Maria Luz Cayuela

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Maria Luz verified their affiliation via an institutional email.

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• PhD Chemistry
• Senior Researcher at Spanish National Research Council

Agricultural soils represent the main source of anthropogenic N2O emissions. Recently, interactions of black carbon with the nitrogen cycle have been recognized and the use of biochar is being investigated as a means to reduce N2O emissions. However, the mechanisms of reduction remain unclear. Here we demonstrate the significant impact of biochar o...

More than two thirds of global nitrous oxide (N2O) emissions originate from soil, mainly associated with the extensive use of nitrogen (N) fertilizers in agriculture. Although the interaction of black carbon with the N cycle has been long recognized, the impact of biochar on N2O emissions has only recently been studied. Herein we reflect on propose...

p>Many recent reviews and meta-analyses of N₂O emissions do not include data from Mediterranean studies. In this paper we present a meta-analysis of the N₂O emissions from Mediterranean cropping systems, and propose a more robust and reliable regional emission factor (EF) for N₂O, distinguishing the effects of water...

Biochar is obtained by pyrolyzing biomass and is, by definition, applied in a way that avoids its rapid oxidation to CO2. Its use in agriculture includes animal feeding, manure treatment (e.g. as additive for bedding, composting, storage or anaerobic digestion), fertilizer component or direct soil application. Because the feedstock carbon is photos...

Climate change mitigation not only requires reductions of greenhouse gas emissions, but also withdrawal of carbon dioxide (CO2) from the atmosphere. Here we review the relationship between emissions reductions and CO2 removal by biochar systems, which are based on pyrolysing biomass to produce biochar, used for soil application, and renewable bioen...

Farming practices such as soil tillage, organic/mineral fertilization, irrigation, crop selection and residues management influence multiple ecosystem services provided by agricultural systems. These practices exhibit complex, non-linear interrelationships that affect crop productivity, water quality, and non-carbon dioxide greenhouse gases (GHG) e...

BACKGROUND Agronomic uses of biochar have been intensely explored in the last 15 years. Recently, a new generation of biochar‐based fertilizers has been developed. Raw biochar (BCH), nitrogen‐enriched biochar (N + BCH) or urea were added to a coir fiber‐based substrate for tomato cultivation, to assess seed germination, growth and fruiting of two c...

Current models predict significant warming and increasing aridity in Mediterranean areas, where crop yields and resilience are challenged by climate change. These conditions exacerbate the loss of soil organic carbon (SOC), a common issue in Mediterranean climates. A better understanding of the soil microbiome biodiversity can help us integrate cro...

Composting is a biological process widely accepted as a waste management technology to treat a wide range of biodegradable organic wastes. During the process, organic materials are decomposed by the action of aerobic microorganisms. As a microbial process, it is affected by those variables promoting or inhibiting microbial growth. The application o...

Meta-analyses show an overall decrease in soil N 2 O emissions after biochar (BC) amendment. Nonetheless, N 2 O mitigation with BC cannot be extrapolated to every BC-soil combination, inasmuch as an increase in soil N 2 O release has been occasionally reported. We hypothesized that BC characteristics are key, and performed two microcosm experiments...

The agronomic use of compost and biochar as soil amendments may exhibit contrasting results in terms of soil fertility and plant nutrition. The effects of the biennial application of biochar, compost and a blend of compost:biochar (90:10; % dw:dw) on the agronomical performance of an organically managed and well established 25-year-old olive orchar...

Soil organic carbon (SOC) sequestration in agricultural soils is an important tool for climate change mitigation within the EU soil strategy for 2030 and can be achieved via the adoption of soil management strategies (SMS). These strategies may induce synergistic effects by simultaneously reducing greenhouse gas (GHG) emissions and/or nitrogen (N)...

Introducción El biochar o carbón vegetal es un material rico en C orgánico que aplicado al suelo es capaz de, entre otras cualidades, permanecer estable durante muchos años. Su aplicación conjunta con fertilizantes nitrogenados puede mitigar la emisión de gases de efecto invernadero (GEIs) (Borchard et al., 2019). Además, también se ha demostrado q...

