The seasonal productivity, quality and response to nitrogen of four indigenous grasses compared with Lolium perenne

To rectify the lack of comparative data on the productivity of some commonly occurring indigenous grasses, seasonal growth curves were obtained during the first year of a 3‐year study by harvesting monoculture plots of Holcus lanatus, Agrostis stolonifera, Festuca rubra, Poa trivialis and Lolium perenne (cv. S23) at monthly intervals in a staggered sequence. Under conditions of high soil fertility (40 kg ha⁻¹ N per defoliation and frequent irrigation) the daily production of dry matter by P. trivialis followed the familiar two‐peaked pattern of L. perenne, albeit at a lower level after flowering. By comparison, F. rubra and A. stolonifera grew more uniformly throughout the year; H. lanatus, like F. rubra, was noticeable for its high productivity after midsummer. With monthly cutting all four indigenous grasses had a higher mean nitrogen content compared with L. perenne; mean digestibilities were also comparable with the exception of F. rubra. During the second year, when inputs of nitrogen and moisture were lower, primary spring growth was most rapid with H, lanatus and F. rubra but the high digestibility of L. perenne meant that harvesting could be delayed to obtain the most forage of a given D‐value. Regrowth, measured from cuts taken in early August and September, was greatest with A. stolonifera and F. rubra respectively. Dry‐matter responses to a total of 60 and 180 kg ha⁻¹ N, applied in three applications on a split‐plot basis, were recorded during the last year. Apart from the early nitrogen application, the indigenous grasses responded well, except for A. stolonifera, especially after flowering. Though the response of L. perenne was consistently high throughout the summer, at least 20 kg DM per kg N, it yielded least of all the grasses at the low nitrogen level. The agricultural significance of these results are discussed. It is concluded that whereas L. perenne performs well at high levels of nitrogen and moisture, the other species do better than L. perenne, especially during mid‐season, when these factors are limiting.