Utilization of abandoned cultivated lands for grazing

Summary The area of abandoned cultivated lands is increasing in Chugoku district, Japan. Many native plants grow in the abandoned cultivated lands and one of these dominant plants is Japanese plume-grass (Miscanthus sinensis Andress.), which is good feed for cattle. Recently, many farmers use these abandoned cultivated lands as pastures for grazing Japanese Black cattle. But little information exists regarding the dry matter (DM) production and the feeding value of the native plants, including Japanese plume-grass, in this district. We examined the changes in DM production for four years and the feeding value of the native plants under the grazing condition. As well, the herbage production and the herbage quality of bahiagrass (Paspalum notatume Flugge) and centipedegrass (Eremochloa ophiuroides (Munor) Hack.) were studied in order to find ways to improve the low DM productivity of the native plants in abandoned cultivated lands. The DM production of Japanese plum-grass under the grazing condition decreased year by year in the abandoned cultivated land. The DM production of Japanese plum-grass in the second year of grazing was 1931 kg DM ha sup(-1) and in the fifth year only 275 kg DM ha sup(-1). With this decline in Japanese plume-grass, the total DM productionof the native plants in the abandoned cultivated land decreased. The total DM production of the native plants was 3324 kg DM ha sup(-1) in the second year, but 2412 kg DM ha sup(-1) in the fifth year. The averages of total digestible nutrients (TDN) content (g kg sup(-1) DM) of Japanese plum-grass and other native grasses in the growing season were 500 and 510, respectively. The averages of crude protein (CP) contents (g kg sup(-1) DM) of Japanese plum-grass and other native grasses in the growing season were 68 and 80, and phosphorus (P) contents (g kg sup(-1) DM) were 1.4 and 1.8, respectively. Centipedegrass and bahiagrass were sown at seed rates of 40 kg ha sup(-1) by sod-seeding in the abandoned cultivated land where the percentage of bare land area was 71. The DM production of centipedegrass and bahiagrass was 9024 kg DM ha sup(-1) yr sup(-1) and 8184 kg DM ha sup (-1) yr sup(-1), respectively. The averages of TDN content (g kg sup(-1) DM) of centipedegrass and bahiagrass in the growing season were 510 and 500, CP contents (g kg sup(-1) DM) were 125 and 109, and P contents (g kg sup(-1) DM) were 2.4 and 3.3, respectively. From these results, the grazing capacity of abandoned cultivated lands under a grazing condition decreased year by year, because the total DM production of native plants decreased. The DM production and the feeding value of centipedegrass and bahiagrass were higher than those of native plants in the abandoned cultivated land. It is necessary to combine abandoned cultivated lands and centipedegrass and/or bahiagrass pastures in order to ensure the maintenance of grazing capacity.