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
Gustav Fystro Anne Kjersti BakkenSammendrag
Surface liming as a means for controlling the soil reaction in established leys was investigated in a series of 4-year field trials. Application of 625, 1250, 2500 or 5000 kg CaO equivalents/ha in spring of the first year caused an immediate rise in pH in the top 0"25 mm of the soil. The rate and range of the response below 25 mm was related to the precipitation at the experimental sites. Lime-induced changes in pH were not dependent on the initial level of soil reaction, whereas the positive response in grass production was greater and more immediate at sites where pH was below 5.3 rather than above. The increases in yields of macro elements were, in most instances, relatively lower than the increases in dry matter (DM) yields. Important exceptions here were the yields of Ca in all cuts and P in the second cuts, and the yields of Mg when dolomite rather than limestone was applied. The concentration of Ca in the herbage was positively a.ected by liming according to ruminant needs. The same holds for the concentration of Mg when granulated or coarse dolomite was applied. Liming lowered herbage uptake of Mn, Co and Zn, whereas Mo uptake was increased. There appeared to be no consistent relationship between liming and the plant uptake of Fe and Cu. Dependent on the initial conditions, liming might both improve and worsen the trace element status of harvested herbage with respect to the demands of ruminant animals. It is concluded that frequent surface liming at low rates might be an appropriate strategy for adjusting the soil pH in semi-permanent and permanent pastures.
Forfattere
Annbjørg Øverli Kristoffersen Mikkel Bakkegard Bernt Olav HoelSammendrag
Field experiments were carried out on three representative soils, to evaluate the effect of various starter fertilizers, together with different rates of band placed phosphorus (P), on nutrient uptake and yield of spring barley (Hordeum vulgare L.) and spring wheat (Triticum aestivum L.). The starter fertilizers were placed in the immediate vicinity of the seed, while the band placed P was placed at about 5 cm below the seeds and spaced at 25 cm between alternate seed rows. As starter fertilizer, monoammonium phosphate (MAP), calcium nitrate (CAN), ammonium nitrate (AN) and triple superphosphate (P20) were compared. In both species, effects of starter fertilizer on P uptake were most marked early in the growing season. At GS 13 application of 20 kg P ha-1 as MAP increased the P uptake by 50 % in barley and by 35 % in wheat, compared to no seed-placed nutrients. In grain, the increase in P content was 8 % for both species. The higher P uptake at GS 13 was supported by observations of higher plant vigour in the treatments with either P20 or MAP as starter fertilizer. The use of N only as starter fertilizer did not increase the vigour of the plants. Band placement of P also gave more vigorous plants in spring barley. The grain yield increased on the silty clay loam and on the silt soil when starter fertilizer was applied, especially with the use of MAP. Smaller and non-significant yield differences were found when starter fertilizer was used on the loam soil. No delay or reduction of emergence was observed with starter fertilizer. Therefore, on soils where root growth or nutrient uptake becomes limited during the first weeks after sowing, application of starter fertilizer is recommended in Norway to both spring barley and spring wheat. Crops grown on silty soils seem to have an especially high demand for easily available P given as starter fertilizer.
Forfattere
Helge Bonesmo Gilles Belanger Ed Charmley GF TremblaySammendrag
The Canadian Timothy Model (CATIMO) is a mechanistic simulation model of timothy (Phleum pratense L.) growth and nutritive value. The growth module features radiation interception and use efficiency, leaf and stem growth and leaf senescence, and a N function based on the critical N concentration of whole plants. The digestibility module features cell wall (CW) concentration and CW digestibility for each of the plant morphological components derived from the growth module. The model was calibrated with measurements taken weekly on the timothy primary growth, in four different years at one location (Fredericton, NB, Canada). In this paper, we compare the predictions of the CATIMO model with measurements from six field experiments not used to calibrate the model. The six experiments were conducted at four sites that covered a range of pedo-climatic conditions within eastern Canada (Lévis, QC; Nappan, NS; Normandin, QC; St. John"s, NF). Across sites and years, the root mean square errors (RMSE) for DM yield varied from 30.9 to 265.9 g DM m-2 with an average of 123.9 g DM m-2; this is about twice the RMSE reported for the calibration site. Omitting one site in 1999, however, reduced the overall RMSE to 72.6 g DM m-2, which is closer to the 65.9 g DM m-2 reported for calibration. The overall RMSE values for N concentration (0.013 g g-1 DM), IVTD (0.052 g g-1 DM), CW concentration (0.104 g g-1 DM), and CW digestibility (0.064 g g-1 CW) were higher than those obtained at the calibration site. At three of four sites, however, the RMSE values were close to those of the calibration site. The CATIMO model seems robust enough to apply to situations different than those used for calibration, at least within eastern Canada.
