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.
2003
Forfattere
J. Holmqvist Anne Falk Øgaard I. Öborn A.C. Edwards L. Mattsson H. SverdrupSammendrag
Negative potassium (K) balances have been reported from grass-dominated organic systems in several European countries, and in these systems delivery of K from soil primary minerals by weathering is probably crucial to sustained productivity. Mass balances and K budgets have been made at eight grass dominated experimental agricultural systems, one each in Scotland and Sweden and six in Norway. Where no fertiliser K was applied the deficits obtained were in the range 37 to 241 kg K ha-1 year-1. An estimate of the weathering rate was determined by the biogeochemical PROFILE model that varied widely between locations (4.2 to 82 kg K ha-1 year-1). This paper is a first attempt to apply the steady state PROFILE model on agricultural soils by using data from experimental sites. The Monte Carlo simulation of the weathering rate calculation showed that differences in specific surface area and soil water content strongly influenced the predicted weathering rate. The results from these weathering rate scenarios were associated with a degree of uncertainty but because all sites had a negative annual K balance, the specific contribution that mineral weathering makes to the long-term replenishment of soil exchangeable K is important. Despite the uncertainties in the weathering rate calculation these preliminary results are still useful in several aspects because the simulations make it possible to compare different agro-ecosystems with different management regimes, climate, soil properties etc. The simulations also indicate which environmental factors are likely to be the most influential on weathering rates. Soil physical properties such as moisture content, bulk density and surface area appeared to be amongst the most important input parameters controlling the weathering rate. There is now a need for improved laboratory experimental data that better describe the kinetics of mineral weathering in order to enhance the accuracy and precision of PROFILE.
Forfattere
Anne-Kristin Løes Anne Falk ØgaardSammendrag
On five long-term organic dairy farms aiming at self-sufficiency with nutrients, soil concentrations of ammonium-acetate lactate extractable potassium (K-AL) and acid-soluble K was measured twice in topsoil (0-20 cm) and subsoil (20-40 cm) over periods of 6-14 years. Organic management had occurred for > 9 years at the second sampling. On average there were most probably field level K-deficits. Even so, topsoil K-AL concentrations were medium high (65-155 mg K kg-1 soil), and did not decrease during the study period. However, for three farms, topsoil K-AL was approaching a minimum level determined by soil texture, where further decrease is slow. Subsoil K-AL concentrations were generally low (< 65). The soils were mostly light-textured, and reserves of K-releasing soil minerals (illite) were low, never exceeding 6% of the mineral particles < 2 mm ". Topsoil acid-soluble K concentrations were low (< 300 mg K kg-1 soil) on two farms, medium (300-800) on three farms and decreased significantly on one farm. Cation-exchange capacity increased on two farms. This may indicate increased amount of expanded clay minerals caused by K-depletion. On self-sufficient organic dairy farms, purchased nutrients will be required by low soil nutrient reserves to avoid seriously decreased yields and quality of crops.
Sammendrag
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Sammendrag
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Sammendrag
Several biocells varying from 100 m3 to about 8000 tons have been established at waste treatment locations in Norway since 1998. We studied biocells by characterizing the waste material by degradation, gas and leachate emission and post-treatment potential, by taking several samples distributed in space and time. Field sample analyses were water content, leachate temperature, redox conditions, oxygen content, electrical conductivity and pH, and gas temperature, O2, CH4 and CO2 concentrations. Waste samples were drilled up by a 10-inch auger down to 6 m depth. The collected samples were analyzed and used for composting experiments. The temperature in the biocelles varied between 10 to 14 ºC in the period from august to December. The waste was characterised as completely or slightly completely degraded after 4 years of biocell storage/treatment, based on "Rotte-test" and respirometer analyses. Microbial analyses showed that the material was free from salmonella, but contained some thermotolerant colibacteria in the most degraded part. Samples from the slightly degraded waste were also free from thermotolerant colibacteria. None of the waste samples showed any inhibition against the germination of plants. The temperature in the most degraded material did not increase significantly during composting. This material can thus not be treated aerobically after removal from the biocell, ie. for reducing pathogens. The factors leachate strenght measured as electrical conductivity, BOD and C/N-ratio best explained the methane content of the biogas in each sampling point. A total production of 593 t landfill gas has been measured from the large biocell. The annual mean methane concentration increased from 28 to 56%, with an overall mean of 48%. This gives a 21% degradation of organic carbon in four years, based on certain assumptions on the incoming waste. The estimated degradation of organic matter is between 50% and 75% in four years.
Sammendrag
Hydrogen sulphide (H2S) is known to be a major odourant in landfills. We have studied H2S production from landfill residual waste with and without added sulphur as waste from plasterboards. We also studied the influence of water content in the waste. The lab experiments were conducted in 30-l plastic containers with controlled water level. We also studied the effectiveness of different reactive layers to remove H2S. The organic waste produced H2S in the order of 40 ppm over a period of 80 days. When plasterboard was added, the H2S production with a high water level increased to 800 ppm after a lag period of about 40 days, and to about 100 ppm after 50 days with low water content. The CH4 concentration in the initial experiment increased to 55% to 70% after 80 days. The CH4 concentration in the second experiment increased to nearly 70% in the container with high water content, slowly declining to nearly 60% between 20 and 60 days. In the container with low water content the CH4 concentration increased to 60% and stayed nearly constant. In the container with high water level a decline in the CH4 concentration was observed coinciding with a presence of CO. The results from the experiments with reactive layers were not available before submitting the proceeding.
Forfattere
Marianne Stenrød Ole Martin Eklo Jens Kværner Tore Sveistrup Pierre Benoit Marie-Paule Charnay Valerie PotSammendrag
Det er ikke registrert sammendrag
Forfattere
Peder Lombnæs Bal Ram SinghSammendrag
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Forfattere
Peder Lombnæs Bal Ram SinghSammendrag
Det er ikke registrert sammendrag
Forfattere
Peder Lombnæs Bal Ram SinghSammendrag
Det er ikke registrert sammendrag