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.
2002
Forfattere
Bernt-Håvard ØyenSammendrag
Det er ikke registrert sammendrag
Forfattere
Wenche Dramstad Wendy Fjellstad Geir-Harald Strand Henrik Forsberg Mathiesen Gunnar Engan Jogeir N. StoklandSammendrag
Det er ikke registrert sammendrag
Sammendrag
Development of environmentally and economically sound agricultural production systems is an important aim in agricultural policy and has a high priority in agricultural research worldwide. Here we use results from the first complete crop rotation period (1990-1997) of the Apelsvoll Cropping System Experiment in central southeast Norway, to discuss the effect of cropping systems and their management practices on environment, soil fertility, crop yields and farm economy, and how this knowledge may be used to develop a more sustainable agriculture. Overall, integrated and organic forage systems results in the least environmental harm, and based upon the present government subsidies, the forage systems also seem the most profitable, along with the organic arable system. Negative nutrient balances is a serious concern that has to be taken into consideration in development of sustainable organic farming systems.
Forfattere
Lars Tørres HavstadSammendrag
Ulike metoder for behandling av stubb og gjenvekst i frøeng av engsvingel (Festuca pratensis Huds.) ble prøvd ut i til sammen 7 årsfelt (5 felt med "Fure" og 2 felt med "Salten") i perioden 1998-2001. I to forsøksfelt hvor stubbehøyden ved tresking var over 30 cm førte stubb-avpussing til avlingsøkning året etter. I de andre feltene, hvor stubbehøyden var lavere, hadde avpussing av stubben ingen positiv virkning på frøavlingen. I områder hvor snødekket om vinteren var ustabilt (kystklima) førte avpussing 5. september eller 1. oktober til dårligere overvintringsevne og reduserte frøavlinger året etter sammenlignet med upussa ruter. I områder med mer stabile vintrer (innlandsklima) hadde avpussing om høsten ingen negativ virkning på frøavlingen. De høyeste frøavlingene ble i alle felt oppnådd på ruter hvor gjenvekst (og evt. stubb) var brent tidlig om våren. I middel av alle felt førte vårbrenning til en avlingsøkning på om lag 9 prosent sammenlignet med ruter som ikke var avpusset eller brent om høsten/våren. Vårbrente ruter produserte også flere frøstengler, med tyngre frøtopper, enn ruter som var avpusset om høsten.
Forfattere
Tor Håkon SivertsenSammendrag
The phenomenon considered is mountain lee waves of short and local scale, and the theory considered is a linearized system of the stationary Navier-Stokes equations, looking at a strictly vertically layered atmosphere. The concept of wave energy, connected to the linear theory, presented in a paper from 1961 by A. Eliassen og Enok Palm, is discussed. This discussion is in a general way connected to the scientific method and a documentation system of meteorological parameters. The meteorological parameters describing this phenomenon and used when testing such systems, ought to be documented according to certain principles. The discussion is in special way connected to the use of boundary conditions when some parameter ( the temperature of the air or the density of the air) is discontinuous at a certain altitude. It is shown that the boundary conditions used by Eliassen and Palm (1961) not always conserves the vertical flux of wave energy at the boundaries with discontinuous parameters. A revised system of boundary conditions preserving the vertical flux of wave energy is then presented. References: Eliassen, A., and Palm, E., 1961, On the transfer of energy in stationary mountain waves, Geofysiske Publikasjoner, Oslo Sivertsen, T., 1976, 1976,On the transfer of energy in stationary mountain waves in an atmosphere with discontinuous parameters, Meteorologiske annaler Vol. 7 No. 3, Det norske meteorologiske institutt, 9 pp
Forfattere
Nicholas ClarkeSammendrag
In natural waters, total organic carbon (TOC) is the sum of particulate and dissolved organic carbon. Dissolved organic carbon (DOC) is operationally defined, usually as organic carbon that passes through a 0.45 µm filter. Cellulose acetate or nitrate filters should not be used for this purpose due to contamination or adsorption problems. Glass fibre filters are preferable. Although the discussion below concerns DOC, much of it applies to TOC as well. Organic carbon is most often determined after oxidation to CO2 using combustion, an oxidant such as persulphate, UV or other high-energy radiation, or a combination of some of these. If only UV radiation with oxygen as oxidant is used, low DOC values may be obtained in the presence of humic substances. A variety of methods are used for detection, including infrared spectrometry, titration and flame ionization detection after reduction to methane. Always follow the instrument manufacturer’s instructions. For determination of dissolved organic carbon, dissolved inorganic carbon must be either removed by purging the acidified (for example with phosphoric acid) sample with a gas which is free from CO2 and organic compounds, or determined and subtracted from the total dissolved carbon. If acidification followed by purging is used, care should be taken as volatile organic compounds may also be lost. After acidification, remove CO2 by blowing a stream of pure carbon-free inert gas through the system for at least 5 minutes. Carbon is ubiquitous in nature, so reagents, water, and glassware cannot be completely cleaned of it. Method interferences (positive bias) may be caused by contaminants in the carrier gas, dilution water, reagents, glassware, or other sample processing hardware (for example a homogenization device). All of these materials must be routinely demonstrated to be free from interference under the conditions of analysis by running reagent blanks. Plastic bottles can bleed carbon into water samples, especially when they are new, or when they are used for low-level samples (less than 200 ppb C). Any new bottles (especially plastic) should ideally be filled with clean water for a period of several days or boiled in water for a few hours before use. The use of high purity or purified reagents and gases helps to minimise interference problems. It is very important to use ultra-pure water with a carbon filter or boiled distilled water just before preparing stock and standard solutions, in order to remove dissolved CO2. The stock solution should not be kept too long (about one week). For most DOC instruments a correction for DOC (due to dissolved CO2) in the dilution water used for calibration standards is necessary, especially for standards below 10 ppm C. The carbon in the blank should only be subtracted from standards and not from samples. For calibration, standard solutions are most often potassium hydrogen phthalate for total dissolved carbon and sodium bicarbonate for dissolved inorganic carbon. The DOC concentration should be within the working range of the calibration. If necessary the sample can be diluted. Sample DOC below about 50 ppb C can be affected by atmospheric exposure. In these cases, sampling bottles should be kept closed when possible, and autosampler vials should be equipped with septa for needle piercing by the autosampler.
Forfattere
Sverre KobroSammendrag
Diagnostic characters of the second-stage larvae of Oxythrips bicolor and Oxythrips ajugae are shown. The larva of the former has not been described prviously.
Forfattere
Tor MykingSammendrag
Det er ikke registrert sammendrag
Forfattere
Tor MykingSammendrag
Det er ikke registrert sammendrag
Forfattere
Stig Strandli GezeliusSammendrag
Det er ikke registrert sammendrag