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.
1999
Forfattere
Steinar DraglandSammendrag
Det er ikke registrert sammendrag
Forfattere
Steinar Dragland Morten MunkebySammendrag
Denne litteraturoversikten er laget i forbindelse med at EU har vedtatt en forordning om maksimalgrenser for nitrat i salat og spinat. Det finnes flere salattyper, men forordningen gjelder bare hagesalat. Oversikten viser hvordan næringstilgang, lysforhold, temperatur, karbondioksyd, tørke, utviklingsstadium, behandling og oppbevaring etter høsting, kan påvirke konsentrasjonen av nitrat i plantene. Det blir påpekt at forskjellige analysemetoder vil gi forskjellige resultater når det gjelder nitratinnhold. Til slutt er det gitt en konklusjon som retter seg mot de som dyrker salat og spinat.
Forfattere
Trond Henriksen T.A BrelandSammendrag
The objectives of our work were (1) to investigate the response of wheat (Triticum aestivum L.) straw decomposition to increasing nitrogen (N) availability (0.5, 0.8, 1.2 and 1.9% N of straw dry matter) in a microcosm experiment at controlled temperature (15°C) and moisture (-0.01 MPa), (2) to elucidate underlying mechanisms at the microbial-community level, and (3) to develop a model according to the measurements. Concentrations of available N (straw N and soil inorganic N) below 1.2% of straw dry matter significantly reduced the rate of carbon (C) mineralization from straw residues, and the growth of total soil microbial biomass (chloroform fumigation-extraction). The negative effects appeared shortly after the pool of soil mineral N had been depleted. The N effect on the microbial community was mainly caused by a reduced fungal growth (ergosterol), while total bacterial biomass (epifluorescence microscopy) was not significantly affected. However, number of cellulase-producing, colony-forming bacterial units decreased with decreasing N availability. In straw-amended soil, decreasing N concentrations reduced activities of exocellulase, endocellulase and hemicellulase, while in unamended control soil the effects were opposite. We developed a model in which three fractions of straw residues, determined by proximate analysis (Van Soest), and a humus pool were assumed to decay according to first-order rate kinetics. In accordance with the microbial measurements, the microbial community was subdivided into three groups consuming readily decomposable, structural and humus materials respectively. When holocellulose decay rate was modified as a function of N availability, the model simulated N effects on C mineralization and microbial biomass growth very well. Our experiment showed that wheat straw mineralization may be retarded at N concentrations well above those frequently found after grain harvest in the field and that effects of N availability should be taken into account when modelling C and N turnover in agricultural soils. Moreover, the trial exemplified a situation where studies of functional groups of decomposer organisms were required to explain and model satisfactorily differences observed at the process level.
Forfattere
Knute J. Nadelhoffer Bridget A. Emmett Per Gundersen O. Janne Kjønaas Chris J. Koopmans Patrick Schleppi Albert Tietema Richard F. WrightSammendrag
Det er ikke registrert sammendrag
Forfattere
Knute J. Nadelhoffer Bridget A. Emmett Per Gundersen O. Janne Kjønaas Chris J. Koopmans Patrick Schleppi Albert Tietema Richard Frederic WrightSammendrag
Humans have altered global nitrogen cycling such that more atmospheric N2 is being converted (\"fixed\") into biologically reactive forms by anthropogenic activities than by all natural processes combined. In particular, nitrogen oxides emitted during fuel combustion and ammonia volatilized as a result of intensive agriculture have increased atmospheric nitrogen inputs (mostly NO3 and NH4) to temperate forests in the Northern Hemisphere.Because tree growth in northern temperate regions is typically nitrogen-limited, increased nitrogen deposition could have the effect of attenuating rising atmospheric CO2 by stimulating the accumulation of forest biomass. Forest inventories indicate that the carbon contents of northern forests have increased concurrently with nitrogen deposition since the 1950s. In addition, variations in atmospheric CO2 indicate a globally significant carbon sink in northern mid-latitude forest regions. It is unclear, however, whether elevated nitrogen deposition or other factors are the primary cause of carbon sequestration in northern forests. Here we use evidence from 15N-tracer studies in nine forests to show that elevated nitrogen deposition is unlikely to be a major contributor to the putative CO2 sink in forested northern temperature regions.
Sammendrag
Det er ikke registrert sammendrag
Forfattere
D Eide B Robberstad Liv OstremSammendrag
Gjødslingsstyrken verkar mykje inn på proteininnhaldet i fôret, men lite på energiinnhaldet. Den kalde og våte sommaren i 1998 gav eit dårlegare fôr enn året før. Dette er resultatet av ein forsøksserie i gamal eng (10 felt) i Sogn og Fjordane
Forfattere
D Eide B Robberstad Liv OstremSammendrag
Resultata frå ein forsøksserie i gamal eng i Sogn og Fjordane (1998) viser store variasjonar i avlingssnivå og avlingsutslag. I gjennomsnitt fekk ein avlingsauke opp til 20 kg nitrogen pr dekar pr år på gamal eng.
Forfattere
Trygve S. Aamlid J.T Foss J.O ForbordSammendrag
Det er ikke registrert sammendrag
Forfattere
Leiv MortensenSammendrag
Det er ikke registrert sammendrag