 13(3), 748; https://doi.org/10.3390/agronomy13030748 - 03 Mar 2023
Cited by 5 | Viewed by 2684
Abstract
Reusing organic wastes in land applications would enhance the recovery of resources, following the concepts of the circular economy. The sugarcane-based sugar industry produces various by-products (e.g., sugarcane filter mud, molasses, and bagasse) that have the potential to contribute to crop production and [...] Read more.
Reusing organic wastes in land applications would enhance the recovery of resources, following the concepts of the circular economy. The sugarcane-based sugar industry produces various by-products (e.g., sugarcane filter mud, molasses, and bagasse) that have the potential to contribute to crop production and soil fertility, owing to their high contents of organic matter and nutrients. Although the agricultural benefits of compost utilization in agriculture have been well-documented, to the best of our knowledge, few scientific data are currently available on the effects of sugarcane filter mud combined with the application of compost for increasing crop production. Thus, a field experiment was carried out to study how sugarcane filter mud, in combination with two compost sources, affected the growth and yield of sweet maize (Zea mays var. saccharata). We compared (i) two types of compost made from brassica residue and household waste applied at a rate of 9 t ha−1, and (ii) two application rates of sugarcane filter mud: 0 and 2 t ha−1 to two controls without any compost application: one with (+SFM) and one without (−SFM) sugar filter mud. The results highlighted that all crop growth and yield parameters benefited more from the domestic waste compost than from the brassica straw compost. Moreover, the addition of sugar filter mud to the compost further boosted the crop performance. Based on the above results, we concluded that the addition of sugarcane filter mud to locally available composts is a feasible approach for more sustainable production of sweet maize, combining efficient waste disposal and the provision of organic matter to the soil. Full article
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16 pages, 2854 KiB  
Article
Evaluating Non-Composted Red Cotton Tree (Bombax ceiba) Sawdust Mixtures for Raising Okra (Abelmoschus esculentus (L.) Moench) in Pots
by Muhammad Yasin, Farhan Anwar, Hassan Noorani, Sher Muhammad, Athar Mahmood, Talha Javed, Baber Ali, Khadiga Alharbi, Ibrahim A. Saleh and Hashem A. Abu-Harirah
Agronomy 2023, 13(1), 97; https://doi.org/10.3390/agronomy13010097 - 28 Dec 2022
Cited by 11 | Viewed by 2149
Abstract
In modern agriculture, the substrate industry prefers porous materials for plants to provide water and nutrients in soilless cultivation. Composted sawdust is such a substrate. The sawdust industry is interested in avoiding composting sawdust because it is time and labor-consuming. The study objective [...] Read more.
In modern agriculture, the substrate industry prefers porous materials for plants to provide water and nutrients in soilless cultivation. Composted sawdust is such a substrate. The sawdust industry is interested in avoiding composting sawdust because it is time and labor-consuming. The study objective was to evaluate whether non-composted (fresh) Bombax ceiba (red cotton tree) sawdust with added nutrients could be an alternative to composted sawdust for okra production. The sawdust was mixed with nutrients in the form of banana peels (a potassium source), eggshells (a calcium source), and urea (a nitrogen source). We conducted two independent pot experiments. Treatments were viz.: T1: non-fertilized 100% sandy clay loam soil (control) (vol/vol); T2: non-composted 100% B. ceiba sawdust (vol/vol); T3: non-composted 80% B. ceiba sawdust + 20% banana peels (vol/vol); T4: non-composted 60% B. ceiba sawdust + 20% banana peels + 20% eggshells (vol/vol); T5: non-composted 60% B. ceiba sawdust + 20% banana peels + 20% eggshells (vol/vol) + urea (@ 91 kg N ha−1). In both experiments, the germination of okra seeds was unaffected by the sawdust mixtures. The phenological development of okra was significantly greater in non-fertilized clay loam soil than in any non-composted sawdust mixtures. Plant height, leaf relative water content, stability index of the membrane, root length, chlorophyll content index, root and shoot dry and fresh weight, stem diameter, and single leaf area of okra were lower in all non-composted B. ceiba sawdust mixtures compared to the control. In contrast to T2, T5 resulted in fewer days before the first flower developed, an increase in the number of pods plant−1, length of pod plant−1, the diameter of the pod, fresh and dry weight of pod plant−1, and the seed numbers pod−1. It is concluded that amending non-composted B. ceiba sawdust with banana peels, eggshells, and urea (T5) enhanced its perspective as a growth medium for okra. Nonetheless, the amendments were unlikely to establish an adequate yield of okra, as was the case with non-fertilized sandy clay loam soil. Full article
