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.
2016
Forfattere
Björn Ringselle Göran Bergkvist Helena Aronsson Lars AronssonSammendrag
Without herbicides, the control of Elymus repens relies on intensive tillage, often in the form of repeated post-harvest stubble cultivations followed by ploughing. This is costly and time-consuming and also increases the risk of nitrogen leaching. Our aim was to quantify the controlling effect on E. repens of single and repeated cultivation and differing time of cultivation in relation to spring cereal harvest. A 2-year experiment was conducted at two sites in the south and east of Sweden in 2011–2012 and 2012–2013. We compared no, single and repeated tine cultivation followed by mouldboard ploughing; the single cultivation was performed directly after harvest or 20 days after harvest; when repeated, the first cultivation was performed immediately or 5 days after harvest, followed by a second cultivation 20 days after harvest. Tine cultivation in combination with mouldboard ploughing resulted in 50–70% lower rhizome biomass, and increased average subsequent cereal yields by 0–130% compared with ploughing alone. Large E. repens populations appeared to be more efficiently reduced by tine cultivation than smaller populations. A single tine cultivation 20 days after harvest tended to result in a higher E. repens shoot density and more rhizome biomass in the subsequent year than tine cultivation directly after harvest. Additional cultivation 20 days after harvest did not improve control of E. repens or the subsequent cereal grain yield, compared with a single cultivation conducted directly after harvest. In conclusion, preventing the growth of E. repens during the early part of the post-harvest autumn period was more important than starving rhizomes with repeated cultivations.
Sammendrag
Aim: The objective was to assess the nitrogen provided to following crops by peas and fava beans, with varying legume residue incorporation and use of cover crops. Meth: Organic field trial, ‘spilt-split plot design’ with 4 blocks. Whole plots (spring 2014) had legumes (pea or faba beans), and sub plots (autumn 2014) had 4 autumn soil treatments with combinations of legume residue incorporation and cover crop. The sub-sub plots (spring 2015) were with and without additional manure fertilization. Res: The root biomass of both legume pre cops had equal nitrogen (N) concentration, but total root biomass was twice as high for fava beans as for peas (5.08 vs. 2.41 kg m-2). Fava bean pre crop with biomass incorporation without cover crop gave the highest broccoli yield (4.10 t ha-1) compared with pea pre crop with biomass incorporation and no cover crop (2.44 t ha -1). Also the last crop in the rotation, lettuce, had 94% higher yield after fava beans (6.6 t ha-1) compared to peas (3.4 t ha-1). Rye as cover crop efficiently assimilated and conserved N during winter, shown by a 4 to 5 fold reduction in soil NO3-N, and nearly 2 fold reduction in soil N-min levels, compared to open soil. Additional manure application affected crop yield, with 3 and 2 fold increase in broccoli and lettuce respectively. Conc: Fava beans as pre crop resulted in higher yields of broccoli and lettuce the following seasons, compared to peas. This was explained twice as much root biomass for that crop.
Forfattere
Janka Dibdiakova Liang Wang Henning HornSammendrag
Characterization of biomass ash melting and thermal behavior is crucial to prevent and reduce ash related problems in biomass-fired boilers, In present work, ash melting behaviours of spruce saw dust and bark were investigated by simultaneous thermal analysis (STA), The decomposition stages of sawdust and bark biomass were characterized by four peaks, respectively, The four peaks are the first relatively small one at temperatures about 317-341 °C, a second large peak at 419-451 °C, a small third peak at 860-1000 °C and a small endothermic peak at 1290-1400 °C, DSC curves of bark sample at both heating rates were shifted towards lower temperatures than DSC curves of sawdust fuels, On average, the degradation process starts 5 °C earlier and the second exothermic peaks in both heating rates are found even 20 °C earlier, The remaining residue of bark samples was approximately two times higher than that of sawdust, The ignition temperatures of both spruce and pine bark were slightly shifted to higher temperatures compared to those of spruce and pine sawdust samples, STA experiments of exanimated biomass fuels indicated that their critical melting temperatures lie in the range of 860-1000 °C, The information obtained in this study qualifies the STA method as a suitable and rather simple method for the determination of ash melting and thermal behavior of woody biomass. © 2016 ETA-Florence Renewable Energies.
