Persistence and Yield of 10 Grasses in Response to Clipping Frequency and Applied Nitrogen in the Allegheny Highlands1

This research was undertaken to assess the influence of harvest schedules and fertilization on the persistence and productivity of four warm‐ and six cool‐season grass species under minimal temperature and moisture stresses. The grasses were clipped three, five, or eight times during each of 2 years. The first clipping each year was taken on April 26, May 7, or June 10 and aftermath clippings were taken at 21‐, 35‐, or 55‐day intervals, respectively. Ammonium nitrate was applied in three equal applications during each growing season. A total equivalent of 168 or 336 kg/ha was applied to each plot. Persistence of Kentucky bluegrass (Poa pratensisL.), tall fescue (Festuca arundinaceaSchreb.), orchardgrass (Dactylis glomerataL.), and Timothy (Phleum pratenseL.) improved as clipping frequency was increased from three to eight cuts per year, especially at the high rate of N. Reed canarygrass (Phalaris arundinaceaL.) and smooth bromegrass (Bromus inermisLeyss.) stands were better if clipping was less frequent. Stands of bermudagrass [Cynodon dactylon(L.) Pers.], indiangrass [Sorghastrum nutans(L.) Nash], big bluestem (Andropogon gerardiVitman) and switch‐grass (Panicum virgatumL.) had deteriorated badly after 2 years, regardless of treatment. Orchardgrass was the most productive species overall and was least affected by the clipping and fertilizer treatments. Dry matter yields of grasses in the second harvest year were differentially influenced by clipping and nitrogen fertilizer (3‐factor interaction = P < .005). At the high rate of N, orchardgrass, reed canarygrass, and smooth bromegrass yields were highest with three clippings, tall fescue and timothy yields were highest with five clippings, and Kentucky bluegrass yields were highest with eight clippings. At the low rate of N all species, except Kentucky bluegrass and timothy, produced highest yields with three clippings. Timothy yields were highest with five clippings, and clipping frequency had little effect on bluegrass yields. Yields were reduced most by infrequent clipping at the high rate of N (Kentucky bluegrass, tall fescue, timothy) and by frequent clipping at the low rate of N (all species except bluegrass). Persistence and yield distribution responses to clipping and nitrogen fertilizer were different from those commonly reported for lower elevations and were attributed to less temperature and moisture stress. Management requirements for warm‐season grasses differ from those for cool‐season grasses and need to be studied in more detail.