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The impact of tillage on the land atmosphere exchange of GHG from a Mediterranean rotation cropland

Presentation of the direct measurements of CH4 emissions from illegally managed waste landfills in Giugliano (Campania, Italy)

A mass balance approach to quantify methane (CH4) emission of four co-located landfills by means of airborne measurements and dispersion modelling was proposed and assessed. By flying grids at different heights above the landfills, atmospheric CH4 densities and wind components were measured along the edges and inside the study atmospheric volume, in order to calculate mass flows in the along- and across-wind directions. A steady-state Gaussian dispersion model was applied to build the concentration fields associated to unit emission from each landfill, while the contribution of each one to the total emission was assessed using a General Linear Model approach, minimizing the difference between measured and modeled mass flows. Results showed that wind spatial and temporal variability is the main factor controlling the accuracy of the method, as a good agreement between measured and modeled mass flows was mainly found for flights made in steady wind conditions. CH4 emissions of the entire area ranged from 213.5 ± 33.5 to 317.9 ± 90.4 g s−1 with a mean value of 252.5 ± 54.2 g s−1. Contributions from individual sources varied from 17.5 to 40.1 g m−2 day−1 indicating a substantial heterogeneity of the different landfills, which differed in age and waste composition. The proposed method was validated against tower eddy covariance flux measurements made at one of the landfills, revealing an overall agreement within 20%.

Net ecosystem exchange (NEE), leaf gas exchange and biochemical traits were investigated in an irrigated maize crop grown under Mediterranean conditions. Sub-optimal irrigation water supply determined a drought stress during the early vegetative growth stage (45-49 days after swing) that decreased NEE. Drought, in the late vegetative stage, also caused a reduction of leaf gas exchange. In the latter period, proline, glycine and serine, as well as sucrose leaf contents increased, while starch, proteins and glucose contents decreased. In the early reproductive stage, the crop experienced a longer dry spell that induced a reduction in canopy as well as in leaf gas exchanges, while protein and free amino acid contents decreased with respect to the late vegetative stage. Both ecophysiological and biochemical data demonstrate a good capacity of cultivar Pioneer PR32D99 to endure the environmental stress, related to Mediterranean summer drought, leading to an elevated dry matter yield at harvest. Photosynthetic apparatus appeared fairly resistant to soil water shortage due likely to the increased leaf content of organic solutes, such as amino acids and soluble sugars. © 2011 Società Botanica Italiana.

Ammonia (NH 3 ) fluxes were estimated by three inverse modelling methods over a sorghum field following the application of 240 kg N ha −1 of urea pills under a semi-arid Mediterranean climate. Ammonia volatilisation started following irrigation, which coincided with the third urea application. The maximum volatilisation rate was reached 7 days after irrigation. A clear dependence of the NH 3 volatilisation on irrigation and rainfall events was observed. The NH 3 fluxes ranged from −2.5 to 45 μg NH 3 m −2 s −1 . The canopy compensation point jumped from 9 μg NH 3 m −3 before urea hydrolysis to 131 μg NH 3 m −3 afterwards, while the soil compensation point varied in the meantime from 24 to 800 μg NH 3 m −3 on average. The soil-dominated observed NH 3 emissions were reasonably well reproduced by a two-layer resistance model. Overall, between 10% and 14% of the total nitrogen applied was volatilised.

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Quantificare le emissioni gassose delle aree di discarica non è sempre semplice: in genere, infatti, la produzione di biogas viene calcolata tramite modelli previsionali che tengono conto solo di parametri riguardanti i parametri chimico-fisici del rifiuto conferito in discarica. Quando però si tratta di gestire o cercare di bonificare delle aree comprendenti discariche abusive di cui non si conosce la natura del rifiuto, tutto diventa più complicato. Inoltre, i modelli non tengono conto delle variabili meteorologiche, importanti se si considera che da esse può dipendere l'emissione di gas serra. Un altro problema è l'assenza di una tecnica che permetta il monitoraggio costante delle emissioni di biogas permettendo l'intervento in caso di eventuali fughe di gas esterne al corpo della discarica, così come prescritto dal decreto legislativo 36/2003. Attualmente, non essendo ancora definito un metodo ufficiale per la determinazione delle emissioni diffuse, vengono effettuate delle misurazioni periodiche del gas di discarica a terra in modo da individuare eventuali "perdite" del sistema di captazione tramite l'uso di una particolare camera di cattura del biogas e di un analizzatore a raggi infrarossi. L'applicazione di una nuova tecnica per il monitoraggio delle emissioni potrebbe rivoluzionare il modus operandi ed aumentare le performance di recupero del biogas. Una ricerca svolta nell'ambito dei due progetti EDDYAPP e BioQuAr, ha quantificato sul campo le differenze in termini di emissioni di gas serra (anidride carbonica e metano, i principali componenti del biogas) tra una discarica in cui si recupera biogas ed una in cui non c'è captazione. Le misure sono state effettuate in continuo per un anno tramite l'installazione di una torre "eddy covariance" su discariche aventi approssimatamente la stessa età. Attraverso queste misure è stato monitorato in modo continuativo il tasso di biogas che viene disperso e che quindi non viene recuperato.

