Abstract
This investigation was carried out on 758 cutting swards in Nemuro district in order to clarify the factors affecting the yield of the swards. Among the results obtained from the investigation, it was especially studied in this paper to verify the difference of the yield of the swards and its causes between regosolic andosol and cumulic andsol. The latter soil was greater in cation exchange capacity, buffering capacity for acidification and nitrogen supplying power than the former soil. The results obtained were as follows ; 1) The decrease of yield with the years in the swards corresponded to the unfavourable change of botanical composition such as the decrease of timothy and the increase of Kentucky bluegrass and red top. 2) Since the above change of botanical composition in the swards on regosolic andosol occurred more rapidly than that on cumulic andosol, the decrease of the yield with the years in the swards on former soil was more remarkable than that on latter soil. Therefore, it appeared that the unfavourable change of botanical composition was influenced by the difference in chemical properties of the soils described above. 3) From the results, it was recognized that the main factor which caused the decrease of yield with the years in the swards was worse response to fertilization, because of the unfavourable change of botanical composition.
