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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.

2023

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Sammendrag

Climate change in combination with land use alterations may lead to significant changes in soil erosion and sediment fluxes in streams. Optical turbidity sensors can monitor with high frequency and can be used as a proxy for suspended sediment concentration (SSC) provided there is an acceptable calibration curve for turbidity measured by sensors and SSC from water samples. This study used such calibration data from 31 streams in 11 different research projects or monitoring programmes in six Northern European countries. The aim was to find patterns in the turbidity-SSC correlations based on stream characteristics such as mean and maximum turbidity and SSC, catchment area, land use, hydrology, soil type, topography, and the number and representativeness of the data that are used for the calibration. There were large variations, but the best correlations between turbidity and SSC were found in streams with a mean and maximum SSC of >30–200 mg/l, and a mean and maximum turbidity above 60–200 NTU/FNU, respectively. Streams draining agricultural areas with fine-grained soils had better correlations than forested streams draining more coarse-grained soils. However, the study also revealed considerable differences in methodological approaches, including analytical methods to determine SSC, water sampling strategies, quality control procedures, and the use of sensors based on different measuring principles. Relatively few national monitoring programmes in the six countries involved in the study included optical turbidity sensors, which may partly explain this lack of methodological harmonisation. Given the risk of future changes in soil erosion and sediment fluxes, increased harmonisation is highly recommended, so that turbidity data from optical sensors can be better evaluated and intercalibrated across streams in comparable geographical regions.

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Sammendrag

Introduction: Conventional rice production techniques are less economical and more vulnerable to sustainable utilization of farm resources as well as significantly contributed GHGs to atmosphere. Methods: In order to assess the best rice production system for coastal areas, six rice production techniques were evaluated, including SRI-AWD (system of rice intensification with alternate wetting and drying (AWD)), DSR-CF (direct seeded rice with continuous flooding (CF)), DSR-AWD (direct seeded rice with AWD), TPR-CF (transplanted rice with CF), TPR-AWD (transplanted rice with AWD), and FPR-CF (farmer practice with CF). The performance of these technologies was assessed using indicators such as rice productivity, energy balance, GWP (global warming potential), soil health indicators, and profitability. Finally, using these indicators, a climate smartness index (CSI) was calculated. Results and discussion: Rice grown with SRI-AWD method had 54.8 % higher CSI over FPR-CF, and also give 24.5 to 28.3% higher CSI for DSR and TPR as well. There evaluations based on the climate smartness index can provide cleaner and more sustainable rice production and can be used as guiding principle for policy makers.

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Sammendrag

This report (D2.5) presents a qualitative and quantitative assessment for nutrients and energy regarding circular fertilizers and biogas production from waste resources. A transformation towards sustainable food production for the growing urban population requires improved circular urban nutrient management. Urban agriculture (UA), like any agricultural system, needs input of resources in terms of growth media, nutrients, and water. Resources that are often imported into cities, especially in the form of food, generate urban waste. Current environmental, social, and economic challenges of cities are seen as opportunities that can be derived locally, as this project demonstrates. The domestic organic waste and wastewater contains energy (thermal and chemical) and nutrients that could play a role in the urban circular economy if proper technology and management are applied. Urban organic waste contains relevant nutrients including nitrogen (N) and phosphorus (P), as well as organic matter, yet less than 5% of the global urban resources are presently recycled. One recycling approach is the composting of urban organic wastes, recovery of nutrients from source-separated urine and anaerobic digestate of blackwater, and biogas and biochar produced as sources of energy. At the NMBU showcase different technologies were assessed to demonstrate how to achieve sustainable and circular urban farming systems. Qualitative and quantitative information about organic fertilizers, making budgets for the nutrient contents of waste resources and organic fertilizer and comparing this with the nutrient needs of the plants in the relevant cultivation area, as shown in this report, can provide better fertilization and less loss to the environment. We need more information on the fertilizer value of waste resources and how these nutrients can be best utilised. Due to the increased interest, more information about health and environmental challenges by implementing circular UA should be obtained

Sammendrag

Constructed wetlands (CWs) are a widely recognised measure for reducing pollution loads and improving the quality of surface waters. The removal efficiency of CWs varies considerably depending on system type and design as well as residence time, hydraulic load, particles and nutrient loading rates. Therefore, there is a need to closely monitor the efficiency of existing measures, look at their efficiency in practice and be able to foresee potential implications for their efficiency in light of climate change and land management intensification. This study presents 18 years of data from a typical Norwegian small CW established in the Skuterud catchment. The main objective of this study was to look at the impact of hydraulic load, particles and nutrient loads (depending on climatic factors such as temperature and precipitation) on CW effectiveness. The results showed an average of 39 % and 22 % annual removal efficiency for sediment and phosphorus, respectively. It appears that good CW effectiveness coincides with a combination of high sediment or phosphorus loads to the CW and a stable runoff of low to moderate intensity. At the seasonal level, the highest sediment and phosphorus removal efficiency is observed in the summer seasons (47% for sediment and 29% for phosphorus), when the sediment and phosphorus loads and runoff are at their lowest, and the lowest in autumn (23% for sediment) and in winter (4% for phosphorus). The relationship between removal efficiency and loads to the CW is not that straightforward, as other seasonal differences, such as erosion patterns, vegetation development, also become important. The conclusion based on the results presented is that establishing CWs can be a good supplement to best management practice in erosion-prone catchments with sensitive recipients.

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Sammendrag

Vermicomposts and composts prepared from sewage sludge digestate and additives (spent mushroom compost, straw, biochar) after 43 days pre-composting followed by 90 days vermicomposting with Eisenia fetida or by compost maturing were investigated regarding the potentially toxic element (PTE) As, Co, Cr, Cu, Mo, Ni, Pb and Zn contents. The average increment in the total PTE concentration for the entire process was ten times higher (104 %) compared to the increment solely in the composting or vermicomposting (9.3 and 9.5 %, respectively) after pretreatment. Compared to the untreated digestate the As and Co concentrations in the final mixtures were 26 and 51 % higher, respectively while for the other PTEs 26 ± 9 % average decrease was observed. Total PTE content was the same in composts and vermicomposts. Average PTE bioavailability (water soluble/total concentration) was statistically the same in vermicomposts (2.5) and composts (2.7), but lower in mixtures with biochar (2.5) than without it (2.8).

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Sammendrag

Agroforestry practices improve soil health which in turn improves crop nutrient concentrations and quality. This study examined how the agroforestry tree Gliricidia sepium intercropped with soybean, groundnuts, or maize affects crop nutrient compositions. The study was conducted in five Zambian chiefdoms for three crop-growing seasons (2019–2022) on 13 farmer-led demonstration trial sites. Seven treatments were tested that included maize, soybean, and groundnut plots with and without Gliricidia interventions. Grain samples were analyzed for crop nutrient contents using standard laboratory methods. Results showed that the treatments significantly (P < 0.05) improved maize nutritional properties except for crude fiber, total carbohydrate, and metabolizable energy. G. sepium intercropping with maize and soybean decreased the antinutritional contents and displayed better functional qualities. All elemental mineral components (except potassium, calcium, and sodium) were higher in the Gliricidia + maize intercrop than in the control treatment. The Gliricidia+soybean intercrop had lower mean mineral concentrations than the control (soybean only) except for Mg, Cu, and Zn. The Giliricidia+groundnut intercrop significantly increased groundnut mineral components except for Nitrogen, Phosphorus, Potassium, and Iron. It can be concluded that G. sepium intercropped with maize, soybean, and groundnuts significantly improved the crops’ nutritional quality.