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.
2026
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No abstract has been registered
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Abstract Background and Aims Efficient phosphorus (P) and management is essential for sustainable arable systems. Cover crops (CCs) are promising, but their performance is uncertain in high-latitudes. This three-year study evaluated CCs’ effects on P dynamics in a P-rich soil undersown in barley in Mid-Norway (63.9°N)—one of the northernmost trials of its kind. Methods A randomized complete block design included three CC treatments: ryegrass (CC1), a ryegrass–clover mix (CC2), and a four species mix including grass, legumes and herbs (CC3), and controls without CC (with/without NPK fertilizer). Soil and plant analyses included total and available P, total N, potentially mineralizable N (PMN), pH, permanganate-oxidizable carbon, root biomass, plant P concentrations, and microbial abundance via qPCR. Statistical analysis was based on Linear Mixed Models (LMMs). Results Cover crops successfully established (average biomass: 1525 kg ha⁻ 1 ), accumulated ~ 7 kg P ha⁻ 1 , and did not reduce barley yields. LMMs showed significant effects of CC treatment on root biomass, total P, and bacteria. Pairwise comparisons also revealed that fungal abundances in CC1 and CC3 were significantly higher than in the unfertilized control. Pairwise regression revealed that soil total P was strongly predicted by root biomass (β = 1.37, P < 0.001). Available P was negatively controlled by microbial pools (Bacteria: β = -9.22, P < 0.001) and residue quality (C:P ratio: β = -0.36, P < 0.001). Conclusions CCs can be used at 63°N without yield penalty. The primary P mechanism is mass-driven sequestration (root biomass) into the stable total P pool. However, P availability is temporally constrained by residue quality and microbial competition. Graphical Abstract
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Cover crops enhance soil quality and organic matter stability, yet the mechanisms linking belowground inputs to persistent soil organic matter (SOM) remain unclear. This study examined the effects of diversified cover cropping in barley systems on root biomass, SOM fractions, soil structure, microbial activity, and yield in central Norway (63.9° N), three years post-implementation. Six treatments were tested: (1) Control (barley without NPK), (2) Biochar-Fertilizer (barley + NPK + 3 Mg ha⁻¹ biochar), (3) Monocrop (barley), (4) Ryegrass (barley + ryegrass), (5) Clover (barley + ryegrass + white/red clover), and (6) Chicory (barley + ryegrass + red clover + chicory + bird’s-foot trefoil). Ryegrass and Clover systems produced 28.65 g m-² more root biomass at 0–13 cm (p < 0.05) and, along with Monocrop, stored 2.2 Mg ha-¹ more mineral-associated organic matter (MAOM) carbon and 0.2 Mg ha-¹ more MAOM nitrogen at 0–20 cm than other treatments. The Chicory system improved soil structure and biology, with higher aggregate stability, lower bulk density, and greater microbial abundance. Barley yields remained consistent across treatments, suggesting that cover cropping and low biochar inputs do not reduce productivity. Strong correlations (p < 0.01) between root biomass and MAOM stocks highlight root development as a key driver of SOM stabilization via organo-mineral associations. These findings underscore the role of root-enhancing cover crops in promoting MAOM formation and long-term SOM persistence, offering valuable insights for sustainable soil management.
