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.
2007
Authors
Anna Arneberg Per Holm Nygaard Odd Egil Stabbetorp Bjarni D. Sigurdsson Edda Sigurdis OddsdóttirAbstract
The aim of this study was to investigate variation in decomposition and vegetation due to afforestation. The ICEWOODS sites containing stands of different tree species and age in the western (Skorradalur) and eastern (Hallormsstaður) parts of Iceland were investigated during the summer of 2004. These stands were compared with treeless pastures. The planted stands represent chronosequences, i.e., different age classes within each tree species were studied. Decomposition was studied by a cotton strip assay. Cotton strip decomposition increased with incubation time and decreased with soil depth. The tree species can be ranked according to increasing decomposition in the following series: lodgepole pine < Sitka spruce< Siberian larch < mountain birch. In general, decomposition decreased with increasing age of the stands...
Authors
Zhihui Yang Bal Ram Singh Sissel HansenAbstract
Farmyard manure (FYM) and fertilizer applications are important management practices used to improve nutrient status and organic matter in soils and thus to increase crop productivity and carbon (C) sequestration. However, the long-term effects of fertilization on C, nitrogen (N) and sulfur (S) associated with aggregates, especially on S are not fully understood. We investigated the effects of more than 80 years of FYM (medium level of 40 Mg ka(-1) and high level of 60 Mg ka(-1)) and mineral fertilizer (NPKS and NK) on the concentrations and pools of C, N, and S and on their ratios in bulk soil, dry aggregates and water stable aggregates on an Aquic Eutrocryepts soil in South-eastern Norway. A high level of FYM and NPKS application increased the proportion of small dry aggregates (<0.6 mm) by 8%, compared with the control (without fertilizer). However, both medium and high level of FYM application increased the proportion of large water stable aggregates (>2 mm) compared with mineral fertilizer (NPKS and NK). The total C and N pools in bulk soils were also increased in FYM treatments but no such increase was seen with mineral fertilizer treatments. The increased total S pool was only found under high level of FYM application. Water stable macroaggregates (>2 and 1-2 mm) and microaggregates (<0. 106 mm) contained higher concentrations of C, N and S than the other aggregate sizes, but due to their abundance, medium size water stable aggregates (0.5-1 mm) contained higher total pools of all three elements. High level of FYM application increased the C concentration in water stable aggregates >2, 0.5-1 and <0. 106 mm, and increased the S concentration in most aggregates as compared with unfertilized soils. Higher ON, C/S and N/S ratios were found both in large dry aggregates (>20 and 6-20 mm) and in the smallest aggregates (<0.6 mm) than in other aggregate sizes. In water stable aggregates, the C/N ratio generally increased with decreasing aggregate size. However, macroaggregates (>2 mm) showed higher N/S ratios than microaggregates (<0. 106 mm). We can thus conclude, that long-term application of high amounts of FYM resulted in C, N and S accumulation in bulk soil, and C and S accumulation in most aggregates, but that the accumulation pattern was dependent on aggregate size and the element (C, N and S) considered.(C) 2007 Published by Elsevier B.V.
Authors
Zhihui Yang Bal Ram Singh Sissel Hansen Zhengyi Hu Hugh RileyAbstract
Understanding soil sulfur pools and associated aggregates S fractions can provide a platform for monitoring S dynamics in soils. A long-term experiment established in 1922 on an Aquic Eutrocryepts in South-eastern Norway was chosen to investigate the effects of long-term fertilization on S fractions in bulk soil and those associated with aggregates. Chloroform fumigation-extraction was used to determine Microbial biomass S (MBS) and the wet chemical analysis method was used to fractionate soil S into ester S (hydriodic acid reducible S), carbon-bonded S (Raney nickel reducible S) and residual S (Raney nickel non-reducible S). High farmyard manure (FYM) application resulted in higher MBS in bulk soil than nitrogen + potassium (NK) application, but it did not differ significantly from the control. Application of FYM at 60 Mg ha(-1) resulted into accumulation of total S, total organic S and carbon-bonded Sin bulk soils, while mineral fertilizer (nitrogen+phosphorus+potassium+sulfur [NPKS] and NK) and the medium rate of FYM did not increase the accumulation of total S and organic S fractions. The macroaggregate sizes (> 2 and 1-2 mm) and the finest aggregate size (< 0.106 mm) showed significantly greater total S concentration than other aggregate sizes. Ester S and residual S were predominant organic S fractions and they accounted for 39 to 52% and 38 to 51% of the organic S, respectively. The macroaggregate sizes (> 2 and 1-2 mm) contained the highest ester S, but microaggregates (< 0.106 mm) exhibited higher carbon-bonded S and residual S than other aggregates. In conclusion, the accumulation of S was dependent on fertilizer type, the rate of FYM application and aggregate sizes.
