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.
2005
Forfattere
Audun KorsæthSammendrag
Two hand-held spectro-radiometers were used to measure canopy reflectance from winter wheat and spring barley in two ongoing fertilizer experiments. Relations between measurements made in June and plant N content (June), above-ground biomass (June), yields and grain protein content (at harvest in August) were studied. For winter wheat, regression models predicted up to 55, 89, 88 and 28% of the variations in N-content, biomass, yields and protein content, respectively. For spring barley the corresponding predictions were 87, 96, 87 and 22%.
Forfattere
Audun KorsæthSammendrag
Apparent soil electrical conductivity (ECa) is a promising indicator for important soil physical and chemical properties. In this paper the method of measuring ECa to characterize within-field variability was tested on a clay soil in S Norway. A field survey was conducted with the Geonics EM38 on a 15 ha field, and 223 soil samples were taken. Most of the measured variables of the topsoil, except P-AL, total N and organic C, were significantly (p£0.05) correlated with ECa. Topsoil Mg-AL alone accounted for 75% of the variation in ECa. Subsoil pH and clay, silt and coarse sand contents were correlated with ECa. The clay content at both depths accounted for 63% of the variation in ECa. After grouping the data on the basis of measured ECa into classes with intervals of 2 mS/m, there were significant differences in soil properties (combinations of clay content, Mg-AL and K-HNO3) between 7 out of 9 classes.
Forfattere
Anne Falk Øgaard Tore KrogstadSammendrag
Potassium (K) release from sources that are not initially exchangeable is attributed to depletion of interlayer K of micas and clay minerals or weathering of feldspars. The aim of the present study was to estimate the K release from interlayer K. Soil samples from 17 field experiments in ley on a range of mineral soils in Norway were used in the study. The change in K fixation capacity was used as an estimate of depletion of interlayer K. It was assumed that the increase in K fixation capacity during three years of cropping was equivalent to the amount of K depleted from the interlayer positions. Mean K fixation increased in the majority of the soils during three years of grass cropping both with and without K application. The increase in K fixation indicated that without K application the K uptake from interlayer K amounted to 43, 28 and 26% of the K yield for clay soils, high K sandy soils and low K sandy soils, respectively. Including K uptake from exchangeable K in the topsoil and from subsoil, the explained K uptake amounted to 79, 69 and 81% for the three groups of soil, respectively. Simple linear regression analyses showed that the change in K fixation during three years of grass cropping was best explained by the percentage of clay in the soil.
Sammendrag
Det er ikke registrert sammendrag
Sammendrag
Laboratory incubations with varying O2 and NO3 concentrations were performed with a range of filter materials used in constructed wetlands (CWs). The study included material sampled from functioning CWs as well as raw materials subjected to laboratory pre-incubation. 15N-tracer techniques were used to assess the rates of denitrification versus dissimilatory nitrate reduction to ammonium (DNRA), and the relative role of nitrification versus denitrification in producing N2O. The N2O/(N2+N2O) product ratio was assessed for the different materials. Sand, shell sand, and peat sustained high rates of denitrification. Raw light weight aggregates (LWA) had a very low rate, while in LWA sampled from a functioning CW, the rate was similar to the one found in the other materials. The N2O/(N2+N2O) ratio was very low for sand, shell sand and LWA from functioning CWs, but very high for raw LWA. The ratio was intermediate but variable for peat. The N2O produced by nitrification accounted for a significant percentage of the N2O accumulated during the incubation, but was dependent on the initial oxygen concentration. DNRA was significant only for shell sand taken from a functioning CW, suggesting that the establishment of active DNRA is a slower process than the establishment of a denitrifying flora.