Novel fertilization strategies, such as the use of biochar-based fertilizers (BBFs) and the co-application of biochar with mineral fertilizers, have shown promising results for mitigating nitrous oxide (N2O) emissions and reducing N losses in agroecosystems. Two greenhouse experiments were performed with radish to evaluate: (1) the mitigation of yi...

In the Mediterranean arid region such as Southeast (SE) Spain, a considerable part of the fluvial network runs permanently dry. Here, many dry watercourses are embedded in catchments where agriculture has brought changes in carbon (C) and nitrogen (N) availability due to native riparian vegetation removal and the establishment of intensive agricult...

Different activation and N-doping treatments were used to produce biochar-based fertilizers (BBFs) with increased N concentration and slow N release. Pristine biochars were produced by pyrolysis of olive tree pruning feedstock at low and high temperatures (400 and 800 °C). These biochars were activated either by ultrasonication, or oxidation with h...

Carbon sequestration in agricultural soils is an important strategy to mitigate climate change which gained renewed attention in the EU soil strategy for 2030. Stimulation of soil organic carbon (SOC) sequestration can be achieved via soil management strategies. However, these strategies may stimulate greenhouse gas (GHG) emissions such as nitrous...

Little is known about the effect of biochar on the degradation of paracetamol in soil, considering the ubiquity of this pollutant in the environment. Given the importance of the electrochemical properties of biochar for contaminant remediation, we investigated the influence of raw and designer redox-active biochars on paracetamol degradation in soi...

In this study, we produced modified biochars with enhanced electrochemical properties to increase PCP remediation in soil. Although all biochars enhanced PCP remediation in aerobic conditions, only a few did in anaerobic soil. The most successful modifications were (i) the preloading of biomass with 10% w/w FeCl3, to obtain a biochar rich in redox-...

We synthesized 20 years of research to explain the interrelated processes that determine soil and plant responses to biochar. Biochar properties and its effects within agricultural ecosystems largely depend on feedstock and pyrolysis conditions. We describe three stages of reactions of biochar in soil: dissolution (1‐3 weeks); reactive surface deve...

Negative environmental impacts of intensive agriculture are often associated with low nitrogen (N) use efficiency. Different slow-release fertilizers have been proposed to improve N use efficiency and reduce associated losses, like the case of biochar-based fertilizers. The main objective of the present study was to produce and characterize novel b...

Worldwide, Mediterranean cropping systems face the complex challenge of producing enough high-quality food while preserving the quantity and quality of scarce water for people and agriculture in the context of climate change. While good management of nitrogen (N) is paramount to achieving this objective, the efficient strategies developed for tempe...

Various studies have established that feedstock choice, pyrolysis temperature, and pyrolysis type influence final biochar physicochemical characteristics. However, overarching analyses of pre-biochar creation choices and correlations to biochar characteristics are severely lacking. Thus, the objective of this work was to help researchers, biochar-s...

Various studies have established that feedstock choice, pyrolysis temperature, and pyrolysis type influence final biochar physicochemical characteristics. However, overarching analyses of pre-biochar creation choices and correlations to biochar characteristics are severely lacking. Thus, the objective of this work was to help researchers, biochar-s...

Biochar has been shown to influence microbial denitrification and mitigate soil N2O emissions. However, it is unclear if biochar is able to directly stimulate the microbial reduction of N2O to N2. We hypothesized that the ability of biochar to lower N2O emissions could be related not only to its ability to store electrons, but to donate them to bac...

Biochar has attracted great attention in the soil scientific community for its interaction with different biogeochemical cycles and its potential environmental and agronomical benefits. However, there is only limited information about its effect on plant secondary metabolism. In this manuscript, a biochar produced from olive tree pruning by slow py...

There is growing evidence on the importance of the redox properties of biochar for many environmental applications. However, its variability and the difficulty in controlling its redox properties could be delaying the use of biochar in those areas that involve the exchange of electrons, like microbial fuel cells or contaminant degradation related t...

The impact of different forms of nitrogen input, biochar amendments and their combination on the yield-scaled N2O emissions were investigated during the cultivation of a representative commercial crop. A field randomized block design with inorganic/organic fertilization and biochar amendment was established during a crop cycle of drip-irrigated bro...

