Opportunities and limitations in use of clovers as N-source in organic farming systems in Norway

From an economic as well as ecological point of view, transfer of clover N to the subsequent growing season should be maximised and the risk of environmental pollution minimised. It is very important in organic farming. Detailed studies on white clover lifespan indicated that the foliage is a main source of readily plant-available N as the leaves are short lived. However, the leaf N is largely lost from the plant foliage during the cold season. The risk of loss may probably be reduced by using winter-hardy cultivars that tend to reallocate resources to stolons and roots which are more persistent than leaves

Maintain Forage Yields in Long- and Short-Term Grasslands in Norway

Various reasons have been invoked explaining the low renovation activity in Norwegian grassland farming: swards are often located in marginal areas, ploughing and reseeding gives low or no yield in the renovation year, and it may be unprofitable to establish a new sward. The establishment of new leys can also prove difficult in seasons with unfavourable weather conditions. Thus, farmers prefer long-term or permanent swards as opposed to ploughed and reseeded swards. The hypotheses of this study is that under equal management conditions, permanent and temporary swards (leys) that are reseeded frequently are equally productive. We present results from an experimental field trial at Særheim (58o47’N 5o41\u27E), SW Norway, which was established 1968. The experiment includes grass plots maintained without ploughing for more than 50 years, and frequently (every 3 to 6 years) ploughed treatments. Three different fertiliser strategies are included: mineral fertiliser (210 N kg ha-1) and cattle slurry in combination with mineral fertiliser (210 kg and 340 N kg ha-1). In 2016, the frequently ploughed treatments and half of the 25-years-old sward was renewed by ploughing and reseeding with grass-clover seed mixtures. The second half of the 25-years-old sward was sod-seeded using perennial ryegrass (Lollium perenne) only in 2017 and grass-clover mixtures in 2019. Herbage yields and forage quality was determined after each of the three annual cuts. In the first year after reseeding, 2017, the leys had significantly higher forage yield than the 50- and 25-year-old permanent grasslands regardless fertilisation strategy. This difference between leys and long-term grasslands was evened out in the second production year. In 2019, the permanent grassland yielded significantly more than in the leys except in the plots, which received 210 kg N ha-1 in combined form. There was no difference in herbage yield between swards that had been renovated by sod-seeding or by ploughing and reseeding

Trans European decomposition index study in arable soils with different crop species diversity using 13C-labelled litter

Póster presentado en la Sessión 8 en el Joint European Stable Isotope Users group Meeting JESIUM 2022 Kuopio, Finland Online 10–14 October 2022.Mixed species systems are currently increasing in area in Europe providing opportunities for sustainable intensification of agriculture. The agroforestry systems cover about 9% of the utilized agricultural area and integrated crop livestock systems occupy a major place in the European agricultural area including perennial forage grasses and grasslands sown with varying degrees of duration. Intercropping and other mixed cash crop systems are currently less developed in the EU. The EU EJP-SOIL funded MIXROOT-C project (2021-2024) is gaining a management-oriented understanding of the effect of mixed-species root systems on carbon flow and organic matter accumulation in European agricultural soils.N