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.
2018
Sammendrag
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Forfattere
Anne Falk Øgaard Lasse Vråle Martin MengedeSammendrag
Sewage sludge is a significant phosphorus resource that should be better utilized in the plant production than today. However, phosphorus in sludge produced after precipitation with aluminium and iron coagulants have low plant availability. This article presents results from plant growth experiments where plant available phosphorus in lime precipitated sewage sludge from Bokerøya and Skådevika wastewater treatment plants was studied. Both wastewater treatment plants normally use iron as coagulant aid, but Skådevika produced in addition a sludge to the experiments without using iron. The growth experiments included a pot experiment in greenhouse with three harvests of Italian ryegrass (Lolium multiflorum) and a two-year field experiment in cereals in Southeast Norway. The results showed that precipitation with lime gives a sludge with higher plant availability of phosphorus than what is earlier found for aluminium/ iron precipitated sludge. This was special the case with moderate use of iron as coagulant aid.
Forfattere
Marit AlmvikSammendrag
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Forfattere
Liv ØstremSammendrag
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Sammendrag
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Forfattere
Björn RingselleSammendrag
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Forfattere
Kjersti Holt HanssenSammendrag
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Sammendrag
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Forfattere
Erik J. JonerSammendrag
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Forfattere
Eva Lieungh Eriksen Heidrun Asgeirsdatter Ullerud Rune Halvorsen Sigrun Aune Harald Bratli Peter Horvath Inger Kristine Volden Anders Kvalvåg Wollan Anders BrynSammendrag
Questions: Substantial variation between observers has been found when comparing parallel land-cover maps, but how can we know which map is better? What magnitude of error and inter-observer variation is expected when assigning land-cover types and is this affected by the hierarchical level of the type system, observer characteristics, and ecosystem properties? Study area: Hvaler, south-east Norway. Methods: Eleven observers assigned mapping units to 120 stratified random points. At each observation point, the observers first assigned a mapping unit to the point independently. The group then decided on a ‘true’ reference mapping unit for that point. The reference was used to estimate total error. ‘Ecological distance’ to the reference was calculated to grade the errors. Results: Individual observers frequently assigned different mapping units to the same point. Deviating assignments were often ecologically close to the reference. Total error, as percentage of assignments that deviated from the reference, was 35.0% and 16.4% for low and high hierarchical levels of the land-covertype system, respectively. The corresponding figures for inter-observer variation were 42.8% and 19.4%, respectively. Observer bias was found. Particularly high error rates were found for land-cover types characterised by human disturbance. Conclusions: Access to a ‘true’ mapping unit for each observation point enabled estimation of error in addition to the inter-observer variation typically estimated by the standard pairwise comparisons method for maps and observers. Three major sources of error in the assignment of land-cover types were observed: dependence on system complexity represented by the hierarchical level of the land-cover-type system, dependence on the experience and personal characteristics of the observers, and dependence on properties of the mapped ecosystem. The results support the necessity of focusing on quality in land-cover mapping, among commissioners, practitioners and other end users.