Abstract
Under a regime of frequent cuttings, seasonal productivity of temperate grasses was followed for five years and the relationship between the productivity and weather was investigated. Six replicated blocks of perennial ryegrass (Lolium perenne), orchardgrass (Dactylis glomerata), tall fescue (Festuca arundinacea), Kentucky bluegrass (Poa pratensis), red top (Agrostis alba), and red fescue (Festuca rubra) were sown in September 1984. Each species was divided into three groups, the first group was cut in the next early spring, and the second group cut a week after, and the third group cut two weeks after the first cut. All of the groups were cut at three-week intervals thereafter. Each species in the three groups was cut every week during the growing seasons (30 times a year) from 1985 to 1989, and top-dressed with 20 kg N+10 kg P_2O_5+17.5 kg K_2O/ha per cutting. The changes in seasonal productivity of temperate grasses had three peaks and two bottoms in the average values over five years. The peaks were around the middle of May, July and September, and the bottoms were around the middle of June and August, respectively. The first peak was high and the third peak was low or obscure every year, but the height of the second peak was greatly affected by the precipitation during the season in each year. The depth of the two bottoms was greatly affected by dry weather. Perennial ryegrass and Kentucky bluegrass were less resistant to drought. Total production over five years was high in orchardgrass and perennial ryegrass, and the productivity during autumn was high in perennial ryegrass. It seems that perennial ryegrass might be the most valuable species for frequent grazing in this area, though it needs careful management to maintain high productivity and requires combined use with some drought resistant species.
