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.
2005
Forfattere
Tor Arvid Breland Anne Kjersti Bakken Trond K Haraldsen Trygve S. Aamlid Tore E SveistrupSammendrag
Temporal changes in the scores of selected soil fertility indices were studied over six years in three different cases of organic crop rotation located in southern, eastern and central Norway (Bakken et al. in press). The cropping history and the initial scores of fertility indices prior to conversion to organic cropping differed between the sites. Crop yields, regarded as an overall, integrating fertility indicator, were in all rotations highly variable with few consistent temporal trends following the first year after conversion. On the site in eastern Norway, where conversion followed several years of all-arable crop rotations, earthworm number and biomass and soil physical properties improved, whereas the system was seemingly degrading with regard to P and K trade balances and contents in soil. On the other two sites, the picture was less clear. On the southern site, which had a relatively fertile soil before conversion, the contents of soil organic matter and K decreased during the six-year period, but the scores of other fertility indices showed no trends. On the site in central Norway, there were positive trends for earthworm-related indices such as worm biomass and tubular biopores and negative trends for soil porosity. The results, especially those from the eastern site, illustrate the general difficulty in concluding about overall fertility or sustainability when partial indicators show divergent trends. Consequently, the study gave no unambiguous support to the initial working hypothesis that organic farming increases inherent overall soil fertility, but rather showed that the effect varied among indicators and depended on status of the cases at conversion. It is concluded that indicators are probably better used as tools to learn about and improve system components than as absolute measures of sustainability.
Forfattere
Øyvind Nordli Finn Måge Frans-Emil Wielgolaski Stein Harald Hjeltnes Anne Kjersti Bakken Oddvar Skre Endre SkaarSammendrag
The analyses are based on phenological observations carried out at international phenological gardens (IPG) at Fana (western Norway) and Kvithamar (Trøndelag), also at the Norwegian University of Life Sciences (Ås, south-eastern Norway) and the research station Njøs (Sogn, western Norway). The longest series are from Njøs (1927) and Ås (1947), whereas no series at the IPGs is older than 1964. For the three southernmost sites (Ås, Fana, and Njøs) all trends are negative, i.e. there has been a change towards earlier occurrences of the phenophases in spring. For the northernmost site (Kvithamar) also positive trends are seen. Four species are cultivated at Fana as well as at Kvithamar. For these species the trend lines are steeper at Fana than at Kvithamar. For the longest series (1927 - 2005) the trend is only -0.4 day/decade but insignificant (p > 0.05). This amounts only to about 3 days earlier occurrence (apple at Njøs) within this period of 79 years. The trend at Ås (1947 - 2005) is also insignificant, although it amounts to about -1 day/decade or about 6 days earlier occurrence within the 59 year period.
Forfattere
Sissel Hansen Anne Kjersti Bakken Turid Strøm Espen Govasmark Håvard Steinshamn Espen Govasmark Sissel Hansen Turid Strøm Håvard SteinshamnSammendrag
There is generally low atmospheric sulphur (S) deposition in northern Scandinavia. Because of this, the herbage S content on 28 organic farms was monitored in order to discover eventually shortage in the S-supply for plants or ruminants in organic livestock production. The S content and the protein content were generally low. In spite of this, the yields were surprisingly good in many locations, and S fertilisation improved yields, biological nitrogen fixation and the protein content of red clover only when the S supply was very low. In a pot trial, increasing S application did not increase the S content of red clover above a certain level. That level depended on the growing conditions. Instead of an increase in the shoots with increasing S supply, there was an accumulation of S in the roots.
Forfattere
Espen Govasmark Arvid Steen Turid Strøm Sissel Hansen Anne Kjersti BakkenSammendrag
Based on a survey on Norwegian organic farms observations it was concluded that today"s feeding practice for sheep and dairy cattle herds was sufficient regarding Cu and Co, but Se should be supplemented to all animals and vitamin E should be supplemented to animal diets consisting mainly of hay.