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19 pages, 1654 KiB  
Article
The Effects of Agricultural Plastic Waste on the Vermicompost Process and Health Status of Eisenia fetida
by José A. Sáez, Angie M. Pedraza Torres, Zbigniew Emil Blesa Marco, Francisco Javier Andreu-Rodríguez, Frutos C. Marhuenda-Egea, Encarnación Martínez-Sabater, María J. López, Francisca Suarez-Estrella and Raúl Moral
Agronomy 2022, 12(10), 2547; https://doi.org/10.3390/agronomy12102547 - 18 Oct 2022
Cited by 3 | Viewed by 2117
Abstract
Nowadays, plastic materials are extensively used in the agri-food sector for multiple purposes. The end-of-life management of these plastics is an environmental challenge because frequent incomplete recoveries after the crop seasons lead to the accumulation of plastics debris in agricultural waste, which is [...] Read more.
Nowadays, plastic materials are extensively used in the agri-food sector for multiple purposes. The end-of-life management of these plastics is an environmental challenge because frequent incomplete recoveries after the crop seasons lead to the accumulation of plastics debris in agricultural waste, which is now recognized as an emerging environmental issue of global concern. However, the effects of plastic debris in agricultural waste undergoing biotreatment have been poorly studied. This study assesses the effects of agricultural plastic waste (APW) (LDPE + LLDPE and EPS) (1.25% f.w.) on the vermicomposting process (45 days) in terms of earthworm health by measuring biomarker responses and the enzymatic activity and quality/stabilization of the vermicompost obtained. The results showed that exposure to all the plastic materials tested had negative morphological effects on earthworm survival and body biomass. In the vermicomposting process, the changes detected in the enzymatic activity of the vermicompost and the biofilm seemed to affect the degradation rate of earthworms and the microbiome of the substrate, as demonstrated by the low organic matter mineralization in the vermicompost exposed to plastic. Although no significant changes were recorded in several biomarkers, signs of oxidative stress were evidenced throughout the glutathione S-transferase and carboxylesterase activity, mainly involving balanced oxidative stress and xenobiotic resistance systems. Full article
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33 pages, 7112 KiB  
Article
Compost Quality Indexes (CQIs) of Biosolids Using Physicochemical, Biological and Ecophysiological Indicators: C and N Mineralization Dynamics
by Héctor Iván Bedolla-Rivera, Eloy Conde-Barajas, Sandra Lizeth Galván-Díaz, Francisco Paúl Gámez-Vázquez, Dioselina Álvarez-Bernal and María de la Luz Xochilt Negrete-Rodríguez
Agronomy 2022, 12(10), 2290; https://doi.org/10.3390/agronomy12102290 - 24 Sep 2022
Cited by 1 | Viewed by 1577
Abstract
The increasing production of biosolids (BS) as a result of urban wastewater treatment generates pollution problems in their management and final disposal, and a better management is needed for their disposal. The composting of BS is an alternative process for obtaining a product [...] Read more.
The increasing production of biosolids (BS) as a result of urban wastewater treatment generates pollution problems in their management and final disposal, and a better management is needed for their disposal. The composting of BS is an alternative process for obtaining a product with potential application as an organic amendment in the recovery of agricultural soils. As a biotechnological contribution, this study analyzed a composting process with BS, bovine manure (BM) and rice husks using four treatments T1 (C/N = 24); T2 (C/N = 34); T3 (C/N = 44); T4 (C/N = 54) for 120 days, in order to develop compost quality indexes (CQIs) through the analysis of 18 physicochemical, biological and ecophysiological indicators. Subsequently, three methodologies—successfully used on soils—were implemented for the development of the CQIs called “unified”, “additive” and “nemoro”. The indicators that comprised the CQIs were nitrification index (NI) and synthetic enzymatic index (SEI). The CQIs made it possible to differentiate the quality of the compost according to the treatments applied. The treatments used resulted in composts considered phytonutritious whose average quality value depending on the CQI developed was considered high (CQIw = 0.62), moderate (CQIa = 0.56) and low (CQIn = 0.30). The developed CQIs can be applied to determine the quality of BS composting systems reducing the cost of monitoring. Full article
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Review

