Forage production by two Lotus species as influenced by companion grass species

A small-plot experiment was carried out with grass-lotus (Lotus spp.) swards on a lowland (185 m) clay-soil site in S-W England. Two species of lotus (Lotus corniculatus cv. Leo and L. pedunculatus, syn. L. uliginosus, cv. Maku) were each sown at 10 kg seed ha(-1) with four grass species each at two grass-seed rates: Festuca pratensis at 6 or 3 kg ha(-1) and Phleum pratense, Agrostis capillaris and Poa pratensis at 4 or 2 kg ha(-1). Assessments were made over three harvest years (1992-94), during which no fertilizers were applied. Mean total herbage dry matter (DM) harvested from cv. Leo swards was 9.0 t ha(-1) in year 1, 8.9 t ha(-1) in year 2 and 4.0 t ha(-1) in year 3, and from cv. Maku swards 6.6 t ha(-1) in year 1, 8.9 t ha(-1) in year 2 and 3.9 t ha(-1) in year 3. Highest three-year mean total yields were with F. pratensis as the companion grass (7.0 t ha(-1) year(-1)), followed by Phleum pratense (7.0 t ha(-1)), A. capillaris (6.9 t ha(-1)) and Poa pratensis (6.2 t ha(-1)). The lower grass-seed rate resulted in a greater proportion of lotus in the total harvested DM in year 1. The higher grass-seed rate resulted in higher yields from F. pratensis swards in year 1, but there were no significant effects for other species or in subsequent years. Lotus as a proportion of harvested DM declined from about 70% in year 1 to about 20% in year 3. The mean DM yield of lotus herbage in years 1, 2 and 3, respectively, was 5.5, 2.8 and 0.8 t ha(-1) from cv. Leo swards, and 4.0, 3.3 and 0.8 t ha(-1) from cv. Maku swards. Lotus herbage was of higher digestibility from cv. Leo [digestible organic matter (DOM) of 661 g kg(-1) of lotus DM] compared with cv. Maku (551 g kg(-1) DM). Mean N content of lotus herbage was 35 g N kg(-1) DM. Digestibility of companion grass herbage was highest for Phleum pratense (557 g kg(-1) DM) and lowest for A. capillaris (493 g kg(-1) DM). It is concluded that lotus may be an alternative legume to white clover for low-input, low-fertility situations. However, further research is needed to evaluate its performance on different sites and under different management regimes, particularly grazing, and to overcome the apparent problems of its persistence.