Sammendrag
With the Directive 2009/128/EC on sustainable use of pesticides, reductions in herbicide use is a European target. The aim of this study was to compare the fi eld-specifi c herbicide use resulting from simulated integrated weed management (IWM) with farmer’s actual use. Two IWM tools applicable for cereals were explored: VIPS – a web-based decision support system, and DAT sensor – a precision farming technology for patch spraying. VIPS (adaptation of Danish “Crop Protection Online”) optimizes herbicide – and dose to weed species densityand growth stage (including ALS-herbicide resistant populations), temperature, expected yield, cereal species- and growth stage. Weeds were surveyed (0.25 m2, n=23-31) prior to post-emergence spraying in spring 2013 (six fi elds) and 2014 (eight fi elds). DAT sensor enables automatic patch spraying of annual weeds within cereals. It consists of an RGB camera and custom-made image analysis. DAT sensor acquired more than 900 images (0.06 m2) per fi eld. Threshold for simulated patch spraying was relative weed cover (weed cover/ total vegetation cover) = 0.042. Treatment frequency index (TFI, actual dose/maximum approved dose summed for all herbicides) was calculated. Without resistance strategy, average TFI for VIPS was higher for winter wheat (0.96) than for spring cereals (0.38). Spring cereal fi elds with resistance strategies gave an average TFI of 1.45. Corresponding TFI for farmer’s applications were 1.40, 0.90 and 1.26, respectively. For one fi eld wherein both tools were explored in 2013 and 2014, TFI values for VIPS were 1.86 and 1.50 due to resistant Stellaria media, while TFI for farmer’s sprayings were around 1.00. DAT sensor simulated herbicide savings of 69% and 99%, corresponding to TFI values of 0.58 and 0.01, respectively. As measured by TFI, DAT sensor showed a higher potential in herbicide savings than VIPS. VIPS is available without costs to end-users today, while DAT sensor represents a future tool.
Forfattere
Yanliang Wang Tore Krogstad Jihong Liu Clarke Moritz Hallama Anne K. Falk Øgaard Susanne Eich-Greatorex Ellen Kandeler Nicholas ClarkeSammendrag
Many arable lands have accumulated large reserves of residual phosphorus (P) and a relatively large proportion of soil P is less available for uptake by plants. Root released organic anions are widely documented as a key physiological strategy to enhance P availability, while limited information has been generated on the contribution of rhizosphere organic anions to P utilization by crops grown in agricultural soils that are low in available P and high in extractable Ca, Al, and Fe. We studied the role of rhizosphere organic anions in P uptake from residual P in four common crops Triticum aestivum, Avena sativa, Solanum tuberosum, and Brassica napus in low- and high-P availability agricultural soils from long-term fertilization field trials in a mini-rhizotron experiment with four replications. Malate was generally the dominant organic anion. More rhizosphere citrate was detected in low P soils than in high P soil. B. napus showed 74–103% increase of malate in low P loam, compared with clay loam. A. sativa had the greatest rhizosphere citrate concentration in all soils (5.3–15.2 μmol g−1 root DW). A. sativa also showed the highest level of root colonization by arbuscular mycorrhizal fungi (AMF; 36 and 40%), the greatest root mass ratio (0.51 and 0.66) in the low-P clay loam and loam respectively, and the greatest total P uptake (5.92 mg P/mini-rhizotron) in the low-P loam. B. napus had 15–44% more rhizosphere acid phosphatase (APase) activity, ~0.1–0.4 units lower rhizosphere pH than other species, the greatest increase in rhizosphere water-soluble P in the low-P soils, and the greatest total P uptake in the low-P clay loam. Shoot P content was mainly explained by rhizosphere APase activity, water-soluble P and pH within low P soils across species. Within species, P uptake was mainly linked to rhizosphere water soluble P, APase, and pH in low P soils. The effects of rhizosphere organic anions varied among species and they appeared to play minor roles in improving P availability and uptake.
