Publikasjoner
NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.
2006
Forfattere
Daniel Rasse Marie-France Dignac Bahri Haithem Cornelia Rumpel Mariotti Andre Claire ChenuSammendrag
Lignin har lenge vært antatt å være en viktig kilde for karbon i jord på grunn av sin lite nedbrytbare polyfenol-struktur i forhold til andre grupper organisk materiale. Studier av omsetning av lignin har imidlertid vist motstridende resultater og de fleste tyder på at en stor del av lignin fra planterester brytes ned i løpet av ett år etter innblanding i jord. Vi har her foreslått en to-pool modell hvor lignin i ferskt plantemateriale (Lp) enten kan opptre delvis beskyttet i jord mot videre nedbryting (Ls) eller blir omdannet til ikke-lignin produkter. Data til kalibrering av modellen ble skaffet ved hjelp av isotopanalyse av lignin spesifikk 13C fra en serie med 0-9 års ensidig maisdyrking etter hvete på en lettleire i Frankrike. Lignin ble kvantifisert ved CuO-oksidasjon som VSC-lignin, det vil si som summen av fenoltypene vanillil (V), syringyl (S) og coumaryl (C). Kalibreringene indikerte at Lp har en omsetningshastighet raskere enn ett år og at 92 % ble mineralisert til CO2 eller omdannet til andre ikke lignin-produkter, mens bare 8 % tilhørte Ls-fraksjonen. Estimert omsetningshastighet av Ls-fraksjonen var 0,05 år-1. Modellen tydet også på at om lag halvparten av Lp ikke var målt fordi det var blitt fjerne gjennom siktingen av prøven (5 mm). Som konklusjon, modellen tydet på at kjemisk bertandighet ikke er tilstrekkelig alene til å forklare omsetningen av VSC-lignin i jord, og at den mest relevante mekanismen funksjonelt synes å være overgang av VSC-ligning molekyler og fragmenter fra nedbrutt plantevev til jord-beskyttede fraksjoner.
Forfattere
Daniel Rasse Marie-france Dignac Haithem Bahri Cornelia Rumpel André Mariotti Claire ChenuSammendrag
Lignin has long been suspected a major source of stable carbon in soils notably because of the recalcitrant nature of its polyphenolic structure relative to other families of plant molecules. However, lignin turnover studies have produced conflicting results, most of them suggesting that large proportions of plant-residue lignin decompose within a year of incorporation into soils. Here, we propose a two-reservoir model where lignin in undecomposed plant residue (Lp) can either reach soil fractions where it is somewhat protected from further decomposition (Ls) or is transformed to non-lignin products. Model calibration data were obtained through compound-specific 13C isotopic analyses conducted in a zero- to nine-year chronosequence of maize monoculture after wheat in a temperate loam soil of the Paris basin. Lignin was quantified by CuO oxidation as VSC-lignin, i.e., the sum of vanillil- (V), syringyl- (S) and coumaryl-type (C) phenols. Model calibrations indicate that Lp has a turnover rate faster than one year and that 92% is mineralized as CO2 or transformed into other non-lignin products, while only 8% reaches the Ls fraction. Estimated turnover rate of the Ls fraction was 0.05 yr-1. The model also suggested that about half of Lp was not measured because it had been excluded from the samples in the process of sieving at 5 mm. In conclusion, the model indicates that chemical recalcitrance alone is not sufficient to explain VSC-lignin turnover in soils, and that, functionally, the most relevant mechanism appears to be the transfer of VSC-lignin molecules and fragments from decomposing plant tissues to soil-protected fractions.
Sammendrag
Chemical recalcitrance of specific molecules is one of the factors governing organic matter stabilization in soils. Little is known about the relationship between the chemical nature and the dynamics of soil organic matter at the long-term scale. Lignin molecules are abundant in plant tissues and are generally considered as slowly biodegradable in soils. In a previous study, using compound specific isotopic tracer techniques applied to agricultural lands converted from C3 to C4 cropping, we showed that lignin turnover was faster than that of total organic carbon. Lignin dynamics was well described by a two-pool model, distinguishing lignins in fresh plant residues and those more closely associated to the soil matrix. These two pools may be transformed into non-lignin products, which includes CO2, microbial biomass and chemical substances, which are no longer recognized as lignin derivatives. The aim of the present work was to study the nature and dynamics of these non lignin products formed during lignin degradation in a laboratory incubation of 13C-labelled lignin with soil. Maize plants were grown for 1 month under 13C enriched CO2. The lignins of leaves and stems were isolated after treatment with cellulolytic enzymes and solubilization in dioxane:water (1:9). The Milled Maize Lignin (MML) obtained had a 13C abundance of 1.4 %. Solid-state 13C NMR spectroscopy of MML before analysis showed that the isolation method produces a lignin-cellulose complex, as indicated by the presence of some polysaccharides (the 60-115 ppm region represented about 40 % of total C of isolated lignins). Lignins were incubated with soil (1 mg lignin/g soil) at 20°C in sealed glass jars and analyzed after 1, 2, 4, 8, 16, 32 and 48 weeks. A control sample was incubated without lignin. We monitored the mineralization, solubilization and incorporation in the microbial biomass of lignin C by measuring 13C enrichments in respired CO2, water-soluble fractions, and fumigated biomass, respectively. Lignins remaining in incubated soils were quantified by CuO oxidation and the 13C contents of vanillyl, syringyl and cinnamyl units (VSC) were measured. After 4 months, 3% of the 13C of the labelled lignin was mineralized. This mineralization rate was less than that found by Martin and Haider (1979) for DHP lignins but more than the 5% per year found in situ by Dignac et al. (2005). Less than 0.5% of incubated lignin C was water soluble and 0.5 % was incorporated into the soil microbial biomass. The main part (96%) of incubated MML remained in soil. We used compound-specific isotopic analysis of the CuO oxidation products and pyrolysis analysis to estimate the proportion of intact lignins remaining in the soil.