Sammendrag
The evaluation of water bodies "at risk" of not achieving the Water Framework Directive"s (WFD) goal of "good status" begs the question of how big a risk is acceptable before a programme of measures should be implemented. Documentation of expert judgement and statistical uncertainty in pollution budgets and water quality modelling combined with Monte Carlo simulation and Bayesian belief networks, make it possible to give a probabilistic interpretation of "at risk". Combined with information on abatement costs, a cost-effective ranking of measures based on expected costs and effect can be undertaken. Combined with economic valuation of water quality, the definition of "disproportionate cost" of abatement measures compared to benefits of achieving "good status" can also be given a probabilistic interpretation. Explicit modelling of uncertainty helps visualize where research and consulting efforts are most critical for reducing uncertainty. Based on data from the Morsa catchment in South-Eastern Norway, the paper discusses the relative merits of using Bayesian belief networks when integrating biophysical modelling results in the benefit-cost analysis of derogations and cost-effectiveness ranking of abatement measures under the WFD. Keywords: Benefit-cost analysis; Disproportionate costs; Eutrophication; Programme of measures.
Forfattere
Qasim Chaudhry Margaretha Blom-Zandstra Satish GuptaSammendrag
Abstract Background. Phytoremediation is a promising technology for the cleanup of polluted environments. The technology has so far been used mainly to remove toxic heavy metals from contaminated soil, but there is a growing interest in broadening its applications to remove/degrade organic pollutants in the environment. Both plants and soil microorganisms have certain limitations with respect to their individual abilities to remove/breakdown organic compounds. A synergistic action by rhizosphere microorganisms that leads to increased availability of hydrophobic compounds, and plants that leads to their removal and/or degradation, may overcome many of the limitations, and thus provide a useful basis for enhancing remediation of contaminated environments. Main Features. The review of literature presented in this article provides an insight to the nature of plant-microbial interactions in the rhizosphere, with a focus on those processes that are relevant to the breakdown and/or removal of organic pollutants. Due consideration has been given to identify opportunities for utilising the plant-microbial synergy in the rhizosphere to enhance remediation of contaminated environments. Results and Discussion. The literature review has highlighted the existence of a synergistic interaction between plants and microbial communities in the rhizosphere. This interaction benefits both microorganisms through provision of nutrients by root exudates, and plants through enhanced nutrient uptake and reduced toxicity of soil contaminants. The ability of the plant-microbial interaction to tackle some of the most recalcitrant organic chemicals is of particular interest with regard to enhancing and extending the scope of remediation technologies. Conclusions. Plant-microbial interactions in the rhizosphere offer very useful means for remediating environments contaminated with recalcitrant organic compounds. Outlook. A better knowledge of plant-microbial interactions will provide a basis for improving the efficacy of biological remediations. Further research is, however, needed to investigate different feedback mechanisms that select and regulate microbial activity in the rhizosphere.
