Theme 2: Forage--Oral Sessions

Description

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'E), 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.

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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'E), 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.