Forfattere
Marie Alexis Cornelia Rumpel Patrick Louchouarn Nicolas Péchot Daniel Rasse André MariottiSammendrag
Fire is the main disturbance for terrestrial ecosystems, with a strong effect on biogeochemical cycles. Especially, part of the ecosystem organic matter (OM) is chemically modified by temperature elevation. Depending on fire severity, a big variety of chemical structures is produced ranging from slightly altered OM to strongly condensated structures. The fate of these pyrogenic OM when added to soil is unclear. Highly aromatic black carbon (BC) may be the most stable part of the continuum. At molecular level, levoglucosan is the main fire product of cellulose alteration. These two compounds have been separately used as tracers of plant biomass burning in aerosols, soils and sediments. Their combined use may provide closer insight into conditions and OM transformations that occurred during the fire. We aimed at quantifying BC and levoglucosan in plant residues after fire. Their production rates were compared to improve the understanding of their relative contribution to soil OM. Litter leaves were collected after a prescribed burning. The >2mm fraction was visually separated into charred (black, shiny) and unburned (brown) particles. BC was quantified by chemical oxidation (K2Cr2O7/H2SO4) and elemental analyses. Levoglucosan was identified and quantified by GC/MS analysis of the total lipid extract. Unburned post-fire leaves contain more levoglucosan than charred leaves, showing that a chemical alteration occurred despite no visual evidence. Moreover BC and levoglucosan concentrations are negatively correlated. This is consistent with their expected production temperatures: levoglucosan may be destroyed at temperature BC is produced. Relative quantity of theses compounds may then provide information about fire severity. However while BC is expected to be stable in soil, levoglucosan may suffer from degradation processes. Consequently, for historical reconstitution their respective fates in soil degrading conditions have to be considered.
Sammendrag
Environment Synthesis) family of crop models predicts cereal growth, development, and yield. CERES simulates nitrogen (N) as a yield"limiting macronutrient. Because N leaching is an economic and environmental concern, this study evaluated if CERES can be used to predict N leaching under different N management scenarios: background leaching in unfertilized corn (Zea mays L.), alfalfa (Medicago sativa L.) residue mineralization, and till versus no"till management. Data were collected during a 7"yr field experiment on tillage practices in a maize"alfalfa"maize succession. Sensitivity analyses were performed for decomposition rates of the different residue pools and the relative proportions of carbohydrate, cellulose, and lignin in the residues. During the last 5 yr, under corn, CERES accurately simulated nitrate leaching from the no"till lysimeters. Nitrate leaching was underestimated in the tillage treatments, possibly because CERES does not simulate tillage. The model is not very sensitive to the decomposition rates and to the composition of the residues
Forfattere
Erik J. JonerSammendrag
Fytoremediering er en kostnadseffektiv og miljøvennlig teknologi til opprensning av forurenset jord og vann ved hjelp av planter. Ulike anvendelser benytter seg av planters evne til absorpsjon og nedbryting, eller synergistiske effekter der samspill med mikroorganismer inngår. Potensialet for fytoremediering i Norge er stort og ubenyttet.
Forfattere
Lorenxo Borselli Torri Dino Lillian Øygarden De Alba Saturnio Josè A. Martinez-Casasnovas Paolo Bazzoffi Gergely JakabSammendrag
Boken Soil Erosion in Europe gir en omfattende oversikt over erosjonsprosesser, omfang og fordeling av erosjon i Europa. Den er delt inn i to deler: " Nasjonale oversikter over erosjon og relaterte problemer " Erosjonsprosesser, erosjonsrisiko og konsekvenser av erosjon og tiltak Soil Erosion in Europe er skrevet som en avslutning og oppsummering på et femårig samarbeid i regi av EU sin COST-aksjon 623: Soil erosion and global change der 20 land og 114 forfattere har bidratt. Boka er svært verdifull for alle som er opptatt av jord- og miljøspørsmål, spesielt forskere og studenter som ønsker å få en oversikt over dette fagområdet.
Forfattere
Lillian ØygardenSammendrag
Det er ikke registrert sammendrag
Sammendrag
Det er ikke registrert sammendrag
Forfattere
Lillian ØygardenSammendrag
Det er ikke registrert sammendrag