Forfattere
Antonio Carlos Ferraz Filho Blas Mola-Yudego José Ramón González-Olabarria José Roberto Soares ScolforoSammendrag
The objective of this paper is to determine the pruning level that does not affect tree growth, increasing the amount of clear wood production in a single lift at age 1.3 years. The experiment was developed in the municipality of Aracruz, Espírito Santo state, Brazil. The pruning intensities considered were: 40%, 55%, 70% and 85% of the total tree height, as well as no pruning for control. The results obtained three years after pruning showed that it is possible to reach up to a 70% of total tree height pruned (mean pruned height of 7.3 m) in a single pruning lift without affecting the size of the 700 largest trees per hectare in diameter. High intensity pruning (85%) translated into negative effects on tree growth. Low intensity pruning (40%) also had moderate effects on growth, possibly due to exposure of negative effects of leaf area removal without benefiting from the positive effects on canopy characteristics. Finally, the paper discusses different thinning regimes and its implications on the pruning regime. The results of this research can contribute to improve the management of fast growing plantations for timber production.
Sammendrag
Norwegian constructed wetlands (CWs) that treat domestic wastewater are classified as horizontal subsurface flow constructed wetlands (HSFCWs). Over the years of continuous performance, the HSFCWs operating under cold climate conditions have shown a high and stable treatment efficiency with regard to the removal of organic matter (>90 % BOD), nutrients (>50 % N and >90 % P) and microbes (>99 % bacteria). The majority of Norwegian HSFCWs are categorised as small (<50 pe) on-site, decentralised wastewater treatment systems. The Norwegian systems consist of three fundamental elements: a septic tank, a pre-filter (i.e. an aerobic vertical flow biofilter) and a horizontal flow saturated filter/wetland bed. The first, primary treatment step begins in the septic tank from which effluents are pre-treated in the second step occurring in the pre-filter/biofilter section and further in the third, final step taking place in the filter bed/HSFCW. The first and third treatment steps are quite common in systems with CWs, but the pre-treatment in biofilter(s) is mainly known from Norway. The main purpose of using the pre-treatment phase is to supply air during the cold season, to enhance nitrification processes, and to reduce the load of organic matter before entering the filter/wetland bed. If constructed and maintained correctly, the biofilters alone can remove 90 % BOD and 40 % N. Various filter/CW beds have been introduced for treatment of domestic wastewater (as complete or source-separated streams) in Norway, but the most common feature is the use of specific filter media for high phosphorus (P) removal. A few Norwegian municipalities also have limits with respect to nitrogen (N) discharge, but the majority of municipalities use 1.0 mg P/l as the discharge limit for small wastewater treatment systems. This particular limit affects the P retention lifetime of the filter media, which varies from system to system depending on the filter media applied, the type of wastewater treated, and the system design and loading rates. An estimated lifetime of filter media with regard to P removal is approximately 15–18 years for a filter/CW bed of a single household. After completing the lifetime, the filter media is excavated and replaced with new/fresh materials, allowing the system to operate effectively for another lifespan. Since the exploited media are P-rich materials, the main intention is their reuse in a safe and hygienic way, in which P could be further utilised. Therefore, the Norwegian systems can represent a complex technology combining a sustainable technique of domestic wastewater treatment and a bio-economical option for filter media reuse. This is a quite challenging goal for reclamation and recycling of P from wastewater. Thus, there are some scenarios of reusing the P-rich filter media as a complementary P fertiliser, a soil amendment or a conditioner, provided the quality is acceptable for utilisation in agriculture. Alternatively, the filter media could be reused in some engineering projects, e.g. green roof technology, road screening or construction of embankments, if the quality allows application in the environment. The core aspect of the reuse options is the appropriate quality of the filter media. As for the theoretical assumption, it should not be risky to reuse the P-rich media in agriculture. In practice, however, the media must be proven safe for human and environmental health prior to introducing into the environment.
