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.
2017
Forfattere
Victor Strimbu Liviu Theodor Ene Terje Gobakken Timothy G. Gregoire Rasmus Astrup Erik NæssetSammendrag
Post-stratified model-assisted (MA) and hybrid (HY) estimators are used with repeated airborne laser scanning (ALS) strip sampling and national forest inventory field data for stratum-wise and overall estimation of aboveground biomass (AGB) stock and change. The study area covered the southern portion of the Hedmark County in Norway. Both MA and HY estimation substantially reduced the uncertainty in AGB change when compared with estimation using the field survey only. Relative efficiencies (relative variance) of 4.15 (MA) and 3.36 (HY) for overall estimates were found. The results suggest the MA estimator for single-time estimation and the HY as more appropriate for change estimation by cover class. With the HY estimator, a nested post-stratification scheme is demonstrated, combining cover classes with change classes, which enables detailed reporting for change according to cause within each cover class, and has the potential to improve the estimation precision. Finally, parametric bootstrapping is demonstrated as an empirical alternative to estimate the model-error component in the HY estimator. The model error estimated with parametric bootstrapping converged to the analytically determined value of the HY estimator within 1000 bootstrap samples.
Sammendrag
Herbage yield responses to K fertilizer application are variable in Norwegian grassland. Excessive K application may increase the risk of grass tetany (hypomagnesaemia) and milk fever (hypocalcaemia). We analysed a series of K fertilizer experiments on grassland with respect to their herbage yields and mineral composition. Our results show the importance of native soil K reserves when considering the need for K application. Soils with a high content of acid-soluble K showed no response to K fertilizer application. The critical K content in grass with respect to yield was estimated to be 17.7 g K/kg DM in the first cut and 20.3 kg K/DM in the second cut, while the critical K/N relationship was found to be 0.83 when a maximum yield reduction of 2.5% was used as a criterion. In these trials, soils with a high content of acid-soluble K had the greatest risk of grass tetany and the highest values of cation–anion balance. Application of potassium chloride had little effect on the cation–anion balance, and thereby the risk of milking fever, because there was a corresponding uptake of K and Cl ions.
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Forfattere
Per Jarle MøllerhagenSammendrag
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Forfattere
Andrew Bierman L Radetsky M Figueiro T Plummer M Rea D. M. Gadoury Aruppillai Suthaparan Arne Stensvand N. Peres R. B. OnofreSammendrag
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Forfattere
Bjørn Arild Hatteland Elena Therese Wulf-Vester Ida Gundersen Nuria Agusti Lene Sigsgaard Nina TrandemSammendrag
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Forfattere
Tomas Persson Henrik Eckersten Oleif Elen Anne-Grete Roer Hjelkrem Joel Markgren Mats Söderström Thomas BörjessonSammendrag
Deoxynivalenol (DON) in cereals, produced by Fusarium fungi, cause poisoning in humans and animals. Fusarium infections in cereals are favoured by humid conditions. Host species are susceptible mainly during the anthesis stage. Infections are also positively correlated with a regional history of Fusarium infections, frequent cereal production and non-tillage field management practices. Here, previously developed process-based models based on relative air humidity, rain and temperature conditions, Fusarium sporulation, host phenology and mycelium growth in host tissue were adapted and tested on oats. Model outputs were used to calculate risk indices. Statistical multivariate models, where independent variables were constructed from weather data, were also developed. Regressions of the risk indices obtained against DON concentrations in field experiments on oats in Sweden and Norway 2012–14 had coefficient of determination values (R2) between 0.84 and 0.88. Regressions of the same indices against DON concentrations in oat samples averaged for 11 × 11 km grids in farmers’ fields in Sweden 2012–14 resulted in R2 values between 0.27 and 0.41 for randomly selected grids and between 0.31 and 0.62 for grids with average DON concentration above 1000 μg kg–1 grain in the previous year. When data from all three years were evaluated together, a cross-validated statistical partial least squares model resulted in R2 = 0.70 and a standard error of cross-validation (SECV) = 522 μg kg–1 grain for the period 1 April–28 August in the construction of independent variables and R2 = 0.54 and SECV = 647 μg kg–1 grain for 1 April–23 June. Factors that were not accounted for in this study probably explain large parts of the variation in DON among samples and make further model development necessary before these models can be used practically. DON prediction in oats could potentially be improved by combining weather-based risk index outputs with agronomic factors.
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