Jump to: Research

17 pages, 1836 KiB  
Review
Spectroscopy Techniques for Monitoring the Composting Process: A Review
by Andrés Pérez-San Martín, Frutos C. Marhuenda-Egea, Maria Angeles Bustamante and Gustavo Curaqueo
Agronomy 2023, 13(9), 2245; https://doi.org/10.3390/agronomy13092245 - 27 Aug 2023
Cited by 3 | Viewed by 1196
Abstract
Composting is described as a sustainable alternative to organic waste reuse from the agricultural and household sectors. The organic matter degradation and stabilization product presents great variability due to the waste composition used. Thus, the use of techniques that allow the monitoring of [...] Read more.
Composting is described as a sustainable alternative to organic waste reuse from the agricultural and household sectors. The organic matter degradation and stabilization product presents great variability due to the waste composition used. Thus, the use of techniques that allow the monitoring of the decomposition process is necessary to determine the quality of the final product. Therefore, this review critically analyzes and updates the chemical spectroscopy methods described for the evaluation of the organic matter transformation in the composting process to optimize and generate amendments for agricultural use. This review examines spectroscopic techniques such as ultraviolet-visible (UV-Vis), infrared (IR), fluorescence, and 13C NMR reported for the evolution and maturation of carbonate structures in composting. In addition, they are used in the study of indicators for monitoring the degradation of complex structures, such as sugars and proteins, for the formation of precursors that are responsible for the formation of highly stabilized substances such as humic and fulvic compounds. Finally, these parameters may be used to elucidate organic matter degradation and its stabilization process, establish patterns that characterize each stage of composting along with its physicochemical characteristics, and monitor potential phytotoxicity levels. Full article
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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

Title: The effects of agricultural plastic waste on the vermicompost process
Authors: José A. Sáez1, Angie M. Pedraza Torres2, Zbigniew Emil Blesa Marco1, F.J. Andreu Rodríguez1, Frutos C. Marhuenda-Egea3, Juan C. Sánchez-Hernández2, Encarnación Martinez-Sabater1, María J. López4, Fra
Affiliation: 1Laboratory of Ecotoxicology, Institute of Environmental Science (ICAM), University of Castilla-La Mancha, Toledo, España 2 Center of Research and Innovation in Agri-food and Agro-environmental (CIAGRO-UMH), University Miguel Hernández, Beniel km3,2, Orihuela, Alicante 03312, Spain. 3Department of Agrochemistry and Biochemistry; Multidisciplinary for Environmental Studies Ramón Margalef, 4Unit of Microbiology, Department of Biology and Geology, CITE II-B, Agrifood Campus of International Excellence CeiA3, CIAIMBITAL, University of Almeria,04120, Spain
Abstract: Nowadays, plastic materials are extensively used in the agri-food sector for multiple purposes. The effect of this plastic as an emerging pollutant of marine and terrestrial environments is a topic of much research. However, the effects of plastic debris in agricultural waste undergoing biotreatment have been poorly studied. This study assesses the effects of agricultural plastic waste (AWP) (LDPE + LLDPE and EPS) (1.25 % f.w.) on the vermicomposting process (45 d.) in terms of earthworm health by measuring biomarker responses and the enzymatic activity and quality/stabilization of the vermicompost obtained. The results showed that exposure to all the plastic materials tested had negative morphological effects on earthworm survival and body biomass. In the vermicomposting process, the changes detected in the enzymatic activity of the vermicompost and the biofilm, seemed to affect the degradation rate of earthworms and the microbiome of the substrate, as demonstrated by the low organic matter mineralization in the vermicompost exposed to plastic. Although no significant changes were recorded in several biomarkers, signs of oxidative stress were evidenced throughout the glutathione S-transferase and carboxylesterase activity, mainly involving balanced oxidative stress and xenobiotic resistance systems.

