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.
2001
Authors
Mekjell MelandAbstract
An intensive field planting of `Edda", "Opal" and "Mallard" plum trees (Prunus domestica L.) all grafted on the semidwarf rootstock St. Julien A was established in 1993 at Ullensvang Research Centre, western Norway at 60 ° North. The objectives were to evaluate four different single row planting systems (vertical axis, free spindle, hedgerow and Y-trellis) and three planting densities ( 0.5, 1.0, 1.5 x 4 m for the Y-trellis and hedge trees and 2.0 x 4 m for the central leader trees) in a northern climate. These planting distances give a range of tree density of 1250 - 5000 trees per ha. The experiment gave a small yield in the third leaf on all canopy systems. During the first four cropping years, the yields/ha were positively correlated with tree density. Cumulative yield per hectare was highest on the Y-trellis and hedge trees with the highest density (5000 trees per ha). In the fourth leaf, the Y-trellis trees gave 15 tons per hectare. No differences in fruit size or the soluble solids content among canopies or densities were found.
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Authors
Morten NittebergAbstract
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Authors
Petter NilsenAbstract
The paper gives a brief overview of the background, history and main results of forest fertilization experiments on mineral soils in Norway. Positive results of initial phosphorus (P) fertilization on survival and growth of Norway and Sitka spruce have only been achieved in the coastal districts of western Norway. Other elements have seldom given any significant effect.In young and old stands of Norway spruce and Scots pine nitrogen (N) fertilization with 150 kg N ha-1 usually gave increment increases in the range of 1-2 m3 ha-1 yr-1, for a period of 6-8 yrs after application. Given individually, no other element has proved stimulating to stem growth in a similar way. In young Norway spruce stands P has often given additional growth response when given together with N. Liming has been shown to have no or negative effects on tree growth. Fertilization experiments have changed from being management orientated towards addressing the problems of possible nutrient imbalances.
Abstract
Materials and Methods: In the field, fresh samples were obtained from different sources. Lake samples were collected from Lake Årungen, which is located in Ås. Stream samples were collected from Ås and Birkenes in southern Norway. All the samples were filtered in the field through 0.45 um membrane filters using syringes. Then the samples were fractionated through Bond Elut SCX cartridges connected to a portable vacuum pump, based on the method of Wickstrøm et al. (2000). A portion of the sample was passed immediately through the cation exchange cartridge. After the fieldwork another portion of the sample was taken to the laboratory where the same fractionation procedure was applied. These two fractions were then analysed for non-labile aluminium. A portion of the unfractionated sample was also analysed for total dissolved aluminium. An additional laboratory fractionation with a time lag was also applied to observe storage effects. Subsequent determination of total elements was done using ICP-AES. Transport, pretreatment and storage can also have an effect on the pH and organic matter concentration of the samples and, through this, on the equilibrium between different Al fractions. To evaluate pH differences prior to analysis, pH values were also measured in the field and in the laboratory. DOC was also determined. Differences between fractionation in the field and fractionation in the laboratory: In this study, non-labile fractions of Al were compared instead of the labile fractions of Al (which can be removed from solution on passage through cation exchange column) that are believed to have the greatest toxic effect on organisms.
Authors
Torbjørn OkstadAbstract
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