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.
2006
Forfattere
Trond MæhlumSammendrag
Det er ikke registrert sammendrag
Forfattere
Trond MæhlumSammendrag
Det er ikke registrert sammendrag
Forfattere
Trond MæhlumSammendrag
Det er ikke registrert sammendrag
Forfattere
Trond MæhlumSammendrag
Det er ikke registrert sammendrag
Sammendrag
Freezing and thawing influence the transport potential and pathways for contaminants by altering the soil physical properties. Firstly, soil frost delays or impedes infiltration of rain and meltwater, reducing the transport rate of dissolved contaminants. But at the same time, particle bound contaminants may be mobilised because the reduced infiltration capacity increases surface runoff and erosion risk. Secondly, freezing water expands and imposes mechanical stresses on the soil, which may cause aggregate breakdown and facilitate particle detachment and transport. The influence of repeated freezing and thawing on aggregate stability of different soils is poorly documented for Nordic winter conditions. The purpose of this study (Kværnø and Øygarden, subm.) was to quantify the effect of variable freeze-thaw cycles and soil moisture conditions on aggregate stability of three soils: Silt, structured clay loam (Clay A) and artificially levelled silty clay loam (Clay B). These soils are representative of two erosion prone areas in South-eastern Norway. Field moist surface soil was sieved into the fraction 1- 4 mm, and packed into cylinders. The water content of the soil was adjusted, corresponding to matric potentials of -0.75, -2 and -10 kPa. The soil cores were insulated and covered, and subjected to 0, 1, 3 or 6 freeze-thaw cycles: freezing at "15"C for 24 hours, and thawing at 9"C for 48 hours. Aggregate stability was measured in a rainfall simulator (representing rainfall) and a wet-sieving apparatus (representing surface runoff). The aggregate stability of Silt was found to be significantly lower than of Clay A and Clay B. Clay A and Clay B had similar aggregate stabilities, even if it was expected that the artificially levelled Clay B would have lower stability. Freezing and thawing decreased the aggregate stability for all three soils, but the effect was more severe on the silt soil. There was no evident effect of water content on the aggregate stability, probably due to experimental limitations. The wet-sieving apparatus resulted in less aggregate breakdown than the rainfall simulator. Rainfall impact seemed to be more detrimental than wet-sieving the more unstable the soil was, that is, after many freeze-thaw cycles, and on silt soil. The results indicate that freezing and thawing is an important factor influencing the erosion risk of the studied soils. In the future, climate change is expected to give more unstable winters with more freezing and thawing events. Combined with more precipitation as rainfall during the winter period both runoff and erosion will probably increase, possibly resulting in heavier loads of particulate bound contaminants to surface waters. The results are also helpful for improving predictions of contaminant fate and transport, as most of the existing hydrological and soil erosion prediction models do not satisfactorily describe soil processes occurring under Nordic winter conditions. This study focused on arable soils with conventional agricultural management, where plant nutrients and pesticides pose a threat to water quality. It would be useful to conduct similar experiments on soils where other organic and inorganic contaminants are of concern, e.g. on soils where sewage sludge and compost have been applied, and soils in road cuttings and on contruction sites. References Kværnø, S.H. & Øygarden, L. submitted: The influence of freeze-thaw cycles and soil moisture on aggregate stability of three soils in Norway.
Sammendrag
To realize the full potential of agricultural biotechnology, concerns about the possible impact of GM plants on ecosystem properties and functions must be addressed. If transgenic crops substantially affect soil organic matter decomposition and mineralization, this could be of serious concern to many farmers in the developing world, as well as to organic farmers in the developed world. These farmers rely on local residues, organic matter and soil organisms for soil fertility, and there is a risk that this could be reduced if crop products cause a slowing down of the natural processes of decomposition and nutrient release by inhibiting the activity of the soil biota.
Forfattere
Aud Tennøy Jens Kværner Karl Idar GjerstadSammendrag
Det er ikke registrert sammendrag
Forfattere
Jens Kværner Grete Swensen Lars ErikstadSammendrag
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Forfattere
Jens Kværner Tore SveistrupSammendrag
Det er ikke registrert sammendrag
Forfattere
Aud Tennøy Jens Kværner Karl Idar GjerstadSammendrag
Det er ikke registrert sammendrag