1,721,040 research outputs found
MULTIPLE ECOSYSTEM SERVICES PROVISION FROM PERENNIAL BIOENERGY CROPS
No full textLa sfida nel 21esimo secolo è quella di fornire cibo e energia ad un mondo in continua crescita demografica e allo stesso tempo conservare l’ambiente. In questa tesi uno scenario alternativo di uso del suolo per la produzione di bioenergia è stato testato: le fasce tampone bioenergetiche. Considerate le problematiche ambientali legate al trilemma “cibo-energia-ambiente”, la struttura del Millennium Ecosystem Assessment sui servizi ecosistemici (SE) fornisce l’opportunità di esaminare l’impatto ambientale di questo nuovo scenario bioenergetico. In questa tesi ho mirato a determinare in che misura le colture bioenergetiche poliennali influenzino la fornitura multipla di SE quando coltivate come fasce tampone. Per raggiungere questo obiettivo, ho combinato una revisione sistematica della letteratura sui SE forniti da colture energetiche poliennali (CEP) con una prova sperimentale su fasce tampone bioenergetiche.
Applicando una metodologia di attribuzione di punteggi agli impatti sui SE estratti dal materiale bibliografico raccolto, ho mostrato come coltivando le CEP lungo i margini dei campi coltivati esista una grande opportunità per sostenere la fornitura multipla di SE. La coltivazione delle CEP come fasce tampone adiacenti a campi agricoli può migliorare i SE di regolazione del clima, dell’acqua e della biodiversità, sostenere la salute del suolo e fornire biomassa dedicata alla produzione di bioenergia. Al contrario, la conversione di margini di campo di prati stabili ha mostrato un impatto netto negativo sulla fornitura multipla di SE.
Tuttavia, due sono i principali svantaggi che sono stati individuati relativamente alla creazione e alla gestione delle fasce tampone bioenergetiche. Primo, diversi sono i fattori sito-specifici di tipo idro-pedologico lungo i margini dei campi che devono essere tenuti in considerazione poiché possono avere un impatto negativo sull’affrancamento delle colture e la loro produttività a medio-lungo termine. Secondo, riguardo la catena di approvvigionamento della biomassa, uno spazio di lavoro limitato per le macchine agricole è stato riconosciuto come principale inconveniente per le fasce tampone bioenergetiche rispetto alle CEP coltivate in pieno campo. Questo limite logistico di natura spaziale può inevitabilmente incrementare i tempi e le operazioni di taglio e raccolta della biomassa e quindi in ultima il consumo di combustili fossili.
Grazie ad una prova sperimentale su fasce tampone bioenergetiche condotta in un terreno sabbioso-limoso con falda acquifera poco profonda contaminata da nitrati di origine agricola, si è dimostrato come fasce tampone coltivate con miscanto e salice siano in grado di intercettare e rimuovere i nitrati in falda (>60%) tanto quanto fasce tampone con specie avventizie. CEP come miscanto e salice, grazie ai loro apparati radicali profondi, hanno mostrato essere in grado di promuovere delle relazioni pianta-suolo-microorganismi lungo l’intero profilo del suolo utili ai fini ambientali delle fasce tampone bioenergetiche. Infatti, negli strati più profondi, una maggiore biomassa radicale ha portato le CEP a superare le specie avventizie in termini di rimozione biologica dei nitrati dal suolo e mitigazione potenziale dei gas serra. Inoltre, i risultati relativi alla produzione di biomassa e le asportazioni di N legata alla fase di raccolta hanno confermato ulteriormente come la coltivazione di CEP lungo i corsi d’acqua sia una strategia win-win: produzione di biomassa e protezione dell’ambiente.
In conclusione, il potenziale rivelato dalle CEP in termini di fornitura multipla di SE suggerisce che la loro coltivazione, come elementi paesaggistici perenni in posizioni strategiche all'interno di paesaggio agricolo, è un'opzione promettente per promuovere l'intensificazione ecologicamente sostenibile degli agroecosistemi.The 21st century will challenge agriculture to feed and fuel a growing world while conserving the environment. In this thesis an alternative bioenergy land use scenario to the conversion of marginal land has been tested: the bioenergy buffers. Given the environmental issues related to “food-energy-environment” trilemma, the Millennium Ecosystem Assessment framework on ES provides an opportunity to examine the environmental impacts of this new bioenergy land use scenario. In this thesis I aimed to determine to what extent do the perennial bioenergy crops affect the delivery of multiple ES when cultivated as bioenergy buffers. To reach this aim, I combined a systematic revision of literature on ES provided by perennial bioenergy crops with a field experiment on bioenergy buffers.