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No abstract has been registered
2025
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No abstract has been registered
Authors
Lillian ØygardenAbstract
Presentasjon ved lansering av FAO : International network on soil erosion INSER
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Foredrag på NJF Nordic Baltic Symposium
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Reducing diffuse nutrient losses to water bodies remains a major problem in the agricultural areas of the Nordic countries. The transition towards a bioeconomy and ongoing climate change raise questions on the future of water quality and freshwater ecosystems and what kind of adaptation strategies could be implemented to maintain both food and environmental safety. The objective of our study was to evaluate the effectiveness of Natural Soil Water Retention Measures (NSWRMs) under current and future climate conditions in retaining water, soil particles and nutrients within the landscape. The hydro-biochemical model SWAT+ was implemented in the Krakstad catchment in southern Norway using the novel approach developed within the EU H2020 project OPTAIN. This approach enables an improved spatial representation of NSWRMs in the landscape. Available discharge and water quality monitoring data were used as reference data for model calibration. The effectiveness of reduced tillage, grassed waterways, sedimentation ponds established in the forested areas and buffers on water retention and nutrient loads was evaluated. Our simulation results indicate that conservation tillage, which maintains stubble on the soil surface during winter, has the strongest impact on reducing soil and nutrient losses towards surface water bodies. Grassed waterways, established in existing erosion prone gullies, could also significantly contribute to water and nutrient retention within the landscape. The implemented NSWRMs did not appear to increase the soil moisture content in early spring even under future climate conditions, which is an important aspect for ensuring soil trafficability and the timing of sowing spring cereals
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Fresh water quality problems in Norway are largely caused by high phosphorus (P) inputs from the catchments. The need for measures in the agricultural landscape, such as constructed wetlands (CWs), are needed and the importance of the measures will most probably increase due to the consequences of climate changes. In agricultural areas in South-Eastern Norway, several hundred small vertical flow CWs were established in the streams during the last two decades, to reduce downstream losses of sediments (SS) and nutrients. The focus of the CWs has been on reducing losses of P and SS, due to the naturally P-rich clay soils of marine origin in lowland areas. Whereas our study included 11 CWs altogether, we here present the data from the CW with the most intensive monitoring, i.e., the Skuterud CW, around 20 years after it was constructed. The catchment’s total area was 450 ha with 61% agricultural land. The CW occupies 0.05% of the catchment area. The methods included analyses of waterflow-proportional water composite samples, water grab samples, sensor monitoring (turbidity), bed sediments, and biological quality elements (invertebrates and benthic algae). Analyses of three years of composite samples showed a retention of 47 % for SS, 41 % for total phosphorus (TP), 4.2 % for total nitrogen (TN), 0.8 % for ortho-phosphate, and a negative retention for nitrate (i.e., nitrate leaching). Monitoring by turbidity sensors (correlations to SS and TP; R2 = 0,7802) during a 5 - month period showed that retention during episodes of elevated water discharges was 26 % for SS and 11 % for TP. Grab sampling gave more confusing results. It was revealed by the sensor monitoring that to assess the retention in CWs by grab sampling at the in- and outlet can be misleading, even if the sampling is done at the same time. The reason is the rapid variation in concentrations. Bed sediments have been removed from the CW several times since it was established, and in total approx. 1140 tons of SS and approx. 1090 kg of particle bound P. However, it is difficult to assess the total amount of retention, as we did not know the extent of leaching of nutrients from the bed sediments over the years. The analysis of invertebrates and benthic algae revealed that the ecological condition was better at the inlet and worse at the outlet (similar for five CWs). The reason is probably that the oxygen levels and substrate conditions are better at the inlet, where the running creek enters, whereas the outlet would have still-standing waters with lower oxygen contents and a clayey substrate. Moreover, this can be due to the method used, as the outlet area had fewer stones where the benthic algae could grow. Hence, it would be better to sample biology a bit more downstream, but that is often not practical, as the CWs often have their outlet into another stream or directly into a drainage system. In summary therefore, our recommendation is to use composite sampling and/or sensor monitoring (combined with grab sampling for correlation purposes), to assess the retention capacity of a CW. However, for cost-effective assessment of the effect of sediments and particle bound nutrients, bed sediments are recommended.
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Fertilizers and pesticides contribute to the pollution of water resources. The areas along streams are affected by climate change as stream bank failures often occur following floods or during prolonged rainfalls. In addition to BMP (best management practices) on the fields, grassed cover buffer zones are one of the most common measures for improving water quality in Norway’s agricultural catchments. Increased focus on buffer zones is important in a future climate perspective, both for food production, natural diversity and water quality. The efficiency of vegetation cover is composed of a variety of factors; therefore, effectives of these measures are to a large degree site specific. Recently, increased attention is given to the buffer zones efficiency, depending on both conditions in the catchments and the design of the buffer zones itself. However, most research is focusing in investigating the effect of buffer zones looking mostly at the surface runoff. According to our knowledge there is no previous research investigating the efficiency of the buffer zones with flower mixture. We focus on these types of vegetation as they also stimulate increased biodiversity. Moreover, previous investigations show that more than 50% of simulated runoff infiltrates into buffer zones with grass and bushes, while within buffer zones with trees there all the water infiltrates into the soil. Herein we show the results of 3 years monitoring surface runoff from buffer zones with different types of plant cover (grass and flower mixture). The idea was to monitor real live surface runoff from the field with autumn tillage (as “worst case scenario”). The results show significant differences, especially in the runoff quality. The visual differences are confirmed by water quality analysis.