Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2000
Authors
Eirik Romstad Arild Vatn Per Kristian Rørstad Viil SøylandAbstract
Multifunctionality is a systems oriented concept. It addresses the fact that in addition to the provision of private goods like food and fiber, agriculture also provides a set of public goods. The most central public good elements are: - Landscape values: biodiversity, cultural heritage, amenity value of the landscape, recreation/access, scientific/educational value. - Food related aspects: food security, food safety and food quality. - Rural activity: rural settlement and economic activity. Moreover, agricultural production results in negative external effects, like nutrient runoff, erosion, and pollution from pesticide and herbicide use. These aspects also need to be considered when designing policies and determining the extent and type of agriculture. The linkages between agricultural production and public good attributes imply that the costs of providing the public goods may vary. Polices directed at changing the amount of some public goods provided by agriculture will therefore influence domestic commodity production, and thereby als
Authors
Tor J. JohansenAbstract
No abstract has been registered
Abstract
The effect of six cropping systems (rotations of either mainly arable or mainly forage crops) on the soil N content was evaluated using mass balances of total N, and the usefulness of such N balances to predict N runoff (total N losses via drainage and surface water) was investigated. All the arable cropping systems resulted in a net reduction in the calculated soil N pool, and the reduction increased with decreasing N input. Only the forage system with the highest N input maintained the initial soil N content. Mass N balances were found to be a useful tool for predicting N runoff, as up to 87% of the variation in N runoff could be explained.
Authors
Gudbrand LienAbstract
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Authors
Tore SkrøppaAbstract
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Abstract
Vi undersøkte fenologi og kjønnsratio (andel hunner) til 15 arter snylteveps som parasitterer havrebladminerflue i Norge. Studiet gikk over 6 sesonger i byggskiftet i et økologisk drevet felt ved Norges Landbrukshøyskole, og det ble brukt Malaisefeller som innsamlingsmetode (en i åkerkanten og en 60 m inn i byggskiftet). Resultatene tydet på at snyltevepshunnene var mer knyttet til kanten enn hannene og verten sin, og at mange av snyltevepsene vandret ut av åkeren en stund før tresking. De to vanligste snyltevepsartene var Cyrtogaster vulgaris (en puppeparasitt) og Diglyphus begini (en larveparasitt). Førstnevnte hadde en særlig nær tilknytning til kanten, og tidligere studier har vist at denne kan overvintre som voksen i f.eks grastuer i kanten. Hos sistnevnte fant vi en tetthetsavhengig kjønnsratio i fellefangstene: Jo flere individer i fellene, jo lavere andel var hunner
Abstract
No abstract has been registered
Abstract
The anatomical response of Norway spruce bark polyphenolic parenchyma cells (PP cells) to inoculation with the phytopathogenic fungus Ceratocystis polonica and attack by its bark-beetle vector Ips typographus was examined.Fungal inoculation on the periderm surface had no effect, while inoculation just below the periderm or halfway into the phloem (mid-phloem) generated detectable responses within 3 wk. The responses included increase in PP cell size and in periodic acid - Schiffs staining of PP cell phenolics, wound periderm initiation from PP cells, and cambial zone traumatic resin duct formation. Fungi were not seen in samples 3 wk after subperiderm or mid-phloem inoculation, but were found in some samples 6 and 9 wk after mid-phloem inoculation.In contrast, inoculations into the cambium resulted in partial (3 wk) or complete (6 and 9 wk) fungal colonization and death of tissue in the infected area. This indicates that PP cells have defenses capable of inhibiting fungal growth. Samples taken near bark-beetle galleries had similar anatomical responses as inoculated samples, validating the inoculation approach to studying defense responses in spruce.These results show that PP cells represent not only a constitutive defense system, but are also involved in local and remote inducible defenses against fungal and beetle attack.