On the Control of Winter Damage in Orchardgrass Sward in Nemuro-Kushiro District : I. Effects of yearlong management on winter damage and productivity in orchardgrass sward

Abstract

The winter damage has been observed often in orchardgrass sward because of adverse climatic condition during winter in Nemuro-Kushiro district. To clarify the control method of winter damage in orchardgrass sward, as managements in spring and summer, cutting frequency (3 times and 5-6 times), level of N, K_2O application (each 15 and 30kg/10a), and as managements in autumn, fertilizer application in late August (5kg N and 10kg K_2O/10a applied and not applied), four dates of final cutting (not cut, mid September, early October, early November), and control of Sclerotinia snow blight disease (controlled and not controlled) were assigned to 32 plots (experiment based on 2^4×4 orthogonal array). This work was carried out at Konsen Agricultural Experiment Station (volcanic ash soil) from 1973 to 1977. The results obtained are summarized as follows: 1) Orchardgrass sward partly decayed by winter damage was able to recover the density and to increase the productivity, through managements with less cutting frequency and high level fertilizer application in spring and summer. The production increased in the following spring, with the increased production by high level fertilizer application during summer. 2) Of the managements in autumn, the fertilizer application in late August increased autumnal productivity, stubble weight and number of newly emerged tillers in late autumn, and consequently increased the production in following spring. Winter damage increased in case of cutting in mid September and early October. On the other hand, the production in autumn was the highest and the production in following spring was high next to not cut in autumn, in case of cutting in early November. 3) It was important to insure regrowth tiller numbers in early spring more than about 1, 300 tillers per m^2, otherwise the productivity decreased. The managements paired high level fertilizer application in spring and summer with the fertilizer application in late August did not increase winter damage so much annually. 4) As mentioned above, decreasing of winter damage and maintenance of high productivity in orchardgrass sward was possible by conbinating managements as follow ; less cutting frequency and high level fertilizer application in spring and summer, the fertilizer application (5kg N and 10Kg K_2O/10a) in late August and final cutting in early November.