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The effect of the nitrification inhibitor 3,4-dimethylphyrazole phosphate (DMPP) on N-fertilized crop growth and soil N2O emissions were studied at two experimental sites in Southern Italy, characterised by a Mediterranean climate and different soil texture. The experiments were a randomized block design of two treatments: crop fertilized with NH4NO3 (considered the control treatment) or amended with DMPP plus NH4NO3 (considered the DMPP treatment). ANOVA was performed to assess differences between treatments and fertilization periods whereas simple and multiple linear regressions were performed in order to assess the effect of the soil-related in-dependent variables on soil gases emissions. Growth of potato plants fertilized with DMPP-added nitrogen was enhanced compared to control plants, whereas no benefit on maize plants grown during summer was observed. N2O emissions measured from soil to potato after the first fertilization with DMPP-added nitrogen was reduced during winter, but was higher than control after the second fertilizer application in spring, leading to comparable N2O emission factors (EF1) between treatments. In maize N2O emissions and EF1 were lower for DMPP compared to control treatment. The effectiveness of reduction in soil N2O emission was influenced by soil temperature and water-filled pore space (WFPS) in both experimental sites. However, the overall effect of WFPS was contrasting as N2O emissions were decreased in potato and enhanced in maize.

A super-site for the measurement of atmospheric pollutants from urban sources has been established in Naples where the complex layout of the coasts and surrounding mountains favours the development of combined sea breeze upslope winds and the evolution of return flows with several layers of pollutants and subsidence. The metropolitan area of Naples has one of the highest population densities in Europe with an important impact in terms of emissions associated with diesel/gasoline exhaust, industrial emissions, agricultural burning and waste disposal problem. In the super-site, located at the meteorological observatory of San Marcellino, an eddy covariance tower has been installed recently on the rooftop of the building: a fast response ultrasonic anemometer (Gill WindMaster) has been mounted on a 10-m mast, alongside three insulated inlet lines through which the air is sampled for reactive, non reactive gases and particulate. The height of the terrace is on average 35 m above the irregular street level, resulting in an overall measuring height of 45 m. Mixing ratios of CO2, CH4 and H2O are measured by an infrared spectrometer (10 Hz, Los Gatos Research); O3 mixing ratios are measured by a fast analyser (10Hz, FOS Sextant) for the calculation of fluxes, and referred to concentrations measured by a slower analyser (2B-Technologies, 205). NO and NOx are continuously quantified (1 Hz) using a NOx analyzer Eco Physics model (CLD 88p) associated with a photolytic converter (PLC 860). Size segregated aerosol are measured by gravimetric method at an hourly/daily frequency through a SWAM 5A Dual Channel (PM10 and PM2.5, FAI Instruments). A faster optical particle counter (4 Hz, FAI Instruments) allows the estimate of fluxes - as well as concentrations - of 22 classes of particles diameter. All analysers outputs are synchronised with the sonic anemometer through a common acquisition at 10 Hz using a CR3000 datalogger (Campbell Scientific). A full weather station is also available as ancillary measurements at the site including two webcams to record exceptional events to aid interpretation of the results. The fluxes are representative of varying footprint source areas, covering the historical centre of Naples, the harbour, and some main traffic arteries of the city. Preliminary results show that, during a stable event in the month of November, the mean urban levels of CO2 are between 420-520 ppm; the mean levels of CH4 span between 1.85-2.48 ppm, and the O3 levels are extremely variable, between 2 and 62 ppb. These follow NOx abundance, with values ranging between 0.5 and 84 ppb for NO, and 5 and 29 ppb for NO2, with an average NO2/NO ratio around 30%. Daily PM10 levels vary between 18 and 55 ?g/m3, and PM2.5 between 12 and 47 ?g/m3. The largest concentrations were measured from air coming from the harbour, coinciding with the presence of cruise ships. The year-long planned measurements will allow to establish relationships between the fluxes of greenhouse gases and the other pollutant species measured, to investigate the controls of the emission and provide relative emission factors for the urban sources.