Forfattere
Bård Pedersen Helge Bonesmo Anne Kjersti BakkenSammendrag
The paper gives examples of how data acquired by image analysis of digital photographs can be processed and interpreted by descriptive, spatial statistics for analyses of two-dimensional patterns in grass-clover swards. We use local quadrat variance methods to identify scales and intensities of patterns in the sward and wavelet analyses to identify individual clover patches and study their dynamics.
Forfattere
Helge Bonesmo Anne Kjersti Bakken Bård PedersenSammendrag
With the overall aim to analyse and understand spatial dynamics in grass-white clover pastures we have developed a method for mapping plant and soil coverage at exact positions at sequential occasions. The method involves obtaining and processing information from digital colour photographs, and software ("Trifolium.exe") is specially designed for the purpose. The positioning system in two experimental fields, image aquisition, software and initial data processing are presented and evaluated.
Forfattere
Sissel Hansen Anne Kjersti BakkenSammendrag
The objective of this study was to investigate whether biological nitrogen fixation (BNF) on organic farms in Norway is limited by a low S-supply. We studied the relationship between the N- and S-status of red clover (Trifolium pratense) from 66 leys on 26 organic farms at first harvest in 2001, and the effect of S-supply on clover yields and N-content in three field trials in 2002 on sites with low S-content in grass-clover swards. The red clover from many leys appeared to be very low in S. The mean S content in the survey was 1.7 g kg-1 DM (max 3.0 and min 0.8 g kg-1 DM). S-fertilisation (30 kg S ha-1) increased the content of S in red clover from 0.8 g to 1.2 g S kg-1 DM in the field trials. At one of the sites, high yields were harvested despite a very low content of S in red clover (1 g kg-1 DM). In the survey there was a positive correlation between the tissue content of N and S in both the grasses and the clover. We conclude that despite low S content in red clover tissue at many sites, neither BNF nor clover yields seemed to be strongly limited because of this.
Forfattere
Helge Bonesmo Stein Rune Karlsen Anne Kjersti Bakken Kjell Arild HøgdaSammendrag
Årsvekst og vekstavslutting hos timotei samt minimum og maksimum N-opptak om høsten er beregna for fem år ved Holt i Troms, Kvithamar ved Trondheimsfjorden, Storsteigen i Østerdalen, Tomb i Østfold, og Øksnevad på Jæren. Ut fra disse beregningene og forutsatt et krav om planteopptak av 4-5 kg N daa-1etter spredning, har vi foreslått frist for spredning av husdyrgjødsel på eng uten nedmolding. Et norgeskart over vekstavlutning hos gras er laget på grunnlag av MODIS satellittdata og indeksen Normalized Difference Vegetation Index (NDVI). På hvert av de fem stedene er det beregnet NDVIkurver for de fem åra. NDVI-kurvene er sammenholdt med grasvekstberegningen, og vi har fastsatt terskler i NDVI for vekstavslutning. Disse terskelverdiene har deretter blitt brukt i arbeidet med å lage kartet for vekstavsluting.
Forfattere
Stein Harald Hjeltnes Jan Meland Torbjørn Takle John Harald Rønningen Tomas HesthamarSammendrag
Artikkelen oppsummerer inntrykk frå ein studietur for å sjå på frukttreproduksjon og plantemateriale i Belgia og Nederland. Gartnerhallen sette saman ei arbeidsgruppe på 5 personar, og finansierte studieturen som skulle klarleggja konkurransesituasjonen og finna strategiar for norsk produksjon. Nær 100% av alle epletre som vert produserte var knipetre - dette er 2-års tre som ber gode avlingar året etter planting. Prisen er ikkje høgare enn for eitt-årig grønpisk i Norge, så konkurransen for norske frukttreplanteskular vert særs hard ved evt. opning for import av eple- og pæretre.
Forfattere
Sverre KobroSammendrag
Hann av Aeolothrips manteli er funnet for første gang. Arten kan lett skilles fra de andre norske Aeolothrips artene ved karakterer på antennene og øynene.