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Mixtures and pure stands of perennial ryegrass, tall fescue, white clover and red clover were grown in a three‐cut and a five‐cut system in southern Norway, at a low fertilization rate (100 kg N ha−1 year−1). The nutritional quality (annual weighted averages) of the dried forage from the two‐first harvesting years was analysed. There was no significant effect of species diversity on crude protein (CP) concentration. In the three‐cut system, we found a significant species diversity effect leading to 10% higher concentrations of acid detergent fibre (ADF), 20–22% lower concentrations of water‐soluble carbohydrate (WSC) and 4% lower net energy for lactation (NEL) concentrations in mixtures compared with pure stands (averaged across the two‐first years). In the five‐cut system, similar effects were seen in the first year only. This diversity effect was associated with a reduction in WSC and NEL concentrations and an increase in ADF, NDF and CP concentrations in the grass species, and not in red clover, when grown in mixtures. This is thought to be a combined result of better N availability and more shading in the mixtures. Species diversity reduced the intra‐annual variability in nutritional quality in both cutting systems.

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Surface liming as a means for controlling the soil reaction in established leys was investigated in a series of 4-year field trials. Application of 625, 1250, 2500 or 5000 kg CaO equivalents/ha in spring of the first year caused an immediate rise in pH in the top 0–25 mm of the soil. The rate and range of the response below 25 mm was related to the precipitation at the experimental sites. Lime-induced changes in pH were not dependent on the initial level of soil reaction, whereas the positive response in grass production was greater and more immediate at sites where pH was below 5·3 rather than above. The increases in yields of macro elements were, in most instances, relatively lower than the increases in dry matter (DM) yields. Important exceptions here were the yields of Ca in all cuts and P in the second cuts, and the yields of Mg when dolomite rather than limestone was applied. The concentration of Ca in the herbage was positively affected by liming according to ruminant needs. The same holds for the concentration of Mg when granulated or coarse dolomite was applied. Liming lowered herbage uptake of Mn, Co and Zn, whereas Mo uptake was increased. There appeared to be no consistent relationship between liming and the plant uptake of Fe and Cu. Dependent on the initial conditions, liming might both improve and worsen the trace element status of harvested herbage with respect to the demands of ruminant animals. It is concluded that frequent surface liming at low rates might be an appropriate strategy for adjusting the soil pH in semi-permanent and permanent pastures.