Compost represents a sustainable alternative for peat (P) replacement in soilless plant cultivation, but its use can be limited by several inadequate physical and physicochemical properties. Biochar can alleviate some of the limitations of compost for its use as growth media by improving the physical properties, decreasing salinity and making the p...

Compost application has been suggested to sustain yields as well as reduce reactive nitrogen (N) loss in greenhouse vegetable production. However, there remains significant gaps in understanding the potential and mechanisms for compost application to reduce N leaching. Here, a leaching column experiment was conducted to examine N leaching under chi...

Aerobic soils are the largest biotic sink for atmospheric methane (CH4). Although agricultural intensification is known to adversely impact soil CH4 uptake, the application of organic amendments (e.g. composts, green residues) in agricultural soils has been found to stimulate the activity of CH4 oxidizers. However, little is known about the influen...

Over the last decades, the agricultural contribution to the global anthropogenic nitrous oxide (N2O) emissions has increased due to the increasing use of N fertilizers, and soil degradation among others (Kammann et al., 2017). The main processes leading to N2O emissions from soil are nitrification, denitrification and dissimilatory nitrate reductio...

Current intensive agricultural practices, although highly successful in terms of production, have been found to be environmentally unsustainable. One of the crucial approaches to increase agricultural sustainability is the recycling of organic wastes, since these materials often contain many beneficial nutrients for soil and agriculture. Recently,...

This paper reports the results on the agronomic performance of organic amendments in the EU 7th FP project “FERTIPLUS—reducing mineral fertilizers and agro-chemicals by recycling treated organic waste as compost and bio-char”. Four case studies on field-scale application of biochar, compost and biochar-blended compost were established and studied f...

The efficiency of biochar for reducing the levels of volatile organic compounds (VOC) was investigated in a composting mixture containing 90% poultry manure and 10% straw (with and without 3% biochar addition) at three different stages of the process. The use of a low application rate of biochar reduced the concentration of VOC during the thermophi...

Biochar has been found to interact with N transformations in soil but the mechanisms remain largely unknown. In this study we investigated the priming effect of combined biochar and urea inputs on soil inorganic N pools through an isotope tracer approach. Biochar was applied in combination with urea in two complementary laboratory experiments: (i)...

Among strategies suggested to decrease agricultural soil N2O losses, the use of nitrifcation inhibitors such as DMPP (3,4-dimethylpyrazole phosphate) has been proposed. However, the efciency of DMPP might be afected by soil amendments, such as biochar, which has been shown to reduce N2O emissions. This study evaluated the synergic efect of a woody...

Mediterranean climate areas are home to highly relevant and distinctive agro-ecosystems, where sustainability is threaten by water scarcity and continuous loss of soil organic-C. In these systems, recycling strategies to close the loop between crop production (and agro-related industries) and soil conservation are of special interest in the current...

Soil amendment with exogenous organic matter (EOM) represents an effective option for sustainable management of organic residues and enhancement of soil organic C (SOC) content. Optimization of soil amendment is hampered by the high variability in EOM quality and pedoclimatic conditions. A possible solution to this problem could be represented by s...

Biochar can reduce both nitrous oxide (N2O) emissions and nitrate (NO3-) leaching, but refining biochar’s use for estimating these types of losses remains elusive. For example, biochar properties such as ash content and labile organic compounds may induce transient effects that alter N-based losses. Thus, the aim of this meta-analysis was to assess...

El uso de inhibidores de la nitrificación como el 3,4-dimetilpirazol fosfato (DMPP) ha demostrado ser una estrategia eficaz para reducir las emisiones de N 2 O. Asimismo, la aplicación de biochar a suelos agrícolas se ha propuesto como herramienta efectiva para mitigar el cambio climático, ya que tiene potencial de secuestro de carbono recalcitrant...

Composting operations taking place at municipal solid waste (MSW) treatment plants represent a source of volatile organic compounds (VOC) to the atmosphere. Understanding the variables governing the release of VOC at these facilities is crucial to assess potential health risks for site workers and local residents. In this work the changes in the VO...