Applying an impact scoring methodology to the effects on ES extracted from literature, I showed that, cultivating perennial bioenergy crops along field margins of former croplands offer a great opportunity to sustain the provision of multiple ES. The cultivation of perennial bioenergy crops on field margins can improve climate, biodiversity and water regulation services, sustain soil health and provide biomass for energetic purposes. On the contrary, grassland conversion showed a net negative impact on multiple ES provision.
Nevertheless, I found two main shortcomings related to bioenergy buffers establishment and management. First, several site-specific factors along field margins must be taken into account, because they can affect crop establishment and buffers long-term productivity. Second, regarding to biomass supply chain, a limited working space for the farm machinery operations has been recognized as the main disadvantages of bioenergy buffers compared to large-scale bioenergy plantations. This spatial logistics constraint may inevitably increase harvest and collection operation times and fossil fuel consumption.
Conducting a field experiment with bioenergy buffers in a nitrate-enriched shallow groundwater, I showed that miscanthus and willow buffers are able to efficiently intercept and remove from groundwater the incoming NO3-N as much as buffer strips with spontaneous species. Yet, due to their deep rooting systems, bioenergy buffers promote significant plant-microbial linkages along the soil profile. At deeper soil layers, a higher fine root biomass led perennial bioenergy crops to outperform patches of adventitious vegetation in terms of biological N removal from soil and belowground GHG mitigation potential. The results on biomass production and N removal via harvesting further confirmed that the cultivation of perennial bioenergy crops along watercourses is an effective win-win strategy: biomass production and protection of the environment.
In conclusion, the revealed potential of perennial bioenergy crops on multiple ES provision implies that their cultivation as perennial landscape elements in strategic locations within landscape is a promising option to promote the ecological sustainable intensification of agroecosystems
Soil and ecosystem services: Current knowledge and evidences from Italian case studies
No full textSoil management is fundamental to all agroecosystems and affects ecosystem processes that are involved in the provision of multiple ecosystem services (ES). Agricultural soils are the habitat for key functional organisms which collectively as soil biota contribute to soil ES provision: supporting biomass production and nutrient cycling, regulating of climate, water and biological control of pests and diseases. As result of an increased awareness on the importance of soil ES, soil science is playing an active role in informing the ecological intensification of agriculture. In this study, the lessons learned from Italian case studies on the usefulness of using a soil health assessment framework based on multiple soil ES are presented. Soil health as an integrative property of agroecosystem management can be evaluated with a set of physical, chemical, and biological indicators representative of essential soil ES. This is the basis of the Soil Management Assessment Framework (SMAF) (Andrews et al., 2004) and it is based on a three-step process that includes indicator selection, indicator interpretation, and integration into a final index. In northern Italy, several field trials have been set up to assess multiple ES provision from bioenergy crops cultivated on marginal conditions and from contrasting vegetable cropping systems. These studies revealed how the use of a comprehensive soil health assessment framework can help: (1) to identify the best soil management practices that deliver multiple ES and (2) to support resource-efficient production. Beyond academic research, the integration of multiple indicators of soil health within the assessment of agroecosystems sustainability is essential if we want to promote ecological intensification of food and bioenergy production
Measurement of total and extractable enzyme activity from soil and decomposing litter
No full textThe total and extractable activities of the enzymes β-glucosidase (bgluc), cellobiosidase (cell), xilanase (xil), chitinase (chit), leucine aminopepditase (leu) and acid phosphomonoesterase (acP) were determined in soil and decomposing litter of miscanthus (Miscanthus x giganteus L.) and black locust (Robinia pseudoacacia L.). The objective was to quantify the enzyme-specific extractability of a desorption-based fluorometric enzyme assay and whether the extractability is affected by soil and litter type. Soil and litter samples were extracted in 2mL eppendorf tubes with glass/ceramic beads and lysozyme solution. Soil suspensions were incubated in a stirring device and aliquotes of the supernatant were dosed in 384-well microplates after centrifugation to determine total activity. The extractable activity was measured on the supernatant taken from incubated suspension. Extractability of soil enzymes (as % of the total activity) was on average as follows: bgluc (3%), cell (11 %), xil (4%), chit (8%), leu (44%) and acP (13%). A significant effect of SOC and FBC/MBC on acP and leu extractability was observed. Extractability of litter enzymes, instead, was on average as follows: bgluc (25%), cell (10 %), xil (19%), chit (16%), leu (31%) and acP (28%). A significantly higher extractability for chit and leu was observed in miscanthus litter (C/N: 71, Lignin/N: 32) compared to black locust litter (C/N: 17, Lignin/N: 6). We also observed that extractability in both litter types increase significantly in bgluc (+405%), xil (+242%), cell (+217%) and acP (+454%) during the late stage of decomposition. This method enabled the quantification of total and extractable activities of several soil/litter hydrolytic enzymes
High-throughput spectrophotometric assay of potential soil nitrate reductase activity
