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The productivity of ten grasses was measured under six cuts per annum for 3 years and three cuts for a fourth harvest year in comparison with a perennial ryegrass (Lolium perenne) control. The grasses were Yorkshire fog (Holcus lanatus), two red fescues (Festuca rubra), creeping bent (Agrostis stolonifera), bent (Agrostis castellana), bent (Agrostis capillaris), smooth meadow‐grass (Poa pratensis), crested dogstail (Cynosurus cristatus), sweet vernal (Anthoxanthum odoratum) and timothy (Phleum bertolonii). Another grass sown, rough meadow‐grass (Poa trivialis), did not persist after the first harvest year. Annual N rates were 0, 120, 240, 360 and 480 kg ha−1. Classified by DM production, the grasses grouped into: high (perennial ryegrass, Yorkshire fog and red fescue), intermediate (creeping bent, bent (A. castellana), crested dogstail and smooth meadow‐grass) and low (bent (A. capillaris), sweet vernal and timothy. With frequent cutting, production ranking interacted with N rate: Yorkshire fog. red fescue and creeping bent were more productive than ryegrass at the 0 N and 120 N rates but not at higher N rates; crested dogstail and sweet vernal outperformed ryegrass at 0 N; ryegrass and smooth meadow‐grass performed relatively better at moderate to high N. DM production of ryegrass was matched or exceeded by some of the other grasses during different parts of the season particularly at low N rates. Notable features from the 3‐cut regime were the outstanding DM production of Yorkshire fog at all N rates and the poor production of bent (A. capillaris) and crested dogstail. High DM response to applied N in both cutting regimes was given by perennial ryegrass. smooth meadow‐grass, red fescue cv. Boreal, timothy, crested dogstail and Yorkshire fog. N concentrations were highest in less productive grasses such as the bents and lowest in highly productive ryegrass and Yorkshire fog. Ryegrass was superior in digestibility to the other grasses, but especially to the red fescues, bents and smooth meadow‐grass. The other grasses, especially Yorkshire fog and bent (A. capillaris) were superior to ryegrass in P, K and Mg concentrations, but not Ca. It is concluded that the annual and/or seasonal production of some of the secondary grasses at low to moderate N rates, e.g. the performance of Yorkshire fog and red fescue, warrant a reconsideration of their poor reputation, particularly within the context of increasing grassland extensification. Breeding to improve selected characteristics, such as digestibility in red fescue, seems justified. Assessment of the grazing and ensiling qualities of secondary grasses require further study.

Four varieties of white clover (small‐leaved cv. Aberystwyth S184. medium‐leaved cv. Grasslands Huia and large‐leaved cvs Linda and Olwen) were sown at 3 kg ha‐1 together with 10 kg ha‐1 perennial ryegrass cv. Talbot. Herbage productivity was measured for three harvest years, 1979‐81, over four annual rates of fertilizer N (0,120,240 and 360 kg ha‐1) and two closeness of cutting treatments (80 and 40 mm from ground level). A simulated grazing regime of six cuts per year at 3‐ to 6‐week intervals was used. Production of total herbage DM was increased by increasing N rate; mean annual DM production ranged from 783 1 ha‐1 with no N to 11701 ha‐1 at 360 kg ha‐1 N. Mean herbage response to N (kg DM per kg N applied) was 73,90 and 108 for the three successive N increments relative to no N. Mean white clover DM production was reduced from 4 14t ha‐1 with no N to 051 t ha‐1 at 360 kg ha‐1 N. The large‐leaved clover varieties were more productive than the small‐ or medium‐leaved varieties at all N rates. Close cutting increased total herbage and white clover by a mean annual 16% and 31%. respectively. White clover varieties did not interact with either N rate or closeness of cutting. It is concluded that repetitive N application over the growing season is incompatible with white clover persistence and production, even with large‐leaved clover varieties or with close cutting, two factors which improved clover performance in the experimental swards.

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The productivity of fourteen grasses was measured under a silage cutting regime of four harvests per year for 3 years (1984-86) with an annual fertilizer N rate of 360 kg ha"', applied at 120, 100, 80 and 60 kg ha"' for successive harvests. The grasses were: red fescue (Festuca rubra) cvs Reptans, Dawson and Ruby, perennial ryegrass {Lolium perenne) cvs Perma and Sprinter, Yorkshire Fog {Holcus lanalus) commercial types I and II, smooth meadow-grass {Poa pratensis) cvs Parade and Arena, creeping bentgrass {Agrostis stolonifera) ev. Penneross, crested dogstail {Cynosurus cristatus) cv. Southlands and rough meadow-grass (Poa trivialis) cvs Dasas, Omega 0tofte and Sabre.