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.
2012
Sammendrag
Cover crops are included in cropping systems in order to achieve various ecological benefits. In stockless organic cereal systems in Scandinavia, nitrogen is commonly supplied by undersowing a legume shortly after sowing. Retarding the growth of annual weeds is considered an additional benefit of using cover crops. However, studies on the influence of undersown cover crops on the growth of perennial weeds are lacking. In this paper we present data from a four- year field experiment on the growth of Cirsium arvense (L.) Scop., Sonchus arvensis L. and Elymus repens (L.) Gould., in cereals with and without undersown red clover (Trifolium pratense L.), combined with contrasting stubble treatments after harvest. Clover did not significantly reduce the growth of any of the weed species. Regression analyses showed, however, that the growth of C. arvense and S. arvensis increased with increasing clover biomass at low densities of clover, whereas at higher densities it decreased with increasing biomass of clover. Amongst the stubble treatments, shallow ploughing followed by harrowing gave the best control of all weed species. The effect was most pronounced on E. repens, and least on S. arvensis, for whichneither the number nor the weed biomass were significantly different from the untreated control. Rotary tilling gave a similar effect, but again less pronounced on S. arvensis. Mowing suppressed E. repens to some degree, tended to suppress S. arvensis (n.s.) but had no effect on C. arvense. Thegrowth and survival of seed-propagated plants of the same species were studied in a one-year field experiment and in a greenhouse experiment, the latter only including the species S. arvensis andC. arvense. The use of a cover crop reduced the number of leaves per plant in S. arvensis both in the field and in the greenhouse. The same effect was found for C. arvense, but only in the greenhouse experiment. In the latter, above-ground biomass of the cover crop explained 67 % of the variation intotal biomass of S. arvensis and 47 % of that for C. arvense. From a practical point of view, the study has shown that undersown red clover has only marginal effects on perennial weeds, in contrast to various stubble treatments which influence strongly on weed growth. In general, soil tillagesuppresses perennial weeds best, but mowing may be a more environmentally friendly alternative for some weed species, such as. E. repens.
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Sammendrag
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Sammendrag
The source of input data for soil physical properties may contribute to uncertainty in simulated catchment response. The objective of this study was to quantify the uncertainty in catchment surface runoff and erosion predicted by the physically based model LISEM, as influenced by uncertainty in soil texture and SOM content, and the pedotransfer function derived soil water retention curve, hydraulic conductivity, aggregate stability and cohesion. LISEM was first calibrated using measured data in a sub-catchment, and then run for the whole catchment for a summer storm event with basic input data from two data sources: soil series specific generic data from the national soil survey database, and measured data collected in a grid within the catchment. The measured data were assigned in two ways: mean values per map unit, or random distribution (50 realizations) per map unit. The model was run both for a low risk situation (crop covered surface) and a high risk situation (without crop cover and with reduced aggregate stability and cohesion). The main results were that 1) using non-local database data yielded much higher peak discharge and five to six times higher soil loss than using locally measured data, 2) there was little difference in simulated runoff and soil loss between the two approaches (mean value versus randomdistribution) to assign locally measured data, 3) differences between the 50 random realizationswere insignificant, for both low-risk and high-risk situations, and 4) uncertainty related to input data could result in larger differences between runswith different input data source than between runswith the same input data source but extreme differences in erosion risk. The main conclusion was that inadequate choice of input data source can significantly affect general soil loss and the effect of measures.
Sammendrag
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Forfattere
Maria Magdalena Estevez Roar Linjordet John MorkenSammendrag
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Forfattere
V.S. Duarte L.P.F Souza R. Costa G.M. Coura Jr A.R. Leite J.A. Freitas O.M. Santos L.C.D. Rocha Ingeborg Klingen I. Jr. DelaliberaSammendrag
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Forfattere
Eivind Uleberg Jens Rohloff Laura Jaakola Kajetan Trost Olavi Junttila Hely Häggman Inger MartinussenSammendrag
After pollination outdoors individual bilberry plants from two Northern and two Southern clones were studied for climatic effects on berry yield and quality in a controlled phytotrone experiment at 12 °C and 18 °C. At each temperature the following light treatments were tested; 1) 12 h natural light; 2) 24 h natural light and 3) 24 h natural light plus red light. The first experimental year there was no difference in yield between temperatures, however, the second experimental year the berry yields was significantly higher at 18 °C. Berry ripening was faster in the Northern than in the Southern clones at 12 °C. Northern clones also showed significantly higher contents of total anthocyanins, all measured anthocyanin derivatives, total phenolics, malic acid and sucrose. Metabolic profiling revealed higher levels of flavanols, hydroxycinnamic acids, quinic acid and carbohydrates at 12 °C.