Title: Agronomic, economic and environmental comparative of different aeration systems for on-farm composting
Authors: Hugo Valverde-Orozco 1, Irene Gavilanes-Terán 2, Julio Idrovo-Novillo 2, Lourdes Carrera-Beltrán 2, Cristian Basantes-Cascante 2, Mª Angeles Bustamante 3, Concepción Paredes 3*
Affiliation: 1 Faculty of Engineering. National University of Chimborazo, EC060108, Riobamba (Chimborazo), Ecuador; 2 Faculty of Science, Higher Polytechnic School of Chimborazo, EC 060155, Riobamba (Chimborazo), Ecuador; 3 Centro de Investigación e Innovación Agroalimentaria y Agroambiental (CIAGRO-UMH), Miguel Hernandez University, EPS-Orihuela, ctra. Beniel km 3.2, 03312, Orihuela (Alicante), Spain.
Abstract: On-farm composting of agro-livestock wastes can be considered the most appropriate method for their recycling. Pile turning is one of the most widely used aeration systems for on-farm composting. However, this system has long composting periods and is inefficient in supplying oxygen and controlling the temperature. To minimise these drawbacks the combination of turnings with forced aeration (PR) is an option; in this work, it was compared to pile turning (PW) as an aeration system for the co-composting of vegetable waste with different manures. In this comparative study, the evolution of the process, the compost quality and the economic and environmental impacts of the process were evaluated. The PR system was more appropriate for obtaining sanitised composts with an adequate degree of maturity. Furthermore, this system reduced the organic matter and nutrient losses arising through ammonia volatilisation and salt leaching, yielding composts with higher agronomic value and a higher total combined value of the nutrients than those obtained using the PW system. However, the energy consumption and associated CO2 emissions were lower for the PW system, since this aeration system was based only on turnings without the use of a blower for the forced aeration as in the case of the PR system.

Title: Spectroscopy techniques for monitoring the composting process: A review
Authors: Andrés Pérez-San Martín1, Frutos C. Marhuenda-Egea2, María Ángeles Bustamante3 & Gustavo Curaqueo4
Affiliation: 1 Programa de Doctorado en Ciencias Agropecuarias, Departamento de Ciencias Agropecuarias y Acuícolas, Universidad Católica de Temuco, Temuco, Chile. 2 Agrochemistry and Biochemistry Department, University of Alicante, Spain. 3 CIAGRO, Departamento de Agroquímica y Medio Ambiente, Universidad Miguel Hernández, Elche, Spain. 4 Departamento de Ciencias Agropecuarias y Acuícolas & Núcleo de Investigación en Producción Alimentaria, Universidad Católica de Temuco. Temuco, Chile.
Abstract: Composting is described as a sustainable alternative to organic waste reuse from the agricultural and household sector. The product generated by organic matter degradation and stabilization presents great variability due to the waste composition used. Thus, the use of techniques that allow the monitoring of the decomposition process is necessary to determine the quality of the final product. Therefore, this review critically analyzes and updates the chemical spectroscopy methods described for the evaluation of the organic matter transformation in the composting process to optimization and generation of amendments for agricultural use. This review examines the use of spectroscopic techniques such as ultraviolet-visible (UV-Vis), infrared (IR), fluorescence, and 13C NMR reported for the evolution and maturation of carbonate structures in composting. In addition, they are used in the study of indicators for monitoring the degradation of complex structures such as sugars and proteins for the formation of precursors that are responsible for the formation of highly stabilized substances such as humic and fulvic compounds. Finally, these parameters may be used to elucidate organic matter degradation and its stabilization process, establish patterns that characterize each stage of composting along with its physicochemical characteristics, and monitor potential phytotoxicity levels.

Title: Circular phosphorus in composting: a review towards agrowaste management sustainability
Authors: Andrés Pérez-San Martín1, Sharon Viscardi2, Aixa González3, María Ángeles Bustamante4, Daniel Blackburn5, Gustavo Curaqueo6*
Affiliation: 1 Universidad Católica de Temuco, Temuco, Chile. 2 Departamento de Procesos, Diagnósticos y Evaluación & Núcleo de Investigación en Producción Alimentaria. Universidad Católica de Temuco, Temuco, Chile. 3 Departamento de Procesos Industriales. Universidad Católica de Temuco, Temuco, Chile. 4 CIAGRO, Departamento de Agroquímica y Medio Ambiente, Universidad Miguel Hernández, Alicante, Spain. 5 Department of Soils, Water and Agricultural Engineering. Sultan Qaboos University. Sultanate of Oman. 6 Departamento de Ciencias Agropecuarias y Acuícolas & Núcleo de Investigación en Producción Alimentaria. Universidad Católica de Temuco, Temuco, Chile.
Abstract: Soil phosphorus (P) depletion and low plant bioavailability are the major problems in agriculture worldwide, especially in developing countries. This problem is exacerbated by the non-renewable nature of the mineral sources of this fertilizer, its poor geographic distribution, and its importance for sustaining crop yields. The recycling of P from waste streams and its reincorporation into the P deficient soils represent a viable alternative that can slow down its indiscriminate mining. Composting is a sustainable alternative to organic waste revaluation, and the agro-industrial sector has positioned itself as a growing source of organic waste source for potential P reuse in agriculture. The aim of this review is therefore to critically analyze the physicochemical and biological factors affecting plant P availability during composting and suggest appropriate measures to optimize P availability from the organic wastes. Among the physicochemical parameters that affect P bioavailability are pH, temperature, organic matter content, metal ion content, humic substances, and heavy metals content. Biological factors that affect P availability are enzymatic activities, the presence of P-solubilizing microorganisms, the release of organic acids, and the manipulation of metabolic processes to increase the generation of humic substances. Finally, we have critically reviewed the current research trends, gaps in knowledge, available alternatives, and criteria for the selection of better methodologies for P recycling through the composting of agro-industrial wastes.