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Gaseous emissions in the atmosphere in relation to anthropogenic activities are a growing menace for the environment at the planetary level. Agriculture and forestry may play a positive role by substituting biomasses to fossil hydrocarbons as a source of energy and via sequestration of carbon in the terrestrial sinks. Monitoring C dynamics in agricultural systems is an urgent priority in view of compiling national inventories of emissions and sinks. Due to the considerable incidence of arable land on emerged lands, the lack of directly measured data contribute to present uncertainties in the assessment of global C budget. The present experiment is aimed at monitoring CO2 and H2O net exchange of an irrigated agricultural system in the course of several growing seasons, in a farm sited in Eboli (Salerno). Alfalfa is presently grown, at its fourth year from establishment. Continuous monitoring of fluxes was started in July 2002 and will be continued throughout all stages of growth. Following, the sod will be cultivated and new crops established, so that C exchange in response to cultivation and management patterns will be evaluated. The eddy covariance flux monitoring apparatus has an open type configuration. A secondary station, logs at a frequency of 1 Hz the environmental variables needed to check energy balance closure and to model NEE response to environment. By adopting the Bowen ratio approach, an independent estimate of fluxes is made - to backup data during eddy station downtimes. Seasonal C budget are checked by destructive samplings of aerial and below-ground biomass. The relevant soil and canopy variables - according with the EC CARBOEUROFLUX project database - are determined at periodical intervals. By the mean of a labelling technique (14C), soil carbon budget will be reconstructed via small scale experiment on monoliths. The combination of direct flux measurement and stable isotopes determinations (13C) allows for partitioning of the different ecosystem factors of C budget. Concurrent CO2 air concentration and isotopic composition will be used to assess sources and sinks of CO2 of the system, adopting the well-known Keeling plot theoretical approach.

Climate evolution will cause significant changes in the quality and availability of water resources, affecting many sectors including food production, where available water resources for irrigation play a crucial role. Strategies focused on managing and conserving water are one way to deal with the impact; moreover concurring adaptation measurements will be needed to cope with the foreseen decline of water resource. This work deals with i) the impacts of climate change on water requirements of an horticultural crop, determined in an irrigated district in Southern Italy, ii) the possible irrigation scheduling options and their sustainability in the future, iii) the adaptation measurements that can be undertaken to protect production, relying on intra-specific biodiversity of agricultural crops. Two climate scenarios were considered: present climate (1961-90) and future climate (2021-2050), the former from climatic statistics, and the latter from statistical downscaling of general circulation models (AOGCM). Climatic data set consists of daily time series of maximum and minimum temperature, and rainfall on a grid with spatial resolution of 35 km. The analysis of climate scenarios showed that significant increases in summer maximum daily temperature could be expected in 2021-2050 period. Soil water regime was determined by means of a mechanistic model (SWAP) of water flow in the soil-plantatmosphere system. Twenty? soil units were identified in the district (in Sele Plain, Campania Region) and simulations were performed accounting for hydro-pedological properties of different soil units. Parameters of a generic tomato crop, in a rotation typical of the area, were used in simulations. Soil water balance was simulated in the present and future climate, both with optimal water availability and under constrains that irrigation schemes will pose. Indicators of soil water availability were calculated, in terms of soil water or evapotranspiration deficit. For several tomato cultivars, quantitative yield response functions to water availability were determined through the re-analysis of experimental data, derived from scientific literature. Variety-specific threshold values of yield reduction in dependence of soil water and evapotranspiration deficit were determined. The spatial pattern of soil water availability indicators was calculated., for present and future climate scenarios and for different irrigation scheduling options. Cultivars' threshold values were matched with indicators' values in all soil units. The future adaptability of the crop in the area is thus evaluated, and adaptation options that exploit the intra-specific biodiversity of the crop are indicated. The work was carried out within the Italian national project AGROSCENARI funded by the Ministry for Agricultural, Food and Forest Policies (MIPAAF, D.M. 8608/7303/2008)