Forfattere
Gustav Fystro Sigmund FjelltunSammendrag
Rapporteringsperioden 1/5 2004 - 1/5 2005 var sett under ett relativt varm (3,5 °C mot normalt 1,6 °C) og det kom litt mindre nedbør (561 mm) enn normalen (575 mm). Nesten 90 % av jordbruksarealet var i 2004 nyttet til eng og beite (inkludert gjenlegg). Dette er på linje med gjennomsnittet for tidligere år. Jordarbeiding ble utført på ca 15 % av arealet, mest på våren. Andel jordarbeidet areal er litt lavere enn årlig gjennomsnitt fra oppstart av målingene. Gjødslingen av nitrogen, fosfor og kalium (11,9, 1,8 og 8,2 kg per dekar jordbruksareal) i rapporteringsåret er nært gjennomsnittet for tidligere år (12,0, 1,8 og 8,2 kg per dekar). Generelt er det moderat/svak gjødsling i nedbørfeltet. Husdyrgjødsel utgjør en vesentlig del. Siden oppstart av målingene er gjødseldyrenheter i feltet gått ned over 30 % (særlig reduksjon i antall sauer). Vannføringen siste rapporteringsår på 204 mm var mindre enn gjennomsnittet på 286 mm i perioden 1993 til 2004. Dette skyldes vesentlig tidspunkt for snøsmelting relativt til 1.mai. Tap av nitrogen per dekar dyrka mark var 2,0 kg siste rapporteringsår, og dette er mindre enn gjennomsnittet på 2.4 kg per dekar for perioden 1993 til 2004. Avviket kan knyttes til tidspunkt for snøsmelting. Nitrogentap knyttet til snøsmelting har gjerne vært 70-80 % av totale årlige tap. Tap av fosfor per dekar dyrka mark var 21 g siste år, mot gjennomsnittet på 37 g for perioden 1993 til 2004. Snøsmelting på jord med lite tele, med liten overflateavrenning, er sannsynlig forklaring på lave fosfortap dette året. Tap av suspendert tørrstoff per dekar dyrka mark var målt så lavt som 3,8 kg siste år, mot gjennomsnittet på 7,5 kg for perioden 1993 til 2004.
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.
Sammendrag
Resultatene med hensyn på effekten mot svartskurv fra beiseforsøk med tolklofosmetyl (Rizolex) og pencycuron (Pestige og Monceren) er litt sprikende. Det var ingen sikre gjennomgående forskjeller mellom svartskurvmidlenes virkning. I noen felt har beisingen ført til utsatt spiring, mens i andre felt har det ført til flere spirer. Angrepet av svartskurv på de underjordiske stenglene har blitt noe redusert ved beising. Det har blitt variable utslag på totalavlingen. I noen felt har beising ført til redusert avling, mens i andre felt har avlingen økt. I gjennomsnitt er det en tendens til avlingsøkning ved beising. I noen felt har beisingen påvirket størrelsesfordelingen i avlingen slik at andelen små knoller har økt. Resultatene med hensyn på potetsikade fra beiseforsøkene viser at det var en tendens til færre potetsikader tidlig i sesongen i ruter beiset med Prestige og mer potetsikader i ruter beiset med Rizolex enn i de ubehandlede kontrollrutene. Seinere i sesongen var det liten effekt av beisingen på sikadeangrepet.
Sammendrag
Strandengområdene på Rinnleiret er av internasjonal til nasjonal verdi i forhold til botaniske og ornitologiske kvaliteter. Deler av Rinnleiret ble endelig fredet som naturreservat i 1995 og verneområdet har store kulturlandskapsverdier. Naturreservatet har også status som Ramsar-område. De siste tiårene har det imidlertid skjedd store forandringer på Rinnleiret på grunn av gjengroing, noe som både skyldes naturlig landheving, forsvarets tidligere aktiviteter og opphør i beitebruken. Gråorskogen, kreklingheiene og tindvedkrattene er i dag i raskt frammarsj, samtidig som de karakteristiske salt- og fuktengene går tilbake. Antall fuglearter og hekkende par er også merkbart redusert de senere årene. I dette prosjektet ble det utarbeidet nytt vegetasjonskart og artslister over karplanter og fugler for hele Rinnleiret. En skjøtselsplan er utarbeidet for naturreservatet og der gis konkrete anbefalninger om restaurerings- og skjøtselstiltak som skal ivareta verneverdiene.