Title: Municipal solid waste management in a decentralized composting scenario: assessment of the process reproducibility and quality of the obtained composts
Authors: Cristina Álvarez-Alonso1, María Dolores Pérez-Murcia1, Encarnación Martínez-Sabater1, Ignacio Irigoyen2, Marga López3, C. Paredes1, Luciano Orden1, Raúl Moral1 and María Ángeles Bustamante1
Affiliation: 1 Centro de Investigación e Innovación Agroalimentaria y Agroambiental (CIAGRO-UMH), Universidad Mi-guel Hernández, EPS-Orihuela, Ctra. Beniel Km 3.2, 03312 Orihuela, Alicante. 2 Department of Agricultural Production, Public University of Navarre (UPNA-NUP), Pamplona, Spain 3 Universitat Politècnica de Catalunya (UPC), Campus del Baix Llobregat, Edifici D4, C. Esteve Terradas, 8 08860, Castelldefels, Spain
Abstract: Population growth, economic development and urbanization have led to an increase in resource consumption and waste production, and waste management has become a global issue. The adoption of the circular economy approach has led to a change in the management of organic waste, treating it as a new resource. Composting, as a technology for recovering valuable ele-ments, breaks down organic matter into mature, stable, low pathogenic compost suitable for ag-ricultural use. The European Union and Spain have implemented new legislation mandating separate collection and recycling of biowaste by biological treatment, and community composting has emerged as a decentralized model of organic waste management, but the lack of standardized control of the process and end product jeopardises the agronomic value, quality and hygienic conditions of compost. The study of 3 cycles of community composting in two small towns in the Valencian Community (Spain) by monitoring the process, physico-chemical, chemical and biological characterization allows obtaining a mature compost, without pathogens and with high added value that guarantees its use in agriculture without causing damage to human health and the environment.

Title: Effect of bulking agent and composting phase on compost tea quality
Authors: H.E.F. Lorin (1); M. Chiarelotto (1); P.E. Rodrigues Silva (1); L.A. de Mendonça Costa†; M.A. Bustamante (2), R. Moral (2), M.S.S.M. Costa (1)*
Affiliation: (1) Research Group on Water Resources and Environmental Sanitation - RHESA, Western Parana State University - UNIOESTE, Agricultural Engineering Graduate Program - PGEAGRI, Cascavel, Paraná, Brazil (2) Centro de Investigación e Innovación Agroalimentaria y Agroambiental (CIAGRO-UMH), Universidad Miguel Hernández, EPS-Orihuela, Ctra. Beniel Km 3.2, 03312 Orihuela, Alicante, Spain.
Abstract: In this study, we investigated the effect of composting phase and bulking agent on macronutrient extraction and chemical, physicochemical, and biological properties of 20 compost teas extracted from different poultry industry waste mixtures. Phosphorus (P) extraction was more efficient during stabilization of the composting mass after the thermophilic phase, but water-soluble P declined as composting progressed. K was more amenable to extraction into compost teas with extraction yield percentages ranging from 30‒70%, followed by N (2‒12%) and P (1‒7%). The germination index GI decreased linearly according to increasing values of electrical conductivity (EC) in the compost teas. EC > 4.75 dS.m−¹ suppressed the phytostimulatory effect (GI > 101%) of compost teas and EC > 8.1 dS.m−¹ was indicative of the presence of phytotoxic compounds (GI < 66%).