Several methods are available for evaluating and correcting the underestimation of trace gas fluxes measured by eddy covariance (EC) method and due to the design and the setup of the employed equipment. Different frequency correction factors (CF) to apply to the measured EC ammonia (NH3) fluxes have been applied using the following approaches: (i) the spectral theoretical transfer function (CFTheor) with and without phase shift; (ii) the in situ ogive method (CFO); and (iii) the inductance correction method (CFL). The NH3 fluxes were measured in an experimental field located in south Italy, above a sorghum crop submitted to Mediterranean semi-arid climate and fertilized with urea. A fast analyser based on Tunable Infrared Laser Differential Absorption Spectroscopy (TILDAS) coupled with a quantum cascade (QC) laser was used to measure NH3 concentration at high frequency. The results showed that correction of the values of NH3 EC fluxes over natural surfaces are necessary for taking into account the dumping of high frequency contribution due to the coupling of ammonia fast analyser by QC-TILDAS and sonic anemometer. In particular, the calculated flux losses ranged between −23% (inductance method, with the CF threshold selected to 2.5) and −43% (experimental-ogive method); while the two theoretical transfer function approaches gave comparable loss estimates, i.e. −30 and −31% for the methods with time lag and phase shift, respectively.

Rice paddy fields are one of the greatest anthropogenic sources of methane (CH4), the third most important greenhouse gas after water vapour and carbon dioxide. In agricultural fields, CH4 is usually measured with the closed chamber technique, resulting in discontinuous series of measurements performed over a limited area, that generally do not provide sufficient information on the short-term variation of the fluxes. On the contrary, aerodynamic techniques have been rarely applied for the measurement of CH4 fluxes in rice paddy fields. The eddy covariance (EC) technique provides integrated continuous measurements over a large area and may increase our understanding of the underlying processes and diurnal and seasonal pattern of CH4 emissions in this ecosystem. For this purpose a Fast Methane Analyzer (Los Gatos Research Ltd.) was installed in a rice paddy field in the Po Valley (Northern Italy). Methane fluxes were measured during the rice growing season with both EC and manually operated closed chambers. Methane fluxes were strongly influenced by the height of the water table, with emissions peaking when it was above 10-12 cm. Soil temperature and the developmental stage of rice plants were also responsible of the seasonal variation on the fluxes. The measured EC fluxes showed a diurnal cycle in the emissions, which was more relevant during the vegetative period, and with CH4 emissions being higher in the late evening, possibly associated with higher water temperature. The comparison between the two measurement techniques shows that greater fluxes are measured with the chambers, especially when higher fluxes are being produced, resulting in 30% higher seasonal estimations with the chambers than with the EC (41.1 and 31.8 g CH4 m-2 measured with chambers and EC respectively) and even greater differences are found if shorter periods with high chamber sampling frequency are compared. The differences may be a result of the combined effect of overestimation with the chambers and of the possible underestimation by the EC technique., JRC.H.2-Air and Climate

International audience; Data sets of biometeorological measurements of ecosystem CO2 flux, combined with harvest and manure data from several European cropland were integrated to provide an assessment of the carbon budget. Sites encompassed different climatic regions and contrasting crop rotations. The influence of different crops and management practices was also assessed to identify some of the major factors contributing to the cropland carbon balance. Since crops are rotated and cropping periods do not always follow the calendar year, net ecosystem production (NEP) as well as net biome production (NBP) sums of full crop rotations or of at least 4 years of longer-term crop rotations and of monocultures were used. In a second analysis NBP sums were correlated to soil properties. Finally, the data were combined with additional data to derive a mean annual GHG balance for the European cropland sites under consideration. Five crop rotations and two monocultures were integrated over 4 years. During 4 years the average annual NEP was −240 ± 113 g C m−2 y−1. On average, 382 ± 117 g C m−2 y−1 were harvested, where as average carbon inputs by manure and seeding was 47 ± 51 g C m−2 y−1. The average NBP of the seven sites under consideration was estimated to be a carbon loss of 95 ± 87 g C m−2 y−1. The full GHG balance of the considered sites was estimated to be 160 g C m−2 y−1 in CO2-equivalents. These results challenge current good practice guidelines that predict neutral carbon budgets for systems where the inputs of manure and crop residues are of comparable magnitude to those associated with the sites examined in this study. Ongoing humus loss in spite of good practice is mainly related to soils with high carbon concentrations which are not in equilibrium but may also be a result of already ongoing climate change. A modification in the good practice guidelines to increase carbon inputs may be required. Results from a representativeness analysis suggest that more than 50 sites are necessary for a European cropland flux network to adequately represent the variability of climate, soil and management within the European continent. Thus, the uncertainties due to the network design are currently bigger than the uncertainty intrinsic in the measurement method