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.
2009
Sammendrag
New results are presented on taxonomic position, pathogenicity and control of the needle cast fungus Kabatina abietis, a species causing economic losses in Christmas tree production in various European countries as well as in Northeast USA. Trials with copper fungicides conducted in 2008 in Denmark, Norway, Germany, Austria and USA against Kabatina abietis were unsuccessful. Though the identity of Kabatina abietis with Sydowia polyspora as well as its pathogenicity was confirmed by a thesis in Norway, it remains unclear, whether the characteristic needle symptoms could be the result of different damaging agents.
Sammendrag
Growth of Norway spruce (Picea abies) trees and nitrogen deposition were analysed at about 500 forest plots throughout Norway in six fiveyear periods from 1977 to 2006. Growth was calculated from five repeated calliper measurements of all trees during this period and using treering series from increment cores of a subsample of trees. From the growth data a `relative growth` variable was extracted, being the deviation in % between observed and expected growth rates. The expected growth was estimated from growth models based on site productivity, age and stand density at each plot. The plots were categorized into four age classes. The nitrogen deposition was estimated for each plot for the same five year periods by geographical interpolation of deposition observations at monitoring stations made by the Norwegian Institute for Air Research. Nitrogen deposition from 1977 to 2006 ranged from 1 to 24 kg/ha/yr at the study plots, with about 15 kg/ha/yr in the southernmost region and 3 kg/ha/yr in the northern region of Norway. For the entire 30year period we found a long term relationship between growth and nitrogen deposition, corresponding to a forest growth increase of 0.7% per kg total nitrogen deposition per hectare and year (r2 = 0.13). This is in line with studies carried out on other data sets and for shorter time periods. This apparent fertilizing effect was most pronounced for the youngest forest, while the effect was weak for the oldest forest. The growth increase was observed in the southernmost part of Norway, the region with the highest nitrogen deposition. However, the relationship between nitrogen deposition and growth varied considerably between the time periods. In two of the periods the relationship was slightly negative: these periods corresponded well with summer droughts occurring in the southernmost part of Norway. Drought, as well as other climatic factors, will influence the shortterm variations in forest growth and may obscure the fertilizing effect of nitrogen deposition in some periods. In conclusion, nitrogen deposition has most likely increased growth in Norway spruce in southern Norway. However, our study also shows that inferences from such correlative studies should be drawn with care if the growth period is shorter than 10–15 years because climatic factors produce temporal variations in the relationship between nitrogen deposition and forest growth.
Forfattere
Per Stålnacke Annelene Pengerud Marianne Bechmann Josette Garnier Christoph Humborg Vladimir NovotnySammendrag
The major objective of this study was to compile and examine empirical relationships between the driving forces and pressures that affect nitrogen cycling. Special attention was paid to riverine loads, fluxes, and concentrations of nitrogen in relation to agricultural factors (e.g., land use and fertilisers) at various spatial scales (plot, field, catchment, river basin, nation, region, continent, and world). Results of the present analyses and assessments reported in the literature indicate that at global, continental and inter-river basin scales, the level of riverine nitrogen loads (pressures) can be readily derived from simple empirical relationships with driving forces like population density and agricultural factors (e.g., proportion of arable land and fertiliser use). It seems that statistically derived relationships do not hold or are much weaker at the scales of single river basins and smaller catchments, whereas nitrogen losses appear to be correlated with fertiliser use at the smallest scales (plot and field). It is important to recognize this spatial nutrient paradox, particularly when such functional relationships are applied in the contexts of management and decision making. The implications for management are given further consideration in this paper.
Forfattere
Marianne BechmannSammendrag
JOVA-programmet omfatter lange tidsserier med kontinuerlig overvåking av næringsstoffavrenning fra små jordbruksdominerte nedbørfelt. Denne overvåkingen bidrar til å kvantifisere jordbrukets tilførsler av nitrogen og fosfor til vann og vassdrag, og danner et viktig grunnlag for tiltaksanalyser som gjennomføres i forbindelse med implementering av den nye vannforskriften.
Forfattere
Audun KorsæthSammendrag
Dyrkingssystemforsøket på Apelsvoll, N-strømmer, avlinger, matproduksjon
Forfattere
Anita Sønsteby Nina Opstad Unni Myrheim Ola M. HeideSammendrag
Det er ikke registrert sammendrag
Sammendrag
Høstgjødsling av jordbær er relativt lite brukt hos oss. Stort sett får plantene passe seg selv etter at høstesesongen er over. Nylig utførte forsøk i kontrollert klima viste imidlertid at nitrogengjødsling idet blomsterdanningen innledes, like etter start av kort dag, kan forsterke blomsterdanningen. Derimot flrte N-gjødsling like før start av kort dag til forsinket blomstring. dette har aktualisert spørsmålet om presisjonsgjødsling av jordbær om høsten.
Forfattere
Matthias KoeslingSammendrag
Nitrogen i kunstgjødsel har bidratt til stor avlingsøkning de siste 50 år. På den ene siden har økt produktivitet i jordbruket sørget for at en gjennomsnittsfamilie må bruke en langt mindre del av inntekten til innkjøp av mat. På den andre siden blir bruk nitrogen fra kunstgjødsel vurdert som kritisk med hensyn til avrenning og høy energibruk under fremstilling.
Forfattere
Sissel HansenSammendrag
Bidrar vi gjennom vårt arbeid til at barn av i dag og våre barnebarnsbarn har mulighet til å møte sine behov ?For å sikre bærekraftig økologisk, husdyrløs produksjon er det viktig å :Senke nedgangen i jordas innhold av organisk materiale, Bedre utnyttingen av nitrogen samlet i grønngjødsel, Tilbakeføre næringsstoff fra samfunnet, Forbedre utnytting av fosfor og andre begrensede næringsstoffIkke etterape løsninger tilpasset konvensjonelt landbruk, men tenke økologi og ha nok innsikt til å se agronomien inn i en helhetlig sammenheng
Sammendrag
Siden 2002 har mellom 150 og 200 produsenter årlig meldt seg ut av Debio. Den viktigste årsaken til utmelding var for mye byråkrati med kontroll og sertifisering. For dem som driver økologisk er det viktigste problemet uforutsigbare politiske rammevilkår. Økonomiske forhold var viktige årsaker eller problemer for alle.