No full textSoil denitrification can either be measured as denitrification rates by quantifying N2O production with the acetylene inhibition method or by assessing the activity of nitrate reductase - NRA (EC 1.7.99.4). We updated the traditional single-tube assay of potential NRA based on soil anaerobic incubation by developing an high-throughput, sensitive and low-cost spectrophotometric assay. We measured NRA across a range of soil types, soil depths and contrasting cropping systems to determine the relative sensitivity of this alternative method as an indicator of biological NO3 removal. The method involves the determination of NO2-N production after adding KNO3 as a substrate and 2,4-dinitrophenol (DNP) as an inhibitor of nitrite reductase but not of nitrate reductase. We combined the use of 2-mL 96-well deep-wells and 96-well microplates for incubation, extraction, centrifugation and determination of NRA. Our results show that the method has a low detection limit (<2 μg NO2-N gsoil-1 day-1), high precision (CV 0.3-2.1%) and enables the detection of significant differences on NRA among: 1) different perennial energy crops cultivated as buffer strips, 2) contrasting soil management practices (including cover crops and tillage systems), 3) different crop growing seasons. NRA was significantly related to NO3 content, DOC and fine root biomass. With this method one hundred samples in two eight-hour working days can easily be processed by a well-trained operator in a well-equipped laboratory, and even more if the weighting and liquid handling are automatized. Our results demonstrate the usefulness of our high-throughput NRA assay in quickly and inexpensively assessing changes in the soil biological NO3 removal as affected by cropping systems
Managing Bioenergy Production on Arable Field Margins for Multiple Ecosystem Services: Challenges and Opportunities
No full textGrowing crops for bioenergy is increasingly viewed as conflicting with food production. However, energy use continues to rise and food production requires fuel inputs, which have increased with intensification. The debate should shift from “food or fuel” to the more challenging target: how the increasing demand for food and energy can be met in the future, particularly when water and land availability will be limited. As for food crops, also for bioenergy crops it is questioned whether it is preferable to manage cultivation to enhance ecosystem services ("land sharing" strategy) or to grow crops with lower ecosystem services but higher yield, thereby requiring less land to meet bioenergy demand ("land sparing" strategy). Energy crop production systems differ greatly in the supply of ecosystem services. The use of perennial biomass (e.g. Switchgrass, Mischantus, Giant reed) for energy production is considered a promising way to reduce net carbon emissions and mitigate climate change. In addition, regulating and supporting ecosystem services could be provided when specific management of bioenergy crops is implemented. The idea of HEDGE-BIOMASS* project is to convert the arable field margins to bioenergy crop production fostering a win-win strategy at landscape level. Main objective of the project is to improve land management to generate environmental benefits and increase farmer income. The various options available in literature for an improved field boundary management are presented. The positive/unknown/negative effects of growing perennial bioenergy crops on field margins will be discussed relatively to the following soil-related ecosystem services: (I) biodiversity conservation and enhancement, (II) soil nutrient cycling, (III) climate regulation (reduction of GHG emissions and soil carbon sequestration/stabilization, (IV) water regulation (filtering and buffering), (V) erosion regulation, (VI) pollination and pest regulation. From the analysis of available data, it emerges that production of biomass for bioenergy on field margins improves ecosystem services, depending upon the soil/agroecosystem health status of arable land displaced by the bioenergy crop. Considering that climate change is a dominant driver for agroecosystem health and perennial bionergy crops tend to stabilize soil C in arable land, it will be necessary to focus our attention to the improvement of climate regulation ecosystem service value in ecologically-degraded arable field margins. This management option seems to be the most sustainable strategy to enhance a win-win strategy: namely, sequestering carbon, producing biomasses for energetic purposes, improving the whole set of ecosystem services affected by soil organic matter, leaving, at the same time, more arable land for food and fiber crops
Improvement of Soil Microbial Diversity through Sustainable Agricultural Practices and Its Evaluation by -Omics Approaches: A Perspective for the Environment, Food Quality and Human Safety
No full textSoil is one of the key elements for supporting life on Earth. It delivers multiple ecosystem services, which are provided by soil processes and functions performed by soil biodiversity. In particular, soil microbiome is one of the fundamental components in the sustainment of plant biomass production and plant health. Both targeted and untargeted management of soil microbial communities appear to be promising in the sustainable improvement of food crop yield, its nutritional quality and safety. –Omics approaches, which allow the assessment of microbial phylogenetic diversity and functional information, have increasingly been used in recent years to study changes in soil microbial diversity caused by agronomic practices and environmental factors. The application of these high-throughput technologies to the study of soil microbial diversity, plant health and the quality of derived raw materials will help strengthen the link between soil well-being, food quality, food safety and human health
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Enzymatic activities and microbial biomass as affected by glyphosate under conservation and conventional agriculture.
