Overseeding clovers and forbs in permanent grassland on peaty soils

There is a growing interest for multi-species swards because of their benefits of nitrogen fixation and increased biodiversity. A challenge for these multi-species grasslands is persistency of clovers and forbs, especially in nutrient-rich peat soils. Attempts to overseed multi-species swards have yielded mixed results, prompting an investigation into two overseeding machines and pre-seeding management strategies to introduce clovers and forbs into permanent grasslands. Given organic matter losses on peaty soils, reseeding is not preferred, necessitating methods with minimal soil disturbance for forb introduction. An experiment initiated in August 2019 on a permanent grass sward on peaty soil, utilized a tine harrow in short grass (<3 cm) and longer grass (10 cm), along with a strip-till cultivator in short grass, compared to complete resowing. Two years of measurements (2020 and 2021) revealed the strip-till cultivator had the highest clover and forb content (39%) of the overseeding methods, followed by the tine harrow in short grass (19%) and long grass (6%) whereas reseeding control resulted in 48% clovers and forbs. All four treatments resulted in similar total dry matter yields. In conclusion, strip-till showed the highest clover and forb content of the overseeding methods, while reseeding showed even higher contents.