Biochar is traditionally made from clean lignocellulosic or waste materials that create no competition for land use. In this paper, the suitability of alternative feedstocks of agricultural and urban origins are explored. A range of biochars was produced from holm oak and a selection of organic wastes, such as greenhouse wastes, greenwastes, a cell...

An exhaustive meta-analysis of 132 long-term (≥ 10 years) studies worldwide was carried out to determine the effects of the use of organic amendments (OA) and OA + inorganic fertiliser (IF) on soil nutrient fertility. The responses of (1) crop yield [over the whole duration of the period (yieldm) and at the end of the experiment (yieldf)], (2) soil...

The recycling of organic wastes in agriculture contributes to a circular economy by returning to the soil nutrients and reducing the need of mineral-based fertilisers. An agronomical and environmental evaluation of a series of biochars prepared from a range of urban and agricultural wastes was performed by soil incubation experiments and pot trials...

De entre las fuentes antropogénicas, los suelos agrícolas son los mayores emisores de óxido nitroso (N2O) a la atmósfera. Se ha demostrado que el biochar, un producto con alto contenido en carbono que se obtiene mediante la pirólisis de residuos orgánicos, reduce la emisión de GEIs, y en especial de N2O, cuando es añadido al suelo. El mecanismo por...

Biochar, the solid carbon product from the pyrolysis of biomass, has been gaining attention due to its many possible applications such as soil amendment and water or air purification. Several effects have been observed when biochar is applied to soil, including reduced greenhouse gas emissions, contaminant degradation and increased microbial activi...

The use of biochar in organic waste composting has attracted interest in the last decade due to the environmental and agronomical benefits obtained during the process. Biochar presents favourable physicochemical properties, such as large porosity, surface area and high cation exchange capacity, enabling interaction with major nutrient cycles and fa...

The development of soil organic C (SOC) models capable of producing accurate predictions for the long-term decomposition of exogenous organic matter (EOM) in soils is important for the effective management of organic amendments. However, reliable C modeling in amended soils requires specific optimization of current C models to take into account the...

Agriculture and land use change has significantly increased atmospheric emissions of the non-CO2 green-house gases (GHG) nitrous oxide (N2O) and methane (CH4). Since human nutritional and bioenergy needs continue to increase, at a shrinking global land area for production, novel land management strategies are required that reduce the GHG footprint...

Uno de los problemas ambientales más importantes asociados con la agricultura es la emisión de gases de efecto invernadero (GEIs) que produce. El CH4 tiene un potencial de calentamiento es 34 veces superior al del CO2 y su contribución a los GEIs de procedencia antropogénica alcanza el 12%. El biochar es el...

Biochar is the solid product that results from pyrolysis of organic materials. Its addition to highly weathered soils changes physico-chemical soil properties, improves soil functions and enhances crop yields. Highly weathered soils are typical of humid tropics where agricultural productivity is low and needs to be raised to reduce human hunger and...

Pyrogenic carbonaceous materials can have a role in several biogeochemical redox reactions as electron transfer catalysts. Low N 2 O emissions in biochar amended soils can be related to its ability to act as an "electron shuttle", facilitating the transport of electrons to soil denitrifying microorganisms. Modifying biochar redox properties could b...

Nitrous oxide (N2O) is the strongest greenhouse gas associated with agricultural soils. Current agricultural practices, based on the use of N fertilizers, can lead to environmental N losses, with some losses occurring as N2O emissions. Among the strategies suggested by the Intergovernmental Panel on Climate Change to decrease N losses through agric...

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Revisión de las principales estrategias de reducción de GEI en sistemas agrícolas mediterráneos, tanto agronómicas como estructurales. Evaluación de barreras y oportunidades de implementación.

El CH4 es el segundo gas de efecto invernadero (GEIs) más importante, cuyo potencial de calentamiento es 34 veces superior al del CO2. La contribución de la agricultura a la emisión de GEIs de procedencia antropogénica alcanza el 12%, siendo el CH4 el responsable de la mitad de estas emisiones; valor que está en aumento debido al crecimiento de la...

The development of soil organic C (SOC) models capable to produce accurate predictions of the long term decomposition of exogenous organic matter (EOM) in soils is important for an effective management of organic amendments. However, reliable C modelling in amended soils requires specific optimization of current C models to take into account the hi...