No full textGlyphosate (N-phosphonomethyl glycine) plays an important role in weed control. Since microorganisms are major soil decomposers driving key biogeochemical processes, effects of glyphosate on soil microorganisms need to be assessed. The influence of glyphosate under conservation (NY) and conventional agriculture (CT) on the soil microbial biomass and soil enzymatic activities was investigated. Soil samples (0-10 cm depth) were collected in 2013-2015 (2th-5th years of the field trial) before and 20 days after glyphosate application (2 kg ha-1). Soil microbial biomass was assessed through an high-throughput dsDNA-based method based. Eight soil enzymatic activities were determined: acetate esterase, β-glucosidase, leucine-amminopeptidase, chitinase, alkaline and acid phosphatase, pyrophospatase phosphodiesterase, phosphodiesterase. These activities were determined using a 384-well microplate-, desorption-based fluorometric enzyme assay. All enzyme activities and dsDNA were not significantly affected by the glyphosate application either under CT and NT. In NT treatment we also observed that all soil enzymatic activities were nearly doubled in three years. Leucine-amminopeptidase, alkaline phosphomonoesterase and β-glucosidase were the enzymes that showed the highest increased over time under NT, respectively of 45%, 64% and 38%. These enzymes under CT showed instead a nearly constant activity. dsDNA was found higher under NT (18g dsDNA gsoil-1) compared to CT (11g dsDNA gsoil-1). Soil enzymes and dsDNA measured with this high-throughput method helped to reveal the non-target effect of glyphosate on soil microbial community and the positive effects of adopting NT
Impacts of willow and miscanthus bioenergy buffers on biogeochemical N removal processes along the soil-groundwater continuum
Full text linkIn this paper the below- and above-ground biomass production in bioenergy buffers and biogeochemical N removal processes along the soil-groundwater continuum were assessed. In a sandy loam soil with shallow groundwater, bioenergy buffers of miscanthus and willow (5 and 10 m wide) were planted along a ditch of an agricultural field (AF) located in the Po valley (Italy). Mineral N forms and dissolved organic C (DOC) were monitored monthly over an 18 month period in groundwater before and after the bioenergy buffers. Soil samples were measured for inorganic N, DOC, microbial biomass C (MBC) and N (MBN), and potential nitrate reductase activity (NAR). The results indicated that bioenergy buffers are able to efficiently remove from groundwater the incoming NO3-N (62%-5 m and 80%-10 m). NO3-N removal rate was higher when nitrate input from AF increased due to N fertilization. Willow performed better than miscanthus in terms of biomass production (17 Mg DM ha-1 y-1), fine root biomass (5.3 Mg ha-1) and N removal via harvesting (73 kg N ha-1). The negative nonlinear relationship found between NO3-N and DOC along the soil-groundwater continuum from AF to bioenergy buffers indicates that DOC:NO3-N ratio is an important controlling factor for promoting denitrification in bioenergy buffers. Bioenergy buffers promoted soil microbial functioning as they stimulated plant–microbial linkages by increasing the easily available C sources for microorganisms (as DOC). First, willow and miscanthus promoted high rates of biological removal of nitrate (NAR) along the soil profile. Second, rhizosphere processes activated the soil microbial community leading to significant increases in MBC and microbial N immobilization. Herbaceous and woody bioenergy crops have been confirmed as providing good environmental performances when cultivated as bioenergy buffers by mitigating the disservices of agricultural activities such as groundwater N pollution
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