Forfattere
Pål Tore Mørkved Anne Kristine Søvik Bjørn Kløve Lars R. BakkenSammendrag
Laboratory incubations with varying O-2 and NO3 concentrations were performed with a range of filter materials used in constructed wetlands (CWs). The study included material sampled from functioning CWs as well as raw materials subjected to laboratory pre-incubation. N-15-tracer techniques were used to assess the rates of denitrification versus dissimilatory nitrate reduction to ammonium (DNRA), and the relative role of nitrification versus denitrification in producing N2O. The N2O/(N-2 + N2O) product ratio was assessed for the different materials. Sand, shell sand, and peat sustained high rates of denitrification. Raw light-weight aggregates (LWA) had a very low rate, while in LWA sampled from a functioning CW, the rate was similar to the one found in the other materials. The N2O/(N-2 + N2O) ratio was very low for sand, shell sand and LWA from functioning CWs, but very high for raw LWA. The ratio was intermediate but variable for peat The N2O produced by nitrification accounted for a significant percentage of the N2O accumulated during the incubation, but was dependent on the initial oxygen concentration. DNRA was significant only for shell sand taken from a functioning CW, suggesting that the establishment of active DNRA is a slower process than the establishment of a denitrifying flora. Laboratory incubations with varying O-2 and NO3 concentrations were performed with a range of filter materials used in constructed wetlands (CWs). The study included material sampled from functioning CWs as well as raw materials subjected to laboratory pre-incubation. N-15-tracer techniques were used to assess the rates of denitrification versus dissimilatory nitrate reduction to ammonium (DNRA), and the relative role of nitrification versus denitrification in producing N2O. The N2O/(N-2 + N2O) product ratio was assessed for the different materials. Sand, shell sand, and peat sustained high rates of denitrification. Raw light-weight aggregates (LWA) had a very low rate, while in LWA sampled from a functioning CW, the rate was similar to the one found in the other materials. The N2O/(N-2 + N2O) ratio was very low for sand, shell sand and LWA from functioning CWs, but very high for raw LWA. The ratio was intermediate but variable for peat The N2O produced by nitrification accounted for a significant percentage of the N2O accumulated during the incubation, but was dependent on the initial oxygen concentration. DNRA was significant only for shell sand taken from a functioning CW, suggesting that the establishment of active DNRA is a slower process than the establishment of a denitrifying flora.
Forfattere
Pål Tore Mørkved Anne Kristine Søvik Bjørn Kløve Lars R. BakkenSammendrag
Laboratory incubations with varying O2 and NO3 concentrations were performed with a range of filter materials used in constructed wetlands (CWs). The study included material sampled from functioning CWs as well as raw materials subjected to laboratory pre-incubation. 15N-tracer techniques were used to assess the rates of denitrification versus dissimilatory nitrate reduction to ammonium (DNRA), and the relative role of nitrification versus denitrification in producing N2O. The N2O/(N2 þ N2O) product ratio was assessed for the different materials. Sand, shell sand, and peat sustained high rates of denitrification. Raw light-weight aggregates (LWA) had a very low rate, while in LWA sampled from a functioning CW, the rate was similar to the one found in the other materials. The N2O/(N2 þ N2O) ratio was very low for sand, shell sand and LWA from functioning CWs, but very high for raw LWA. The ratio was intermediate but variable for peat. The N2O produced by nitrification accounted for a significant percentage of the N2O accumulated during the incubation, but was dependent on the initial oxygen concentration. DNRA was significant only forshell sand taken from a functioning CW, suggesting that the establishment of active DNRA is a slower process than the establishment of a denitrifying flora.
Forfattere
Trond MæhlumSammendrag
Det er ikke registrert sammendrag
Forfattere
Tore SkrøppaSammendrag
Det er ikke registrert sammendrag
Forfattere
Lars Nesheim Gustav Fystro Olav HarboSammendrag
På tre forsøksfelt i ung eng vart det årleg tilført frå 0 til 5 kg fosfor per dekar i dinatriumhydrogenfosfat (Na2HPO4 x 2H2O). Dette stoffet vart nytta for å unngå samanblanding av verknad av svovel i superfosfat, som er mykje brukt i tidlegare gjødslingsforsøk med fosfor. Målsettinga med feltforsøka var å finne kritiske verdiar for fosforinnhald med omsyn på plantevekst under praktiske tilhøve. Sjølv til dels sterk P-gjødsling førte berre til liten auke i opptak av P i planter, og også til små avlingsutslag, på jord med relativt lite tilgjengeleg fosfor. Slike uventa små utslag medførte at samanhengen mellom plantene sin P-status og avlingsutslag vart dårleg bestemt. Det vart likevel observert ein trend til avlingsreduksjon ved låge P/N-verdiar. Av i alt 10 kg tilført P i gjødsel over to år vart berre 9 % funne att i avlinga.