An integrated assessment of the potential of different management practices for mitigating specific components of the total GHG budget (N2O and CH4 emissions and C sequestration) of Mediterranean agrosystems was performed in this study. Their suitability regarding both yield and environmental (e.g. nitrate leaching and ammonia volatilization) susta...

Background and aims Despite the high interest in biochar as soil amendment, the number of field studies is still limited, being experiments with perennial crops in arid lands particularly lacking. This study evaluated the application of compost and biochar in a drip-irrigated organic olive crop in a calcareous soil in South-East Spain. Methods Duri...

Many recent reviews and meta-analyses of N2O emissions do not include data from Mediterranean studies. In this paper we present a meta-analysis of the N2O emissions from Mediterranean cropping systems, and propose a more robust and reliable regional emission factor (EF) for N2O, distinguishing the effects of water management, crop type, and fertili...

The use of biochar has been revealed to have beneficial effects during the composting of manures and other N-rich materials by reducing N losses and enhancing the rate of the process. However, the impact of biochar has not been explored in other complex organic matrices with low N nitrogen that may hinder the composting process. The main novelty of...

A composting study was performed to assess the impact of biochar addition to a mixture of poultry manure and barley straw. Two treatments: control (78% poultry manure + 22% barley straw, dry weight) and the same mixture amended with biochar (3% dry weight), were composted in duplicated windrows during 19 weeks. Typical monitoring parameters and gas...

There is actually a common consensus in using biological technologies for the treatment of organic wastes. For instance, composting is used for aerobic biological stabilisation of organic wastes. The amount of materials and the variety of wastes composted are increasing. However, composting is inherently a process generating gaseous emissions. Gree...

A previously published meta-analysis of biochar impacts on soil N2O emissions by Cayuela et al. (2014) found a “grand mean” reduction in N2O emissions of 54 ± 6% following biochar application to soil. Here we update this analysis to include 26 additional manuscripts bringing the total to 56 articles. The updated meta-analysis confirms that biochar...

The agricultural recycling of olive mill and winery wastes through composting and land application is reviewed in this manuscript in terms of the impact on greenhouse gas (GHG) emissions and the potential for soil C sequestration. The rich lignocellulosic composition and the low N availability of olive mill wastes have been revealed as the driving...

There is actually common consensus to use biological technologies for the treatment of organic wastes. For instance composting involving the aerobic biological stabilization of organic wastes is gaining popularity. The amount of materials and the variety of wastes composted is increasing fast. However composting is a process emitting gases some of...

The presence of polycyclic aromatic hydrocarbons (PAHs) has been postulated as a mechanism by which biochar might mitigate N2O emissions. We studied whether and to what extent N2O emissions were influenced by the three most abundant PAHs in biochar: naphthalene, phenanthrene and pyrene. We hypothesised that biochars contaminated with PAHs would sho...

In spite of the numerous studies reporting a decrease in soil nitrous oxide (N2O) emissions after biochar amendment, there is still a lack of understanding of the processes involved. Hence the subject remains controversial, with a number of studies showing no changes or even an increase in N2O emissions after biochar soil application. Unraveling th...

Agricultural soils are a major source of N2O emissions. Increasing awareness on greenhouse gas emissions due to climate change has focused scientific research on strategies to reduce their release to the atmosphere. Biochar amendment has shown to affect carbon and nitrogen transformation and retention processes in soil. In particular, numerous labo...

The use of biochar, a carbonaceous material obtained by pyrolysis of biomass, is known to interact with key processes involved in soil N cycling: mineralization, denitrification, nitrous oxide emissions and N fixation. Soil Sand (%) 52 Silt (%) 21 Clay (%) 27 pH 8.1 EC (dS m-1) 0.51 TOC (%) 1.7 TN (%) 0.3 . Feedstock and biochar description Soil de...

Solid phase microextraction (SPME) is a fast, cheap and solvent free methodology widely used for environmental analysis. A SPME methodology has been optimized for the analysis of VOCs in a range of matrices covering different soils of varying textures, organic matrices from manures and composts from different origins, and biochars. The performance...