Title: How can bio-waste be managed in the context of a circular economy? Example of managing proximity, process monitoring and quality of compost produced.
Authors: Cristina Álvarez-Alonso1, María Dolores Pérez-Murcia1, Silvia Sánchez-Méndez1, Encarnación Martínez-Sabater1, Ignacio Irigoyen2, Marga López3, Isabel Nogués4, Concepción Paredes1, Luciano Orden1,5, An
Affiliation: 1 Centro de Investigación e Innovación Agroalimentaria y Agroambiental (CIAGRO-UMH), Universidad Mi-guel Hernández, EPS-Orihuela, Ctra. Beniel Km 3.2, 03312 Orihuela, Alicante, Spain. 2 Department of Agricultural Production, Public University of Navarre (UPNA-NUP), Pamplona, Spain 3 Universitat Politècnica de Catalunya (UPC), Campus del Baix Llobregat, Edifici D4, C. Esteve Terradas, 8 08860, Castelldefels, Spain. 4 Research Institute of Terrestrial Ecosystems, National Research Council, Via Salaria km 29,300 Monterotondo (Rome) Italy. 5 Estación Experimental Agropecuaria INTA Ascasubi (EEA INTA Ascasubi), Ruta 3 Km 794, Hilario Ascasubi, 8142, Argentina
Abstract: The sustainable management of bio-waste, mainly food and pruning waste, is currently a challenge due to the increase in its production. This high-potential waste stream plays a key role in the path towards a more circular economy, as it can be used to obtain high-value organic fertilisers such as compost. In this regard, in 2019 the campus of the Public University of Navarre (UPNA) launched the CaMPuSTAJE programme, which aims to manage the bio-waste generated in campus kitchens through community composting. UPNA students and graduates are involved in the daily management of the programme, which aims to promote experiential learning and applied research in sustainability and circular economy. The main objective of this work was to monitor in detail the evolution of the main process indicator parameters related to the quality of the final material during four composting cycles within this initiative, as well as to evaluate the quality of the final compost obtained. For this purpose, a control of the thermal profile and an evaluation of the physical, chemical and microbiological characteristics were carried out during the development of the process, as well as a complete characterisation of the agronomic and hygienic-sanitary quality of the final compost. This community composting initiative demonstrates that the on-site management of local bio-waste through community composting contributes to the circular economy of the area and makes it possible to obtain a final compost of high agronomic quality that meets the requirements of Spanish legislation in terms of heavy metal content and pathogenic micro-organisms, thus posing no risk to human health or the environment.

Title: Circular phosphorus in composting: a review towards agrowaste management sustainability
Authors: Andrés Pérez-San Martín1, Sharon Viscardi2, Aixa González3, María Ángeles Bustamante4, Daniel Blackburn5, Gustavo Curaqueo6*
Affiliation: 1 Universidad Católica de Temuco, Temuco, Chile. 2 Departamento de Procesos, Diagnósticos y Evaluación & Núcleo de Investigación en Producción Alimentaria. Universidad Católica de Temuco, Temuco, Chile. 3 Departamento de Procesos Industriales. Universidad Católica de Temuco, Temuco, Chile. 4 CIAGRO, Departamento de Agroquímica y Medio Ambiente, Universidad Miguel Hernández, Alicante, Spain. 5 Department of Soils, Water and Agricultural Engineering. Sultan Qaboos University. Sultanate of Oman. 6 Departamento de Ciencias Agropecuarias y Acuícolas & Núcleo de Investigación en Producción Alimentaria. Universidad Católica de Temuco, Temuco, Chile.
Abstract: Soil phosphorus (P) depletion and low plant bioavailability are the major problems in agriculture worldwide, especially in developing countries. This problem is exacerbated by the non-renewable nature of the mineral sources of this fertilizer, its poor geographic distribution, and its importance for sustaining crop yields. The recycling of P from waste streams and its reincorporation into the P deficient soils represent a viable alternative that can slow down its indiscriminate mining. Composting is a sustainable alternative to organic waste revaluation, and the agro-industrial sector has positioned itself as a growing source of organic waste source for potential P reuse in agriculture. The aim of this review is therefore to critically analyze the physicochemical and biological factors affecting plant P availability during composting and suggest appropriate measures to optimize P availability from the organic wastes. Among the physicochemical parameters that affect P bioavailability are pH, temperature, organic matter content, metal ion content, humic substances, and heavy metals content. Biological factors that affect P availability are enzymatic activities, the presence of P-solubilizing microorganisms, the release of organic acids, and the manipulation of metabolic processes to increase the generation of humic substances. Finally, we have critically reviewed the current research trends, gaps in knowledge, available alternatives, and criteria for the selection of better methodologies for P recycling through the composting of agro-industrial wastes.

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