Sammendrag
Mineable rock phosphate is a limited resource. Replacing mineral phosphorus (P) fertiliser with P-rich secondary resources is one way to manage P more efficiently. The Norwegian potential to replace mineral P fertiliser with total P in secondary resources was analysed here using substance flow analysis. The results obtained were integrated with data on P plant-availability in secondary resources and showed that, theoretically, plant-available P in manure alone could fulfil the Norwegian demand for P fertiliser. However, P in manure is inefficiently utilised due to the geographical segregation of animal husbandry and arable farming, which contributes to considerable P over-application to agricultural soil. In Norway, agriculture and aquaculture drive P consumption and losses at similar levels, and the amount of P in fish excrement and feed losses from off-shore aquaculture pens (fish sludge) is of the same order of magnitude as P in manure. Fish sludge is currently not collected or utilised, but lost to coastal marine waters. All other secondary resources represent relatively small amounts of P, but may still be important regionally. Political incentives are thus needed in current regulations to efficiently close P cycles. To achieve P recycling in practice, it is essential to know the relative agronomic efficiency (RAE) of secondary P products compared with mineral fertiliser. Nine secondary P products were analysed here: Two biomass ashes, meat bone meal, fish sludge, catering waste, two food waste-based digestate products, dairy manure and chicken manure. The RAE of these secondary products studied in a bioassay with ryegrass (Lolium multiflorum) varied widely, partly depending on soil pH. Fertilisation effects were mainly attributable to the solubility of the inorganic P species contained in the secondary products. Combining sequential chemical fractionation and non-destructive speciation methods revealed that P was mainly present as calcium phosphates of differing solubility. Further analysis showed that microbial and physicochemical soil processes induced by the secondary P products studied were of little overall importance for total P uptake in barley (Hordeum vulgare). Based on the results obtained, two chemical extraction methods for predicting the RAE of secondary products with unknown fertilisation effects are suggested: At soil pH <6.5, RAE should be predicted by the fraction of inorganic P in the secondary product (% of total P) that is extractable in H2O. At soil pH >6.5, RAE should be predicted by the fraction of inorganic P (% of total P) that is extractable in 0.5 M NaHCO3 (Olsen P).
Sammendrag
Large areas of cultivated grasslands are annually abandoned and no longer used for production in Norway. Such areas will over time be encroached by shrubs and trees. Knowing that access to spring and autumn pastures is a limiting factor for sheep farmers, we tested the effect of grazing abandoned grassland on sheep production. We also assessed herbage production by looking at plant community development, pasture production, herbage quality and pasture utilization by sheep and heifers. The experiment was run for two consecutive years; 2014 and 2015. The sheep production was assessed by studying one sheep flock with 83(88) ewes(lambs) in 2014 and 77(106) ewes(lambs) in 2015, which was assigned each year with respect to age of ewe and number of lambs born to three treatments: 1) control; common farm procedure with short spring grazing period before summer grazing on range pasture, 2) spring extended; 4 weeks extended spring grazing period on abandoned cultivated grassland before summer grazing on range pasture, 3) whole season grazing on abandoned grassland. Assessment of herbage production was done by sheep grazing the whole area for one month in spring and autumn. During the summer, the area was assigned to three replicated treatments: a) control with no management, b) grazing heifers and c) grazing sheep with offspring. The stocking rate was 1.8 LU/ha, in both b and c, for a duration of one month. Pasture production and herbage intake was estimated using grazing exclosure cages. Weight gain from birth to autumn as well as slaughter weight were significantly (P<0.05) higher in lambs assigned to treatment 2 with four weeks extended spring grazing period (259 g/day and 15.7 kg) compared to treatment 1 (238 g/day and 14.3 kg) and treatment 3 (216 g/day and 13.2 kg). Herbage consumed during the summer period was on average 211 g DM/m2 and the pasture utilization was 55%. The annual consumption and utilization was 336 g DM/m2 and 62% in the grazed treatments and 28 g DM/m2 and 15% in the control, respectively. Total annual pasture production was on average 72% higher in the grazed treatments compared to the control. There was no difference between the grazed treatments on annual herbage production, herbage intake or pasture utilization. The use of abandoned cultivated grassland for extended spring grazing improved weight gain and slaughter weight of lambs. Further, grazing stimulated herbage production
Forfattere
Anders Nielsen Merethe Aasmo Finne Maria Gulbrandsen Asmyhr Jan Ove Gjershaug Lawrence R. Kirkendall Vigdis Vandvik Gaute Velle Hugo de Boer Kjetil Hindar Nina Elisabeth Nagy Eli Knispel Rueness Odd Terje Sandlund Kjersti Sjøtun Hans K. StenøienSammendrag
Det er ikke registrert sammendrag