Authors
Alhaji S. Jeng Roshan Bajracharya Bishal K. Sitaula Bed Mani Dahal Subodh ShermaAbstract
No abstract has been registered
Authors
Daniela Sauer Isabelle Schülli-Maurer Ragnhild Sperstad Rolf Sørensen Karl StahrAbstract
The coastal areas of Scandinavia provide suitable conditions for studying soil development with time, due to glacio-isostatic uplift. Our study area is located along both sides of the Oslofjord (Vestfold and stfold). The climate in this area is rather mild although it is located between 59 and 59 40 latitude. The mean annual temperature ranges from 5.4 to 6. 0 C. Precipitation is 9751094 mm year1 in Vestfold and 751829 mm year1 in stfold. Due to the steadiness of the uplift, no separate terraces were formed in the study area, but soils continuously get older from the coast inland. We established two soil chronosequences comprising six pedons each, one in Vestfold (1650 9000 years) and one in stfold (300011050 years). The ages were estimated by use of several sea level curves established for various locations in the area, based on calibrated radiocarbon datings. The parent material is loamy marine sediment. The geological basement below the sediment consists of basic magmatite (monzonite, latite) in Vestfold and predominantly acid magmatite (granite) in stfold. Higher precipitation in Vestfold leads to earlier beginning of clay illuviation. Clay coatings are perceptible in Vestfold already in the 1650 years old soil. In stfold they become visible for the first time in the 3500 years old soil. The E horizon becomes lighter with age, but its thickness stays constantly around 40 cm in both areas. The development of the characteristic albeluvic tonguing starts after 4000 to 5000 years. The tongues initially develop mainly along intersections of cracks. Due to ongoing leaching they increase in length and width, progressively consuming the prisms in between the cracks in the upper part of the Bt horizon. Base saturation in the upper 25 cm exhibits a decrease with time which can be best described by an exponential model, while pH (water) stays constantly at pH 4.4 0.4 in all soils covering a range of 1650 to 11050 years in age. These findings indicate that the soil pH is buffered by protonation of surface charges occupied by exchangeable base cations over a time span of more than 9000 years. The Fed/Fet ratio shows an increase with time which can be described by both, a linear or potential model, reflecting progressive iron release from mineral weathering. The Feo/Fed ratio shows a linear decrease indicating increasing degree of iron oxide crystallization.
Authors
Clive Kaiser Lars Sekse Mekjell Meland Lynn E. LongAbstract
No abstract has been registered
Authors
Guro Ådnegard Skarstad Laura Terragni Hanne TorjusenAbstract
No abstract has been registered
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No abstract has been registered
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No abstract has been registered
Authors
Carl Gunnar FossdalAbstract
In collaboration with the NARC platform at Ås, we have taken the Norway spruce phytochrome and PaChi4 promoters and introduced them into Arabidopsis using GFP and YFP expression vectors in order to study their effect on expression under long and short day treatment. Said in other words we use of GFP and YFP as reporters and Arabidopsis as a host for the Norway spruce promoters in order to study their possible regulation by day-length in this model plant system. In completely separate experiments in collaboration with the NARC platform at Ås, we have introduced the Norway spruce glycohydrolase PaChi4 into Arabidopsis to examine what effect this might have on the response to wounding and to pathogens. The PaChi4 enzyme is produced at very high levels in tissues with high level of host cell death (PCD) following fungal infections and it might be a marker for or directly involved in PCD. We have obtained transgenic plants and the first examination for any day-length dependent expression of the GFP and YFP reporters in the transgenic Arabidopsis lines is currently being pursued while the examination of the PAChi4 enzyme overexpressing lines are yet to be initiated.